X-carriage.stl hole centers


#1

X-carriage.stl hole centers are 0.3 to 0.35mm different between the X-end-idler.stl and X-end-motor.stl after I print them… so the x carrige is tight on the bearings as I try to slide them.

I’m using Igus DryLin Bearings which I am guessing need a more precise alignment.

I redrew the x carriage with 0.3mm closer bearing centers… and I’ll print it and report back my finding.


#2

I redrew the x carriage withe the centers 0.4mm closer together and this lined up much better with the ends.

STL File: www.ynet.com.au/images/Wilson%20II/x-carriage_0.4_center.stl

Slides very nice now.


#3

I sat down tonight to try to get to the bottom of this. It wouldn’t be entirely surprising if I fudged a dimension somewhere between openSCAD where the X ends are created and Sketchup where I did the X carriage. However, I’m finding in the cad, the holes are lined up properly. That is, they are 50mm center-to-center in both the skecthup model for the X carriage and the X ends models. I am not sure what could explain the discrepancy you are seeing, but one thing that occurs to me is that the X ends are printed standing up, so that the distance between the rods is a matter of your Z axis accuracy, but the X carriage is printed horizontally, so the distance between the rods for it would depend on either your X axis or Y axis accuracy depending on how you rotate the part on the build plate. Since your measurements show the holes on the X ends being the ones that are .3mm too close together, is it possible the Z axis is not quite right? Or maybe there is some logical reason having to do with the slicer that would cause a one-two layer mistake on that print?

I’m open to ideas if you can think of something for me to try.


#4

Since posting I came to a similar conclusion that 1. the print orientation could add some error if 2 different parts are printed 90deg to each other. 2. That my holes in the motor and idles ends are loose where the 10mm smooth rods go (i’ll get a measure and insert here).

So with the combination of these 2 points would easily attribute to a 0.3 to 0.4mm error. I think with these Igus DryLin Bearings I’m making my life a little harder as well.

So yes printing all 3 parts in the same orientation as we printed the carriage would be a good test. The smooth rod holes for me on all parts of the printer are way too big and on Y and Z I’ll have to put tape on them. For my own design I try to go for having to run a drill down the holes to ‘clear them out’ but I do understand people making them loose to cover the variety of printer performances out there.

The funny side for me is we are discussing such a small error on a sub $1000 printer built on a dining room table… love it.