Build and Intro

**swisscheese** · 21-10-2013

Hi,
I could have done that but a bit meh with the fuss involved.

I think I will mount it with bearings moving with spindle. It just makes everything a lot easier. I'll take into account the lost rigidity of spindle mount without the rails. 20mm thick aluminium seems to be the standard isn't it? I think it should suffice. And yes having some hywin type rails would be nice but the ballscrew is the limiting factor at the moment as I can't machine into the aluminium so their profile could be lowered. Hmm maybe a project after this is complete is to make a new z axis with hywin rail.

The table is bolted to the ground in 8 spot(one each leg) so I'm guessing this might mean I don't need triangulation?? Will wait and see. The epoxy leveling was done after. This means that I can never move the machine(as it would have twisted when I bolted it down), at least without redoing the epoxy each time.

**EddyCurrent** · 21-10-2013

I'm going with 20mm aluminium plate. It sound like a good idea to fasten the machine down but I think you could still have adjustable feet too just in case

I'm not an expert on cnc (yet

) but from your pictures, my past engineering life and what I've learned from this forum, I'm thinking the square tube bracket down to the x axis ball screw is not strong enough. It would be better if there was a triangular fillet each side to prevent flexing, I can imagine it vibrating causing tiny oscillations.

**JAZZCNC** · 21-10-2013

Originally Posted by swisscheese

The table is bolted to the ground in 8 spot(one each leg) so I'm guessing this might mean I don't need triangulation?? Will wait and see. The epoxy leveling was done after. This means that I can never move the machine(as it would have twisted when I bolted it down), at least without redoing the epoxy each time.

If you had triangulated and made a stiff frame then yes you could have moved the machine. Even now you can move the machine but you will need to ensure the frame is not in twist when set in new location. The rails will still be on the same plane if no twist exists has they levelled on same plane and the only thing you can introduce is twist.

Regards the rails on front then mostly depends on how much extension you have on the front plate when cutting and also what your cutting. If mostly extended and cutting harder materials, hard woods,aluminium etc then it will make enough of difference to matter. Low extension and softer materials it will hardly make difference.

**swisscheese** · 23-10-2013

Thanks for the replies

Few Questions

How tight should the belt be? As in should I be able to turn the pulley on one side a little bit(maybe 8th of a turn) while holding the pulley on the other side still? It runs between the two sides and has a center distance of about 1100mm.

Also with the pulleys the length of the bore is about 29mm and it has two set screws. The shaft for the pulley on the end of the ball screw is only 15mm long. Should I be concerned that the shaft isn't long enough? Is tightening down the set screws onto the round shaft fine or should I grind down two flat areas on the shaft for the set screw to tighten onto?

thanksssss