Designing a better bed

[routercnc]

Hi DC

Constrained layer damping sheets need an outer layer of thin steel bonded to them to make them work. I don't think you'll get much from just wrapping something in the butyl material.

They work well on large thin sheet materials such as air conditioning ducting panels etc., but you'll not get much if anything on small beams. If you do it will be at very high frequencies where the deflections are tiny, so of no practical benefit for what you need. Also by the time you flood this with the epoxy quartz that is where the benefits will come from.

I wonder if you'd be better off with a couple of 80x80 steel RHS beams across the width, filled internally with sand, then fill the whole area with sand and topped off with a 10mm ecocast aluminium plate tapped with a matrix of M8 holes . . .?

[davegrennan]

What size is your bed to be DC?

[D.C.]

It's 1320x720

[Boyan Silyavski]

Please read post #165about my thoughts and price comparison on most available materials

There is no doubt for me UPN140 is the cheapest , strongest, stiffest... It is almost mounted on my machine and i confirm that its brutally strong and was a great idea.

basically for your bed it will cost 100 euro or less , here in Spain / 100kg ~16kg/m /

[michaelw]

(1)

Designs for any machine beds come in two classes :

(a) Those which are set up in place once only and can remain in place for service life of machine .

(b) Those which have to be more regularly re-sited .

Considering only (a) pro tem the cheapest and most rigid bed is usually a deep cast concrete block with all the precision machine components bolted down to it .

(2)

Composite construction for machine beds is usually non preferred .

Your proposed design would be better with much smaller section reinforcing rods with grip into the epoxy mix . Common ragged reinforcing rods would be ok .

Personally if I wanted to use epoxy concrete construction I would just cast a solid slab of sufficient depth but with no reinforcing at all .

(3)

There are other types of machine bed :

(a) Based on (eg) quarry slabs of rigid slate .

(Think billiard tables and DMM's)

Granite would be super excellent but probably be too expensive for your purpose .

(4)

Consideration must always be given to how machine bed sits on the workshop floor .

Concrete block cast in place on adequate sub surface is usually ok anyway but any slab type bed mounted (relatively) loose on floor needs mountings which do not distort bed and which usually need to allow for some levelling .

Mountings in any case have to sit on floor and sub surface of sufficient rigidity .