??? On PM 3520b VFD

[Joe Meirhaeghe]

Has anyone here figured out how to adjust the VFD Inverter on the Powermatic 3520b??? I' like to turn it down so I can get it to run around 20 to 25 rpm.
If anyone here can explain the sequence on how to do it I'd really like to know.
Thanks Joe

[Harvey M. Taylor]

50 rpm is the absolutely the lowest I have gotten mine to turn. Why would you want it any slower? Max.

[Joe Meirhaeghe]

50 rpm is the absolutely the lowest I have gotten mine to turn. Why would you want it any slower? Max.
I need it slower for finishing the way I finish.
I can get by with 50 rpm for small stuff say 4"to 6" dia. However I often turn large dia. pieces & 50 rpm gives me way to fast of a rim speed to apply finish using my system of finishing.

[Jeff Nicol]

Joe, I think you could make a simple machine using a small gear motor from surplus center to create a very slow turning shaft to mount a chuck or face plate to do your finishing on. If you are spraying finish while the lathe is spinning that could get messy no matter what you do. I don't think you will ever get the motor to run that slow, it is the motor that is stopping you from getting that slow. It has to have some power to get it to spin and overcome th friction of the bearings and armature etc. 50 rpm is pretty slow!

Jeff

[Dick Sowa]

I recommend that you give Powermatic a call. They really stand behind their tools and have (from what I have heard) great customer service. If it could be tweaked to go slower than 50 rpms, then they certainly can tell you. I also have a 3520b, and would be interested to hear what they say. Although I think 50 rpms is fine for anything I do.

Powermatic is owned by WMH Tool Group, Inc. Here's their contact page. http://www.wmhtoolgroup.com/About.aspx?nav=OurInformation

[John Shuk]

Any possibilty of making a handwheel with a handle to turn the spindle by hand while finishing? I really would be leery of trying to tweak the VFD. If you gain on the low end you may lose somewhere else in the RPM range. The change you are proposing to make would require a very experienced tech to help you with and it might be tough to get the help you may need to get things back to where they are now.IMHO.

[Joe Meirhaeghe]

Joe, I think you could make a simple machine using a small gear motor from surplus center to create a very slow turning shaft to mount a chuck or face plate to do your finishing on. If you are spraying finish while the lathe is spinning that could get messy no matter what you do. I don't think you will ever get the motor to run that slow, it is the motor that is stopping you from getting that slow. It has to have some power to get it to spin and overcome th friction of the bearings and armature etc. 50 rpm is pretty slow!

Jeff
Jeff
I don' spray finish while on the lathe.
I know of several people who have the PM 3520 & 3520A and they will go down to zero rpm's. It's done throught the VFD. Powermatic raised the lowest rpm to 50 due to motors overheating in the lower rpm range when used for long periods of time.
I however would only be runing it at the lower rpm for a few minutes at a time.

[Dick Strauss]

Joe,
Reed Gray (aka RoboHippy) has made the changes you mention. He uses the extra slow speed to sand warped bowls. Try PM'ing Reed to see how the VFD levels change has worked out for him. Powermatic tech support will help you out as well.


Good luck,
Dick

[Jeff Nicol]

Joe, Just like what you said slowing it down takes away the air movement and puts the motor in jeopardy of failure. Not sure I would want to do that, but that is up to you. I just think there would be a better solution. I will go out to the shop and whip something up to show you what I was thinking about.

Here is what I came up with after thinking about it and what would be the fastest and simplest. I took a little 12V gear motor that I had and made a little pulley with two rubber O-Rings to drive the hand wheel on the lathe. The motor is mounted to a hinge with a spring for tension. The wood frame was just a quick way to mount the whole thing and it cruised along at a slow 13rpm. Hope this helps and gives you a different look at it and saving your big motor in the long run. I will post a video of it running on my website www.woodennicol.com (http://www.woodennicol.com)

Good luck,

Jeff

[Reed Gray]

I have hundreds of hours of sanding at 10 to 20 rpm over 8 years on my old PM, and a hundred or two on the Robust. When Brent English talked me through the process of lowering the minimum speed on my Robust, he expressed concern that it could over heat. I carefully checked the motor for a few weeks, and it didn't get as hot as when I am doing normal turning. My guess is that is because the motor is running too slow to build up any heat. The 3520A model would go down to almost 0 before turning off. My guess it that PM changed that on the PM because they figured no one would use those speeds, not because of danger of over heating. The converters on the PM and Robust are different, but both can be programmed for a lot of different things, as in speeds, and torque. I am not an electrical engineer, but you do need a technician to help you. One reason PM does not include the hand book on the converter is that they don't want us to mess with them because we don't know what we are doing. I asked them to send me one, and they did. Read about as well as Chinese to me. I think it would be a lot easier to adjust the converter than to add a gear motor.
robo hippy

[Jeff Nicol]

I have hundreds of hours of sanding at 10 to 20 rpm over 8 years on my old PM, and a hundred or two on the Robust. When Brent English talked me through the process of lowering the minimum speed on my Robust, he expressed concern that it could over heat. I carefully checked the motor for a few weeks, and it didn't get as hot as when I am doing normal turning. My guess is that is because the motor is running too slow to build up any heat. The 3520A model would go down to almost 0 before turning off. My guess it that PM changed that on the PM because they figured no one would use those speeds, not because of danger of over heating. The converters on the PM and Robust are different, but both can be programmed for a lot of different things, as in speeds, and torque. I am not an electrical engineer, but you do need a technician to help you. One reason PM does not include the hand book on the converter is that they don't want us to mess with them because we don't know what we are doing. I asked them to send me one, and they did. Read about as well as Chinese to me. I think it would be a lot easier to adjust the converter than to add a gear motor.
robo hippy
Reed, You are probably right on the gear motor. I was just trying to offer other options if not able to figure out the drive. I have a teco drive on my 1236 lathe and it will go down to 1 or 2 rpms but has very little torque. I think this is because the motor is 220 3ph run on 115 1ph so a lot is lost in the process. It works great for letting CA glue dry as it turns real slow though!

Just like goofing around, I made a finishing table like it so I could spray lacquer on as the piece turns and that works very well!

Good luck to all

Jeff

[Dave Schell]

On the Hitachi VFD I used for my Vicmarc, I can set the low end RPM very easily - technically though, you are setting the frequency, not the RPM when adjusting the VFD. What brand/model VFD is on the PM? Have you tried finding the owners manual online? If you can find the manual, most have pretty clear instructions on changing the right parameters to set startup and max frequencies.

[Dave Ogren]

Here might be a thought. The motors do not run well when they are reduced into the 1 hertz range, but they usually run well at 2 hertz. That means that the full speed the motor is running at 60 hertz you should be able to divide by 30 and depending what your ratios are at full speed you will be able to approximate the RPM at 2 hertz. This is why some of the larger motors (2 horse power and up) come in a variety of RPMs, including 1400 and even 1100. I know that this won't help you a lot because you are not going to swap out the motor, but might help those who are thinking about building their lathe from the ground up. If also sort of explains the RPM range. Good Luck.

Dave

[Joe Meirhaeghe]

Joe, Just like what you said slowing it down takes away the air movement and puts the motor in jeopardy of failure. Not sure I would want to do that, but that is up to you. I just think there would be a better solution. I will go out to the shop and whip something up to show you what I was thinking about.

Here is what I came up with after thinking about it and what would be the fastest and simplest. I took a little 12V gear motor that I had and made a little pulley with two rubber O-Rings to drive the hand wheel on the lathe. The motor is mounted to a hinge with a spring for tension. The wood frame was just a quick way to mount the whole thing and it cruised along at a slow 13rpm. Hope this helps and gives you a different look at it and saving your big motor in the long run. I will post a video of it running on my website www.woodennicol.com (http://www.woodennicol.com)

Good luck,

Jeff
Jeff that looks like a viable option. However I don't happen to have a 12v gear motor laying around.:( Send me the motor & I'll try it out.:)

[Joe Meirhaeghe]

Jeff that looks like a viable option. However I don't happen to have a 12v gear motor laying around.:( Send me the motor & I'll try it out.:)

:confused: Seriously Jeff.
What's the spec's on the motor you would use for this & where could I get one??

[Steve Busey]

Joe, a quick Google search on "12V gear motor" returns plenty of choices. If you have an industrial supply house near you, they may be able to set you up with something. HTH

[Jeff Nicol]

:confused: Seriously Jeff.
What's the spec's on the motor you would use for this & where could I get one??
Joe, Go to SURPLUS CENTER on the internet and see what they have. I looked n my catalog I get from them and they have so many that I got goofy eyed looking at them! They also have some clock gear motors that run on 115V and would work even better I think. The ones I have are about 20rpm I think I would have to do a test count to be sure as they are not marked. I did also find a website that has all the instructions on the VFD that is on my machine. My PM3520B has a Delta S1 on it, is that the same as yours? If so you could check out the info there.

Jeff

[Reed Gray]

I called WHM tool Group and asked a technician. No one has asked that question before. He will talk to a supervisor and test it out on an in house lathe and get back to me. Will keep you posted.
robo hippy

[Joe Meirhaeghe]

Joe, Go to SURPLUS CENTER on the internet and see what they have. I looked n my catalog I get from them and they have so many that I got goofy eyed looking at them! They also have some clock gear motors that run on 115V and would work even better I think. The ones I have are about 20rpm I think I would have to do a test count to be sure as they are not marked. I did also find a website that has all the instructions on the VFD that is on my machine. My PM3520B has a Delta S1 on it, is that the same as yours? If so you could check out the info there.

Jeff
Jeff
My VFD is also a DELTA S1 model 015S21U
Could you please send me the web site?
Thanks Joe

[Joe Meirhaeghe]

I called WHM tool Group and asked a technician. No one has asked that question before. He will talk to a supervisor and test it out on an in house lathe and get back to me. Will keep you posted.
robo hippy
Thanks Gary.
I work retail & have a very hard time contacting business during buisness hours. Please do keep me posted. & email me with their results.
Thanks again Joe

[Reed Gray]

Well, I got a responce from PM, and it left me with more questions. I got a call from David Gentili (1-800-274-6846). He said it can be done but voids the guarantee on the motor. Reason being heat build up. To do this, you have to remove the converter and send it to the factory so they can 'remove the lock out'. I told him that on my old PM, I raised the braking time, and did it over the phone, and he was surprised because they have had the lock out in for a while. He also said that the A model would turn off at around 50 rpm like the B model. I told him that mine would go down to almost zero before turning off. I guess mine was an antique (now more than 9 years old). He had no explanation for while I sanded out 8,000 or so bowls, on both my PM and Robust, there was never any heat build up, that his model did. Maybe they are protecting us from ourselves.
robo hippy

[Jeff Nicol]

Jeff
My VFD is also a DELTA S1 model 015S21U
Could you please send me the web site?
Thanks Joe
Here are 2 websites for the Delta S1 manual the second one is best I think

http://www.chudov.com/manuals/Delta-S1-VFD/

http://www.powercontrol.com.au/Delta/VFD-S%20Manual%20part%201.pdf


Jeff