Progressively worse accuracy along X and Y axis
Hi,
Last week I was printing a model that i made, it is basically a square with square holes at each corner. In the holes i have printed bars that go in.
I Noticed that the holes on one side was a perfect fit, the bar could move free, but on the other side the bar didn't go in. I did some investigation and it turns out that the furter along the X axis and Y axis I print the holes the worse it gets. I used extra clearence on this model to avoid this kind of problems. I did some investigate and have done the following:
- Maintenance, lubrication etc.
- Squaring the XZ, YZ, XY axis according to prusa manual
- Tensioning the belts according to the prusa app
None of them worked. I wanted to get more data on this issue so i printed 6 20x20x20mm cubes (lots of fillet in the corners to avoid bulging), 3 equally spaced on the top row and 3 on the bottom row (TL = Top Left, TC = Top Center, TR = Top Right etc....)
TL-----TC-----TR
| |
| |
BL-----BC-----BL
Meassured the X, Y and Z values of each of these positions
TL: X = 20.21, Y = 20.11, Z = 20.11
TC: X = 20.14, Y = 20.04, Z = 20.13
TR: X = 20.04, Y = 19.94, Z = 20.08
BL: X = 20.17, Y = 20.15, Z = 20.05
BC: X = 20.02, Y = 20.00, Z = 20.06
BR: X: 20.00, Y = 19.98, Z = 20.04
Difference in X between Left and Right cube are around 0.16 mm
Difference in Y between Left and Right cube are around 0.17 mm
I know a 3d printer is not super accurate but what is strange to me is that it is not consistent, it varies with the distance along the axes.
Is this normal? Any suggestions on how to fix it?
I have had this printer for 5 years now, maybe it is just old.
RE: Progressively worse accuracy along X and Y axis
Yeah this is normal. Quick improvement is to do a general maintenance, screw in loose screws, tighten belts, cancel wobbling of each part and so on. Yet you will not be able to fix certain things in that way and it nay need additional changes (to the point if scaling print in one dimension or adjusting other factors in the slicer or even compiling your own firmware)
You can look around over the net about calibration guides - and don't use calibration cube because it is actually not the best solution to test the printer for dimensional correctness.
See my GitHub and printables.com for some 3d stuff that you may like.
When everything else has been dialled in correctly you end up facing basic physics: You are printing hot plastic onto hot metal - and then it cools down and contracts. Worse, the degree of contraction often depends on the lay of the filament - it's worse along the extrusion than at right angles.
So: for parts where the dimensions really matter print once, measure carefully and calibrate the dimensions in the CAD. If you have problems with holes or other sub dimensions try ticking Print Settings >Layers and perimeters > Advanced > External perimeters first
Cheerio,
RE: Progressively worse accuracy along X and Y axis
Thanks for your replies. I will go over the printer a bit mor thoroughly to see if i can get rid of some slop. I haven't done that in 5 years so that wouldn't surprise me if that was one issue at least.
When everything else has been dialled in correctly you end up facing basic physics: You are printing hot plastic onto hot metal - and then it cools down and contracts. Worse, the degree of contraction often depends on the lay of the filament - it's worse along the extrusion than at right angles.
So: for parts where the dimensions really matter print once, measure carefully and calibrate the dimensions in the CAD. If you have problems with holes or other sub dimensions try ticking Print Settings >Layers and perimeters > Advanced > External perimeters first
Cheerio,
Yes physics is a bitch sometimes. My concern is that this model is basically a cube with identical holes or slits in each corner. Two of the corners (closest to X) was printing fine but the two corners that are further from X origin was smaller. Meaning the geometry was the same on all corners and it still turned out differently. It could be that the corners further from X origin is further from a heat source or closer to a draft and the shrinkage is more in that area. I print in a hotbox because it is too cold here otherwise, so the ambient temperature is quite consistent around the printer.