A project log for MultiBot CNC v2

A low cost 3D printed CNC that can be built with minimal tools yet is capable of great things.

David TuckerDavid Tucker 10/01/2021 at 03:140 Comments

So I needed a tailstock for my rotary axis so I can use my spindle with it.  I came up with this over engineered solution that is working well but is way overkill for what my small rotary axis needs.

This is truly 3D printed with only one M6 bolt/nut and a skateboard bearing in the tip. The whole thing is very solid, all but the quill at least.

One unique idea is that there is a small (3D printed) socket hidden behind the quill so you can insert hex driver accessories in place of the quill.

The big downside here, other than just being rather large, is that the 3D printed threads are a big pain.  They are fiddly to clean up and they tend to get sticky.  If you lightly heat them with a hair dryer they will reform as you thread the parts together, that can help a bit.  The key is lightly, only heat for a few seconds at a time, it is easy to over do things and ruin the part.


Anyway this would be great if you had a small wood lathe you were working on, but it needs to be slimmed down to go with my rotary axis.  In particular the rotary axis does not have a whole lot of holding power and does not spin very fast.

The simplest idea is to just put a nail through a board and use the tip as a rest, or any similar setup with a pin and holder.  This works because our rotary axis is not rotating fast so we don't have a lot of friction.  This is by far the cheapest and simplest solution.  It does have three downsides however.  

The next idea is to add in a proper quill and bearing to the setup but not use any sort of a fine adjustment. That takes care of the first problem of wear on the end of the workpiece but nothing else. This adds only a small amount of complication, we have added a bearing and have to fabricate multiple parts, but it is still relatively minimal.

The last step is to go all in and add a fine adjustment to the setup so we can apply a clamping force and quickly release the tension and swap workpieces without needing to readjust the base and risk messing up the alignment.  I like the idea of using a threaded rod or bolt for this setup, I will try to find something tomorrow to act as the base.  That should give me the same precision and stability as my 3D printed solution but hopefully in a smaller package.