New CNC router 8x4 For Cutting Multiple Materials

[ciscoeuk]

Not a bad start, but a few changes will make it a lot easier to construct and stronger. The most important factor is how do you intend to fix the box section for the bed (25mm) to the rest of the frame? It looks like it's just welded on at the moment, which makes the bed nice and strong, but the issue is with such a large Z-axis (450mm) you want to be able to adjust the height of the bed. The general idea is for sheet material you put the bed high up, so where it is in your drawing, then for the occasions where you need more Z-travel you drop it down. This is easy enough to do if you drill a series of holes in the 6 vertical pieces, support the cross pieces for the bed on two 8' long prices of box section, then attach them to the frame with M12 bolts. If that's not clear then look at my build log. You've got no chance of cutting 12mm aluminium and having 450mm Z-travel, without having an adjustable height bed.

It'll be a lot easier to make if you use 50mm box section, or something bigger than 25mm, for the bed and use less of it. Also add in some diagonal pieces to the main frame since without them it will skew relatively easily.

Since you want to use this for cutting aluminium, if only occasionally, I wouldn't use rack and pinion since the resolution and rigidity will be worse than with ballscres. You can easily use a ballscrew and 3Nm nema 24 motor on the 1500mm axis, however to use ballscrews on the 2500mm axis requires a large ballscrew and big motors, or rotating nuts.

JONATHAN
thanks for the advice and taken on board,

i have decided to cut the z axis height down to 400mm ballscrew as the y gantry is 2x8 ali box

decided this after i found out the you can mill sections at a time and glue together to for a fibreglass/vac form plug i think mach 3 has that ability or was it artcam????

at a later date build a cnc router for carving vac form plugs,the later cnc 800 x 800 from ali extrusion and plate this does not have to so stiff and rigid as it only carving foam/plastics and MDF and pine

since i posted i have modified the frame to be very rigid, see pics




i know that using 50mm box would be better and save some pennis but i decied to stick to the 25mm as a way of spreading the weight and of course it looks nicer but this may change

as for the x axis and using rack or ballscrews the jury is out on that at the mo , thanks for the spanner by the way LOL

i will post my idea for using rack and pion and a lock plate,

i will have that idea up soon

speak later, buy the way i am on skype if u want to face to face pm me

ATB

ric