Right then, after much dithering I've decided to go with the 2510 screws and some nema 34's. I've not picked the motors and drivers yet but looking at what's been recommended I can clearly get something that will work in a 34 package so it's time to press on with the design :-)

Since I'm using 50mm box for the frame I can't directly mount the screw bearing block onto the frame. I'm hoping to get around that by mounting the bearing block and motor on a plate (green) which then bolts onto the frame. The picture below shows the business end of the screw but there's a similar plate at the other end as well. Good idea / bad idea?

The plate is currently drawn at 100x300x5mm as it was going to be steel but I'm now thinking aluminium would be better as it would be easier to work (I want to provide some vertical adjustment holes for example). Will 5mm aluminium be strong enough?

The motor housing is drawn in 20mm aluminium which looks far thicker than I need but I have very little experience to go by. Would 16mm or even 12mm be strong enough? I'm going to drill and tap the edges to join the pieces together so it can't be too narrow :-). Ideally I'd like to use the same thickness plate for parts on the gantry and Z-axis so that I can just buy one large piece of plate which, fingers crossed, will be cheaper.

Finally, what grade of aluminium should I go for? The motor housing and probably a few other bits will need to be milled out; I've got decent variable speed router so I was going to give it a go with that (taking very light cuts and with a template). I seem to remember someone saying they were using C250 but it looks like 6082 is easier to machine from what I've read.

Cheers

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