Tuesday, September 2, 2008

Bed Covers

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.

3 comments:

Andy D. said...

What plastic are you printing with? I heard from Bruce Wattendorf (via nophead's direction) that he uses antistatic foam as a base for ABS. I have tried it, and the ABS adheres perfectly, but can still be peeled off without damaging the surface too much. There may be other solutions as well. I ordered mouser electronics PN 809-122250, but it was quite expensive. There is probably a cheaper material or provider out there that also works well with ABS.

Steve DeGroof said...

Nice idea. I should check to see if I have some lying around the house.

Arthur said...

If antistatic foam works, then what about ESD mats used for soldering, which are denser and can lay flatter?

or Modulan:
http://plasticssrt.com/Modulan.aspx

I'll be trying both once I get my Mcwire going.

Cool blog btw.