LMS 8.5 x 20

MAE

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Anyone know if this machine can somehow be slowed down to lower than 100rpm?
 
Hi MAE,

I asked Chris at LMS if it could be done and he said not that he was aware of. I would like to slow mine down some for threading, but the more I practice, the more comfortable I'm getting with it.

"Mcripper" posted a mechanical mod he made to slow down a smaller Hi Torque lathe using an additional belt and some custom made pulleys and mounting brackets. He essentially added a "low" speed range. It's quite a project. Very impressive. http://www.hobby-machinist.com/show...own-mod-for-hitorque-lathe?highlight=hitorque

Let us know if you find an easier way.

Tom
 
Given that the machine has a BLDC motor, it should be capable of going down to about 1 RPM. This sounds like it is limited in the controller software. I would contact LMS and see if they can offer any advice.
 
Thanks guys. I don't know anything about controls but I wonder if you could just put a different speed pot on it.
 
Tom

This is off topic but how accurate does yours thread fine pitches like 32 and higher.
 
Thanks guys. I don't know anything about controls but I wonder if you could just put a different speed pot on it.

I'll give you a qualified MAYBE. Let's say it currently has a 5K ohm pot, going to a 10K won't hurt it. Maybe it's worth a try. The problem may be that the analog signal from the pot is converted to digital in the controller, so once the voltage reaches a certain low point, the digital output the the BLDC controller just won't go below it's programmed low set point. In that case all that putting in a 10K pot would do is limit the range of the pot. I'm not sure if it's possible to do what you want without going into the firmware and reprogramming it.
 
MAE,
Sorry, I haven't tried anything finer than 20 tpi, yet. It did 20 just fine, though. I have no reason to think it won't do finer threads okay, too.

Jim,
I asked Chris, the owner of LMS, about slowing it down and he said he didn't know how to do it and had not heard of it being done.

Both,
Are you guys talking about changing an internal speed pot? The 8.5x20 doesn't have an external pot for controlling speed. It uses membrane buttons to change speed in 10rpm increments. As for 1 rpm, I'm sure you know that could present a motor cooling problem. I have wondered if that's why the minimum from the factory is 100 rpm, for prolonged threading sessions, but haven't found an answer.

Tom
 
Jim,
I asked Chris, the owner of LMS, about slowing it down and he said he didn't know how to do it and had not heard of it being done.

Both,
Are you guys talking about changing an internal speed pot? The 8.5x20 doesn't have an external pot for controlling speed. It uses membrane buttons to change speed in 10rpm increments. As for 1 rpm, I'm sure you know that could present a motor cooling problem. I have wondered if that's why the minimum from the factory is 100 rpm, for prolonged threading sessions, but haven't found an answer.

Tom

I didn't know it does not have an external pot. In that case, you are changing a counter in the controller with the keypad, thus the entire system is digital. In that case, the only option would be to make firmware changes. I have seen analog control of BLDC motors, but it is always converted to digital in the controller through an A/D converter.

As far as motor cooling, is that motor not cooled by a fixed speed fan driven by it's own small motor? All of ones I have seen are cooled that way, not dependent on motor RPM for cooling.
 
Well that stinks. I never noticed the speed control until you mentioned it. It really goes up by increments of ten? That's not mentioned anywhere in the specs. You figure that would be good to know.
 
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