Powermatic 3520c

[Paul Durden]

Does anyone do anything besides set their powermatic 3520 lathe on a concrete floor? I have it pretty much leveled, but still get some vibration with larger bowls and til they are trued up. Or maybe this is just the norm?

 

[Dave Landers]

Mine's sitting on the concrete floor. You want to make sure that in addition to being level, that there's equal weight on all the feet (ensure that one foot isn't being a spineless wimp and shirking its duty).
Out of balance stuff - I start at a low speed. If the lathe starts bouncing, I turn the speed down. You can increase speed as the blank gets more balanced.
Some people build a box or shelf between the legs (hanging on those brackets cast into the legs) with a couple hundred pounds of sand or something similar. I used to have that, but don't find it necessary now (and it made cleanup under the lathe a real pain). That doesn't prevent the lathe from bouncing with unbalanced wood, but does change the dynamics, and may let you start at a bit higher speed. An option to try if you're regularly roughing large unbalanced blanks.

 

[robo hippy]

Once my lathe is leveled up, I do mark on the floor where the feet are when it is all leveled up. Any lathe that isn't bolted down to the floor will walk around a little bit. I think this holds true even if you only turn smaller things because there is always some vibration. My final step to leveling a lathe is to put an unbalanced piece on the lathe at slower speeds, 500 or less, then raise one foot just slightly off the ground. This should cause some vibrations. I then lower that one foot down till vibration stops, then maybe a minute or 3 past that point, just a hair. It seems that when I lock that nut in place, it is just enough pressure to make that one foot very slightly high. Concrete is ideal. It can be done on wood floors, but those who do usually put more reinforcing under where the lathe sits. Floors can flex a bit. This is more of a problem with houses that use floor joists on 2 foot centers rather than 16 inch centers.

robo hippy

 

[Gerald Lawrence]

I have high density rubber pads under my 3520B. And it does not vibrate . did level the bed . Have not checked it lately. All that Stuff did for I underneath I tried. It does work but heaven forbid that tool I drop to roll under the.

 

[Paul Durden]

Did you mean "does not vibrate" with the high density rubber pad. that would be and easy mod if so.

 

[Darryl Fective]

I put an end to the lathe dancing with a thick plywood shelf between the legs, then loading it up with (11) bags of tube sand. I used some chain and an eye bolt in the center of the shelf to support the middle of the shelf (hanging from the lathe bed) to keep it from sagging.

Starting a blank between centers allows you to move the axis of rotation to where it is balanced. It doesn't take long to do, and allows higher RPM's much sooner.

 

[Gerald Lawrence]

Did you mean "does not vibrate" with the high density rubber pad. that would be and easy mod if so.

Thanks , left out a word. Since I put the lathe on the pads it does not do the big bowl out of balance dance. Of coarse it could be that my turning skills have improved also.

 

[Daniel Henry]

I have a 3520c. At the risk of being argumentative, I have a contrarian opinion. I don't add weight nor do I anchor the lathe to the concrete floor. I want to know that the piece is unbalanced. In my convoluted mind the vibration not noticed due to anchoring or added weight is being absorbed by the bearings and structure.

 

[John K Jordan]

Does anyone do anything besides set their powermatic 3520 lathe on a concrete floor? I have it pretty much leveled, but still get some vibration with larger bowls and til they are trued up. Or maybe this is just the norm?

Don't know if this was mentioned, but every time I move a lathe I check the alignment of the headstock with the tail stock. Even if the bed is level, uneven pressure on a foot can actually twist the cast iron bed. This can create various problem, especially when doing small and precision work.

Procedure:

• Clean the morse tapers on both the headstock and tailstock - remove dust, rust, any irregularity in the steel from galling, etc. (You can usually feel such irregularity with a finger.)
• Seat a center with a point in both the headstock spindle and the tailstock. Make sure the tapered surfaces on both are clean and undamaged.
• Move the tailstock up close to the point
• If the points are not aligned horizontally (looking down from above), adjust one foot. For example, if the tailstock point is a little toward you, either crank down the front right or left far end adjuster a bit. This should twist the bed back into alignment. Unless the bed is horribly twisted, it should only take a minor adjustment, just a 1/2 turn or so. You can watch the points move together.
• If the alignment is off vertically, it's another issue.

I've had to do this on my PM3520B and Jet 1642s. Once when Mark StLeger was demoing he noticed a misalignment which would give him difficulty completing the next piece. During the break, I spent 2 minutes and aligned the lathe and he continued with his amazing turning!

The misalignment doesn't matter much for long spindles, bowls, or platters. Could cause some stress when holding a large piece in a chuck and using the tailstock for extra support.

BTW, I consider the alignment important but it doesn't really matter if the lathe is exactly level, the bed on a plane perpendicular to the earth's axis. In fact, for a good reason I formed my shop floor with a three inch drop over 62' - has no effect on any tool.

JKJ