Please correct me if I am wrong

[Dustin beyer]

Not a splined drive like yours

 

[Dustin beyer]

If you have a 1750 rpm 4 pole motor yes they do fine being over speed but 3450 rpm 2 pole motors don’t like to be over speed that much and yes the more you go below 60 hertz you loose significant torque but being a 3450 5 hp even running at 30 hertz there’s still more torque than needed. But if I change my countershaft pulleys from 3.5-7 to the hi speed that’s a 7”-3.5” I can probably get 8-9,000 rpm but that’s not what I’m after. I work with pretty much all steel rarely aluminum and I’m sure the bearings wouldn’t last very long and even being a 5 hp motor a can still grab the spindle and slow it down but with the 4x reduction I have it on now you can’t slow the spindle if you had to I slip the collets before anything. I was in the process of installing a Bp style back gear but since my machine has the drive hub like it does and not a internal splined shoulder drive hub like the bp I had to make a way to shift between backgear and open belt pulley I was going to maybe use a over run clutch from a power feed unit that engaged the rapid traverse but since I’ve tried this new setup I don’t think I need the back gear and I don’t know if its worth the extra spinning mass and pulleys and pinion gear spinning if I don’t need it

 

[tonyfoale]

Yeah I have a Webb Cham head as well i debated doing the same thing by just bolting a stapped pulley to the original variable speed pulley half until i seen how much those pulleys sell for!! But did you keep the back gear on the machine or remove it?

I removed the back gears. I love simplicity. Most of my work is aluminium so I was more concerned with high speed rather than slow. So far even when I have been doing steel with a big cutter it has worked fine. I have worked with this setup for several years now and it has been great.

 

[tonyfoale]

My machine doesn’t have a drawbar or splined drive like yours it’s has this

Do you have more info on that?