Extruded plastic not sticking to bed

Hi all,

I have just finished building a Mendel and all works fine (with the exception of a minor glitch see [pdf417.blogspot.com]).
The problem now is that when the Mendel starts printing, the plastic doesn't stick to the bed.
I've tried different materials as a bed surface glass, acrylic, wood, laminated wood and masking tape but all give the same result.
The material is 3mm round ABS and the extruder temperature is set at 230C.
Are there any other settings I need to apply to make the extruded plastic stick? (all settings are at default except the extruder temperature)
And what should be the distance between the extruder nozel and the bed? Can't seem to find that anywhere.
Also what's the best material to use as a surface for the bed?

Hope someone can help cos I'm desperate now.

Thanks for reading

Regards

P

I'm still reading about repraps and haven't build one yet, but I read that a heated bed might help for making ABS stick to the bed (source: [hydraraptor.blogspot.com] )
I hope that helps.

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my blog: [reprap.tman.be]

The distance to the bed should be just enough to fit the extruded filament under so ~ 0.4 mm.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

raise your extruder, extrude some filament and use that as a spacer between the extruder tip and printbed.

Brill, Thanks for the info. I will try these tonight and let you know.

Regards

P

ABS does not stick to glass, hot or cold and I have never been able to stick it to cold wood or laminate. With a cold bed your options are limited. Acrylic should work but polycarbonate, which looks very similar needs to be heated. Temperature is crucial with acrylic. There is quite a fine line between it sticking and welding on permanently. Before I had a heated bed I used Foamex. I have read that double sided carpet tape works very well.

When extruding the first layer the nozzle should ideally be at the bed plus the layer height, but sometimes it needs to be a bit lower to get a good grip. I used to do my first layer outline lower than the infill but no longer need to since using PET tape on a heated bed in a closed box and cleaning it with acetone before difficult builds. I don't think Skeinforge allows the first layer outline to be different from the infill. The problem with having the infill too low is there is too much plastic so the nozzle ploughs through it and rucks it up.

You generally need a raft to build ABS on a cold bed. It is easier to get the raft to stick as you can squish it down more without affecting the object.

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[www.hydraraptor.blogspot.com]

Another option... I can confirm it works.

Someone on IRC mentioned Dry Mount adhesive.. comes in a spray-can.

I happened to have a can around and gave it a try when I couldn't get my ABS to stick to a (too cool) kapton layer..

Spray a light layer on.. let it dry... print on it... It sticks quite well, but the adhesive strength is not that high, so the part can be quiet easily removed...

Need to remove the adhesive from the bottom of the print after.. I used some label remover, then alcohol.

Al...

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[araspitfire.blogspot.com]

Thanks for all your suggestions. I now managed to get a print (if only partial) by mounting a pre-heated acrylic bed. By preheated I mean literally pre-heated by sticking it in the oven at 150C for 30 minutes. see my blog for further details (http://pdf417.blogspot.com/)

Regards

P