Drag Knife Spindle Attachment.

Cheap "Roland Type" drag knife holders are readily available on ebay for small money. I ordered one without great expectations. I found that while they have their limitations, they certainly can do a job. One of the key factors for success is a solid mounting but one which allows the knife some flex in the vertical. Allted (designer of the MPCNC) came up with a very neat idea to use attachment arms between the backplate and the holder to allow this flex. Full credit to Allted is given for coming up with that excellent idea.

http://www.thingiverse.com/Allted/about
http://www.thingiverse.com/thing:1860310

I wanted a simple but effective way to mount this to my CNC. I have a 2.2kW water cooled spindle and noted that at the bottom it has a 10mm high collar with a diameter of 72.15mm. I thought that a clamp type mechanism would work well and so it has proved to be. The clamp inner diameter is 72.5mm which makes a beautiful fit to the collar of the spindle. The hole spacing is