The turbocharged 14.5

[RandyWilson]

Does anyone know off hand the primary pulley ratio for a 14 1/2"? And motor speed? I assume a 16 would be the same. I put a handheld tach on my spindle last night, it's running more than double what my documentation says. The slowest direct drive measures 460, should be 215. The motor and pulleys have been changed, long ago by appearances. The math says it's a four pole motor.

 

[tq60]

Is yours single or 3 phase?

Original motor?

Ours is 3 phase 2 hp and we could measure if needed but it is a bit difficult. ..junk in the way...

Suspect if single phase possibly a 3600 rpm motor may have been used resulting in the double speed maybe.

We have a photo someplace of the motor plate as we needed it to search for vfd and it was in a spot we could not see...

Seems to be 1700 or similar common standard speed but being 3 phase could be other general low speed.

Others may have better data handy or later we could look.

Normal speed motor would require substantial change to double end speed.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

 

[RandyWilson]

No no, don't go to that kind of trouble. I was just hoping someone had the specs at hand to appease my laziness.


The motor and pulleys have been changed. That is obvious because it has a single large/wide belt. And the flame-cut a notch in the pedestal to clear. It is 3 phase. By marking the spindle and motor pulley, I eyeball counted 3.8:1 motor to spindle with the flat belt on the slowest pulley. Based on the 460 spindle speed, this gives a nominal motor speed of 1750, which sits within error margins of calling it a four pole motor.

Then to make matters more complicated, these alternate pulleys appear to be variable speed; looks like an old F440 (aka snowmobile) drive. So it's very possible that loaded speed will be different than free-running.

I just ordered a pulse tach off alibaba.

 

[Bob Korves]

The ratio of the diameters of the pulleys determines the change in speed. Two inch motor pulley and four inch drive pulley with a 3450 rpm motor gives a 1725 driven pulley speed. With V belts the measurement is to about the center of the belt inner and outer diameters. You are trying to slow it down to 215 from 460. If you make the motor pulley .47 the size it is now, or make the driven pulley 2.14 times larger, you will be there. Changing the motor to one with half the rpm would do the same approximate job.

 

[woodtickgreg]

Or just run a vfd to slow it down. If it runs ok at the higher speed and doesn't appear to be heating up that could be a good thing as it might run carbid tools better. Dunno?

 

[RandyWilson]

Thanks Bob, but that didn't answer my question. I asked what is supposed to be there because I'm curious what is supposed to be there. This isn't because I'm going to change anything. I just want to learn about the machine. It's certainly not important enough for someone to spend time digging in and measuring their machine.

 

[woodtickgreg]

You have not been able to find an original parts break down?

 

[RandyWilson]

The South Bend parts manual just says to measure the current pulleys when ordering new.

Like I said, this is just a curiosity thing. Unless this variable drive does strange things under load, I'm not going to change anything. The only place there would be trouble is if I needed slower than it will allow. While the VFD will drive the motor at 30hz, even 20hz, I'm a bit skeptical of the durability that far out of designed operating parameters.

 

[RandyWilson]

It's definitely a variable pulley. I may be able to slow things down a bit by adjusting it, though it is pretty much at the minimum radius already. Before that can happen, I will need shorter belts. Both the v-belt and flat belt adjustments are maxed.... the motor touches the floor when the cam goes over-center.

 

[woodtickgreg]

Well that definitely is not a stock set up. I can see why it is running so fast. Do your bearing caps for the spindle get warm when it is running? Kind of a shame someone hack the cast base like that to get that set up to work. Maybe a shorter belt would have been all they needed to do to install that instead of hacking the casting. Do those 2 pulleys move in and out like a variable or are they now fixed in place?