Concrete bench suggestions

[Bill Shields]

Willing to bet that by the time you look at all up cost of doing concrete-> concrete, rebar, mounting plates, drain holes, forming, ties, lifting lugs, etc -> you will find that the $$ of the concrete top is not that cheap..either out of pocket or personal time....even if you assume your time is worth nothing (which it most assuredly not)

[TLutman]

Yes, time is valuable. As for material costs, most of what’s needed is freely available to me. Still, I will check the cost of plate.
I have moved a 60 gal compressor and 2 workbenches today. The combo mill is next in line, and I think I will put some steel shims between it and the wood top temporarily. I just know as soon as I set the thing on the floor I’ll need it for something.

[Mr Ron]

In my 50 years of designing structures for Naval ships, I've never seen a concrete foundation onboard a ship. All foundations on board a ship were composed of angle irons and steel plate. These foundations were for machine tools like 16" lathes, milling machines, shapers, etc. The only place concrete was used was in the laundry as deck covering to absorb vibration from the dryers. If you visit any machine shop, I don't think you will see concrete used for a machine foundation. Not saying concrete can't be used, but even with a concrete top, you still have to reinforce the concrete with steel members to prevent cracking of the slab.

[Inspector]

Mr Ron concrete foundations for small machines may not be in common use but the place I worked until retirement had them under most of the heavy mills. They even had a Swiss made machine with a working length of over 60 feet, that had 80 pilings in the ground, topped with a rebar cage, with at least 4' thick concrete poured to make the bed of the machine. The concrete was topped with the sections of the steel bed 4" to 6" thick. The strength and stability of that milling table relied on the concrete structure being part of the machine. The two spindle machine also had quick change 3 and 5 axis spindle heads to suit the work being done. It surprised me at how thin the steel beds were when they were bolted to the concrete. I was used to seeing tables being several feet thick with the concrete just being a foundation and not structural to the machine.

If the OP wants to use concrete as a thick table to place his lathe on he should have no problem as long as he builds adjustable pads onto it for levelling and is willing to wait for the concrete to cure. Up to him to try. Beast of a job to move it to the other side of the shop though.

Pete

[Bill Shields]

I have to see both sides of this:

concrete FOUNDATION is one thing (of which I have poured more than a few), which is entirely different than a concrete bench top...

then there is the concrete foundation with epoxy grout to help hold / level the machine

[TLutman]

Reality chimed in yesterday and told me no, I will not be using the wood top anymore. It also disagreed with it only taking an hour to move a 2500lb grinder 20ft into its final place.
I have come to accept the lathe will be out of order for a couple weeks. There are some items I need to address on it and it is easier to do with it on the floor. I have an engine hoist to move it about if needed since it’s more than a couple guys can handle (500lbs).

That also gives me a chance to rearrange other tools to see if I like it.

As for that top, it really wouldn’t be that big. I can get away with 24x30” but am planning on 24x36. Steel, concrete, probably doesn’t matter weight wise. They are both too heavy to just grab and move.