I have a flat-bed (wish it were V- preferably South Bend, but...) metal working lathe adequate for my needs, up to including barrel work, that I took out of my old shop (now an apartment) where I had it's moderately heavy steel table bolted into the concrete floor.

Can't do that in my garage, as I have slab heating and I don't know where the tubes run. I wasn't there when the slab was poured to set bolts and didn't know where I might want it, anyway. Still don't. A work in progress....

Think you machinists that an 6' X 8' base slab of concrete 6-10 inches thick (the less I can get away with the better) would stabilize this enough? I'm not going to be doing "professional" - this is a hobby thing, primarily for myself, or a very few friends. Not that that makes much difference in what is minimum or better.

I have an old WWII era Eskimo Scout rifle once owned by Charlie Sheldon (who "modified" it into a usable hunting rifle) to rebuild into replica shooting condition for a friend - if one of us doesn't die first.

I'm thinking a couple embedded rings/ rebar etc reinforcing in the pad would not be amiss if necessary to move it with a Bob-cat or such . The garage has 16 foot walls, so there is height to lift. Rather not drag it on that epoxy-paint floor.

Any alternatives you can think of?

Look for machinery foot pads. My Grizzly came with them and I think they also sell them separately. No bolting to the floor, the feet just set on the pads.

Hey las, before you get to involved, maybe try and get your hands on a high quality infrared camera. Start with a cold slab, and turn on the heat, and see if you can map out your piping? I've got a light duty flat bed lathe as well, I feel your pain! (mine's a Craftsman/Atlas 12X36). It's actually not a bad little lathe, just painfully slow, as you have to take really light cuts.

Jeff

Atlas is mine too. Thanks for the suggestions. Now that I have the slab heat going, and if I can rent a camera(doubtful), both are preferable suggestions to what I've been thinking. I'll research. Not planning to do it until next summer at the earliest anyway.

I can always turn the heat off for a week or so to cool, then start over if I can find a camera. Pads sound better tho.

There is not much you can do to stiffen up one of those lathes besides adding mass. Not enough cast iron in the bed. Bolting to the floor might help but completely depends on the cabinet it is sitting on. I would suggest building the heaviest, stiffest cabinet you can. A 3" thick poured concrete top would go a long way toward damping vibration from that lathe. I have a 6x18 and a 12x36 and found that adding ballast to the table and underneath helped significantly with surface finish.
I have seen lathe bases made from cinder blocks with a slab top and you wouldn't have to worry about bolting that to your floor.

Perhaps you could use a digital thermometer, the type you simply point and press the trigger, to locate the heating tubes.

Yep. If you know any commercial electricians, home inspectors, or heat loss studies, etc....maybe you could borrow one? My lathe came with the factory cabinet style stand with undermount motor. I bolted it to the floor, and put a tool chest on the lower shelf, and have the heaviest tooling possible in it to add weight. It'll never be what I'd like for it to be, but every little bit helps. I also get much better finish using good old HSS tools as opposed to carbide. Cheaper too!

Jeff

a grouted steel plate would be a better base than concrete

Make a frame on the floor where you want to anchor the lathe down out of 2x4 and caulk it so it will hold water.

Turn off the water pipes in the floor... (then freeze a thin layer of ice on that spot, then turn the floor on and mark the tubes.... )

Buy a bunch of dry ice and fill it just enough water to cover the surface, then put a blanket / sleeping. Bag over it until it freeze - then go turn the heater on and see what melts first... ??

I had an Atlas /Craftsman 12x36 lathe made in 1939.

It was on a cart with castor wheels. I rolled it all over the rough car port, threading and chambering some really accurate rifle barrels 12 years ago.

The bed flex is but a minor attribute to those lathes....the cross is awful light. You're just forced to take small cuts. I had the same lathe on a heavy base" but it's still no 4k lb lathe.....but if you treat it like a 300 lb lathe, it can do great work.