Lathe stability on a wood floor

[Jed Malcore]

I’m in the process of moving my shop to a back room in my garage (thinking this will be easier to heat). The problem is, it’s a raised wooden floor (about 15” to 8” off the ground supported like a deck and the floor itself is plywood). I threw a couple 2x10s under my powermatic 3520 to distribute the weight) I’m still getting enough shake/vibration when running a dried roughed out bowl that Is going to bother me and make me feel like I may get motion sick from the shake.

Any suggestions on reinforcing, strengthening and strengthening the floor without breaking the bank?

Thanks in advance

[Brian Tymchak]

Is the floor built with cross bracing between the joists?

[Jed Malcore]

No it is not, its 2x6 straight out from the foundation.

[Jim Becker]

Unless you stabilize the framing, even another layer on top of the floor isn't likely going to solve the problem when you are turning unbalanced objects. That mass whirling around at speed is a strong force!

If you have access from below, great. If not, you'll have to pull the floor and work from above.

[Brian Tymchak]

No it is not, its 2x6 straight out from the foundation.

2x6 is usually woefully inadequate for foor construction. I think for anyone to offer good advice more info is needed.

Can you provide more information about the current construction?

• Dimensions of floor
• Supporting structure and position of beams (if any)
• Attachment to foundation
• Spacing of floor joists
• Age of construction
• What is beneath the floor?

[Bill Dufour]

For a metal working lathe which weighs a minimum of 2x yours they throw a 1/2" metal plate under each end. then it is bolted down carefully to get it aligned. For wood the bolts just need to hold it down not align so much easier job.
I would put down a piece of plywood floor which is at least one inch thick. Make it long enough that it is on top of a joist at each end where it sticks out beyond the base. I assume the lathe is set perpendicular to the joists?
The width front to back is as wide as possible but not a trip hazard. Set some thick rubber on top of the plywood under the lathe feet
Then all thread or long bolts through the floor with square washers underneath. I would weld nuts to the washers and drill small holes and screw the washers to the floor so I do not have to go under to hold back the nut. I suppose for ww lag bolts would be okay.
Under my Air compressor I placed rubber retread hunks found on the side of the road.
Bill D.

[Andy D Jones]

Yep, 2x6 flooring joists are not sufficient unless the span is very short (too small for a shop if there are no intermediate supports). What is the span between joist supports?

As a stop-gap, I would open up the floor in that area, and put in some footings to support the joists right where your lathe feet touch down. If your lathe feet touch down between joists, add 2x6 cross braces under the lathe feet, and put in the footing(s) under them. Use joist hangers for these cross braces (perhaps upside down?).

-- Andy - Arlington TX

[David Walser]

Jed -- Others have given excellent advice on how to beef up the floor supporting your lathe. (I particularly like the idea of putting in some piers in the ground to support each end of the lathe.) Once you've done that, be sure your lathe is leveled -- end to end and front to back. Too many turners neglect this important part of setting up a lathe. If a lathe isn't properly leveled, it will vibrate no matter how solid the floor is. And, don't make the mistake of just bolting the lathe down to an unlevel floor. That will just twist the lathe's bed -- not what you want, at all.

Good luck!

[roger wiegand]

Can you elaborate on what happens if the lathe is not level? I'm having trouble imagining what the source of vibration might be in having one end a half inch higher than the other for example-- not that you'd do it on purpose, but it seems like shims, for example, to achieve precise leveling introduce another point of flex and potential vibration. Taken to an extreme (a thought experiment method I am unfortunately steeped in), would you expect a lathe to vibrate horribly in zero gravity where "level" doesn't exist, or on a ship at sea moving with the waves?

With my lathe (a Robust AB) the instructions for any time the lathe is moved were to slightly loosten the attachment between the lathe bed and the legs, then rock the lathe in position so that it settles into a "relaxed" position in the cradle formed by the legs, with nothing twisted and everything in firm contact, then retighten the screws. No mention was made of leveling, and I've never actually checked.

Jed -- Others have given excellent advice on how to beef up the floor supporting your lathe. (I particularly like the idea of putting in some piers in the ground to support each end of the lathe.) Once you've done that, be sure your lathe is leveled -- end to end and front to back. Too many turners neglect this important part of setting up a lathe. If a lathe isn't properly leveled, it will vibrate no matter how solid the floor is. And, don't make the mistake of just bolting the lathe down to an unlevel floor. That will just twist the lathe's bed -- not what you want, at all.

Good luck!

[Andy D Jones]

Can you elaborate on what happens if the lathe is not level? I'm having trouble imagining what the source of vibration might be in having one end a half inch higher than the other for example-- not that you'd do it on purpose, but it seems like shims, for example, to achieve precise leveling introduce another point of flex and potential vibration. Taken to an extreme (a thought experiment method I am unfortunately steeped in), would you expect a lathe to vibrate horribly in zero gravity where "level" doesn't exist, or on a ship at sea moving with the waves?

With my lathe (a Robust AB) the instructions for any time the lathe is moved were to slightly loosten the attachment between the lathe bed and the legs, then rock the lathe in position so that it settles into a "relaxed" position in the cradle formed by the legs, with nothing twisted and everything in firm contact, then retighten the screws. No mention was made of leveling, and I've never actually checked.

Agreed. Lathes vibrate because they (including the workpiece) are not dynamically balanced, and/or to a much lesser extent, torque ripple from a single phase motor. It has nothing to do with whether the lathe is level.

-- Andy - Arlington TX

[Bill Dufour]

Metal lathes are leveled with some precision to get them into alignment. To get everything parallel the easiest reference is level. Bed twist is an issue for a precision metal lathe. Bed twist is meaning less on a wood lathe unless it is so bad you can see it with the naked eye. At that extreme the casting is ready to snap. With a metal lathe you want everything flat and parallel within a few 1/1000" over the bed length.
Bill D

[Jim Becker]

The bigger issue here with the OP's situation is...balance...as I mentioned previously. Woodturners who mount chunks of wood for bowls and vessels are pretty much guaranteed to have some meaningful time spinning before the workpiece becomes balanced enough to stop vibrating and it doesn't take a huge piece of wood to make an 800 lb machine shake, rattle and roll, even on solid concrete. A stable base for the machine is essential to at least mitigate the effects of that vibration. So that floor, being pretty wiggly as described, isn't up to the job.

[Jed Malcore]

agreed... and therefore, moved the lathe back to the shop until i come up with a better solution! Thanks for all the help!