Integrated spindle/tool mount for brushless outrunners

Mostly Printed CNC - MPCNC Advice
1

I’ve been working on an integrated spindle/ tool mount build for my mpcnc, and I have to admit, it’s been more difficult than I thought.

The idea was simple enough. Print a tool mount that housed a set of 608 bearings as close to the center of the tool mount as possible. Fit an er11 c8 100l collet through it and use a spacer and a gt2 pulley to both secure and preload it.

Turns out, it only works with a specific motor, specific gearing, and specific belts per build. That’s way too much plastic and changing out of parts if one wanted to try different configurations.

I think I found a solution. I’ve broken up the part into a few peices. I’m test printing v1 of an integrated bearing/spindle/toolholder tonight, and the idea is to print the motor holders independent and mount them to the tool mount.

This way, basically, you have a spindle mounted as close to center of the z as possible, and can have a few different motor mounts if needed for different gear ratios or motor sizes.

For the issues encountered.

The bottom emt mount screws in the tool mount get partially blocked by the bearing holders. May not get as much torque tightening them. Is this an issue?

Tensioning seems to be dependent on my motor mount at the moment. What ever tension needed is currently designed into thetcenter distances of the pulleys and belt. he Any familiar with gt2 or 3 belt mention systems? Is there an easy way?

 

 

2

Here’s a rough print of the basic idea. Is this too much stick out for the collet? Should I try to move it up?

IMG_20180710_065353568.jpg
IMG_20180710_065353568.jpg2448×3264 1.14 MB

3

My DC spindle sticks out a little more that that, so should be okay. A little shorter would be nice if you can manage it though.

4

I think I can move it up the distance of the flat spots on the tool holder. I don’t know there real name. I will have to move the lower emt mounting holes down though. Getting closer to the end of the plasic will weaken it a bit. Maybe I can compensate by adding a third set as close to the top of the lower bearing holder.

5

Ok so I tried a test print with the spindle holder moved, and I really don’t like the way it came out.

What if I simply mount it a half inch up on my z axis rails? That would technically reduce the stick out, wouldn’t it?

6

That would probably work.

 

Oh, just thought of something. Mine is mounted like that. If you’re planning on doing any 3d carving, with it mounted like that, the Z rails may get in the way. That’s happened to me once so far. My end mill wasn’t long enough.

7

Good thought. :). What size is the Chuck on your spindle? You could use the same er11 collet I use as an extension. Mine was about 9$ so they are not real expenaive. I think you can get them in varying lengths and shaft diameters. You can cut it to the lenghth you need.