What causes this

So I have this problem on most anything that I print that's over 2" tall. Near the bottom layer corners bend inward I notice it seems to be related to inner fills, Like if I have a solid layer at 1/4" from the bottom then it will stop at the 1/4" mark but if there is a solid layer at 1/2" then it may end at 1/2"

It does not happen every time even with the same object.

I thought it was heat (or lack of heat) so I built an insulated box around my machine and it's plenty warm inside. I thought I had it cured by printing brims (object came out perfect but next print of the same object with the same brim failed.

Can filament color affect this? I noticed the majority of good prints are certain colors but it's not enough to draw a conclusion. The parts seem to be sticking down well as it's a job to remove them yet on the corners where there is an issue it's always off the bed but it's a very tiny amount. Like if the inset of the problem is nasty at 1/4" then only 1/64" of the corner was bent up (I think it's the caving in that causes the corner to lift and not the other way around).

Forgot to mention, I am printing ABS with a heated bed, glass with PET and ABS/acetone wash on it. .35mm nozzle 240c with the bed at 100c (my bed is either on or off, no temp control).

Edited 1 time(s). Last edit at 12/13/2012 12:36AM by tmorris9.

What's the temperature inside the box?

Not sure but it's probably around 35-40c Not an oven but it would be uncomfortable to live in.

I have been doing some testing with a 1" cube, I tried a few things that all failed to make a difference, then I noticed that after printing the cube was still soft. I figured maybe I have too much heat so I turned off the heated bed when it was around 65c and printed (it would get cooler and cooler) and the cube came out 99.9% perfect.

So now I guess I need a way to lower the bed temperature. My machine came fully assembled (Airwolf 3D) and with a switch to turn the heat off and on (not going through the board).

While I am a repair tech I am not that familiar with these printers electronics yet. Mine has a gen6 board in it and runs repetier software so I am not sure if I can control the bed through the board or not.

Anybody have suggestions?

Thanks!

Example with heat on all through print and off upon print start (starting at full temp but cooling as it goes).

So am I right that the bed needs to be cooler or am I overlooking some other variable?

P.S. My bed actually gets to about 107c when left on. I wonder what the best temperature would be for a heated bed with ABS?

... try to reduce the bed temp in 5deg-steps until the print won't distort in the lower region - it's a known effect with too hot bed temp .. heard people calling this 'elephant legs' ('Elefantenfüße' in German)

The 107degC reading could be wrong - some are printing with 110degC without problems ...

---

Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

VDX Wrote:
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> ... try to reduce the bed temp in 5deg-steps until
> the print won't distort in the lower region - it's
> a known effect with too hot bed temp .. heard
> people calling this 'elephant legs'
> ('Elefantenfüße' in German)
>
> The 107degC reading could be wrong - some are
> printing with 110degC without problems ...


I have no way to reduce the bed temp. It's either on or off. That's my problem.

The 107c reading is accurate I am using a quality infrared thermometer that I use to use for a thermal printing company, it's accurate to +/- 0.1c That is at the center of the bed which is hottest, it's closer to 103 near the outside edges.

You need a PID controller for the bed. Or upgrade the electronics.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

... do you have a coating on your bed?

Especially with shiny/specular surfaces and/or translucent coatings like Kapton or PET you should better use a contact thermometer or thermistor ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I have a Mendel in a box that gets to around 45C when the surface of the PET covered glass is at around 105C and I don't have that problem printing parts up to 100mmx100mmx70mm. I agree with the others that your bed temperature might not be stable enough or it's too high. If you measured the temperature before you placed your printer in the box, then it's probably too hot when in the box and you'll need to turn down the voltage to get it to the correct temperature.

akhlut Wrote:
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> You need a PID controller for the bed. Or upgrade
> the electronics.

Yea, I am trying to figure out which is best. I have set up PD controls a few times in the past. I don't know how easy it is to swap out my gen6 for a gen6 deluxe (supports heated bed). It's not the electronics that worry me it's the software or firmware on the board. If I can just throw the same firmware that came with my machine on it (they gave me a copy on flash drive) or if it needs to be altered or completely different.

I think I would rather go with new controller as I could set up the temp in software and have it cut off when long prints are done (this would be a big plus).

Not sure who to ask about the changing of hardware and firmware. If I can get an actual answer then I would move forward with that method (although every place seems to be out of the gen 6 deluxe right now).

If you have any ideas let me know.

Thanks

I think this kind of warping in the upper part of print, or randomly having one piece warp and next ok, is because air drafts. Put it the other way, from human activities that are apparently non-related. I suspect is the same case when 1cm print height is ok and then the warp starts all of the sudden in the upper part (yellow piece)?. If it would be a warp due to adhesion to bed, temperatures or generic problems, it would be in the lower part. It would also be consistent, in the exact spot all the time, not so random on the same piece (black boxes).

I had a issue almost identical with this, and was tricky to figure it out. I print in first room and when the door to outside opens it makes a very chill air current in the area which turns into weird warping like that. Also opening the window to refresh air, etc, makes same thing. Some temperature drops and chill air currents that are not so visible but can turn to be significant for the printed piece. Even more now since its winter. I suspect this case may be the same, as the warping seems non-consistent and random, this is a good explanation.

I resolved this by covering the printer with a towel, sort of half chamber, so the heated bed keeps prints hot without any air drafts inside at any time. You can try this, but be very carefull, if its too covered, the extruder assembly can heat up and the filament can get stuck inside extruder from being too soft. To try this you need a good extruder else it tends to get stuck. So can try run tests covering the printer, but do it gradually from bottom to middle and then upper, and if extruder is ok with it and if prints improve. Sort of topless - roofless heated chamber all around. And during these tests, try to not open doors and windows, especially now as its winter (at least at me).

I understood that the printer was inside a box so air drafts shouldn't have been an issue.

brnrd Wrote:
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> I understood that the printer was inside a box so
> air drafts shouldn't have been an issue.

You understood correctly.

huh, never mind me then cheers