Centroid Community CNC Support Forum

After watching one of Franco's videos where he plans to use a DMM AC servo motor for spindle, I'm wondering how you would connect this to the Acorn? I'm assuming the motor is looking for step/direction. If wired into the 4th axis on the Acorn, can you do that? And then how would you control the spindle? I'm pretty clueless with G-code/M-code, but assuming there's gonna be some messing around necessary to get it all to work? I've sent an email to DMM and perhaps that will help inform me on how this will work out.

I emailed DMM today and, assuming I understood what the guy is telling me, the Dyn4 driver can take the 0-10v signal from the Acorn. The Dyn4 must be used because the Dyn2 driver doesn't have the encoder output to the Acorn. And, interestingly enough, the Dyn4 will run on either 110 or 220v AC.

ScotY wrote: ↑Tue Nov 21, 2017 8:58 pm I emailed DMM today and, assuming I understood what the guy is telling me, the Dyn4 driver can take the 0-10v signal from the Acorn. The Dyn4 must be used because the Dyn2 driver doesn't have the encoder output to the Acorn. And, interestingly enough, the Dyn4 will run on either 110 or 220v AC.

That is correct. Use the analog spindle output from Acorn to Dyn4 servo amp. AND if you intend on using the encoder on the AC servo motor, you need to belt that servo motor to the spindle with a timing belt at 1:1. No V belts, no poly belts....Make sure the belt is strong enough for the torque from the motor.

Marty

Hi Marty,

That's what I need to do in order to use the DMM servo motor. My mini mill uses a v-belt. I would need to find a way to replace this with some sort of timing belt and pulleys.

I'm looking to purchase a 750 watt servo motor. Any suggestions on size/type of timing belt to use? My current spindle pulley has a 30mm bore with a keyway. The motor has a 14mm shaft. I want to gear it 1.5:1. The motor runs around 4000 rpm max and I want 6000 rpm at the spindle. I'm not sure I'm going to have enough room. I also don't know how I would cut a keyway.

Is there a setting in CNC12 that would allow ratio adjustment for the spindle? Hadn't thought about that until you mentioned gearing 1:1.

Literally just posted about this in another thread.

Okay, so I'm still struggling with finding an appropriate belt/pulley setup. However, I have been poking around in the CNC Wizard and there does not appear to be any way to adjust the drive ratio between the spindle and motor...at least there is no setting in the wizard. But perhaps there's a hidden secret way to do this? CNC12 seems incredibly powerful, I can't help but think there's a way. Anyway, it would be very nice to be able to do this so as to not limit my maximum spindle speed. I am wanting to use a 1:1.5 ratio to speed up the spindle.

If you want to thread and rigid tap spindle encoders must be connected to the spindle in a one-to-one ratio.

If you want to use the DMM motor at some other ratio. You'll have to install another encoder on the spindle 1:1 and use that to connect to Acorn.

Alternatively, it is quite affordable to buy a small three phase motor and vfd that will all run off 110vac.

Thanks for the info, Keith. In case anyone wants to know why it must be 1:1, Keith said in a PM that there's some sort of marker signal the encoder outputs and this makes a 1:1 ratio a requirement. I'm assuming it's some kind of once per revolution signal.

ScotY wrote: ↑Sat Nov 25, 2017 5:43 pm Thanks for the info, Keith. In case anyone wants to know why it must be 1:1, Keith said in a PM that there's some sort of marker signal the encoder outputs and this makes a 1:1 ratio a requirement. I'm assuming it's some kind of once per revolution signal.

It uses the marker to know where the revolution starts. It's like "home" for every revolution.
However, Acorn "monitors" every pulse of the encoder during it's revolution after that. That way if the spindle changes speed slightly, it can coordinate the other axis to match. This is particularly important for threading and rigid tapping.

Clay

ScotY wrote: ↑Tue Nov 21, 2017 10:58 pm Hi Marty,

That's what I need to do in order to use the DMM servo motor. My mini mill uses a v-belt. I would need to find a way to replace this with some sort of timing belt and pulleys.

I'm looking to purchase a 750 watt servo motor. Any suggestions on size/type of timing belt to use? My current spindle pulley has a 30mm bore with a keyway. The motor has a 14mm shaft. I want to gear it 1.5:1. The motor runs around 4000 rpm max and I want 6000 rpm at the spindle.

A lot narrower than you think. Personally my favorite belts are Continetal Silentsync (formerly Goddyear Eagle PD), however they are not easy to get, have limited length selection, and they're pricey. They are the quietest synchronous belt you can find.
On my current lathe project I will using an 8mm wide belt with a 1000watt motor@3000rpm. I am gearing 1:1
6000rpm is pretty high speed for most timing belts under continuous duty.

I suggest start looking at the stock drive products website for engineering data.

Clay