Wobblycogs CNC Mk2

[JAZZCNC]

Now for the problems...

I've been reading loads of threads and I'm getting concerned that 45x60 profile in the gantry isn't strong enough and that I should probably go with 60x90. It's a damn sight more expensive and I don't want to upgrade if it won't help but I'd rather have a machine that was a bit over built than a bit under built.

Absolutely would go bigger and even at 60x90 you won't be over building believe me.!! . . like the Famous film words.? "Don't under estimate the force" Wobbycogs.!!

The plan currently has SBR16 rail all over but I (and and a lot of other people it seems) have noticed there's not a lot of clearance (e.g. none) on the z-axis ballnut. The million dollar question is do I switch to SBR20 rail or try and rout out a pocket for the ballnut on the z-axis if needed?

Either has you can always pack for clearance and it keeps Z axis compact and light. Bigger will give clearance at the cost of weight and extra standoff.

And the big one... At the moment the rail is mounted straight onto the profile. Ooops, school boy error. I think I'd get away with it on the x-axis as there's a good 6mm of aluminium to bolt into. On the y-axis though it's clearly not enough as drawn. Presumably a 10mm plate bolted to the profile will fix this? Does it need to be toolplate?

Yes use a 10mm plate but wouldn't bother with tooling plate has the rail base will have more error than the standard plate so waste of money if your not going to skim the rail base.!

Some other, probably stupid, ideas have come to mind though, would this machine be capable of engraving and or cutting brass? I've cut a couple of small bits of brass with a hacksaw and it seemed similar to aluminium in hardness. I've also considered making the x-axis significantly longer, say 1000mm of cutting length, I'm trying to resist that though as I still want to build my Mk1 machine which will be designed to handle large pieces.

If it will cut Ali properly then it will cut brass Ok.