Wobblycogs CNC Mk1

[Wobblycogs]

I've done a lot of reading of build logs in the last week and a fair bit of tinkering in sketchup to (hopefully) improve the design. I thought it was about time to do an update and to find out if I'm going in even vaguely the right direction.

First off we have the gantry connection to the rails and x-screws. I noticed a lot of people were advised to make this connection stronger so hopefully this will be strong enough.

The block that attaches to the ball nut is a 50mm lump of aluminium. The green bolts are M8x90 and go most of the way through. The blue bolts are M6x30 and screw in to the block between 15 and 20mm. After seeing someone else's build I've gone for a two plate gantry design as I think it'll be simpler in the long run. There will be slotted screws holding the two plates together so fingers crossed I should be able to get the screw and gantry connections aligned. I'm not keen on the three M6 bolts close together on the top plate but I think they've got to stay. They are there to counter any torque applied by the green bolts and face plate if things aren't 100% square.

I've slightly redesigned the bed to make it simpler to build and to move the legs to be directly under the x-rail. It's shown bolted together but I've decided to weld at least some of the joints so that I get it done this century.

Now here's where I'm going a little off-piste with the gantry I think. I read the recent thread discussing gantry designs and liked the L shaped solution made from 45x90 extrusion. I also liked the C shaped designs so I thought why not try and combine the best of both worlds and use some 90x90 heavy extrusion (this is now in the sketchup library if anyone else wants it). I'm guessing this will give me both vertical and horizontal strength and the extra bit of mass should help damp any vibrations a bit.

I'm currently pondering running the y-rails along the front of the gantry rather than top and bottom as most people do. Although this will cause the Z-axis to stick out about 50mm more than the top and bottom rail design it will also allow me to maximize my y-cutting distance and have a slightly wider y-bearing spacing. The gantry side plate will be braced front and back and reduced in size to only what is required as the design progresses.



One thing that is starting to concern me a little is cutting all this aluminium. I have a good selection of wood working tools but not much in the way of metal working tools. Do you think it would be possible to hand route 20mm aluminium? From what I've read slower bit rotation is better, the slowest my router will go is 10,000rpm which seems to be slower than most so I think I'm in with a shot but some advice would be much appreciated. Cheers :-)