Epoxy granite or mineral casting

[mike mcdermid]

Has anyone actually done this in the UK or found a recipe that works for small machine bases

Thanks

Mike

[boldford]

I can't help thinking aggregate of the appropriate size bonded with Biresin G26 Resin (5kg) may be a way forward for DIYers.

[mike mcdermid]

The resin system isn't a problem as I do composites in my day job I really cannot see a way of reading the 380 odd pages of theory on CNC zone and coming up with aggregate sizes
so was hoping someone here might have done the deed already

[boldford]

The resin system isn't a problem as I do composites in my day job I really cannot see a way of reading the 380 odd pages of theory on CNC zone and coming up with aggregate sizes
so was hoping someone here might have done the deed already

For economy I'm guessing the trick is to use as much aggregate as possible ensuring it is adequately embedded/wetted (IYKWIM) in the binding (resin?) material.

[Jonathan]

For economy I'm guessing the trick is to use as much aggregate as possible ensuring it is adequately embedded/wetted (IYKWIM) in the binding (resin?) material.

Yes that's the general idea - I've read the thread on CNCzone and a lot of it is discussing what threshold is too much aggregate since they want to save money on epoxy.

A lot depends on what you want to use it for. The thread on CNCzone is so long because they are trying to find a mixture capable of providing a stable accurate surface which will directly support linear guides. If you're only using it to fill gaps in a casting for damping, or if you embed pieces of metal and fasteners which can subsequently be machined then clearly the requirements aren't so strict...

[mike mcdermid]

Yes that's the general idea - I've read the thread on CNCzone and a lot of it is discussing what threshold is too much aggregate since they want to save money on epoxy.

A lot depends on what you want to use it for. The thread on CNCzone is so long because they are trying to find a mixture capable of providing a stable accurate surface which will directly support linear guides. If you're only using it to fill gaps in a casting for damping, or if you embed pieces of metal and fasteners which can subsequently be machined then clearly the requirements aren't so strict...

Jonothan for me its easier to mould something that is all and its what im used to working with, i have the skills to mould things and this means i can do stuff at home very easily rather than pay for it machining or casting ,its as easy to mould and epoxy into place as it is to machine metal to thousandths, I suppose it depends on your background I know we have had cast bases supplied before and its purely position and glue that gets the tolerances

That was my worry they are being tight on the resin volume.Jonothan did you gleen anything on the start point for sizes you could quickly post up I have read that many combinations on there?
I do know the companies that pour this its done with technology (equipment) not dissimilar to laying concrete foundations I have seen it done and it is a lot wetter than anything aproaching the 10 percent figures I have seen touted towards the end of the thread, The rails (precision rails) were mounted on grout which was similar to moglice but with ceramic spheres in it and it did indeed look like grout till it glossed over,this glossing seems to indicate far more resin richness as the heavy particulates sink

Im assuming its coming down to a scaling factor some of the aggregates they put in the grinding bases of the carbon machines we design are up to 25 odd mm I'm thinking the smaller the machine base you scale accordingly with a wall shickness ratio

I might just have a go this weekend

[mike mcdermid]

Ok an update

DO IT IT IS EASY

if you want to read through 400 pages of guessing suggesting and theorizing go follow the cnc zone "experts"

I recently visited 2 companies who manufacture epoxy granite machine bases and actually are "experts" One manufactures CMMs the other very LARGE gantry mills made from Carbon fibre basically it is rocks in resin the guys gave me the full tech spec right down to the epoxy resin system which comes from HUNTSMAN ,nothing fancy rare special about it ,the rocks are quartz ,as guessed scaled to fit the section that is to be filled nothing fancy no fillers of spheroidal this that or the other ,just different sized grains and some fibres

there is nothing clever about it fill a mould and vibrate it

no flaming off with torches to burst bubbles etc analyzing sizes to the nth degree the applications engineer even pointed out how complicated lots of folks think this is ,cost to cast a machine 1000 a ton which was still cheaper than cast iron for a hobby sized machine your talking 100 quid

[Peter.]

I love it when practical experience makes a mockery of the theorists

[boldford]

Ok an update

DO IT IT IS EASY

if you want to read through 400 pages of guessing suggesting and theorizing go follow the cnc zone "experts"

I recently visited 2 companies who manufacture epoxy granite machine bases and actually are "experts" One manufactures CMMs the other very LARGE gantry mills made from Carbon fibre basically it is rocks in resin the guys gave me the full tech spec right down to the epoxy resin system which comes from HUNTSMAN ,nothing fancy rare special about it ,the rocks are quartz ,as guessed scaled to fit the section that is to be filled nothing fancy no fillers of spheroidal this that or the other ,just different sized grains and some fibres

there is nothing clever about it fill a mould and vibrate it

no flaming off with torches to burst bubbles etc analyzing sizes to the nth degree the applications engineer even pointed out how complicated lots of folks think this is ,cost to cast a machine 1000 a ton which was still cheaper than cast iron for a hobby sized machine your talking 100 quid

That's really interesting. Like much "technology" there's always those that want to make it seem like Black Magic.

Then an honest broker comes along and all the hype disappears.

[martin54]

Being new to all this I went & had a read of a couple of articles when I saw this thread so I would have a better understanding of what it was all about.
I could be wrong (often am) but from what I picked up what they are trying to achieve is not the same as filling a machine to increase it's weight or help with vibration dampening. Haven't read the long thread on their forum but I think that is why they are still theorizing & testing different mixes.