Thats cool, i appreciate honesty from experience. I can weld, i use a MightyMig 170 so the steel base will not be a problem, i was intending to do that from the outset. Working bed wise, what should the solution be? i chose moisture resistant MDF as it is alot more stable, and i dont want to go on and on about MDF but i have around 30sheets a month come through my shop so it seems crazy not to use it for the major parts.

Can i use the torsion box on top of Steel framework to better effect? i will be laquering the bed and all/any MDF components, IME they would be highly unlikely to swell or expand once this has been done and i have been working with it for years, tolerance wise any expansion would be 0.05 on its thickness over 5 years. But as i said i do value opinion and experience, so if you have or any other users had a moisture resistant MDF bed, laquered etc, and it was still subject to expansion then i would definitely like to hear exactly how it occurred and what the stimulus was for the change/expansion. I am not saying you are wrong JAZZ at all, i am glad you raised the potential issue. But i wouldnt use it if i wasnt sure. Most people use ali tables but this is mega expensive and i need to keep budget low, obviously i am thinking about quality as a paramount, and the initial decision for an MRMDF bed was not a light hearted one as i have not seen a lot on here.

All above set aside though, if i do choose 2400/2500mm for X, then i would probably have to look at a more suitable solution as i think over that distance there is likely to be creep and settling etc. So if i go half sheet, i think i would chose MDF torsion, but full sheet will need an alternative, suggestions anyone? i will still be using a disposable bed.


I was looking at square rail and HWIN carriages last night, as opposed to round supported rail, again cost was forefront in this option, it works out cheaper for the longer lengths, which might help if i do tackle a full sheet machine.

Gantry wise, i have sketched this up on paper but not drawn it on cad just yet. I was aiming for the sides to be Alu laser cut, then a torsion box beam for the Y axis rails to run off, again HWIN and square, then Z axiz pretty much similar across everyones machines with round rail and screw.

Motion wise, X and Y im not at all sure what to do. I think Y could benefit from screw, but X if it is 2400/2500mm long, i think whip as mentioned is the issue. As i am beginner to screw drive, and rack & pinion, maybe i should just bite the bullet and go for r&p as suggested. The other option i thought of was running it via belt fixed at a point to the gantry and a pully at either end of the X axis. This could run both sides of the gantry off one central motor but i also thought this would have low tolerance, when thinking about belt stretch, slip, etc.

What is my options for X motion, is it just R&P? I cant really see any other suitable way.