corners of printed barts are bending up

Hi guys, together with my friends we have finally build working Prusa Mender printer.We managet to get it working but we have encoutered quite a problem with parts bending up in proces os printing.We are printing on glass with ABS (at 230°C extruder and 110°C bed-it seem that glass is colder so we put temperature up to 130°C)We also tried ABS juice on the glass (ABS+acetone) and even on a sanded glass.But it doesnt seem to have any noticeable effect.There is problem especialy with long straight parts.Rounded ones are printed well.Do you know about any setting in Skeinforge that may help us with this issue?Or is there any way of better adhesion?
Printing directly on the heated bed is a no-go since its not flat.

kapton tape is always a good way to go, not cheap but works

Bear with me....In slic3r, there is a setting called "brim". Brim draws a single layer perimeter of a given width around the object, much like the "brim" of a hat. One specifies how wide the brim will be. The brim acts like tape to help reduce corner curl. The wider the brim, the more the effect should be pronounced. (free IP: it would be neat if we could assign more brim in areas more prone to lift....)

I do not know off hand if Skeinforge has a similar setting, someone else can answer that better, but if so, I'd recommend that you try it. If not, you might consider using Slic3r for these problem parts, to take advantage of the brim feature (again, that';s if Skeinforge doesn't already have it...I'm not trying to promote this over that)

Enclosing or enshrouding your printer may help as well, to maintain a warmer ambient environment and reduce convective air currents that may compromise the integrity of your print.

Boorish addition: One thing that should be remembered is that the temperature profile of the heated bed is "ideally" uniform across the entire print area, but in reality it's far from it, in part due to boundary effects and in part due to the pedestrian PCB design of the MK series boards, so although you may read N degrees at one central point on the platen, (that ideal point where the various reprap wikis tell us to place the thermistor) the four edges will see a reduced temperature, and the corners even more. Without doing a study and running the numbers etc, it seems to me from previous that the thermal profile non-uniformity could be contributing to the problem you're experiencing.

If your heated bed isn't already insulated, you might also consider insulating it to reduce that problem.

PET tape is much better than Kapton tape. Kapton tape rips easily and so it doesn't last long. PET tape is a lot thicker and so it can last for months and months.

As far as brim in Skeinforge, you set a skirt with multiple loops and a distance of 0. That's basically what a brim skirt is. For parts with sharp corners, you can also design one layer circles centered at the corners of the part with your CAD software.

Edited 1 time(s). Last edit at 03/04/2013 09:29AM by brnrd.

brnrd... Correct me if I'm wrong, but I believe that by saying "That's basically what a skirt is." you meant "that's basically what a brim is", yes?

right. I figured it was possible. I just didn't think it through (since a brim is essentially a series of single layer skirts).

And the bit you said about targeted brims seems a cool benefit of skeinforge...

Edited 1 time(s). Last edit at 03/04/2013 09:07AM by xiando.

well in skeinforge is something simillar to skirt and we are using it...there is also a "raft" setting which print something like matrix under the printed object but it just ripps off like without it

i may try those tapes but i dont know where i can buy them...im from czech rep.

Edited 1 time(s). Last edit at 03/04/2013 09:25AM by digitos.

A raft is a pain to remove from the part so most people don't use it. A brim is much easier to remove without a trace.

I was told that window film for home and automotive use, which may be easier to find in hardware stores, is usually made with polyester (PET).

Edited 1 time(s). Last edit at 03/04/2013 09:37AM by brnrd.

brnrd Wrote:
-------------------------------------------------------

> As far as brim in Skeinforge, you set a skirt with
> multiple loops and a distance of 0. That's
> basically what a brim skirt is. For parts with
> sharp corners, you can also design one layer
> circles centered at the corners of the part with
> your CAD software.

As far as I know, skeinforge does not allow you to specify multiple loops. Multiple layers - yes, but multiple loops - no.

However, there IS a user contributed skirt plug-in that replaces the stock skirt.py file that DOES include brim capability. I have it on my system and it works well, although I seldom use the brim anymore. Perhaps with ABS it might be more useful, but I do mot of my printing with PLA, and the PVA glue trick works quite well for me.