What could be the difference? A question on 3520b's

[Roger Chandler]

I have had opportunity to turn on 6 different Powermatic 3520b lathes......although I do not own one........this was at demos I have done and other members of our clubs......their shops.

I turned on one last Saturday for my finial demo.............now an observation I have regarding the different machines, although the same model.

I have noticed about 3 of the machines were whisper quiet in operation, and two of them made significant noise when spinning and one was sort of in between the two extremes. I have a Grizzly G0698 18/47 lathe, and it is quieter than the two that made the most noise and a little more noisy than the 3 that were whisper quiet.

Now..........could belt tension account for the differences in noise level? Perhaps bearing noise on the older units, but some of them were the most quiet of the six I have turned on.........so age does not seem to be definitive.

Any explanations for the difference?

[Greg Ketell]

My 3520b was making "weird" noise one day. I finally realized I had my "knock-off" brand live center installed. I backed off the pressure and the lathe was once again a whisper.

So the main question is: what kind of noise? Could it have been the belt? maybe. Or bad bearings? yep, that's possible. Loose bearings? uh huh. Bad live center? Definitely.

[Roger Chandler]

I noticed the noise with just the spindle turning with a chuck installed.........no tailstock pressure. Having worked on 6 different 3520b's, I am pretty much a fan of them........I just noticed the difference in the way they performed......for instance......at one club I belong to the 3520b there makes a good bit of noise........then at the other club I belong to, theirs is very quiet.

I turned on a fellow members in his garage shop and it was whisper quiet..........then last Saturday at another members shop, his was pretty much as noisy as the first one I mentioned at our club. I was turning a finial for the demo......certainly not any sort of load on the bearings or any tailstock pressure to speak of, but a good bit of noise..........

the best way I can describe it is a whoof-whoof sound and like a fan running at the same time............makes me wonder if belt tension has anything to do with that sound?

[Jeff Nicol]

Some folks have had issues with the sensor for the RPM readout, it can loosen up and actually click while the motor is turning. Next if you have a chuck on and it is in a position where the jaws are where the scroll gears are basically in neutral so that the jaws while actually move and create a harmonic vibration even if you have a piece of wood in the chuck. This can be checked by just tightening the chuck. If those are not the issue then the belt could be the problem if slack or even over tight. One last thing, inside the access door for the belt you will see the wires for the RPM readout, this can actually vibrate around and hit the shaft of the motor and make the woof woof sound.

If it is the bearings those would be easy to check with no tension on the belt and turn the spindle by hand, if they are loose but not grinding, you can tighten the star nut on the handwheel side of the headstock to put a little bit more pre-load on the bearings. In the owners manual it states this as it comes from the factory pre-set and over time and break in the bearings can loosen up a bit and this will take care of that.

Hope that helps with most of these issues,

Jeff

[Brian Kent]

Roger, what are your other impressions of the G0698 compared with the 3520b? Same universe or worlds apart. Are you satisfied with your Grizzly?

[Roger Chandler]

Roger, what are your other impressions of the G0698 compared with the 3520b? Same universe or worlds apart. Are you satisfied with your Grizzly?

Brian........my Grizzly G0698 has been a stellar performer since day one. I have not had one single issue with it......I will add that I am meticulous about the way I do things.........some people have stripped out the ratchet handle that tightens the toolrest in the banjo........it is my opinion and you can take that for whatever that is worth to you, that many just do not allow the thing to seat properly before their hurk & jerk technique just strips it out, but it is the identical handle that is on the 3520b and Jet 1642 evs..

My belief is that the 3520b is a better lathe and heavier, more nicely machined..........but, there is probably not a better value in a full featured lathe on the market than the improved version of my lathe the G0733...

The G0733 has 2 hp, and the same inverter as the 3520b....fully variable speed with almost identical controls to the 3520b....reversing, over 4" of quill travel and other features very similar to the 3520b. It does not have a handwheel, but one can easily be made in the shop for it, and it does not have the cage and extra set of centers for a comparator.

There are other owners here on SMC and of course you can get more info on the lathe at the Grizzly Green Monster Group........If I recall, you joined that group.

If I had my preference between the G0698 and the newer G0733...........it would be the 0733 because of the upgrade in motor and inverter. It is basically a bigger version of the Jet 1642 evs 2 hp.........same features except cage and handwheel!

[Brian Kent]

Thank you very much, Roger. You have offered a perspective I have been looking for.

[Fred Belknap]

Brian I have both machines. There isn't much you can do with the 3520B that you can't do with G0698. The PM is a little heavier but the Griz has another 10" or more between centers. The PM is quiter but the Grizzly runs great. The PM will keep it's value much better than a Griz. Getting rid of a Griz can be a problem, they don't have a good reputation. The PM is a much nicer machine. Roger those little locking handle on the Grizzly all stripped out, I ordered some replacements and cured the problem, no big deal. The Grizzly as it comes from the factory won't accept 1" after market tool rests without some work and the talon chuck I had wouldn't screw all the way on the spindle. I know these aren't insurmountable problems but I think they should be taken care of at the factory.
edit: BTW the face plate on the Grizzly is 6" while the one on the PM is only 3"

[Brian Kent]

Thank you, Fred. I am not buying anytime soon, but I like looking as far into the future as I can so I know how to balance future resources with other parts of life.

[Roger Chandler]

Thanks for the additional Fred.......I had forgotten that the toolrest hole in the banjo is in metric size.......simple fix with a 1" drill bit. My nova inserts fit pretty well........I did have an issue with the wood river insert from Woodcraft...........but I did take a file and turn the lathe on and take off a slight little bit on the spindle shoulder to make everything mate up well. I don't think it is a Grizzly issue as much as it is an issue from the chuck manufacturers who have inconsistent machining at times.........I have had Nova inserts be different from one another, depending on the manufacture date they were made. Of course Teknatool changed over to China from Australia for their machine work and it all went down hill!

[Rick Markham]

I love mine, I guess I have a quiet one. I have two motors for mine (don't ask.) one has significantly less "fan noise" when running wide open than the other. Both run exceptionally quiet, but there is a noticeable difference (very minor.) There doesn't appear to be any design difference in the two motors, or fans on the motor. I just chalked it up to different production runs.

[Brian Kent]

Rick, do you have the Grizzly or the Powermatic?

[Roger Chandler]

Rick, do you have the Grizzly or the Powermatic?

Rick has the 3520b

[Dennis Ford]

I have turned on several 3520Bs and one 3520A, the only noise (other than a slight hum) I have heard was a clicking from the speed sensor when its mounting worked loose. They are great machines but are definitely getting expensive; lathe prices have gone up much more than other equipment in the last several years.

[Bob Bergstrom]

The only noise I have had on my 3520 is that the drive belt was not in the groves properly and the edge of the belt was rubbing on the hub. I would think if the belt is not in the same groves on both pullies it would be similar. I have tighten mine pretty tight when coring big bowls and no noise other than a squeal if the cutter has a catch.

[Rick Markham]

Rick, do you have the Grizzly or the Powermatic?

Whoops! As Roger stated, I have the 3520b :)

[Mike Peace]

Were all of the PMs you used running with the same pulley setting. I hope this is not too basic but it is louder when set to the low pulley for bowls with a max speed of 1500. I pointed this out to a demonstrator who was turning spindles at a symposium. It was much easier to hear him talk after he changed the pulley setting! The noise is much louder then when set on on the high speed pulley running at the same speed.

[Roger Chandler]

Were all of the PMs you used running with the same pulley setting. I hope this is not too basic but it is louder when set to the low pulley for bowls with a max speed of 1500. I pointed this out to a demonstrator who was turning spindles at a symposium. It was much easier to hear him talk after he changed the pulley setting! The noise is much louder then when set on on the high speed pulley running at the same speed.

The two loudest ones were both on the high setting. One was for a lidded box demo and just last week the other for a finial demo........on the finial demo, I was turning at about 2500 rpm.

The quietest one I turned on is a fellow members 3520b and it was whisper quiet...........again high setting, but I was teaching him how to do lidded boxes as well.......he is 81 years old and a retired mental health doctor.....but is fairly robust for his age!

[Josh Bowman]

Mine made a clicking/popping noise that I finally found to be a bearing on the motor. I love my PM 'B', but have noted perhaps a design flaw as compared to the 'A' and the Jet 1642. The 3520B's motor shaft is very long as compared to the other two and I feel that me putting tension on the belt might have broken the bearing, due to the leverage you can exert on the motor bearings and caused the popping bearing noise. So base on that, I only let the weight of the motor tension the belt with just a little nudge to insure it doesn't slip.