installing and setting up a c axis

[bhdh405]

can or has any one used a clear path fractional hp motor to run there spindle with and then used it for positioning the chuck to do live tooling off of. my system has a acorn board but that can change easly to something that will work. i have not found anything that describes how the c axis is set up and works but it is probable hiding out there some place so any help would be greatly appreciated.
butch

[eng199]

Posts that may be relevant:
https://centroidcncforum.com/viewtopic. ... ayr#p65389
https://centroidcncforum.com/viewtopic. ... xis#p75429

[MichiganCNC]

That was my idea too, to somehow use the Clearpath fractional hp motor simultaneously as the spindle motor and as the C axis motor without needing to have a clutch mechanism in between two separate motors. Or even use a large Nena34 motor.
It all depends on your torque requirements for when you are cutting in C axis mode. But if you put a 1:2 pulley system on to get more torque, then the spindle mode top speed is cut in half.

[MichiganCNC]

The Clearpath fractional hp motors can run on 120V single phase or on 240V single phase or 208V three phase, but when run on 110V single phase the rpm’s only go up to 1000 (1/2 of the others). I don’t know why, I was going to ask them about it.
The nice thing with them is you can buy the optional winding blower motor to keep it cool even when turning slowly at C axis machining speeds.

[MichiganCNC]

CNC4PC.com has a breakout board specifically for the Clearpath motors for use with Acorn, which seems neat cause it has the Clearpath Molex signal connectors on it - plug and play. C86ACCP ,also another one for Acorn 6

[MichiganCNC]

In this post Suntravel describes how to switch using M51 from spindle mode to C axis mode.
https://centroidcncforum.com/viewtopic. ... 429#p75429

But I wonder if since it acts just like a large stepper motir, if one could simply rename it to be the A axis, and simply step theClearpath hp fractional motor fast for spindle use and slow for C axis use.
Perhaps one could even forego a spindle speed encoder and just assume that the steps from a large motor on a small lathe would not be missed and this the spindle rpm equals commanded rpm in steps.
Worth a try.

[MichiganCNC]

This post says to purchase the enhanced resolution option on the Clearpath motors.

https://centroidcncforum.com/viewtopic.php?f=60&t=5531

[suntravel]

I am running the the C-axis drive with 8000 steps and 4.5:1 reduction.

This makes 36000 steps for one revolution, so the CNC can control in 0.01 deg resolution and the C-axis have 2500 oz-in torque

This is only good for light milling with ok precision.

Take it into consideration if you choose a spindle servo to drive the C-axis with one servo and 1:1 or 2:1 reduction.

My small production CNCs have 10hp servos and 90000 line encoders for parts up to 30mm diameter

Uwe

[MichiganCNC]

Thankyou Uwe.
Clearpath says about the enhanced resolution option:

—For the SDSK, MCPV, and SCSK models, the Enhanced option provides position setting capability of 1/32000th of a revolution. The Regular option is 1/4000th. The Enhanced option also increases the available RAS (jerk limiting) settings on the SDSK models.

Everyone (me especially) needs to realize that the Clearpath motors are *NOT* steppers but are *SERVOS* with control cards that present them as steppers to the outside controls. Thus they actually should keep themselves from “losing steps” like a stepper would. Well, at least up to their physical torque ability to prevent that.