Powermatic 3520B Vibration Issue

[jason lambert]

Well I bought a big mustard before the price increase and right our of the box it had a vibration between 600-1200 RPN not a big vibration but enought to feel. I called Powermatic and they sent a new upper pully since it was dinged up and thought that may be off balance. A-Pro Machinery came and installed it with some nice channel locks and scored up the new one as well. Once they left it still had a vibration a little better but still vibrates. I called back powermatic and they sent them back out and they told me all machines vibrate at a certain speed. I asked and this was the first one of these lathes they worked on and I tried to explain it shouldn't vibrate. They closed the ticket and that was it.

So my question is do you big musterd owners get a vibration at certain speeds? It is had to quantify but lets say I can't stand a nickle on end on the machine but it probably would not/ or just about vibrate a penny flat.

none of the jets, oneways or others that I have worked on vibrate this bad. Did I just get a lemon? I called powermatic again and asked them just to send out a new headstock and I would send the old one back since it was banged up right out of the box but they willnot all they will send is parts and told me I can install them.

[Tony De Masi]

I've had mine a bit less than two years with absolutely no vibration issues. It's one of the things I checked for when I got it. Ran the machine the full range of speeds with no issues at all. It will probably be a PITA but I would keep bugginng CS until it is resolved to your liking.

Tony

[Pete Jordan]

Jason,

The only time I have had vibration was when I forgot to tighten the headstock lever on the back after I moved it down the ways.

[Philip Morris]

Jason,
I can't speak to the 3520, but I can comment on your reference to other lathes. I had a Oneway 1640 and had a mild vibration between 1400 -1600 rpm. It was enough to cause the control pendant to vibrate slightly. I called Kevin at Oneway and he said that all large machines have some place in the rpm range that will vibrate, but that with the variable speed you should be able to slow down or speed up to avoid it. It surprised me that they could not design the vibration to occur outside the rpm range of the lathe.

I'm sure that others will respond to this with opposing views. I just thought I would pass on what I was told by the manufacturer of another quality machine.

[Jeff Nicol]

I have had my 3520B for 2 years and when I first set in up with the cheap little adjustable feet on it, I vibrated all the time no matter hom hard I tried to level it. So I took a 2 1/2" plank of white oak and mounted the lathe to that across the ends then shimmed that. But like all things that spin and have motors on them there will be some place in the range of speed when everything is right and a harmonic vibration will occur. Not every pully, gear, belt or shaft is perfect in every way. So if the belt has a little bump in it and it vibrates at a cetain speed that is what it is. When I worked in commercial heating and air conditioning with big fans that are 6' across sometimes we would tighten everything up again and the vibration would quit or change where it did it on a slow ramp up to the working speed. So if it can be eliminated buy speeding up or slowing down a little that is most likely what you will have to do. My first cheapy beater lathe never had a vibration in it until I put on a different motor and a Vfd to make it variable speed, now somewhere between 400 to 550 rpm it has a little vibration and goes away as I chage the speed.

I know I am being redundant but I hope it all works out for you!

Jeff

[Gary Herrmann]

Jason, I have no vibration in mine at all. A score pulley could contribute if the belt is hitting it at all. Take a pic and send it to them saying this is how your guy installed it.

Have you also leveled the lathe from end to end and side to side as dead on as you can? As you know, cast iron will flex. When I was setting mine up I was impatient and just wanted to turn it on. It vibrated some since I hadn't finished leveling it at that point.

[Richard Madison]

Jason,

My original Jet 1642 had a vibration. After checking the belt for flat spots we removed the belt and found that the motor had the vibration. The replacement does not vibrate. Suggest you try this if you haven't already. The motor should not vibrate.

[ROY DICK]

What Gary suggested. level, level, level. Anytime one item is in motion something has got to and will vibrate a little, but if it is accessive after leveling, I would call them back. It took a while for me to fine tune mine.
I sure hope you get this corrected for in mho it is one sweet machine.


Roy

[Reed Gray]

The only times any of my lathes have vibrated is when there is an unbalanced chunk of wood on it, this includes a PM3520A model that I turned on for 8 years. With no chuck or face plate, I wouldn't think that there would be enough weight to make it vibrate. Check for run out on the spindle. I have heard of bad motor bearings making things vibrate at certain speeds.
robo hippy

[James Biddle]

Ditto to what Gary and Roy said about the leveling. Mine ran perfectly smooth after the initial tuning. A few months back, I moved the lathe over a couple of feet and noticed the vibration right away around 1000~1200 rpm. I re-leveled the table and its back to smooth again. So you know, we're talking precision leveling here, not torpedo leveling. Take your time and you'll be rewarded.

[Philip Morris]

Jason,
Again, for what it is worth. With my Oneway, it was not so much an issue of being level in the sense that a carpenter would use the term. It was more that there was equal pressure on each foot.

My 1640 had two pads that were inserted under the legs at the headstock end. There were allen bolts in each leg that were turned to equalize the pressure on the rest of the legs. Like others have said, it can require "fine" tuning in that only a 1/4 turn on the bolt would make the difference of equal weight on all the legs or one with little or no weight.

My method of testing the weight distribution was to go around the machine and kick the legs with steel toe boots (a dead blow hammer would also work). A thud indicated good weight on the given leg. A ping or movement meant the leg was not sitting firmly.

[Sean Troy]

The collar behind the handwheel may not be tightened to specs. I had that problem once with my 4224. Tightened it and the problem went away. You don't want to crank it down but at least check to see how easy it is to move it to the tighter side. You'll need to use a tool and place the edge of the tool in one of the grooves on the outside of the retaining collar and gently tap with a wooden or deadblow hammer and see if the collar moves towards tightening.

[jason lambert]

I leveled the lathe but did not check pressure on each foot I will check that tonight I did make a video to send powermatic with the link below 3722 is the better one. To bad the sound you can't hear the ticking and the frame rate is a lttle slow but I can actually see the vibration but I was able to meter it. Let me know if this seems normal for this machine.

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[Jim Koepke]

Resonance is a strange thing. Many of the ideas given before this will likely correct the problem.

At one time my employment was in the field of drafting. One company built breathing air compressors. One was designed by the head engineer's wife. It never worked successfully, it would usually seize or fly apart.

Looking at the design drawings, the reason to me was quite clear. The shafts and piston rods were all dimensioned to match the wave length of the operating speed of the compressor. When I tried to explain this to the head engineer, he looked at me as if I was a nut and said such a thing was not possible.

The other company that employed me made diesel engines for ships and backup generators for the nuclear industry. There, resonance was considered in all designs. Structural members of control panels were never evenly spaced and there was not a repeated dimension in the spacing of the studs for large structures.

So, some design engineers get it some do not.

The base on my lathe was made by the previous owner. A few places have been found where clamping some weight or a scrap of wood across the supports will dampen the vibes.

Of course, having all the feet firmly on the ground is also a big factor in this.

jim

[Dave Mueller]

Jason,
I built my own lathe, and found that I had a vibration at a specific speed. It turned out to be vibration of the belt between the two pulleys. Since mine is driven by a V-belt, not a flat belt, this may not apply to your lathe. Anyway, it's worth a look. If it is the belt vibrating, you might be able to lessen it by tightening the belt a little.