Printing in ABS

[Trevor Thompson]

I know that few modellers print in ABS - but in case it is of interest to anyone:

I have always had priblems with distortion when printing tall objects. For example this section of wall frame for Tan-y Grisiau station building:

Can you see the way the corners have lifted. As the object gets taler the material extruded shrinks and causes the model to curl, lifting the corners off the bed.

I have found what I think is a solution. On my slicing software there is an option to compensate in different axes:

The above screenshot shows the alterations to the settings that I have made. As default the compensation facility was turned off. Your software may use different words but this might be a guide.

The result is:

This print has almost finished and there is no sign of it lifting or distorting. Probably the best result I have ever achieved.

Trevor

[philipy]

Interesting Trevor, thanks.
I rarely use ABS but a couple of months ago I had to use it for a job for somebody, creating long, thin, pcb 'standoffs' - 75x8x5.5mm with threaded holes in both ends and a couple of transverse ones. I had problems with elephants foot and also lifting at one end, which looked similar to yours although obviously on a much smaller scale.
The elephants foot I solved by simply curving the bottom part of the sides inwards slightly to allow for the spread.
The lifting was eventually resolved by reorientating the part on the bed and printing it at 90deg to the original. It wasn't simply a bed adhesion issue, it only became apparent when the print was about half way up and I'm sure it was to do with bed temperature, extrusion temp and I did also wonder if my printer enclosure might be too good and was trapping too much heat!

[Trevor Thompson]

As the temperature has dropped the prints I have been making have started to lift in the corners again.

That caused me to play with settings again - and further tampering didn't make much difference.

However further research on the internet made me wonder if it was temperature related. The advice was that this sort of issue was caused by the print cooling too quickly.

I tried insulating the printer enclosure with wool:

That has completely cured the problem.

So I am convinced that the distortion when printing (particularly tall objects) is caused by the print cooling too quickly. It seems that the whole print must remain above 80 degrees C until the printing has finished - and then it needs to cool slowly and evenly.

Trevor