Advice on Mammoth CNC Router Build - Steel Framed - 2440mm x 1220mm cutting area!

[JAZZCNC]

What about self levelling floor resigns ?

The problem comes from the type of resin.? I think Car paints and self leveing Floor paints which are manily polyester resins contain high solvent levels which evaporate and can cause sinking etc.

[Wejjmeister]

The problem comes from the type of resin.? I think Car paints and self leveing Floor paints which are manily polyester resins contain high solvent levels which evaporate and can cause sinking etc.

They wont shrink or sink but they do not harden to the same levels as paints are meant to be somewhat flexible to resist cracking etc, so it wouldn't be suitable for this particular job as it would 'give' unlike the epoxy resins used in these forums before which cure fully.

[EddyCurrent]

ba99297, Sorry, it sounds like I did not understand what you meant with the clear coat, I did not think there was enough strength in clear coat when it hardened.

[EddyCurrent]

Anything of use here ?
Epoxy Resins Shopping Pages

[Wejjmeister]

Thanks for that, as for the former comment, I would have covers all along the open section to prevent swarf ingress, would this suffice?

[Jonathan]

Potentially - depends on the covers.

[Wejjmeister]

Potentially - depends on the covers.

Could always put the slot in the outer sides and make it so the gantry overhangs a little more and they attach on the side? Was trying to keep the rails and screws as close to each other as possible thats all.

[Jonathan]

Was trying to keep the rails and screws as close to each other as possible thats all.

That is a sensible priority.
I'm being intentionally vague here since, as you've realised, you've got to weigh up the factors and if I just say how I'd do it, then you might miss out on finding your own better solution. Ideally you need to minimise distance mentioned for rigidity, not allow swarf to build up on the ballscrew (especially if rotating nut) and not cost an unreasonable amount.

[JAZZCNC]

Best way is to use a rotating nut. If not, then at this length you'll want two angular contact bearings at both ends to get a respectable speed. Search on Google 'ballscrew critical speed' for more information.

100% Agree I wouldn't use rotating screws at this length.

Thanks for that, as for the former comment, I would have covers all along the open section to prevent swarf ingress, would this suffice?

Could always put the slot in the outer sides and make it so the gantry overhangs a little more and they attach on the side? Was trying to keep the rails and screws as close to each other as possible thats all.

The covers will still fill up the way you have them now. The little extra the Gantry will extend to make it so slots are on outside won't make any differance to how this machine performs so it will be worth doing no matter if rotating screw or Nut.

Don't get caught up in the over analysing the machine because while important your only talking a very small differance which won't a make a JOT of differance to the cut quality or speed needed for cutting woods, plastics and even for the level of Aluminium cutting this machine will be capable of dealing with.

Shit in the Screws or Nut will make you REGRET NOT doing it EVERY DAY were has you'll never even notice the screw being closer to rails.!!

[Wejjmeister]

Exactly what I feared!! I will do some more thinking, need to research rotating nuts first as I'm not at all familiar with these, then I can hopefully come up with something. The covers are pretty resilient though and will stop most foreign bodies, with those plus regular cleaning I think it may be the best option as it gives the most strength.

I'll give it some thought! Any other glaringly obvious mistakes in the design??