Hi All
I have been thinking on a build it yourself spindle belt transmission and VFD motor drive for a while,….
to be used in a Epoxy frame CNC Mill. .
The following links have been very useful
For the belt transmission I like the following mechanism as used by Fadal a US company, now mothballed in new hands. They made a range of CNC machines, some of them used a novel drive system employing Polly V belts. The belts were constrained within a containment that kept them clear of the pulleys except when an idler wheel was pressed against the back It sounds complicated but would be fairly simple to make.. This mechanism allowed the belts to be alternately switched in and out allowing the speed ratio to be changed automatically by the CNC system, although it could be done manually if you do not want to mechanise it.
(Oh…. and yes in recognition of the Myford Mavens The tri lever system was similar but not the same) Fadal did it rather well!…..Sorry I could not resist……I Ducks for cover!
Item 14 in the following thread is of note:"
Quote: "I have a Fadal VMC 15 with a 10,000 rpm spindle. This has a 2 speed, 8 rib poly belt drive system. This was a factory build option, same parts as the larger machines. Nice and quiet , same belts for 10 years. I think the drive ratios are 2-1 for 10-2500 rpm and 1-2 for 2501-10,000 rpm. The torque is good in low range aprox. 250 ft lbs and it will push a 1.500 drill no problem. The milling performance is limited by chatter on larger tools and deeper cuts. The VMC 15 is not a heavy duty machine.
**LINK**
From this general Google search:
**LINK**
The following Blog is definitely worth studying also:
It covers in an easy to understand way some of the issues involved in designing a spindle and drive system very well. Get a cup of coffee first you will be reading for a while,
**LINK**
From the blog a link to parts manuals that show the device.
Get a set of manuals for the 4020 machine
The links worked for me.
**LINK**
Regards
John