My print grows... gets wider?

Hi Guys,
I am new here, but have been lurking for a little while now.
I have got my Makerfarm i3 working very well so far and I am quite happy with my prints. I do however have one issue that I can't seem to solve. As I print my parts they get bigger? By this I mean that at the print base they are the size that they should be but as they print higher they slowly start to go off square and become bigger.
These parts have been drawn in Scetchup then fixed in Netfab.
Please have a look at my pictures. I would appreciate all advice.

Thank you
Kind regards
Andreas

I think the opposite is happening. The bottom corners are curling up and inwards making the bottom smaller.

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[www.hydraraptor.blogspot.com]

Hi Nophead,

I did some more prints yesterday and measured them. You are acctually right, they are smaller at the bottom then what they are supposed to be.
What is cousing this? How can I make it go away.

My bed is heated to 110*C printing with ABS.

Kind regards
Andreas

I get size change from bottom to top depending on cooling, and when I had cooling from one side rather than 360deg this also created distortions. How are your fan/s directed?
David

You might try reducing your bed temperature to 100°C after the first layer (or so) to see if that makes any difference.

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

I have no fan. I am however assuming that I have a draught in the room that the printer is standing in as it is near an open window.
Temperatures are changing rather quickly when I print. As I like printing quite slowly some of these part take about 45 minutes to one hour to print, and it that time the room temperature falls by about 5-10*C from the late afternoon sun to the early evening chill.

I have another thought on this though. As I measure my printed part I realise that the bottom is smaller by about 0.5mm then the top. Could it be that the printer is actually printing it smaller? When I print calibration parts like the thin 0.5 wall though I get the measurement that they are supposed to be.

I am a little lost on this one.

Thanks for your help
Kind regards
Andreas

Please guys,

I need some more help with this one. I have tried 100*C on the bed. I have also tried covering the printer and I still get the same results.
Printing the same part in PLA gives perfect results.

Please Help.

Kind regards
Andreas

That curved bottom looks a lot like what I am getting with my printer - in my case it usually only happens with much bigger object which takes a very long time to print. Also, I am using PLA, not ABS.

Just curious.. does this always happen, regardless of the shape and size of the object? Also, did you let it naturally cool all the way down to the room temperature after printing is done, or did you took it off the heated bed when things got cooled enough (but still quite higher than the room temperature), or did you cool it rapidly (like putting the whole thing in a freezer)?

Hi Yamster,

For some strange reason this only happens with the parts that I draw myself. I printed a 100mm X 100mm object yesterday with none of this going on.
I do tend to not let everything cool down all the way before taking them of the bed.