Cancelled - Modified OX CNC for Mitre Cutting (Picture Framing)

--- UPDATE BELOW ---
Hi Everyone,

I've been reading alot, but first post and first build.

I'm embarking on an interesting idea...
We make picture frames on-spec, and have tried the usual setups of guillotines and drop saws, but nothing seems accurate enough (and getting a perfect 45° cut from a drop saw is near impossible at the tolerance we want it at).
Of course commercial solutions are available, but at $40,000 AUD, it's somewhat above what i'd like to spend right now.

So i'm thinking of building a new machine that basically uses a small OX, but is modified to suit my needs.

I've made up some renders using available models, just to see if everything would roughly fit together, and can't see any major problems.
Though i'm unsettled on materials for some things (belt drive over rack/pinion etc), but all things i can work out as i go.

Basic modifications:-
1. The Y axis is inverted, and the whole machine inverted. So the gantry will "hang" rather than stand. This is so our long lengths of moulding can be run along the support table underneath.
2. I'm building a sort of torsion-boxed support frame (3m on either side of the CNC) from laminated timber beams. The top surface is 35cm wide. I will build support for the whole structure, but it should be strong enough to maintain a good platform.
3. The addition to the whole thing will be a stepper controlled measurement "stop". Basically we can butt one end of the moulding against it and know the CNC will cut precisely the length we want. We have manual versions, but why not computerise it This will be a secondary part of the build, but everything will be made with the intention of doing so.
4. The measurement device runs on supported rails and linear bearings, mainly because it seems to be the best approach for 3m span.


Obviously the Ox will be supported too. I'm thinking thick vertical posts with cross bracing, as part of the overall structure.

Anyone care to provide any input or major issues?

I figure i can buy the Ox kit, make the torsion box support structure, and see how everything goes together...

Any thoughts and input are more than welcome.

Rob





OK - so i've actually abandoned this idea.
Based on some tinkering and the feedback received, i've decided that the best approach is working with the mitre saws.

WHAT I LEARNED:-
1. The mitre saw is capable of making a repeatable, straight cut.. HOWEVER....
2. The mitre saw IS NOT capable of making an accurate cut at +45° as well as -45°.
3. The horizontal swivel throws out the camber of the saw - this is what causes endless chasing of non-square cuts...

SO:-
1. I need TWO mitre saws (i can still swivel one back to 0° for a square cut, then back to angle, without throwing out the adjustments), so i can accurately calibrate each for their respective cuts.
2. I'm still going to build the CNC measuring guide, so i'll update this here.

Far less exciting than a CNC Mitre Cutter, but will probably actually get the job done more reliably and better.

Rob