Bolting Lathe to Floor

[Neil Bosdet]

Hi All,

I recently bought the Robust American Beauty. I was hoping the girth and weight of the unit would be enough to keep vibration down but I'm finding it's not. I cored a bowl blank a couple of days ago. I had bandsawed the blank so it wasn't far out of true. The max speed I could get was about 400 rpm even after everything was completely trued up and I was coring. I'm thinking I need to bolt it down. My shop has a hardwood floor raised on sleepers from a concrete floor. So, I have 2x4's on edge with a ¾" subfloor and then ¾" hickory floor. Nice and solid but I'm finding out, not enough.

So, here's the question. How would you suggest I go about bolting this down? I'm thinking bolting to the hardwood and subfloor would be insufficient. One good shake and it would come loose. If drill through the wood flooring and head for concrete, what system of fastener would you suggest? I'm puzzled.

Thanks, Neil

[Kevin Jenness]

400 rpms isn't that low for coring.

Some people contend that bolting a lathe down is too hard on the bearings and weldments. I'm ok with it but it's worth considering. Heavy industrial machinery is often shimmed and bolted to concrete. I had my General 260 bolted down through an Advantech floor on sleepers with 1/2" threaded rod embedded in thickened epoxy in a 5/8" hole 4" deep in the concrete slab. The drawback is that when you want to move the lathe you will have to lift it off or cut the bolts flush with the floor. You may want to look for long threaded anchors set flush with the floor.

You could use long Tapcons or pot(epoxy anchor) shorter fasteners into the wood floor but a serious event could break them loose. A friend, a professional with 30 years full time turning, recently had a 14" or so dry bowl blank explode. His Oneway 2436 with the outboard attachment, easily 1/2 ton, moved 6" as a result. I'm not sure what that says besides the fact that there is considerable energy embodied in spinny things and it is best not to be in the path when they go sideways.

I haven't yet felt the need to bolt down my Oneway (nominal 850#). If it starts shuddering it's probably a good idea to turn down the speed.

[Richard Coers]

Your floor is too flexible. Bolting it to that floor won't help. You have to get back to the concrete for bolting to work. A round blank doesn't mean it's balanced. There can be density differences in the wood. 400 is fast for coring, but you didn't mention the diameter of the blank.

[Neil Bosdet]

Blank was 14”

[Michael Schuch]

I would take the wood flooring and the subfloor out of the picture. I would bolt some ~5" round spacers directly to the concrete and make the spacers tall enough that they come all the way up through the floor and sub-floor. Then bolt your lathe to the spacers. Which would mean drilling some 5" holes in the floor/sub-floor at each corner of the lathe.

I have always had really good results with concrete anchors. The kind where you drill a hole in the concrete then pound the anchor in. When the anchor stud is pulled up by a nut the sleeve around the anchor expands in the concrete.

https://www.amazon.com/Wensilon-4-1-...=sr_1_3?sr=8-3

You could go to a steel supply and have them cut some 6" long 5" round solid bar stock for the spacers. Or weld your own up out of some round tubing. I would probably use 2 concrete anchors per spacer then thread the middle of the spacer to accept the bolt holding the lathe down. If you could find some really long concrete anchors (~10") you could go all the way from the concrete floor, through the spacer and bolt the lathe directly to the anchor.


https://www.amazon.com/CONFAST-Hot-Dipped-Galvanized-Wedge-Anchor/dp/B072PQQ793/ref=sr_1_4?sr=8-4


Another possibility would be to cut a big rectangle hole in the floor and poor a concrete pad level or slightly proud of the wood floor. Maybe use 2x6's to frame the pad. You would want to set anchors in the concrete pad and tie them to the rebar to bolt the lathe to.

[roger wiegand]

I had the same problem with almost exactly the same floor setup. First be very sure you've "settled" the lathe, per the instructions provided by loosening the leg bolts and rocking it until it's solid. I then positioned the lehs so they were over the sleepers (mine were 2x4's on their sides 12"oc so I was able to accomplish that fairly easily), then Hilti bolts through the floor, sleepers and int the concrete. It's worked great.

[Neil Bosdet]

Those anchors are good. I have long ones I could try. I hadn't thought of boring large holes through the flooring in order to have the lathe have direct contact with the concrete through a pad or spacer. Great idea but I don't want to cut huge holes in the floor. I move my machines often enough that I would worry about it. Thanks very much.

[Neil Bosdet]

Thanks Roger. I think I will try this along with Michael's suggestion with the concrete anchor. Hilti bolts would require a sleeve I think, causing me to drill larger holes in my floor. Am I thinking of the wrong fastener?

[John Kananis]

I have a different lathe but I've been considering making a shelf of 2x4's on edge and stacking pavers onto the shelf (sand bags are messy if they tear). I have brackets molded into the cast iron legs (laguna 18/36) but I'm just not sure if it's too much weight for the cast iron so I'm still considering.

[Bill Howatt]

The rigidity/stability of the machines "legs" has to be considered. Bolting, or loading up the base near the floor, a machine with flimsy supports up to the bed level will vibrate because of the weak supports.

[roger wiegand]

I used a wedge anchor like these https://www.hilti.com/c/CLS_FASTENER..._7135/r8863215, hole the same as the nominal size, as I recall. One on each leg. I don't know how these come out, if at all if you want to move the lathe.

9571251093534.jpg

[Wally Crawford]

First, as Roger suggested, make sure the lathe is "settled" per installation instructions. I would call Brett at Robust and talk to him before I bolted it down. Let us know what you decide.

[Kevin Jenness]

As one fellow said, Think of it this way: if adding weight to a lathe is good then adding the weight of the entire world is even better.

[Eugene Dixon]

First, as Roger suggested, make sure the lathe is "settled" per installation instructions. I would call Brett at Robust and talk to him before I bolted it down. Let us know what you decide.

Be nice to hear Brent's thoughts.

[Kevin Jenness]

From the Robust website:

Q? Is it OK to bolt the lathe to the floor?

• Yes, so long as you don’t twist the bed, there’s certainly no technical reason not too. Please keep in mind that when an unbolted lathe starts to move or dance across the floor, that’s nature’s way of telling you to slow down and balance your work. You’ll lose this feedback if you are bolted to the floor. Also keep in mind the wood will fail before the lathe will, and flying wood can cause serious injury or death.