speed on 3520

Re: speed on 3520

Gary, the minimum speed in my 3520 is 48 rpm

Re: speed on 3520

Before my controller went bad, I could go to Zero rpm but its replacement will not slow to even 50 so I would l0ve to find a solution that gave me back my Zero!  p.

Re: speed on 3520

My 3520B will go as slow as the 50 RPM specification stated.

That is pretty darned slow....plenty slow for anything I have ever needed....like spinning wet finish to prevent runs, etc..

I am curious.....what does he wish to do that requires 25 RPM?

Re: speed on 3520

Full disclosure - I don't have a powermatic (but did have a Jet for several years). I believe there's a setting in the VFD that controls minimum speed. seems like the information may be available through the mustard monster site or from someone who has had to program a new VFD...

Small Word for Caution

Don't forget that your big motor in TEFC.  If you run your lathe at such slow speeds for too long, there won't be enough air flow to keep the guts within operating range and you can fry that motor.  When running my Stubby that slow for finishing a larger jar, I had to run a small fan to keep the motor from overheating.

thanks, all, for your comments

I'm not sure he said why he wanted to go to 25 -- perhaps finishing -- but he does make some unusual pieces too.  

Another WC'er also mentioned the temperature issue to me privately, so that could be a limiting practical factor.  

Oddly enough, the demonstrator, who said likes to go near zero for applying finish, and prompted the question, has a Stubby.  He didn't mention the temp problem with it -- apparently he limits the time.  

Re: thanks, all, for your comments

I'm certainly not going to argue against the possible problem with overheating at low RPMS. However, if the low speed is used for pieces that are at their last stages of completion, especially finishing, then the load on the motor is very little compared to doing the normal cutting and the workpiece is very light.

Bill

Re: thanks, all, for your comments

Rather than potentially damaging the lathe motor, I suggest he build a stand alone rotisserie type unit for the slow rotation, allowing continued use of the lathe during the drying process.