Steve's RepRap Journal

Chain of Events

2008-12-06T11:32:00.002-05:00

Yesterday, one of the Y belts slipped again. This caused the carriage to skew slightly...
...which caused the Y flag to miss the opto...
...which caused the carriage to crash and snap the Y flag.

I readjusted the Y axis yet again and replaced the Y flag.

Shortly after that (and possibly related) the thermistor failed. The printer was plotting at the time but, when the thermistor is an open circuit, the extruder PIC stops responding to the host. This resulted in the extruder sitting in one spot, churning out molten filament.

I replaced the thermistor, slapped on some JB Weld and let it sit overnight. The new thermistor had different characteristics (100k vs 10k), so I had to update Rz and Beta. Everything else stays the same.

Currently putting everything back together.

(later)

Apparently, on putting it back together, I swapped the pins on the extruder motor. Caused a bit of confusion for a while but no damage.

Sphere

2008-11-30T15:24:00.007-05:00

I tried an experiment in support material. The idea was to use the same extruder for both support and build. The host software allows you to do this but it's a relatively recent change. It's not available in any of the official releases (I think, correct me if I'm wrong on that) but, if you build from the SourceForge source, you can do this.

The first thing I did was create a second extruder in the host settings. I copied all the Extruder0 settings and made them Extruder1, then set NumberOfExtruders=2. Extruder1's settings differ from Extruder0's like this:

ExtrusionInfillWidth(mm)=2.4 (instead of 0.8)
NumberOfShells(0..N)=0 (instead of 1)
ExtrusionSpeed(0..255)=175 (instead of 215)
MaterialType(name)=support (instead of ABS)

The intent here was to make a sparse and loosely-bonded mesh. The lower extrusion speed causes the ABS to be stretched into thin threads. The wider infill width creates an open weave pattern. The zero shells removes the outline around each layer. The end effect is a structure that looks a bit like a plastic pot scrubber.

To test, I used a 20mm sphere with a support object. I exported the two objects as sphere.stl and sphere-supt.stl. Now, to get the two objects to print together, you have to do this:
1. Load sphere.stl (when prompted, choose ABS)
2. Select the object (this will bond the object to the next one loaded)
3. Load sphere-supt.stl (when prompted, choose support)
4. Position and orient the (bonded) object in the build area

Note: The select-and-load thing to bond objects is a relatively new feature too.

The first image above shows the object as printed. The blobiness is mostly due to not having a proper nozzle cleaner yet. The second image shows the object after picking the support material off using my fingernail. The support material crumbled off fairly easily from the lower layers but was more difficult on the upper ones. The third shows the object after cleanup using a Dremel.

The upper layers of the support object are probably unnecessary and do more harm than good. The build can support itself once it's past a 45 degree overhang. I might try again with smaller support object.

Sure, it's a long way to go to make what's essentially a marble but it was an interesting experiment. I haven't tried anything with a purely-horizontal overhang yet. Not sure how that'll turn out.

Y Axis Cleanup

2008-11-30T14:47:00.003-05:00

I think I found the Y axis problem. It looks like the X motor mount was catching on impefections of the rod it rides on. Two points seem to be a problem:

1. The block that constrains the lower side had a sharp inside edge. This seems to have been due to the molding process. Mine are molded parts, not printed or laser-cut. I removed both of these blocks (one on either side of the motor) and ground down the edges.

2. The rod was also catching on the side of the hole it passes through. When properly calibrated, the rod shouldn't even touch the plastic. I could've sworn I had that right in the first place. Best guess is that the X axis shortened over time due to a) X belt tension and b) the fact that I didn't tighten the X axis rods enough. I loosened the X belt, adjusted the X axis length and tightened everything back up again.

After that, I cleaned and lubricated the Y axis rods and used the stepper exerciser to run it through its paces. Seems to be behaving now.

Y Axis Troubles

2008-11-29T21:18:00.003-05:00

Been having a lot of trouble with the Y axis. Seems to jam frequently, especially when traveling in the negative direction. What's worse is, since the Y axis is driven by two belts, if one belt slips and the other doesn't, the X axis skews, making things even worse.

A Host of Problems

2008-11-16T23:49:00.002-05:00

Decided that the 0.8.3 host wasn't versitile enough. Tried downloading the latest source. Messed around with Eclipse and SVN. Eventually got a compile. Ended up deleting the old properties file and letting the host build a new one. The properties had changed so much, they didn't really apply anymore. Played with the values until I got it more or less printing.

Ran into difficulty with orientation. Opened the minimug object and, as usual, rotated it on the X axis to get it upright (ctrl-X). Started the print and got what looks like a vertical slice through the center of the model (tapered square-ish U shape). The print seemed to be centered on the warmup segment as well.

Set RepRap_Machine to Simulator to save on filament. Still got the same behavior. A lot easier to see using the simulator. The simulation starts with a vertical slice through the middle and works its way across to one edge. After it finished, Hit Print again and it printed correctly. WTF! Restarted the app, loaded minimug again and got the sideways print. Second print came out right, though.

Restarted and loaded the file again. Played with the 3D window a bit to see if the model was really on the grid and not intersecting it. Hit Print and this time the first print came out right. Again, WTF!

Half an hour of fiddling later figured it out: The model prints incorrectly only when it's selected. As long as you deselect the model first, you're fine. Mentioned this to Adrian. Fixed now.

Set up the properties to avoid lifting the head between segments. Also zeroed any extruder delays. Turned on the foundation parameters (raft).

Tried printing a RepRap ring. Foundation printed OK. Partway through the first "real" layer, the head homes, sits there for a bit, then picks up where it left off. But the extruder motor stays off for the remainder of the layer.

Checked to make sure I had all the pause and wipe parameters off. Kept doing this periodically. Happened to look at the screen at the right time and noticed the heater warmup dialog pop up. Turns out the head was cooling off, which caused the warmup routine to kick in, which apparently caused the extruder motor to stop for the rest of the layer.

Reason the warmup routine kicked in is that, somewhere in the past few days, I messed up Extruder0_hm, causing it to have trouble maintaining its working temperature. Set the value correctly. Will try again tomorrow.

More Mods

2008-09-07T21:32:00.007-04:00

I've almost got the machine to the "set it and forget it" point. It's more like: set it, watch to make sure the first layer sticks properly and check once in a while to make sure it isn't completely messed up.

Here are some recent tweaks...

Floating bed, mounted on 3 springs and held down with bolts. Makes leveling a lot easier. Also takes some of the pain out of a head crash.

Z opto guide (the blob of polymorph). It's essentially an inverted V with the opto's gap at the apex. Keeps the Z opto flag from running into the opto posts.

Drilled a hole through the shaft couplers (both Y and Z) and inserted a pin.

Added a lubricator (oily rag) to the filament guide (bent paper clip).

Two-ply balsa raft (two sheets of balsa glued together cross-grain). Held down with carpet tape. I tried using antistatic foam but it works a little too well. It's extremely difficult to remove without ruining the foam.

Adjustments

2008-09-06T23:37:00.002-04:00

Filament wasn't feeding at a consistent rate. Eventually figured out that the drive coupling was slipping relative to its gear. Had to remove the gear assembly to tighten it (added a bit of superglue to keep it in place) and took the opportunity to add grease to the gear motor internals.

Also noticed an increasing about of drift on the X axis. Tracked that down to the X motor pulley working itself loose. That was a bit more difficult to fix. Didn't really want to disassemble the X motor bracket just to tighten the set screws. Managed to achieve the same result by rotating the pulley until the set screw lined up with the X axis, then slipping an allen wrench between the belts. Did this for both set screws.

Currently trying to print a "motor holder" onto an antistatic foam raft.

Bed Covers

2008-09-02T14:08:00.001-04:00

I've been experimenting with various raft materials. The MDF bed isn't suitable for a build. The melted plastic doesn't stick to it. What you need is something that sticks to the Here's a list of things I've tried:

Polymorph (ShapeLock)
- easy to use, sticks well, reusable
- heat from extruder softens it, allowing warping
- hard to get perfectly flat

Adhesive Paper (full-sheet labels)
- sticks to bed
- plastic doesn't stick

Adhesive Plastic (self-adhesive laminating sheets)
- sticks to bed
- plastic doesn't stick

Plastic Canvas
- doesn't work at all

Carpet Tape
- sticks to bed
- plastic sticks but not well enough to prevent warping

Balsa Wood (1/8" sheet)
- plastic sticks well provided first layer is low enough
- curls easily across grain, allowing warping

Balsa Wood (2 sheets glued together with orthogonal grains)
- plastic sticks well provided first layer is low enough
- minimal warping

I found it's critical to have a perfectly level bed. In order to get a good first layer, you need to get the nozzle extremely close. If you get too close, though, the nozzle will dig into the surface. This is especially bad if the head is moving in the negative Y direction. In that case, the surface catches the nozzle and drives it downward, resulting in either a gouged surface or a damaged head.

One thing I've been meaning to do is add a Z-bed like the one shown here. It's basically a secondary bed mounted on springs. This will allow easier adjustment and should also make head crashes less painful.

I also need to replace the Z opto flag with something a bit less flexible. There's a tendency for it to slip to the side a bit and miss the slot on the opto. Also, if I'm adding the Z-bed, it'll need to be longer anyway.

Best Laid Plans

2008-08-26T23:33:00.005-04:00

Tried printing the "motor-holder" model. From left to right: 1) Y belt slipped a bit, 2) Y belt slipped a lot, 3) actually printed reasonably well.

This a first attempt at "gear-bush-holder", which I modified (hopefully correctly) to print without support. About 1/3 of the way through, the Y motor coupler came loose.

Mod Squad

2008-08-25T22:28:00.005-04:00

Some modifications I've made...

Blobs of polymorph on the X and Y carriages to keep them from wobbling so much...

A bent paperclip to keep the filament out of the way...

A piece of plastic tubing clamped to a bookcase to feed the filament...

Growing a Part

2008-08-23T23:54:00.002-04:00

Tightened up the X and Y axes a bit to keep the head from wobbling. Started on a motor bracket...

After a few layers, the Y axis skewed and I had to stop the build. Two things seem to be happening here:

1. I've set the layer height too small. After a few layers, the nozzle is dragging through the work.
2. The Y belts are too loose, causing them to skip off their drive pulleys under load.

The net effect is that the build runs fine for a few layers, then slips in the Y direction.

Tightened the belts and adjusted ExtrusionHeight. Will try again in the morning.

Supply and Demand

2008-08-16T21:14:00.005-04:00

I tried printing off Vik's RepRap ring today...

...which the kids thought was really cool...

...so, to avoid sibling infighting, I had to make a second one. I imported the STL into Art of Illusion, converted it to a triangle mesh, scaled the mesh by 0.75 and exported the model as a new STL. This gave me a new ring at 3/4 size...

...for little hands...

The Ascent of Mug

2008-08-14T23:04:00.002-04:00

Some attempts at the minimug model.

Containment

2008-08-13T21:26:00.004-04:00

Found that my Y axis was slipping on one side. Tightened the Y belts, X belt and all of the pulleys. Realigned the Y axis. Adjusted the infill width from 1mm to .8mm.

Melted some ShapeLock and made a 3mm-thick raft, attached it to the print bed. Started a new build.

Got most of the way done and realized I was running out of filament. Did an "in-flight refueling" by patiently holding a new piece in place until the drive screw grabbed it.

Waited for it to finish printing (about 1 1/2 hours). Soaked in hot water and peeled off the raft.

Cleaned up the lumps and threads with a Dremel.

Here's the result. It may not be pretty but it holds water. Or, more to the point, it holds single malt. Cheers.

Zeroing In

2008-08-13T10:15:00.001-04:00

After months of trying to get the original extruder working, I finally gave up and got a new one. Someone (I won't mention who, to avoid them being inundated with requests) took pity on me and sent me a fully-assembled and tested extruder. This one has a number of refinements over the original:
- the drive screw is straight, no flexible shaft
- the motor is geared down to improve torque
- the nozzle is smaller, machined from brass stock instead of an acorn nut
- all wires are soldered to a 15-pin D-sub connector

Another thing I noticed is that the springs are much heavier on this extruder. I'm not sure how important this is to the operation of the extruder but I suspect it's responsible for at least some of the problems I had.

I haven't opened it up yet but I suspect the bearings are done better than I managed as well.

Once I wired in the new extruder (I had to get my hands on a female 15-pin D-sub), I tried a few extruder tests, calibrated the heater and measured the extrusion rate.

The extra gearing makes a huge difference. The motor isn't under as much strain and the flow is much smoother. I'm currently extruding ABS (from McMaster) at a leisurely 3mm/s. I could probably go faster but I don't want to strain the PTFE barrel.

I need to update the PIC firmware and host software at some point but I want to print a complete model first. Trying not to change too many variables at a time.

Last night, I managed to get an entire shot glass printed. My infill is a bit too loose, so it leaks. It also looks like the Y axis slipped a bit part way through the build.

It's close, though. I suppose I should pick up some scotch at the liquor store, just in case.

Glimmer of Hope

2008-07-22T12:00:00.000-04:00

I'm on my Nth rebuild of the extruder and I think I'm finally getting somewhere. Things I've learned:
- Lubricating the filament helps a lot. I've now got a piece of oil-soaked cotton strapped to the inlet of the extruder.
- The bolts holding together the two halves of the extruder body should move freely in the holes. If they're too tight, drill out the holes.
- Keep the drive speed down. I can push the extruder to 12mm/s but 8mm/s is more reliable.

I've currently got the extruder clamped to the frame to make testing easier. I've been timing the 250mm drop from the nozzle to the tabletop to determine extrusion speed.

Next step is to mount the extruder on the carriage and recalibrate the Z axis.

If all else fails, I can always order a new extruder from BitsFromBytes. The new design looks pretty good.

Small Drill Bits

2008-06-27T22:41:00.003-04:00

Found some small drill bits. The set includes 10 bit ranging from 80AWG (0.34mm) to 61AWG (1mm). It's available through Amazon for $10.

Update

2008-06-21T07:05:00.002-04:00

Trying to rebuild the extruder. Using a larger PTFE barrel (60mm x 25mm dia) and heater barrel (60mm long). This allows more overlap between the two barrels (25mm), reducing slippage. The extra length also reduces heat transfer to the plastic extruder body. The additional mass makes it harder to heat, though.

Currently trying to get the filament to push through consistently.

Rework

2008-04-04T08:08:00.002-04:00

Having a lot of trouble getting a reliable extrusion. I had two PTFE barrels, both of which are distorted too much to be useful. I had two extruder clamps (one quick-fit, one regular). Both have suffered heat damage.

See, here's the problem I'm running into. Plastic, when subjected to heat and pressure, tends to sag. This means that, under normal operation for extruding HDPE, the nozzle tends to edge downward. I've had a couple tests so far where everything started out fine but ended up with the nozzle grinding into the bed.

I'm beginning to think that the current extruder design just can't do HDPE reliably. It wasn't really designed to do it in the first place.

Current plan: Rebuild extruder using stronger components. I've got a 1" diameter piece of PTFE on order. I might end up making an extruder clamp out of MDF. I think I'm going to buy some CAPA to see if it's any easier to use.

Polymorph Substrate

2008-03-22T12:44:00.002-04:00

Blobs #2 and #3 both broke free of the base before the build completed. This prompted me to search for a substrate that would hold the build in place and be relatively easy to remove afterward. Tried a bunch of things, most of which don't work.

One thing I tried shows promise. I melted some polymorph (aka friendly plastic) and flattened it into a sheet roughly 1mm thick. I ran a layer on this, holding it down with my hands and trying not to burn my fingers on the extruder. It worked fairly well, considering the sheet was a bit uneven. A polymorph sheet has the additional advantage of being reusable. You can melt it in hot water and re-form it.

Now I just need to find a way to make flat sheets of polymorph.

Blob #1

2008-03-20T22:14:00.002-04:00

Ran into some problems with the extruder. It's very hard to keep it extruding at a consistent rate. Currently using compression springs tightened down pretty hard. That seems to keep things going.

Spent some time playing with the various settings. Documentation on what each setting does can be found here. Noticed that, with my version of the host software (0.8.3), setting Extruder0_OffsetZ to 0 caused occasional I/O errors. Setting it to 1 seemed fine, though.

The blob pictured above is supposed to be Minimug.stl and it's roughly the right size and shape. The key word here is "roughly". This run was done at the highest extruder speed I could manage, the heater running a bit hot and no fan attached. End result? It's a bit wibbly and it leaks. Definitely not toast-worthy.

Got some good information out of it, though:
A margarine container lid works well as a build raft. The plastic sticks to it nicely.
The parts that printed correctly are quite solid. Very good adhesion between layers.
The X, Y and Z scaling's pretty close. Might need a bit of tweaking but not much.

Next step will be to run it again at a slower speed.

If At First You Don't Succeed...

2008-03-15T08:15:00.002-04:00

...get out the hacksaw. The extruder broke again. This time it was the flexible shaft snapping. Decided to eliminate it entirely and have the motor drive the screw directly. Added a filament guide made from a bent paperclip to keep the filament away from the motor.

Shakedown

2008-03-11T20:42:00.003-04:00

Attached the extruder board. Left the extruder off and added a resistor to simulate the thermistor. Loaded the minimug model and ran a build to see if it could make it through without shaking apart. The Y motor coupling came loose but everything else seemed to work reasonably well. Drilled out a pit for the Y coupling grub screw. Should keep it from slipping.

The good news is that it finished the build without a) crashing the host software, b) coming apart or c) bursting into flames.

Cleanup

2008-03-11T08:35:00.003-04:00

Picked up some cable clamps to attach the PCBs to the frame. Used some zip ties to clean up the wiring.

Attached a pencil to the head bracket and used the line tool to draw 3-4-5 triangles (actually 60x80mm). The pencil was a bit wobbly but it was enough to verify that my XY frame is square.

Axis-Backwards

2008-03-10T08:00:00.003-04:00

Hooked up the electronics. Just the comms and 3 stepper drivers. Left the extruder board out of the loop for now. Don't seem to have any PCB mounts and the diagonals I would've mounted them on aren't installed, so I just left them hanging in a rat's nest arrangement while I did a systems check.

Fired up the host app and opened the stepper exerciser. First thing I noticed was that the Y axis kept moving in the same direction no matter where I moved the slider. Turned out to be a mechanical problem with the Y opto. It was reading "home" even when not blocked. Once I fixed that, I noticed that both the X and Y axes were running backwards. When I moved the slider in the positive direction, the stepper would move the head away from the corresponding opto. I reversed the order of the wires on both motor connectors and that seemed to fix it.

This is very odd because, at the time, the instructions indicated that the Y and Z motors should be wired one way and the X should be wired opposite. As it sits now, I've got the X and Z wired one way and the Y opposite. The instructions have since been edited and there's now only a single note indicating that the X stepper is the odd one out. There used to be a table showing the wiring of the Y and Z versus the X but it's no longer in the wiki. I managed to find an archived version of the table and I've edited it to the wiring arrangement I'm currently using:

Pin (X & Z axes)	Pin (Y axis)	Colour
1	4	Red
2	3	Black
3	2	Green
4	1	Yellow

Note: The above is the wiring for the Nanotec motors.

The good news is that the Z axis worked perfectly the first time. I had made three mods to it:
1. Used a metal motor coupler
2. Added a belt tension idler
3. Removed the backlash springs and screws

The end result is a Z axis that moves smoothly with very little strain on the motor. As far as I can tell, the weight of the bed is more than enough to prevent backlash.

After a bit of fiddling, I worked out that I'm getting roughly 10 steps per mm on X and Y and 300 steps per mm on Z. Total travel on X and Y is about 230 mm and Z is at least 90, depending on where the nozzle ends up.

Opto Flags

2008-03-09T17:12:00.003-04:00

Installed the optos and flags. Had a little trouble working out the Z flag. The instructions show this configuration:

...but I couldn't find the Z flag base. I had a few leftover bits but not that one. I opened up Art of Illusion and started looking at the models. Found "z flag adjuster housing", which looked like one of my leftover bits. So, I googled "z flag adjuster" and found this:

From there, I assembled something that looked like that from the parts I had on hand and bolted it to the bed. Looks about right.

Squaring Up

2008-03-08T20:35:00.003-05:00

Added the diagonal ties to the sides. I did only one per side, hence the extra tie brackets for the tension idler. I had to shim the 5/16" rod in order to get a tight fit.

Squared up the X, Y and Z. Didn't have a squaring jig, so I did a lot of tweak-and-measure. I haven't added the fan or extruder. Going to hold off on that until later.

XYZ

2008-03-08T17:09:00.004-05:00

Installed the Y axis assembly. The cobbled-together Y motor coupling fits, provided I put the drive pulley on backwards (collar away from motor).

Ran into a problem with the Z belt. It ended up a bit loose. Rather than take it apart and redo the whole thing, I built a tension idler out of spare parts (scrap studding, washers, nuts, diagonal tie brackets, compression spring, pulley). Seems to keep things from slipping.

Tension

2008-03-07T21:28:00.002-05:00

Installed the base diagonals. Pretty straightforward. The tie brackets from BitsFromBytes don't have embedded nuts but the intent is to tighten the nuts on the diagonals until the plastic distorts enough to grip the uprights. Seems to work just fine.

Spliced together a Z belt. Ended up sanding down the belts before gluing them together. Seems to hold better that way. Used a blob of polymorph to make a splicer.

Wrapped a zip tie around the Z motor to hold it steady.

Top Frame

2008-03-07T08:22:00.004-05:00

Added the top frame. Verified that all four sides were the same length. Slid it down onto the Z studding to square up the bed. Tightened the bed bolts.

Raised the top frame to its proper height and locked it off. Noticed that one of the Z studding assemblies was missing a nut and washer. In the middle. Bugger. Wound the studding up as high as possible, slipped it out of the corner block, removed half the nuts, washers, etc. Threaded the parts back on, double-checking the parts as I put them on. Wound the studding back into place.

Measured the height of the Z drive pulley above the corner block. Adjusted the other four pulleys to the same height. Tightened up the nuts on the four Z studding assemblies, adding grease where it seemed appropriate.

This image also shows the improvised motor coupling. Seems to work reasonably well. Have to see how it does under load.

Bed Time

2008-03-06T21:53:00.003-05:00

Cut, drilled and installed the bed. The bed is 400mm square and 12mm thick. That translates to about 15.75" square and 1/2" thick. I bought a 24x48x1/2" sheet of MDF and cut it down to size.

The holes are 5.4mm and 7mm. Meh, call it 7/32" and 1/2". While drilling the holes, I put a piece of scrap under the sheet and drilled through both. Makes for cleaner exit holes. Here's a pic of the exit holes in the bed (green) and the scrap (red).

Here's the bed installed with all 12 bolts (loosely) in place. There weren't any bed clamps in the parts kit, so I'm assuming they aren't needed.

Going Vertical

2008-03-04T23:13:00.004-05:00

Finished the 3 studding idlers and the studding drive. Attached them to the bottom frame. Mounting the motor's a real pain. I had to take it apart and redo it a couple times before I got it right. The cobbled-together motor coupling sees to work just fine.

Coupling

2008-03-03T20:02:00.004-05:00

I picked up some 5/16" threaded rod couplings (7/8" long) and some 6-32 grub screws at the hardware store. The inside diameter of the threads is just slightly larger than the motor shaft. I bored out one end with a 5/16" bit to a depth of about 1/4", then drilled and tapped two 6-32 holes along the length. The grub screw for the 5/16" bore is about 1/8" from the end. I made two of these: one for the Y motor; one for the Z.

The image here is a test fit using some scrap rod. I've put the Y drive pulley on backwards to give myself more room for the coupling. The motor shaft isn't quite as snug as I'd like but it should do.

The current plan is to use the McMaster pulleys and belts. I've bored all six pulleys to 5/16". One of the Y pulleys is slightly off center. I may need to replace it.

Springs

2008-03-03T18:31:00.002-05:00

Found some compression springs at the hardware store. They were over with the screen door accessories. There are two pair in the blister pack: 1/2"x1 1/2" and 7/16"x 2 1/8". I used the longer ones.

Parts Problems

2008-03-02T22:01:00.002-05:00

Started on the studding idlers. Looks like the Z idler pulley size has changed since I ordered my parts. Using the plastic ones from BitsFromBytes instead of the aluminum ones from McMaster. Those had the wrong bore (1/4") anyway.

Also looks like the springs I got from McMaster are the wrong size. They're 9/32" OD, which makes them smaller that the studding they're supposed to slip over. I can probably find some reasonable springs somewhere.

It also looks like the toothed belts and pulleys I got from McMaster are a different pitch than the RP'd pulleys. Not sure what I'm going to do about that.

XY Frames

2008-03-02T13:56:00.010-05:00

Assembled the two XY frames. Lessons learned:

It's easy to overtighten the grub screws and crack the plastic.
When assembling the top frame, you need to run the two upper rods through the X axis assembly.
The "Bearing insert 180 X" in the X axis assembly is the one with the oblong hole.
It's really hard to push an 8mm rod through a 5/16" hole.

Here are some pictures of the two frames stacked on top of each other. Note that all four corner blocks on the top frame have the face with 4 holes facing inward, along the line of the X axis. As far as I can tell, this will allow me to mount the Y bearing brackets correctly.

Drill Bits

2008-02-29T23:38:00.004-05:00

Spent the evening drilling out the corner blocks. Four vertical holes with a 5/16" bit (roughly 8mm). Five horizontal holes (one around back) to clean out the trapped nuts using a 5/32" bit (roughly 4mm), followed by an M5 screw to clean up the threads.

Bits and Pieces

2008-02-29T08:13:00.003-05:00

Ran into some problems with the corner blocks for the XY frames. Each of the blocks has 3 trapped nuts. I did the same thing as before: drill with undersized bit and self-tap with grub screw. It just now occurred to me that I could use an M5 screw to do this instead of a grub screw. I overtightened one of the grub screws and cracked a block. Superglued it back together. Fingers crossed. Need to drill out the vertical holes in the blocks. I'll have to dust off the drill press. Hoping a 5/16" bit will do.

Also noticed that the diagonal tie brackets don't have trapped nuts. Not sure how I'm going to attach those to the frame. I'll have to improvise.

X Axis

2008-02-26T21:05:00.005-05:00

Turns out Home Depot has 3' lengths of 5/16" rod. I picked up 3 to make up for the metric/imperial problem with the ones from McMaster (1 metre > 3 feet). Should be good enough for use in the XY frame.

Assembled the carriage and X motor bracket. Did the drill-and-self-tap thing with the grub screws again. The rods were difficult to push into the motor bracket. Required a "tap gently with hammer while cringing" approach. Used a store-bought pulley on the motor.

X Idler and Constraint Bracket

2008-02-25T22:27:00.003-05:00

Unpacked the plastic parts and started assembly. Y opto flag seems to have snapped during shipping. Easy enough to glue back together.

Noticed that Mcmaster-Carr sells 3-foot lengths of 8mm rod instead of 1-meter. Kinda screws up the cuts. Will need to order 3 more rods.

Assembled the X Idler and Constraint Bracket. Used a C-clamp to press the rod into place. The grub screws gave me a bit of trouble. Had to pre-drill with an undersized drill bit, then force them through using a hex bit in a screwdriver. Alternated driving it in, then backing off until the grub screw broke through.

Parts

2008-02-25T18:22:00.003-05:00

The plastic parts arrived today from BitsFromBytes. I'd been tracking in on the UPS site for the past few days, watching hop from town to town:

Bristol->Barking->Stansted->Philadelphia->West Columbia->Raleigh

This afternoon at about 1:00, the status changed to "Delivered". Unfortunately, I still had 4 hours of work until I could come home and check it out. Took 6 days door-to-door, by the way.

As you can see, I chose basic black. I also chose the regular finish, so I've probably got some drilling to do. Currently cleaning up and setting aside the electronics and extruder to make room for the hardware build.

Early Adopter

2008-01-29T19:19:00.000-05:00

I just ordered a molded parts kit from BitsFromBytes. That'll tack another $400 onto my costs, bringing the total up to about $1200. Now, that may seem like a lot for something that may or may not work and that you have to put together yourself. On the other hand, you could look at RepRap as the 3D printing equivalent of the Apple 1 or Altair. If you adjust for inflation, those kits would cost about $2000 today.

Thermistor Mounting

2008-01-20T19:30:00.000-05:00

I've been trying different methods of mounting thermistors. I tried JB Weld-ing one to a 3/8" washer but it dissipated too much heat. So, I resorted to the second most common engineering material (after duct tape): a bent paper clip. This seems to work quite well. It holds the thermistor in place without affecting the heater performance.

Thermist-O-Rama

2008-01-19T17:25:00.000-05:00

I spent the afternoon measuring thermistors. I got 5 100K thermistors from DigiKey. They were the 5% ones ($0.80 each). Here's the technique I used:
1. Wrap the thermistor with PTFE tape and attach to the tip of a cooking thermometer. The one I used is good up to 230C.
2. Attach wires to the thermistor, keeping them separate. If the wires cross, they might short out when the insulation heats up.
3. Attach a multimeter to the wires to read the resistance.
4. Let the whole thing sit for a while to bring it to room temperature. Note the temperature and resistance. Use this as T0 and R0.
5. Put the thermometer and thermistor into a toaster oven set to 225C.
6. Wait for it to heat up and note the temperature and resistance. Use this as T and R.
7. Plug the values into the calculator and get beta and Rz.

The betas came out around 3900 for all five, with Rz around 336000. I put a 0.22μF electrolytic cap in for C3. As far as I can tell, that'll give me 1 degree increments up to about 280C.

Models Undergoing Plastic Surgery

2008-01-13T10:49:00.000-05:00

I've been using Art of Illusion to alter some of the Darwin parts. My aim is to make as many of the parts single-head printable. That means eliminating any overhangs greater than 45 degrees. There are quite a few. I've put together a spreadsheet of the models used in the Darwin Cartesian robot and the extruder here. The files marked in red are ones I can't figure out how to fix. I have a zip file of the altered STL files here.

I've been inflicting these models on Vik, who's been attempting to print a Darwin set in PLA. He gave me some tips on how to export STL files from Art of Illusion:

Make sure the object doesn't have any children
Convert to triangle mesh (0.1 accuracy is OK)
Edit mesh
Simplify mesh
Save
Export

I used 0.1 on the "simplify mesh" step as well. The export process can be either ascii or binary; can't be compressed, though.

Keeping Busy

2008-01-11T23:06:00.000-05:00

Waiting for RRRF to get RP parts in stock. Meanwhile, I've been playing with Art of Illusion. Figured I might as well make myself useful, so I started cleaning up some of the Darwin RP part models to make them single-head reprapable.

Also looking at coming up with a thermistor configuration that has decent accuracy at high temperatures. I juggled some numbers and I think that a 1uF cap with a 1000K, 3890 beta thermistor might do the trick. Ordered 5 thermistors and a capacitor assortment from DigiKey so I can try some experiments. Also ordered another PIC, just in case.

Complications

2007-12-30T16:44:00.000-05:00

My goal for this weekend was to extrude enough HDPE to represent the volume needed to make the minimug object. The host app says it's 2955.9 mm³, which translates to 418mm of 3mm filament. So the idea was to mark a point on the filament where it's entering the extruder and another point 500mm up from that. If I could get the extruder to run continuously between those two points, it should eat (and therefore extrude) enough plastic to create the piece. Here's how that went:

Extruded a few cm. Cable/drivescrew connection broke. Tried soldering it. No luck. Cleaned it up. applied JB Weld, left it to cure for 15 hours. Baked for 2 hours at 200C according to nophead's suggestion.

Reassembled and started again. Extruded a few cm. PTFE barrel slipped out of clamp. Backed up the filament, put the barrel back in clamp, tightened it up again. Clamp broke. Drilled a couple holes through the extruder body and PTFE barrel, one on either side of the hole (i.e. cutting a chord through the barrel). Sank two drywall screws through the holes. There, that's not going to budge. Extruder is now starting to look like Frankenstruder's ugly brother. Broke yet another thermistor. Replaced thermistor.

Reassembled and tried again. Extruded a few cm. Despite having a hose clamp around it, heater barrel slipped out of PTFE barrel. Internal threads are stripped. Had a spare PTFE barrel. Replaced barrel and tightened hose clamp with power driver. Terminal on gear motor broke. Resoldered and used a zip tie as a strain relief.

Reassembled and ran without the nozzle to clean out the gunk. Took the opportunity to mod the nozzle according to Vik's suggestion. Screwed the nozzle back on, waited for it to heat up.

Extruded a few cm. Nothing fell apart!

Marked the filament for a 500mm segment. Set the extrude speed to 50 (about 1/5 full power). Extruded a full 500mm in 33 minutes. That's about 1.8 cubic mm / sec.

Measured the extruded output: 3170mm. That works out to a diameter of 1.2mm. Extrusion speed works out to 1.6mm/sec.

Cranked the extruder speed to maximum. Marked 50mm. Took 84 sec to extrude 320mm. That's 4.2 cubic mm / sec. Diameter consistent at 1.2mm. Extrusion speed works out to 3.8mm/sec.

If I've got all the numbers right, that'd work out to a 3-day extrusion time for a RepRap kit. Not too shabby. The volume rate is good but I'm using a large nozzle, so the linear rate is low. I might have to run some tests with a smaller nozzle.

Lessons learned:
- Baking JB Weld helps a lot.
- The clamp on the extruder body doesn't seem to be enough to hold things in place.
- When using a hose clamp, tighten the crap out of it, then retighten when it heats up.
- Always use strain reliefs on soldered connections.
- Grinding down the inside of the nozzle helps a lot.
- Clean out the heater barrel now and then.

Things Get Affected By Things

2007-12-27T11:20:00.000-05:00

The new extruder firmware was doing odd things. I was using the heat profiler and noticed that the temperature leveled off at about 77C. I looked at the heater LED and noticed that it was alternating between flickering and being off. About 6 seconds flickering; about 6 seconds off.

Troubleshooting mode...
- Maybe it's the heat profiler. Try the extruder exerciser. Same symptoms.
- Remove the thermistor from the heater barrel and let it cool down. Symptoms go away.
- OK, so, it's an interaction between the temperature sensor and the heater control.
- Replace the thermistor with a variable resistor.
- Start at 10k and decrease. Heater cuts out at 8.8k (temperature reads 77C).
- I've got C3 at 20nF. Try 10nF. Heater cuts out at 17.5k (temperature reads 89C).
- Try 100nF. Up to 130C.
- 200nF? 156C. Close enough.

I'm not entirely sure why it's cutting out like this. I'm guessing something in the extruder firmware is acting up, causing the safety cutoff to kick in at a lower than intended temperature. Whatever the cause, increasing the value of C3 seems to be a viable workaround.

After bumping the C3 to 200nF, my heater profile came out like this:

That gave me some numbers so I could adjust the hm value. It was pretty close at 1.1 but I dropped it to .9, just to make sure I got a decent heater temperature. I cranked up the heat, loaded some filament and tried extruding some HDPE.

I managed to extrude 2770mm (109") of .8mm (1/32") plastic. That works out to about 1.5cc.

Near the end, I pushed the extruder speed to maximum. The JB Weld joint between the drive screw and the wire cable snapped. That's a lot of torque. To be fair, I probably messed up that joint. I think that was the first thing I glued using JB Weld and I'm not sure I mixed it properly.

I'm now on thermistor number four, having fried or mangled the previous three. This one came from a cheap indoor outdoor thermometer, similar to this one. There are two thermistors in it. I used the outdoor one, setting aside the other for later.

Frankenstruder

2007-12-26T18:18:00.000-05:00

This is the current sate of the extruder. It has:
- sandpaper to keep the PTFE barrel from slipping
- a hose clamp to keep the heater barrel from slipping
- a terminal block glued to the hose clamp to connect to the nichrome wire
- PTFE tape wrapped around the heater
- a thermistor cannibalized from a thermometer, embedded in JB Weld and strapped to the barrel

And, yes, "it's alive". Well, pretty much. It doesn't fall apart, melt or catch fire, which is a big step up.

Funny thing, though: The firmware is being difficult. The old firmware (v1.0) runs the heater properly but flakes out on the temperature readings. The new firmware (20071219) seems to do better at temperature readings but flakes out on heater control over about 80C.

I wonder if there's some sort of interplay between the RC factor of the thermistor input and the duty cycle of the heater output.

Extrusion

2007-12-23T22:10:00.000-05:00

I managed to get the extruder to put out some plastic without falling apart. After trying various things, two mods made the most difference:
1. Zach's suggestion of using a hose clamp on the Teflon / heater barrel connection worked extremely well.
2. The other end of the Teflon barrel kept slipping as well, so I wrapped it in some doubled-over sandpaper.

I cranked up the heat and pushed some filament through. Here's the result. When stretched out, it's about 14".

Unfortunately, I seem to have destroyed another thermistor in the process. On my next order, I might have to stock up on a few.

Extruder Barrel #2

2007-12-21T21:11:00.000-05:00

I built a new extruder barrel. This time the nozzle can be removed easily. I did a simple test of heating it up and manually pushing HDPE filament through. Worked fairly well. After I got some plastic pushed through the nozzle, I let it cool down and disassembled it. Here's what I found:
These images show the motor end and nozzle end, respectively. On the motor end, there's a small amount of pooling. I'm guessing the gap is due to the shape of the drill bit. The nozzle end has quite a bit more pooling. The gap there is caused by the shape of the acorn nut.

What I'm wondering is, does this create extra resistance for the filament? If so, is there any way to prevent it? My first thought is to fill in the gaps with JB Weld. Maybe even turn the nozzle cavity into a taper.

Turning Up The Heat

2007-12-20T07:26:00.000-05:00

Figured out what was wrong with the heater. When it heated up, the electrical connections came loose. It'd get up to about 135C and start to cool down again. Nichrome doesn't solder well. I cobbled together half-assed crimp connections for it and, for good measure, wrapped the barrel in insulation.

This time, the temperature got up to 160C fairly quickly. I turned on the motor and let the filament feed in.

I'm not entirely sure what happened because the insulation blocked my view. Somehow, though, the heater barrel came out of the Teflon spacer. It doesn't look like the threads are stripped. There was a large blob of melted HDPE in the gap but none came out of the nozzle. I'm guessing the nozzle is clogged.

As it sits now, the extruder barrel is in pieces. The connections for the thermistor tore loose when the barrel came out.

Next steps:
1. Try to reposition the thermistor onto the barrel instead of the nozzle so that the nozzle can be easily removed for cleaning.
2. Remove the nozzle, heat it up and clean it out.
3. Reassemble and try again.

Moving Forward

2007-12-18T21:44:00.000-05:00

I didn't like the profile of the drive screw. It was too high overall and one end stuck up more than the other. I used a heat gun to heat up the CAPA and a pair of pliers to push it down.

Once it cooled down a bit, I assembled the extruder without the barrel. I used the longest cap screws in the kit to clamp the two halves together, using the tubing as springs. I fed some HDPE through it, just to see if it'd push filament. Did this first with the motor hooked up to 2 AA cells, then switched to the extruder board.

Ran into problems with the RepRap host app. Serial errors. Turns out that the extruder board (or at least the firmware I'm using) gets very unhappy if a) the thermistor cap comes loose or b) you plug the heater into the thermistor connector.

Once I got that working, I determined which way the motor leads should hook up so that the extruder pushes the filament in "forward".

Since I had everything hooked up anyway, I added the heater barrel to the extruder. The clamp wouldn't tighten down quite enough so I wrapped the end of the barrel in electrical tape.

I ran a piece a filament into the barrel until it started to complain and then fired up the heater. Couldn't get the temperature above 140C, though. May need to re-do the heater barrel. Or maybe it just needs a bit of insulation wrapped around it.

Anyway, here's some video of the drive screw pushing HDPE filament.

Getting My Bearings

2007-12-17T22:15:00.000-05:00

I went ahead and used the bearings from RRRF, following Zach's instructions. I used a Dremel with a cutoff wheel to cut the bearings in half. Then I heated up some CAPA (using hot water in a coffee cup) and stuffed it into the two indentations and shoved the half-bearings into the blobs. I used the drive screw to line up and sink the half-bearings into the CAPA.

After letting it cool, I trimmed the excess CAPA with a razor. I removed the half-bearings, put some JB Weld on and re-seated them, using the drive screw to line them up again. The main thing I wanted to ensure was that, when I pushed the drive screw toward the motor, it sat on both bearings. This would be its normal position when it's pushing filament.

Extruder Kit

2007-12-16T23:25:00.000-05:00

I started on the extruder head kit (thanks Zach). The body is made from molded parts based on the RP'd extruder. Things I've noticed so far:

On the plastic parts, some holes weren't completely clear. Easy enough to drill out, though. One of the motor mounting holes was missing entirely. I temporarily mounted the motor using the one hole, lined it up and drilled the second hole using the motor as a template.

The feeder screw assembly refused to solder. I ended up using JB Weld instead. Currently curing.

I realized a bit late that I was supposed to cut down the braided wire to fit the distance between the motor and screw. Fortunately, I figured this out before the JB Weld had hardened. Note to self: Test-fit everything first.

I've avoided soldering the wires on the motor for now. Not exactly sure which direction the filament will go under power, so I've just twisted the wires on until I'm ready to test.

Not sure what I'm going to do about the bearings. The ones that came with it have fairly thin walls. I'm wondering if they'll slip out of place under axial load. Options: 1) Use the supplied bearings. 2) Use Vik's washer configuration. 3) Grind down a piece of brass stock to fit. I'm leaning toward option 3 since it'd provide the most support. Maybe I'm overestimating the forces involved here, though.

The bolt to tighten the barrel clamp is a bit too long. It butts up against the extruder body. Options: 1) Cut a chunk out of the extruder body. 2) Cut down the bolt. 3) Find a shorter bolt. 4) Stack a bunch of washers under the head.

I can see a Home Depot safari in my future.

Adrian Bowyer Lecture

2007-12-13T08:17:00.000-05:00

A lot of people ask me what RepRap really is. I don't think I explain it very well, to be honest. Here's an explanation from the man himself.

Holding Pattern

2007-12-12T09:58:00.000-05:00

I currently have an extruder head kit on order from RRRF. BitsFromBytes is now selling a plastic parts kit made from molds of RP Darwin parts. RRRF should be getting these in stock at some point, so I'll probably wait until they do, rather than do overseas shipping.

Extruder on Order

2007-12-02T12:53:00.000-05:00

I somehow managed to completely miss the fact that Zach had extruder kits available at the RRRF store. It contains some parts I've already got but it doesn't hurt to have spares.

Extruder Barrel

2007-10-28T21:52:00.000-04:00

It occurred to me that, while I didn't have all the parts for an extruder head, I did have enough to assemble the barrel. That allowed me to do a proper temperature profile and get a nice closed-loop system put together. I ran the profiler and then opened the extruder exerciser screen.

I don't have any CAPA filament so I set the temperature to 140C. Holding the Teflon barrel with a pair of pliers, I pushed some HDPE filament through. Works reasonably well. A bit tough pushing the filament through by hand. Could be the barrel wasn't really 140C.

Subversion

2007-10-27T14:46:00.000-04:00

Tried following the instructions on this page to build a new extruder hex file. The zip file on here uses an old SourceForge hostname. Needed to update the hostname using this command:

svn switch --relocate https://svn.sourceforge.net/svnroot/reprap/trunk/firmware https://reprap.svn.sourceforge.net/svnroot/reprap/trunk/firmware

Updated to the latest version. Doesn't build. Figured out how to update to older versions. Browsed through the various versions here. Updated to version 588:

svn update devices -r 588

...under the assumption that 588 was equivalent to the hex file I'm currently using. Appears to build correctly. LED comes on, heater works, motor works, temperature works.

Updated to 626, the first with dual extruders. Doesn't build. Missing directories.

Tried 662. That one builds OK.

Burned the hex file (now called extruder_0_.hex). Works fine.

Note: Occasionally getting "missing separator" error on make. Replacing Makefile from the original zip seems to fix that. Files look identical. Probably a cr/lf problem.

Tried ver 926. Works except that temperature reads -51C at room temperature. Interesting.

Went back to 662.

Smaller Cap

2007-10-25T21:12:00.000-04:00

Found a 10nF cap on an old ComputerEyesRT board (circa 1991). No idea why I still had one lying around. Swapped out the 50nF cap. Adjusted the extruder capacitor setting to 0.00000001. Note: I've got two leads on the holes for C3 and have been trying out caps by soldering to the leads. Less wear on the board from soldering and desoldering.

Re-ran the profiler. Fewer I/O timeouts and false readings. Still noticing a change in duty cycle on the heater but it's less pronounced.

I haven't looked at any of the PIC code but I'm guessing the heater is controlled by a software PWM loop. If that's the case, temperature measurements and serial communication will mess with the duty cycle. Best you can do is avoid polling too often.

Extruder Board Test

2007-10-25T20:03:00.000-04:00

Re-did the temperature measurements. Ended up using two cups of water: one at 6C, one at 70C. Had to be careful not to get both leads of the thermistor wet. Ambient temperature of the workbench now shows as 26C.

Wired up the gear motor using leads clipped off the stepper motors. Tested it using the Extruder Exerciser screen. Note: Hitting "Reverse" at full speed is bad.

Attached the nichrome wire using a couple clip leads. Wrapped one loop around the thermistor to see if I could measure the temperature change. Ran the Heat Profiler. Got a few timeout errors and false readings while retrieving temperature. The heater LED dims slightly when the PC polls for temperature.

Suspect the temperature measurement is interfering with the PWM. Could be because I'm using too high of a value for C3. Larger value -> longer measurement time -> stealing cycles from heater routine. Could also explain the I/O timeouts.

Thermal Ware

2007-10-24T22:51:00.000-04:00

Tacked a 50nF cap into C3 on the extruder board and hooked up the thermistor to P2. Set the Extruder0_Capacitor value to 0.00000005. Pulled up the Extruder Exerciser screen. Temperature was way off. Started reading the thermistor calibration page.

Did some measurements with a multimeter, meat thermometer and heat source. Got some R and T values. Plugged them into the formula. Got a beta and Rz value. Used those on the extruder settings. Pulled up the Extruder Exerciser again. Temperature jumping between 16C and 33C.

Tried the whole thing again with a different thermistor. Completely different beta and Rz. Temperature's consistent now but a bit on the high side.

Suspect the first thermistor was flakey and I was sloppy on the measurements for the second one. Will try again later when I have a bit more time.

Primetime Serial Program

2007-10-24T20:32:00.000-04:00

My new PIC programmer showed up. This one's a PIC-PG2C serial programmer. Messed with it for about an hour before I got it to program a 16F648A using IC-Prog. What I learned:
1. Can't use a 40-pin ZIF socket with this programmer. The inner and outer rows of pins have different pinouts.
2. IC-Prog should be configured for a JDM with nothing inverted.
3. Using the Direct I/O setting with XP is bad.

XYZ

2007-10-20T23:44:00.001-04:00

After getting the first board to work, the other two were fairly straightforward. Ended up using a smaller heatsink on one L298N. Got all three connected in a token ring and ran the Stepper Exerciser again. All three lights flashing. Modded the Y and Z motors and hooked them up. Had all three motors turning at once.

X Stepper

2007-10-20T19:26:00.000-04:00

Finished the UCB. Used the stepper test board to verify the stepper driver was working. Only 2 LEDs came on and the L298N got hot. Finally figured out that the stepper test board was the problem. Two of the pins were shorted. Fixed that. All 4 LEDs on. Slowed the stepper speed and could see the LEDs sequencing.

Stepper motors arrived yesterday. Just in time. Modded one for X axis. Plugged it in. Didn't budge. Realized I forgot to set the X axis power to 100%. Fixed that. Motor started turning. Played with the speed and direction a bit, then shut down and finished the board as a Stepper Motor Controller Board. Re-tested. Works just fine.

Did notice that Mouser sent me 5 small heatsinks and 2 large instead of the other way around. Looks like the shopping list generator swapped the part numbers.

UCB Talking

2007-10-20T16:47:00.000-04:00

I got the X,Y and Z chips programmed and soldered up the Universal Controller Board. I followed the instructions dutifully and everything went well, up until I tried the third test. This should have brought up the Stepper Exerciser screen. Instead, I got a series of error messages in stdout, all saying:

sendMessage error - retrying

I tried jumpering the serial lines for loopback and the screen came up. It told me no devices were present but that's what I expected. At least I knew the serial drivers were working correctly.

OK, maybe the X chip didn't get programmed correctly. I swapped it for the Y chip. It started working (yay), then stopped (boo). Same error messages.

Poked around online to see if I could find others with the same problem. Didn't find anything helpful. So, I resorted to my standard fallback strategy for debugging: poking around a bit.

With the stdout screen churning out its error messages, I started to prod the board, looking for bad connections. I touched something and the exercise screen came up. OK, close it and try again. Figured out that touching pin 18 kicked the chip to life. Traced pin 18 to the Sync connector, which wasn't installed yet. Also R11, also not installed yet. So the Sync signal was floating.

Went back to the forums and searched for R11. Yep. The test often fails without R10, R11 and P3 installed. Rather than install them, I just shoved a couple spare resistors in and jumpered p3 with a piece of wire.

That got the UCB talking consistently. Tried the X, Y and Z chips. All worked correctly.

Auntie MAME

2007-10-19T21:31:00.001-04:00

So, I was sitting there at work today, grumbling to myself that my PC doesn't have a parallel port (and no spare slots). I need to burn the microcontroller firmware and my PIC programmer hooks up to a parallel port. What kind of PC doesn't have a parallel port?

As I sat there, it suddenly occurred to me that I had another PC at home. Sort of. A couple years ago, I built the kids a MAME machine out of spare parts I had lying around. It's ugly but it stands up well to punishment.

Inside the cabinet is a PC. A 166MHz Windows 95 box. And, yes, it has a parallel port. So, I...

opened up the front of the MAME cabinet, exited MAME, pulled out the mouse and keyboard
pulled the cabinet away from the wall
plugged the parallel cable in
used a CD to copy IC-prog from my PC to the MAME machine
hooked up the programmer and propped it up on a crate beside the machine (see lower right of image)
loaded the hex files onto 3.5" floppy and transferred them as well
used IC-Prog to burn the microcontrollers
put everything back the way it was

I've got a serial programmer on order, so hopefully I won't need to do that again.

Serial Loopback

2007-10-18T08:05:00.000-04:00

Finished the Power/Comms board. Serial loopback working. Started on a Universal Controller board.

Soldering

2007-10-16T22:02:00.000-04:00

More parts arrived. Bunch of stuff from Small Parts Inc. I seem to have forgotten to order the M8 threaded rod. It can wait.

Started soldering the Power/Comms board. The 12- and 2-pin headers are tough to insert. Bent a couple pins. Should be OK.

Turns out the board only uses the 12V line from a PC power supply. Had a 12V 3A supply lying around. Wired it up. Looks good. Light comes on. 78L05 produces 5v.

Without Parallel

2007-10-14T13:51:00.000-04:00

My current PC doesn't have a parallel port. Bugger.

And More Stuff

2007-10-13T14:28:00.000-04:00

Got a package from RRRF: filament, PCBs, extruder parts.

Zach says RRRF will be stocking the bearings and extruder screws, as well as the custom plastic body parts.

Found someone who's already burned the microcontrollers. I'll try this just as soon as I can scrounge up a 15V power supply.

As it sits now, I've got enough that I can start soldering some circuit boards.

Hexed

2007-10-13T11:54:00.000-04:00

So, I went through the trouble of downloading and installing Cygwin so that I could build the HEX files for the microcontroller firmware, only to realize later that all I needed to do was download them from SourceForge.

Cygwin

2007-10-12T09:53:00.000-04:00

Downloaded and installed Cygwin, a Linux emulator I'll need to build the firmware.

Need to scrounge up a power supply for the microcontroller programmer. Also need one for the RepRap itself.

More Stuff

2007-10-11T20:55:00.001-04:00

Got a package from Mouser today. This is the bulk of the electronic components. I should be able to start programming the microcontrollers. The circuit boards should be coming soon from RRRF. At that point, I can start soldering.

First Package

2007-10-10T21:11:00.001-04:00

The first package arrived today from McMaster-Carr. Pretty fast turnaround. Steel rods, springs, pulleys and toothed belts.

Shopping

2007-10-08T22:33:00.000-04:00

Used the RepRap BOM generator to get a shopping list.

Note: It specified 16 toothed belts instead of 16 feet. Also specified 4 packs of springs instead of 4 springs.

Used Newark for the stepper motors. On back-order. These seem to be in short supply. Wonder if there's another type that would be roughly equivalent.

Costs So Far
$26.85 - MicroController Pros
$97.10 - RRRF
$94.30 - Mouser
$182.16 - Newark
$97.26 - Small Parts Inc
$169.47 - McMaster-Carr

Total so far: $667.14

(Raises eyebrow at "cost will be less than $400 US for the bought-in materials" quote on RepRap site.)

Still Need:
- split bearing
- extruder screw
- printed parts

Hoping RRRF starts selling this stuff. Really not looking forward to machining my own extruder screw.

Getting Started

2007-10-06T11:00:00.000-04:00

Finally got the core RepRap software running on my PC. Tried running a few models through the simulator. Looks OK.