Cold bed adhesion

Here's the short version: I have a Kossel. The Kossel does not have a hot bed. I use PLA. I cannot print anything bigger than a few centimeters. How do I fix this?

I have a basalt bed (one of Nicholas Seward's spare Simpson beds) with blue painter's tape on it. I have tried bare stone, but it doesn't seem to work very well. I'd rather not use a heated bed, but I could. I have not tried hairspray, glue stick, or PVA glue, but I've heard those only work well with hot beds. I have a roll of "Koptan" Kapton tape, I may try that.

Is it normal to be unable to print a ~8cm diameter circle without it warping and pulling up? I have my head calibrated to where it barely touches a piece of paper between it and the bed. Is this too high? I'd really like to avoid hurting my nozzle, as it's the single most expensive part of my machine.

I use SainSmart PLA at roughly 210C. I have a spool of PushPlastic, I could try that, but I'd rather not. My j-head can probably handle ~230C, should I go hotter? Do I need new filament?

Any help would be greatly appreciated.

Edited 1 time(s). Last edit at 04/01/2014 01:07PM by epicepee.

I'm building a custom printer that dosent have a heatbed (for now, it will, in the near future).

I tried blue painter's tape.. for some reason, it dosent work well.. I have some cheap green tape roll from my local bogbox store that works better.

as for the nozzle, try to put it close as possible to the glass so that it will compress the first layer a bit.. not as close as it will clog the nozzle.

I try to have a good friction with my piece of paper.. (a normal sheet, not the think ones).

That should help, you can try it.. pretty sure the glass will move before you hurt the printhead.

Quote
Rigor_M
That should help, you can try it.. pretty sure the glass will move before you hurt the printhead.

I have a 3/8" basalt sheet, resting on and held by steel bolts. It's not moving or bending any time soon. That's why I'm cautious. My belts will *probably* skip, but I want to be careful.

Edited 1 time(s). Last edit at 04/01/2014 01:11PM by epicepee.

I never heard about that material.. could it be the reason its not sticking ?

But in that sense, yeah, be careful

"That material" being SainSmart PLA? SainSmart is just another manufacturer -- in theory it should be identical to everyone else's.

Not the PLA, I ment the bed. Usually, ppl use glass or aluminium... sometime, Garolite is used for printing nylon.

Different PLAs filaments (from different manufacturers, or even with different colours from the same origin) have a different warping behaviour, you might want to experiment with samples from other sources.
Also how much moisture the filament have "sucked" from air seems to impact the amount of warping - you could to look for a seller which would deliver the PLA in sealed bags with desiccant.

I usually doesn't need to heat my bed when printing PLA on Blue Tape for objects which doesn't have a X or Y dimension greater than 12cm.

Ideas that you could try :
- "crush" the first layer a little more into the blue tape. Might make it more difficult to remove without destroying the tape, but it helps.
- warm up the basalt plate (using an hairdryer for instance) before printing.
- put a towel over your printer during the print, to avoid air from cooling everything and so that the heat from the machine (hotend only in your case) accumulate (poor man's heated chamber).

---

Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

So, I tried hairspray on bare basalt. I also squished the filament more. It worked beautifully -- I'll experiment some more. Would Kapton tape help?

I stubbornly went quite a while without a heated bed and the best tape I found was green painters tape. I assume it's the same stuff as blue tape.

I don't think kapton tape works well for PLA.

However I would seriously recommend a heated bed - small ones aren't very expensive and it simply makes the whole 3D Printing process so much more pain free.

First layer sticks fine, every time!