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Concrete machine bench?

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John Hill:
I am slowly getting the new workshop sorted but the machines are still on blocks or stuck in temporary places.

Here is the idea for them, my 12x36 lathe, tiny shaper, drill press and maybe slow cut saw will all go on one 1200 x1600mm table that will be made of concrete! :bugeye:

I have been talking to someone who can cast such a thing, the 100mm thick top and the support will be in one piece weighing quite a bit, close to a ton.  The base part will be in a shape of a letter 'H' (laying flat) with two solid ends and a connecting part through the middle.  The top will be as flat and level as possible with a gutter cast around the edge.

Everything except the lathe can be just bolted to the table top but I am still thinking of how to mount the lathe so that it can be levelled,  it has four bolts at the headstock end and two at the tailstock end.  My idea at the moment is to set bolts in the table with nuts between the table and the lathe casting so that I can wind them up to level the lathe, once it is level I will fill the space with grout, any future levelling will need shims or I will be able to drive wedges under the feet of the table.  I am not really settled on these details as yet.

If the machines are carefully placed and I do not fit the chip sheild on the lathe there will be, albeit somewhat restricted, access to the backside of all the machines plus of course one surface will be easier to clean.


Anyway, concrete bench, daft or what?

Bernd:
John,

Here is a thread from HMEM that might interest you. Kermit built a "sort" of concrete table for his lathe. Concrete Lathe Bench

Bernd

loply:
What are the advantages of making the bench from concrete?

If it's mass for anti-vibration you're after I would suggest topping the concrete with a layer of nicely finished plywood, and hard varnish it.

Repairing the concrete as and when it chips, pits and stains will be more difficult then resanding/revarnishing/replacing a sacrifical wooden top. Heaven forbid it should eventually crack...

If you don't hugely long for the antivibration properties of such a heavy bench then I would just make a thick wooden one?

John Hill:
Thanks Bernd, that bench Kermit made is a work of art!  He showed some good ideas there.

Loply, the attractions of concrete include mass, stability and hopefully vibration damping.  It should also be cost effective compared to steel or wood construction.   I am not overly concerned with dings and chips as most of the surface will be covered with machines and I do have a wooden top workbench for all that hammering and bashing activity,  good point though and having plywood sections to cover areas between machines would be a good idea. One of the ideas I have been discussing with the concrete casting people is to have a wooden batten around the outside to make a more 'people friendly' edge.
I will be pretty upset if it cracks!

PekkaNF:
I don't know. It is an interesting design challenge.

Few random thought comes into my mind:
* Might be a good idea to make the base separately. You could level it after curing and place it over a thin rubber mat to pervent it from walkking and reduce further vibration
* You need a way to seal and paint it. You don't want oil and chemicals into concrete.
* You need to consider hardpoints in advance. Concrete works well in compression. Plastic or conduit pipes into mould to make holes for screws?
* You need to design the machine mounts such way that it will allow shrinkage of the concrete. Concrete shrinks rather long time.
* There are books and stories about concrete table tops.

PekkaNF

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