a Steel Box Section Build with SBR20 & Ballscrews Plus a few questions

[grain_r]

thanks very much for doing it all the same.

[njhussey]

Quick tip....when creating a part, say a 50 x 50 leg, once you've created it select it all and right click and create a group. It's much easier to move it, rotate it etc. without messing about with the other parts it's placed next to. Might be teaching Granny to suck eggs but I've just tried moving some bits and it's creating some interesting shapes....

[EddyCurrent]

Just a thought.
If you made the Z backplate wider, keeping the Y bearing blocks where they are due to short rails etc. you could then move the Z bearing blocks wider and fit a wider Z front plate.
This might give you the opportunity to mount the spindle in 3 positions, left, right, centre, not ideal but maybe useful ?
Or maybe you could then mount another device beside the spindle such as a laser head, 3D printer head ?

[grain_r]

Hey Neil,

I'm sorry about that your certainly not teaching granny, I gone more on the lines well that seemed to make the shape I want at the time. I will certainly group then from now on the makes a lot of sense I tried to do it with layers instead of the grouping and then selecting the layer to move things around. Although I certainly got further on sketch-up than on Autocad 3d up to now that's next weeks job then (Well Maybe)

Thanks Eddy that sounds like it would be worth a look at I also though about a plasma cutter for the future for stainless although thats as far as I've gone with it. I appologize not having used one of these things would I be able to set a home and then use different paths for the further cuts ? I'm certainly not worried about having to swap the spindle around between then that would get the hoped for cutting area when I forgot about the bearing blocks when I felt like a shopping trip before I knew anything at all.

thanks

Rob

[EddyCurrent]

I appologize not having used one of these things would I be able to set a home and then use different paths for the further cuts ?

Rob, I think this is what you mean.
Home switches use the 'machine coordinates' whereas the work piece you are cutting uses 'machine coordinates', so a search for those terms should bring up some further reading.
Like a piece of graph paper the home switches will be at 'machine coordinate' X0,Y0 and if you clamped a piece of wood on the table for example and moved your spindle to the bottom left corner, that could be your X0,Y0 'work coordinate' and that's what you typically set to zero in Mach3 for example so that X0,Y0 in your g-code starts cutting in the right place.
So really you can give the machine an X0,Y0 work ccordinate starting point just about anywhere on the cutting table.
Think of the machine as big piece of graph paper that is in a fixed position (machine coordinates) and the work piece as a smaller piece of graph paper that can be moved about on top of it (work coordinates).
So on a 900 x 600 machine, if you put a workpiece with it's bottom left corner in the middle of the bed, that corner might have 'machine coordinate' X450, Y300 and 'work coordinates' X0,Y0

There's also offsets/fixture coordinates that could be usefully employed; http://www.cnccookbook.com/CCCNCGCod...orkOffsets.htm

[grain_r]

Ah OK so if I had a movable spindle on the plate I can just set the coordinates on the work piece and then even thought the spindle has moved Mach3 would still know where to start from, from that same cutting path, I Wouldnt have to reset back to 0,0 and then get a new cut path. to get a continuous cut.

[EddyCurrent]

Ah OK so if I had a movable spindle on the plate I can just set the coordinates on the work piece and then even thought the spindle has moved Mach3 would still know where to start from, from that same cutting path, I Wouldnt have to reset back to 0,0 and then get a new cut path. to get a continuous cut.

That's right, as long as you tell Mach3 where work 0,0, is you're good to cut.
I've just realised you might be considering moving the spindle in the middle of a job, that's going to give you problems but could be done if planned for in advance, you could split the job up into, 'sub jobs' for example.
I would stick to, one job = one spindle position.

[JAZZCNC]

Hi,

Just looked at machine drawing and it's looking nearly there but 2 things both been picked up on and one Neil pointed out but think you've missed is the Z lower axis bearings conflicting with bolting together. This is a common Err that I and many others have done in the past so don't beat your self up. lol

The Long ballscrew mounting needs some attention.! These are areas where you need some adjustabilty for setting up and alignment so you will be best to mount the End bearings on plates that can be easily adjusted and like wise the mounting point on the Gantry needs to be more accessible. Try not to make the screw go thru the fixed mount but rather have ballnut mount that bolts to the gantry drop plate.
This will make screw alignment much easier and allow finding best performance just that bit simpler.!

Looking good and will soon be time to put the pen down and start cutting.!!