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Prints are compressed on 'Z'


#1

Hello All,

I have read all posts near what I am experiencing but could not find a fix.

I print a calibration block of 30mm x30mm x 10mm (Z). The print looks very good and the X and Y dimensions are very close to 30mm (like 29.95mm) but I can’t get the block to get higher than 9.3-9.4mm. This is a 6-7% error on Z. I need to print engineering parts so this error is enormous.

The block sits on a 0.3mm base. After removing first layer, it gets to 0.25mm. I added the base in Solidworks so we are not in the case where the base’s layers are overlapping the block’s layers in CW. It really sits over it and total height is 10.25mm. The slicing seems right since I get 205 slices (10.25 mm).

I print at 50um (XY) and 50um Z. The slice thickness in CW and Kudo interface are both set to 50um, that’s for sure.

I use 3DSR engineering hard and added 0.5% black pigment in it to avoid light bleed in case it would affect the Z resolution. No change.

I tried many exposures from long to short (from 15 sec to 4 sec). No change. I use high lift height and low lift speed (10 to 12 mm/min) to make sure this is not the problem.

I measured the precision of the linear stage with my caliper and it seems to be fine.

The Z height showed on the interface while printing is fine. Ex: at layer 100, the height shows 5mm.

I don’t know what to do anymore. Any help would be greatly appreciated!

Thank you


#2

One other information.

The base is 5 layers and should measure 0.25mm, it finally measures 0.45mm.

So the base is thicker than it should but the block is thinner than it should.

A bit difficult to understand…


#3

It almost sounds to me like you’re having some issues with layer shrinkage then. The extra black pigment might be creating too much light absorption and the layers are shrinking a little bit from being over cured. If the model managed to print at 4sec exposure I wouldnt go up… Try turning the exposure time down instead to where the model will still successfully grow but might not have the shrinkage that is causing your part size deviation.


#4

Thank you very much for your help. Highly appreciated. Printing at low exposure did not fix the problem. I tired many different exposure time from low to high… I also removed the pigment. Something that helped me was to put a sheet of paper under the build plate to zero the plate. It seems a little gap under the plate has helped. But I must confess, I made so many trials that at some point I could not make only one change to identify the exact cause. I did everything I could to get a good print because it was more than urgent. So I am not 100% sure this was the issue. It is better now but still get some compressed parts here and there.