Author Topic: Tom Senior mill CNC converison  (Read 44 times)

Online Charles

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Tom Senior mill CNC converison
« on: August 16, 2017, 12:49:29 PM »
Looking at the big pile of half completed projects, and the lovely August rain I decided to finish the CNC conversion of my milling machine - I've been making / purchasing parts for this for over a year now, and looking at the accumulated pile of stuff I realise that the only thing missing now is the stepper motors, easily solved with a quick trip to eBay  :D

I stripped the mill down some time ago and took a load of pictures / measurements, then modelled the 3 axis's drive systems in Solidworks, so I've been able to make the bits for the conversion using the mill. But now I've started taking it apart, any further parts or alterations can only be done on the lathe, or using the pillar drill at work.

Starting at the bottom the existing Z axis nut mounts into a substantial cast iron holder which will happily accept a ballnut, only one problem: the ACME nut is 1 1/2" diameter, and the ballnut is 36mm. So, into the lathe, skim the bore, press in a plug of aluminium and bore to 36mm. Once the nut is a nice slide in fit, take it to the pillar drill and drill & tap through it for some fixing bolts.

The Y axis is an odd mount - see the drawing below - unfortunately when I offered this up it fouled the bottom of the cavity in the knee casting :doh: after much head scratching the solution was to cut the bottom of the flange off of the nut, cut the bottom of the carrier away, and reduce the height of the carrier by 4mm. This necessitated making some temporary cheeks to fit the carrier so that I could grip it in the 4 jaw. Next problem will be modding the bearing mount to raise the axis of the screw by 4mm

The x axis went in smoothly, the nut wont fit through the hole in the casting, so is reliant on the fixing bolts for alignment, but as the screw is supported both ends I'm hoping this will be OK...

Next challenge is removing the crank & bevel gear that drove the Z axis - it appears to be retained by a taper pin, through the collar just behind the gear, but its not responding to the application of my hammer. Any ideas? before i get the grinder out....