Wobblycogs CNC Mk2

[Wobblycogs]

The design has progressed a bit so I thought it was time to get a bit of feedback...



I've decided to try to increase the maximum material thickness to more like 100mm (up from 50mm before). To achieve this though I seem to have ended up with an unusual bearing block placement on the z-axis, see image 2. The idea is to be able to lift the z-axis high enough so that the bottom of the gantry is the limiting factor for the material depth. As drawn I have 180mm top to bottom between the z-axis bearing blocks but I could easily increase this - I was thinking 250mm would compensate for the additional over hang of the z-axis.

The gantry has changed design several times . It started out as two pieces of 45x45 heavy (a bit like this) then got changed to two pieces of 60x90 heavy , then to a single piece of 90x90 heavy.

I finally settled on two pieces of 45x60 heavy with a backing plate of 10mm aluminium, the unsupported span is 610mm. The deflection calculator on the Metallin website (using the closest match) seems to think the z-axis deflection should be ok. Using 60x90 heavy would reduce deflection, I'm sure, but it was expensive and reduced the x-axis cutting. I think this is probably a fair compromise.

The belt arrangement of the x-axis has been improved. The ratio is now 1:1 and there's better belt contact with the stepper pulley.

I've not added the y or z-axis steppers into the diagram yet (should be fun). Also still to be drawn is a chip guard for the y-axis screw. There will be a thin plate with a long slot (and maybe brushes) for the y-axis connection to the z-axis assembly.