Open source group project, anybody interested?

[Wotsit]

I like the epoxy granite idea and have followed the thread for a long time but it seems to me a bit to involved for a mid level machine, and has some complicated problems. Do you agree? - Would make a great bed though.

I think the composite idea is a good one, alu box filled and reinforced? Sand in polyester resin / concrete with rebar. Thoughts? Calcs? I wonder what 5kg of resin's exothermic reaction is like?

I agree that linear rails or supported round rail are the minimum for a project of this type

What is a good enevlope? For me it would be 2' x 4' ish

[Wotsit]

Deleted by wotsit to keep the thread on track

[Wotsit]

Deleted by wotsit to keep the thread on track

[Wotsit]

Deleted by wotsit to keep the thread on track

[Ross77]

Im sorry but I didnt read all that because it is a subject in its self that I'm not interested in it and it sounded like salesmen speak.....:whistling:

My initial thougths were a cheap workable solution to DIY cnc. Stuctural epoxy in the Uk is expensive and as far as I can tell has a poor modulas of elasticity( it still bends) and dosnt solve the high density required to reduce vibration. (Im talking about the machine frame and not the bed)

Yes it has excellent sticking qualities but so dose a better known natural product:heehee:

Srinkage of concrete is a problem but is controllable and the comments on strength laughable. Yes concrete dose get stronger with age but its characteristic strenght is at 28 days. after that it get stronger.

The shrinkage is due to its water content, but I propose to use minimal water and lots plasitiser and as the concrete is only used for the compression then any skrinkage can be zeroed out with shims ect.

For a stucture to work you have to undersand all the forces and all the reactions......................................... .............................................and if you want cheap you have to make compromises:heehee:


As a final note. When I started using my lathe I soon realised that the quality of the finish was proportional to the type(quality ,shape) of tool and speed of the spindle

So dose this mean we should be focusing our efforts on the spindle and operators capabitiy?

[Ross77]

Not to put you under any pressure Gary but would you concider a group order? may be for X#linear rails and X# ballscrews? What would the min quantiy be?

Just thinking the option of a cheap ish reliable cnc machine would ulltimatly require the support of a willing suppller?????

[Gary]

Not a problem, you just need to tell me what and the quantity.

Not to put you under any pressure Gary but would you concider a group order? may be for X#linear rails and X# ballscrews? What would the min quantiy be?

Just thinking the option of a cheap ish reliable cnc machine would ulltimatly require the support of a willing suppller?????