Small rigid router - Design advise needed

[JAZZCNC]

thats not going to work

no ways you gonna bolt it together so that the rails come out within a decent tolerance ....
have a read about epoxy leveling a frame if you havnt already ?

Depends how it's done. Epoxy leveling isn't the be all and end all solution. I've said this many many times but for a good DIY machine you need to build in as many oppertunity's for adjustment as possible and bolting allows plenty of scope for shimming etc to get machine accurate.
If done correctly then it's actually better than epoxy because you can fine tune to very high tolerence.! Only thing is it takes much more time and patience.

belts aint gonna make it any smoother .... id run a coupler on the two axis' , so much easier and cheaper

Actually can make a huge difference esp on all steel machine that's running analog drives with limited resonance handling. This is actually the main reason to use Belts and the ratio option and flexabilty is just a bonus.

Often folks running direct drive don't realise they have resonance problems and just accept that the speeds and performance they are getting is just the max level they can tune to or achive from there motor/drive setup. When often the reality is that the same motors/drives when run on belts and unaffected by resonance will achieve much higher and smoother performance.

[mitchejc]

@JAZZCNC
Thanks for the great input. I'm going for the belt option. I think I got decent steppers and drivers but I'll do anything that might deduce resonance and I like the possibilities that the belts give e.g. change the ratio if I needed. Not sure with a ballskrew system but I know from first hand experience with rack an pinion that belts also offer little bit of safety margin with strong steppers and would jump teeth or snap when things go horribly wrong.

I've thought long about Blackrat's suggestion not to bolt the sides down but there's much weaker points in the design so I'm pretty sure that not the weakest link. The other thing is I'm really a novice welder so I'm not very confident I'll be able to build the base and gantry sides as one unit to any reasonable tolerances. With the bolt on plan I do limit that factor a little as I have the opportunity to shim an adjust a little like you suggested.

I wish I could hear silyaski machine take an aggressive cut into a piece of alu then maybe I can put my mind at rest about the steel structure resonance :-) Has anybody tried to fill the steel sections of the gantry etc with high density polyurethane foam and would that make any difference with resonance? I'm referring to the two part stuff that can be pored thru relatively small holes and then it foams into a plastic like solid to fill the entire void.

[JAZZCNC]

Has anybody tried to fill the steel sections of the gantry etc with high density polyurethane foam and would that make any difference with resonance? I'm referring to the two part stuff that can be pored thru relatively small holes and then it foams into a plastic like solid to fill the entire void.

No it doesn't work very well there's not enough density. The best success i've had is with kiln dried sand. Very cheap and simple with good results.

[mitchejc]

@JazzCNC

Thanks Jazz, the sand makes sense. I'm bit worried about adding more weight to the gantry as I estimate it's already +- 80-90kg Z & spindle included but I guess a 20-30kg of sand is not going to hurt or will it? My plan is to run 8nm easyservos, will that work or do I need to back off a bit on the gantry weight?