ever modify spindle speed range?

[spindlenut]

I was in a customer's shop working on a lathe, and they asked my opinion on their Fadal. It has a 7500 RPM, single-speed timing belt spindle. They say they never use even half that RPM, and would rather have more torque at lower speeds to match their type of work. They wondered about changing the motor and spindle pulleys to get a different drive ratio.

They said even a change of 20% would be useful. I think changing pulleys to drop top speed from 7500 to 6000 wouldn't be a big challenge. I was more concerned with the electrical side. You would then have to program 7500 to get the motor to run top speed so the spindle would be at 6000.

It appears the CNC puts out an analog speed command to the drive unit. There is a parameter "SPINDLE TYPE" for spindle speed. Can this parameter only be set to values that were factory-stock RPMs for the various models, or can it be set to 6000, or any other speed, as long as it is slower than the original 7500?

Also, there is a param "RPM FACTOR", for Spindle RPM Adjustment Factor, with a permissible range of 0-31. The manual is not helpful, merely saying "This parameter should only be adjusted by trained maintenance personnel." So, are there any Fadals experts here that can explain these params to me? I suspect that the customer could indeed modify the machine, but I don't want to suggest that without actually knowing it first.

Thanks for your ideas.

spindlenut

[SBC Cycle]

That's an interesting question. I wonder how that would affect something like rigid tapping.

[Edster]

I have a 94 fadal vmc15 with a 7500 rpm single speed spindle. The pulleys that were on the machine were the multi v ribbed pulleys. They had two ranges one was 1:1 and the other was 2:1. I think they were the same pulleys as the two speed machines but without the second belt and air tensioners.

The previous owner had the machine set up with the 2:1 pulleys and the max spindle speed was 3750 rpm.

I upgraded the pullies to the cogged pulleys with a 1:1 ratio because of belt slippage issues when tapping bigger holes with threadforming tools. And I needed the 7500 rpm for aluminum. The machine rigid tapped fine with the spindle set up for 3750 and 7500. Just make sure the parameters are set right in the control.

I still have the old pullies if your interested.

Good luck.

[spindlenut]

Originally Posted by Edster Just make sure the parameters are set right in the control.

Thanks for the reply, Edster. Yeah, that's the point of my post. What should be the values of the params be? Logically, the SPINDLE TYPE param would be set to the max RPM. Is it just that simple? How about the RPM FACTOR? Even the name doesn't describe what it does.

Originally Posted by Edster I still have the old pullies if your interested.

OK, I'll keep that in mind. As they are already equipped with a timing belt, and plan do slower, heavier cuts, they may want to stay with that setup. But, I'll ask.