15 hp vmc on 10 hp converter? Temporary test

upthebikes · Jul 2, 2020

Taking delivery of a new-to-me vmc soon, and the deal got done quick.

3 axis Fanuc OM Japanese machine, spindle rated 15hp. I currently run a 10hp balanced phase craft panel from our member jim here with a toshiba 10hp converter duty motor. I don’t think I’ll have time enough before the machine gets here to source and build a larger converter ...

In order to inspect the machine and make sure nothing was damaged during rigging / transport etc, I’d like to hook up existing power to it and check it out. Thoughts that this might work? Am I at risk of damaging any drives by doing so?

I am guessing a low voltage alarm would pop up if this doesn’t have enough juice.

Thanks!

Hardplates · Jul 2, 2020

I would imagine the only time you might have trouble is starting the spindle which can be circumvented by adjusting the accel rate either through the controller or the spindle drive itself.

upthebikes · Jul 2, 2020

Thanks for the reply, I did not think of adjusting the accel via control. Good idea.

vmipacman · Jul 2, 2020

Mills dont have the inrush or startup torque anywhere near lathes do. You’ll be fine. Especially for “testing”. Could probably take up to a 50% cut without running into trouble.

Bobw · Jul 2, 2020

vmipacman said:
Mills dont have the inrush or startup torque anywhere near lathes do. You’ll be fine. Especially for “testing”. Could probably take up to a 50% cut without running into trouble.

What he said. A VMC spindle is a tiny little thing. And takes almost nothing to get them going.

Lathes.. Totally different story. A lot of mass at a large diameter to get moving.

You should be fine.

upthebikes · Jul 2, 2020

Thanks everybody.

Mud · Jul 2, 2020

If you have any other 3 phase equipment that you can run at the same time without load, just idling like lathe motors, turn them on and let them run at the same time - they will work like larger idler motor. It worked for me.

Garwood · Jul 2, 2020

I would take it real easy on spindle starting/stopping with a 10HP RPC.

If it were me I wouldn't even try to run the spindle at higher speeds without a 30+ HP converter.

Spindle drives don't do well starved for power. Or the wrong voltage.

upthebikes · Jul 2, 2020

I’ve got 3 2hp mills, 1.5hp drill and a 1 hp cold saw I could flip on first, good idea for idlers.

My 7.5hp vmc worked just fine, but that has sold and moved out in prep for the new one.

Mill takes 230, my output is balanced and at 235 so should be OK there I think. Machine comes with a full set of manuals so I can dig through before I push the button.

And again not going to cut anything, just want to see if all basic functions are there.

rpseguin · Jul 2, 2020

You should be fine, as the spindle is unloaded. The only load is turning its own mass and swirling air.
My VMC’s 10HP spindle consumes less than 1 KW when swirling air at 8000 RPM.

You probably won’t need to, but you could also set spindle accel parameters.

rpseguin · Jul 2, 2020

If you’re willing to be patient, you can set accel parameters and spin up just about any motor size you want.

I found a 200HP Toshiba motor at the scrapyard and my friend bought it.

We tested it hooked it up to a 100HP ABB VFD fed by a 14 gauge orange extension cord that was carrying 480V 1ph out of a 240V to 480V transformer.

We were even able to drive the 1700RPM motor up to 80Hz/2400RPM

YouTube

Bobw · Jul 2, 2020

rpseguin said:
If you’re willing to be patient, you can set accel parameters and spin up just about any motor size you want.

I found a 200HP Toshiba motor at the scrapyard and my friend bought it.

We tested it hooked it up to a 100HP ABB VFD fed by a 14 gauge orange extension cord that was carrying 480V 1ph out of a 240V to 480V transformer.

We were even able to drive the 1700RPM motor up to 80Hz/2400RPM

YouTube

I USED to run RPC's. I've got a big old Mazak. Not Huge. 10" chuck. 20hp continuous.
25 for 30 minutes. so that's like 75 HaasPower.

Could not get that sucker to start in High gear. Even bringing the spindle ramps back
to 10 seconds, it still couldn't do it. Low gear 0-1200 would start at a 5 second ramp,
so that's what I did. 1st gear until real 3 phase got here.

But on that same phase convertor, just messing around, I got up to a 23hp cut on a Fadal
before it started to bog. I don't know if that was the phase convertor, or the spindle
drive.

3 phase day was awesome. The second the electrician said we are good to go, I ran inside,
fired up the lathe and ran her in high gear. Wasn't as good as sex, but it was still pretty
special.

Edit: Duh, it was either a 20 or a 25hp RPC. I don't remember, had one of each for a while.

Garwood · Jul 2, 2020

rpseguin said:
If you’re willing to be patient, you can set accel parameters and spin up just about any motor size you want.

I found a 200HP Toshiba motor at the scrapyard and my friend bought it.

We tested it hooked it up to a 100HP ABB VFD fed by a 14 gauge orange extension cord that was carrying 480V 1ph out of a 240V to 480V transformer.

We were even able to drive the 1700RPM motor up to 80Hz/2400RPM

YouTube

The accel and decel parameters in a Jap spindle drive likely aren't that flexible. A VFD is kind of a universal multi-use device. A Fanuc spindle drive does not take prisoners. It kills every pixie it can to get the tool up to speed. Set all the way to max ramp up time gives you like an additional 1/2 second to reach programmed speed.

15 Fanucpower is A LOT of horseponies. That's a real big motor. that's like Haaspower squared or whatever the formula is.

mmurray70 · Jul 3, 2020

Garwood said:
The accel and decel parameters in a Jap spindle drive likely aren't that flexible. A VFD is kind of a universal multi-use device. A Fanuc spindle drive does not take prisoners. It kills every pixie it can to get the tool up to speed. Set all the way to max ramp up time gives you like an additional 1/2 second to reach programmed speed.

15 Fanucpower is A LOT of horseponies. That's a real big motor. that's like Haaspower squared or whatever the formula is.

Anybody here have any real world experience with reducing Fanuc Spindle ramps? My next lathe will likely be Fanuc control and I will definitely need the slower ramp time to keep peak demands reasonable.

Hardplates · Jul 3, 2020

mmurray70 said:
Anybody here have any real world experience with reducing Fanuc Spindle ramps? My next lathe will likely be Fanuc control and I will definitely need the slower ramp time to keep peak demands reasonable.

I think its dependent on the control and drive. I have an OT-c that I have played with regen limiting F-20 on the drive. In the past I had to limit it more than factory to not trip my phase perfect. Now that I don't use the phase perfect I have it set to regen more than original specs. F-19 is accel deccel rate which I have never played with as I've never had an issue with inrush, only when trying to dump power back into the grid.

I do have a Mitsu Meldas 300m series control that I have played with accel/deccel quite a bit from the controller which I believe is in milliseconds from 0 to max. The controller is far more advanced than a Fanuc O but it doesn't seem to have a regen limit option or any option to adjust accel and deccel independently.

jermfab · Oct 14, 2020

Upthebikes, your inbox is full. I have a reply to your PM

upthebikes · Oct 15, 2020

Oh ok, thanks. I’ll clear it in a few minutes here.

As an update for this, the 10 hp converter worked fine for testing, no accell decell adjustment necessary.

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