Here are 3 of my older spindle mounting plates. Each is secured with 4- 1/4-20 allen cap screws. The one on the left (Porter Cable) was the first one made. It works fine, quite noisy, and limited to 1/2 inch or 1/4 inch router bits. I did make some sleeves for other sizes but the factory collets I have are limited and it is 20K rpm fixed speed. I use a universal speed controller to go from about 10k to 20k rpm. Plenty of power at high rpm just a bit fast and noisy.
Next up is the Dewalt DW660 that has collets for 1/8 and 1/4 so that takes care of the small bits. Variable speed via the universal motor controller.
Problem with that controller is that it does not have much torque at the lower RPM ranges. It works fine until you put a load on the bit and then it looses quite a bit of rpms. When running at the higher rpm range with either router it has less power than if you just run the router direct.
The Plate on the right is for the pen. I can plot a print up to 32x32 inches with it. Needs a redesign but it worked well enough to prove the machines accuracy for me..
Here is a link to the CNC Machine thread:
That is it until I post my new RC Spindle!