Hello @Anonymous
Thanks for attaching the file! The problem here is that your Xforms are scaled way, way up which is reducing your precision. I wouldn't have guessed this without the file so thank you again for attaching it!
First, let me show you how you can tell if you have Xform issues. If you right click on the scale icon, you get this currently:
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You can see that these splines are scaled up 68000%. What we need these to read is 100% (give or take) in order to maintain proper accuracy with the cap holes and other tools. But, clearly they are the current size you would like them to stay, so in order to keep their size but remove the scale history, we need to reset the Xform.
It's easy, I'll show you!
First, you need to select the spline you want to reset the Xform on. You then go to the Utilities menu (hammer) and click like the following image:
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Then make sure that your Xform is just above your editable spline shape by dragging it down under the extrude and "collapse to". We do this because going down a stack below an Xform can lead to weird results except in specific cases, so it's easier and cleaner to collapse it. See below image.
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Once you've done that, right click on the scale icon again and you should find that they all read 100% now. If you now add your Cap Holes, you should be good to go! (Note, you may have to delete your old Cap Holes and add a new one.)
I tested this on all your parts and it did work, if you have trouble let me know!
Please hit the "Accept as Solution" button if my post fully solves your issue or answers your question. This lets me know that I was effective in helping you, and thank you for doing so.
Best Regards,