Wobblycogs CNC Mk2

[Wobblycogs]

Another weekend comes and goes with much work on the house and little on the CNC, sigh. Anyway, after getting a tick for the gantry I've been going around the design putting in all the bolts. I figure it's better to find bolt hole collisions at this stage rather than when I come to build the machine. It's a really slow process even (even using the hole wizard) but I think it's worth it. For example I thought most holes would be using M5 bolts with some M6. In reality it's turned out most will have to be M4 with some M5. Also the thread depth on the linear bearings is surprisingly short so some careful counterboring will be required. The Z-axis stepper has grown a bent metal box cover. I'll probably end up adding a hinged flap on the front at some point - there was a front originally but I realized would wouldn't be able to fit the stepper through the hole I'd left!



The X-Axis is still has quite a bit of work to be done on it. As you can see there's no stepper, pulleys etc. The rails and screws are in the final location though as this is dictated by the rails. After reading this thread I'm toying with the idea of designing in the ability to use liquid coolant when cutting aluminium, I suspect that might be biting off more than I can chew at this stage though. I think I'll keep it in mind as a potential future improvement.

The rails, fingers crossed, should be with me fairly soon. Parcel Farce reports that they are in the country awaiting customs clearance. So far my first purchase from the far east seems to be going smoothly. Phew.

I got to thinking over the weekend about whether I would manage to finish this project (actually when because I'm going to finish it if it kills me) and it occurred to me that a lot of projects don't seem to make it past the planning stage and a good few seem to fail in the building stage. I wonder what percentage of people who want to build a CNC actually finish the task and end up with a machine that works (at least reasonably well).

[JAZZCNC]

The Z-axis stepper has grown a bent metal box cover. I'll probably end up adding a hinged flap on the front at some point - there was a front originally but I realized would wouldn't be able to fit the stepper through the hole I'd left!

I would make the Z front plate just bit narrower than Rear plate and put a full cover over the z axis so it protects rails and everything.
Easy done with 1.5mm Ali sheet, just make a cardboard template and then cut around. Don't need fancy bender or saws just score profile edges with stanley knife, trim with tin snips into straight length then bend to break off.
Easy folded with simple scores on fold lines (back side.!!). The pics below show cover which was folded by hand without clamping to make a permanent template then unfolded, (see pic.). . . If you clamp the sheet on top surface before folding and fold on edge of board then makes a better fold.

Takes about 30mins to make.!!

[Wobblycogs]

That looks more like a tank than a cnc machine :-). I bet it effective at keeping the chips out though.

Well, I've been hard at it putting bolts in the design and I think I've got to the point were there's not much point adding any more as they clearly wont clash. So with that done here are some shots of what will get built unless anyone comes up with a show stopper. my estimate for maximum cutting sizes are X: 840mm, Y: 840mm and Z: 125mm assuming a 50mm bit. I cab squeeze a bit more out of Z by moving the spindle up a series of holes.

[CraftyGeek]

Is the plan still to mount it vertically?...how is it going to be attached to the wall?

[Wobblycogs]

The original plan was to go vertical but the design has grown quite a bit since then to the point where it's not practical to vertically mount it, at least not in my current workshop anyway. When I move to a bigger workshop I might look into mounting it vertically again but to be honest I think what will probably happen is I build a steel base for it and use underneath the machine for storage.

[CraftyGeek]

Ah, ok - my next question was going to be how will you level it if its going to be horizontal...but I guess you'd put adjustable feet on the steel frame in that case?

Also - I got my wrist firmly slapped by Jazz for my design with the stepper motor mounted on the Z axis front plate...he said it should be on the Y axis plate instead to help keep it out of the way & reduce the weight on the z axis.

[Wobblycogs]

For now I'm going to put feet on what you see as the machine will either be on the floor or a bench somewhere. Once it's in it's final home on a proper frame there will be "something better".

I agree having the stepper on the front of the Z-axis isn't ideal but I don't see it being enough of a problem for me. I moved it from the back plate to the front plate because I had to get power and water to the spindle anyway. Having the stepper on the back plate made getting the cables over more difficult so the front plate seemed like a better choice. As I see it there are a couple of other advantages as well, it's allowed me to lift the z-axis screw up away from the chips a bit and the weight of the stepper will act as a pre-load on that axis.