Question/issue with cad file - Bogie Wheels

[knickels]

Not sure if this is the right place to post this - if not, steer me to it please :)

Starting to build a copy of Sawppy for my lab. I noticed in the onshape file
that the side holes in the Bogie Wheels part don't go all the way through.

There are two steps in the time line, "Bogie Mid Side Washers Bridge Assist" and "Bogie Rear Side Washers Bridge Assist" that appear to actually add an 0.5mm bridge between the washers and the bolt hole. I've suppressed these two steps in the image below.

I guess I could print as-is and then drill it out, but I'm wondering what the purpose of these bridges are.

[Roger-random]

(Administrative: this issue #45 was converted to a "Discussions"/"Q&A" item as I felt it was a better fit.)

These counterbore holes are printed facing towards the print bed and would otherwise require printing with supports. The thin bridges were added to the design as an alternative to supports because they use less material.

The instruction to drill them out are in the Print Overview section, though the explanation of why was admittedly terse.
https://github.com/Roger-random/Sawppy_Rover/blob/main/docs/Print%20Overview.md#print-post-processing

There's a little more information about these and other Sawppy design details here:
https://hackaday.com/2018/05/08/how-to-build-anything-out-of-aluminum-extrusion-and-3d-printed-brackets/

If your situation with printer/filament/etc. is better with supports, you may certainly suppress the steps as you have done and print with supports.

Whichever way you go, please reply here and let everyone know how things turned out!

[nbering]

As a "satisfied customer" of this design, I actually prefer to drill them out, and have borrowed this technique for other designs.

I find that most printers need to leave a single-layer gap between the supports and the circular hole, or you wouldn't be able to remove the supports easily. And my 3d-printer does a poor job of printing circles with that little gap. There just isn't enough contact with the layer below, and I end up with something more like an octagon than a circle, because the filament just drags instead of sticking.

In some cases you might be able to print with the order as infill-before-walls and the walls won't have that problem because they have infill to stick to. But this drilled-out single layer works perfectly every time.

[knickels]

Now that I understand why, I did go ahead and leave them in, and had good luck printing them then drilling out the holes. My bambu lab x1 carbons and p1s both do a pretty good job with supports, so I hadn't had to worry much about this before.