Anchoring lathe - should I or shouldn't I and how to?

[mikoyan31]

Making progress on my old Faye and Scott beast. I've even turned out a couple pieces I needed for other projects.

I find myself in the enviable, or perhaps unenviable position of pouring my own concrete floor and base for my machines. My garage is gravel floored and as such is a blank slate. Using a homeowner cement mixer of about 1950 vintage, I'm creating a floor in sections about 4" thick. So now I'm in a quandary.

My lathe sort of looks like this pattern maker's lathe bit with a different saddle, change gears, lead screw, etc.

The feet have about 1/2" holes in each one either to bolt it down or to install leveling legs. I've been reading here and elsewhere, some claim that gravity is enough, others bolt and shim it up solid. Here's what I see as my options.

- Manufacture some leveling feet and just sit the machine on the pad once it cures
- Drill appropriately spaced holes in the cured floor and tie the lathe down with wedge anchors, leveling with shims
- Make a CAD (Cardboard Aided Design) template of the positions and cast J-bolts in when I pour that section of floor and bolt down/shim the machine

So folks, if you were in the position of doing custom concrete work for machine tools, how would you go about it? I also have a camel back drill press to bolt down eventually, but that's more for safety and less for rigidity.

 

[YYCHM]

How about posting a picture of your lathe and pad?

 

[mikoyan31]

How about posting a picture of your lathe and pad?

Well it's a general mess but it's even worse now as everything is moved and piled and....

When I was originally positioning it, roughly where it will live. Drill press might live where it is as well.

What the pad will look like. I'm making the floor in sections. Yes I suck at concrete work.

And how I'm mixing it up. Takes me the best part of a morning to mix, wheel, pour and screed a section 4'x8' (the size of the reinforcing mesh)

 

[johnnielsen]

My opinion is that any lightly built or medium build floor standing lathe can benefit from be fastened down to a concrete pad. The reasons I say that are:
- Some lathes may have a twist in the bed and this can be corrected in many cases by shimming the legs and tightening down via anchors.
- If you machine larger offset items that cause a crankshaft type of action, or are prone to vibration (chattering), fastening the lathe to the ground will help dampen them.
A larger, heavily built single casting lathe does not necessarily need to be leveled or fastened down unless you are working close it's capacity. If it is fastened down, it can only benefit.
Remember to install on a single piece of concrete; never straddle a concrete seam.

 

[whydontu]

Further to @johnnielsen comment, lathes tend to be long and narrow, with a high centre of gravity. They are very tippy. Bolt it down.

 

[Former Member]

I had several experiences with this.

On my Logan Lathe I had it both free floating for about 20 years and 10 years bolted down and shimmed. Both worked well. Bolting down ensured that the lathe didn't move if an off balance part was turned or if it got bumped hard.

On my current installation of the BB CX707 (about triple the wt of the Logan) I have it installed vibration control adjustable machinery pads.

Advantages with the heavier lathe:
- You can move it with effort if needed, otherwise it doesn't move.
- Pads conform to imperfections on the floor, making just that little bit easier to adjust.
- Any vibration external or from the lathe stops at the pads. Quieter running, better finishes.

IMHO controlling vibration thru hard fastening cause more vibration thru harmonics and standing waves. Pad isolation dampens them producing a better finish.

As to tipping over, not a concern, if it tipping is a concern you have other issues to address.

On a lathe with with only 4 mounting points (ie Logan) hard fastening allow better control to fine tune. On large or more modern lathes (CX707) it has 8 pads allowing fine tuning even with floating pads.

 

[mikoyan31]

Thanks all for the information. I'll be bolting the beast down.

Now the question remains, install the anchors when I pour this section or drill after it's cured and use wedge or epoxied anchors.

Not being an expert, I'm thinking cast in place will be stronger, better tie in to the slab, etc. I'm willing to be corrected because as I've learned over the years, what may LOOK like common sense and logic is nothing more than a way to be wrong with certitude. I'm also thinking of making this section 4'x10' instead of 4x8. The lathe has approximately a 7' long footprint and I don't want to be tying it down right at the edge of the pad. I'll have to get creative with the wire mesh, but I have an angle grinder and a welder.

 

[Aliva]

You could easily install anchors when you pour but you better be spot on with your dimensions. As you said drop in wedge anchors will work fine, you just have to wait till the concrete cures, that could be anywhere from a month to a year depending on your mix ratios and climate. I would go for the drop in. If you decide on drop in, drill the holes deeper than the total length of the anchor. If you decide in the future to move the machine or replace it, all you have to do is pound the anchor flush with surface, no need to cut them.

 

[Susquatch]

So folks, if you were in the position of doing custom concrete work for machine tools, how would you go about it? I also have a camel back drill press to bolt down eventually, but that's more for safety and less for rigidity.

I originally planned to anchor all my machines. But it was too difficult to align the feet for my lathe so I put it off thinking maybe tomorrow.

10 years later and it's still working great without them.

At this point, I find myself wondering why I would want to.

When I got my big Mill into position where I wanted it, the first thing I thought about doing was anchoring it down. A year later, that idea is dead.

I think good vibration absorbing machinery levelling feet are all that is required. I think maybe they are even better than solid anchors.

But I really don't know.

Just my thoughts for whatever they are worth.

 

[DavidR8]

I drilled a number of holes in my pad and installed the type of anchors that use driven in with a pin and then accept a bolt. I use them to bolt down my compact bender. They are flush or slightly below the surface of the floor and are no bother when the bender is not installed.

 

[mikoyan31]

I'm convinced. Drill later and use the appropriate anchor.

Also I'm going to modify the drive so I use pillow block bearings for the driven cone and build a platform only somewhat above the head stock, not hanging from the rafters. That will also need to be bolted to the floor as well.

As an aside, I borrowed my neighbor's engine crane. Even on the gravel floor it's a TON easier to move the equipment. I've had one on my "need one" list, it's going to the top of it.

 

[jcdammeyer]

How about this as an idea in addition to the pad. And I'm totally guessing if it's needed. In the 4 corners where you expect to put the feet dig down a bit deeper in those 4 places to put deeper footings. An extra 8" square (or round) and 6" deep?
Not sure if this is a good idea or not.

 

[Susquatch]

How about this as an idea in addition to the pad. And I'm totally guessing if it's needed. In the 4 corners where you expect to put the feet dig down a bit deeper in those 4 places to put deeper footings. An extra 8" square (or round) and 6" deep?
Not sure if this is a good idea or not.

I think it's a GREAT idea. If you are gunna put anchors in, you might as well do it right.

When we built engine dyno test cells or RTS test cells, it was standard procedure to pour "Siesmic Mass Bases" and even to isolate them from other foundations. This dramatically improves the vibration characteristics associated with testing. It would be the same for machines. Mass is good - period.

Whether that translates to better machining I can't say.

For an RTS test cell, those seismic masses, were huge! 30ft x 30ft x 30ft. They also required very specific concrete and continuous pours.

 

[ducdon]

I'll leave the decision of to anchor or not to anchor to you. However I think adjustability is important on a pad surface without footings. My garage floor is a poured pad and it moves about seasonally. Any time I want to do accurate work I should re-level.

 

[Former Member]

I'll leave the decision of to anchor or not to anchor to you. However I think adjustability is important on a pad surface without footings. My garage floor is a poured pad and it moves about seasonally. Any time I want to do accurate work I should re-level.

Why???? Also long as you your doesn't twist as it moves, who cares what it does and what strange angles you lathe sits.

Now if your pad twists you have other issues to address before setting up your lathe, like running as the building covering lathe will come down shortly.

 

[ducdon]

Why???? Also long as you your doesn't twist as it moves, who cares what it does and what strange angles you lathe sits.

Now if your pad twists you have other issues to address before setting up your lathe, like running as the building covering lathe will come down shortly.

Poured pads float. As frost comes in and out of the ground it would be nice to think that process takes place equally, but cracks in the floor suggest that it doesn't. The building won't fall down but is does move around.

 

[historicalarms]

To take this footing/base thing to an extreme...Buddy of mine that owned the machine shop with all the extreme huge machines I showed in a previous thread a couple years ago. When he poured the floor for the big Lathe and the two milling machines, he dug the floor area out 8 ft deep, backfilled 4 ft of pit run compacted to a density test of 110% and then poured 4 ft thick of 1" re-bared "almost no slump" concrete....dont think it has moved so far.

 

[Former Member]

Poured pads float. As frost comes in and out of the ground it would be nice to think that process takes place equally, but cracks in the floor suggest that it doesn't. The building won't fall down but is does move around.

Poorly designed and engineered pad. Pad should stay straight and flat designed correctly (sorry my background is Civil Engineering). Note I didn't say level.

My first shop was built on a pad, it moved but never cracked, proper reinforcement. BTW I designed it and built it.

 

[LenVW]

Getting the proper aggregate support is important, but, so is using the correct reinforcing mesh and rebar. Concrete will crack eventually, the key is to ‘limit’ the effects and make the crack appear where desired. This is encouraged with proper ’cuts’.

 

[Mcgyver]

That is nice looking old lathe. I don't usually bolt mine (they are quite heavy or light enough to sit on a bench) but that one looks like it could easily be top heavy, esspecially with a motor and backgear up top. Probably a good idea to bolt it.

Poured pads float. As frost comes in and out of the ground it would be nice to think that process takes place equally, but cracks in the floor suggest that it doesn't. The building won't fall down but is does move around.

and not just float, the concrete itself moves about. It doesn't stop curing in 28 days, that's just when its usable, but keeps curing and moving basically forever. I couldn't quantify that, just pointing it out...it can be easily be enough to affect a lathe cut. i.e. levelling is not a one time event.

As for the strength of a slab, I've been involved in millions of square feet of industrial design builds and while fiber or rebar or mesh is important, what a slab really does is distribute a point load over the base. The thickness and compaction of the base (layer(s) of aggregate between soil and slab) is key. It gets engineered along with with the slab and soil bearing and is what lets a floor support a load. That 6" inch floor they pour in a new building might have 8 or 12" of compacted crushed aggregate underneath and wouldn't stand up without it.

I know you are just pouring a little slab with minimal weight on it, so I'm not trying to make a meal out of it, but its germane to the topic of slabs: how they perform is not just the slab, but the slab, base and soil bearing conditions.