Steel Framed Router

[JAZZCNC]

The linear rails are 25mm dia for the Y axis and 20mm for the X and Z, and hoping to use a 2510 ballscrew for the Y a 1610 ballscrew for the X and 1404 ballscrew for the Z. (hope I haven’t confused the X and Y).

If these are profiled linear rails you dont need 25mm they will be massively over kill. 20mm will be more than enough, even 15mm will be good enough. I'm talking profiled linear thou not round supported.

25mm ballscrew is also not recommended for a machine this size, you've probably gone with 25mm because of the 10mm pitch not being available in 20mm.
25mm screws are large and they produce a lot more inertia which has to be stopped and accelerated this means big strong motors needed amongst over things which all make it not ideal.! . . . Bigger is not better when it comes to some things, screws being one of them.!
At the size your looking to make 16mm is getting on the edge of being whippy thou with carefull aliagnment and sensible speeds you would be ok.
You could go with 20mm 5mm pitch and gearing 1/2 this way you get the speed thou at the cost of a little torque. I can tell you from experience 6nm Nema 34's will handle 1/2 setup without any problem. There is an up side with 1/2 gearing as well to this if you find you ever need the extra resolution of 5mm pitch and higher torque it's a simple pulley change and away you go.

You could go with rotating the nut but it gets a bit more involved, thou does work well if done right.

With the steel box section frame you will also get lots of resonance which has a big affect on quality of cut esp when cutting hard materials so a big tip if you go all steel is cap the ends and fill the frame with kiln dry'd sand it makes a big difference.

Definatly go with twin screws on the X axis it makes a very accurate strong stiff machine. Either with a motor on each screw slaved together or one motor with belt between the 2 screws.
Dont be put off by the belts they work fine and more than good enough for the work you intend to do. I have a machine that use's this 5mm pitch 1/2 twin screw belt setup and I cut every thing from steel to plastic with it no problems and it's super accurate. Even cut cast iron with it last week for the first time without any trouble.!
Not a pritty thing but it gets the job done and very very reliable and super accurate.

Cheers.

[Jonathan]

25mm ballscrew is also not recommended for a machine this size, you've probably gone with 25mm because of the 10mm pitch not being available in 20mm.

Maybe 16mm screws with 10mm pitch - RM1610.

25mm screws are large and they produce a lot more inertia which has to be stopped and accelerated this means big strong motors needed amongst over things which all make it not ideal.!

I was about to suggest looking into using rotating ballnuts...

You could go with rotating the nut but it gets a bit more involved, thou does work well if done right.

But you beat me to it! You might be interested in how I did the rotating ballnuts on my machine:

http://www.mycncuk.com/forums/showth...t-design-ideas

They work well, so I guess I did it right.

I agree with using belts and two ballscrews on the X-axis. Spacing the bearings further apart will help prevent the gantry racking a bit, however it's still not ideal.

i wouldnt look at my build for any design inspiration,its a bad build and a lot of good materials wasted,im on the verge of scapping most of it and starting again:tup:,

Oh don't say that ... you're doing yourself a disservice. There's still room for improvement on mine and there always will be. The distance parallel to the X-axis from the Y ballscrew and cutter is far too great on my machine for instance.