New build in Kent, on Dexion base

Hi all,
This is my first build of a cnc router. The budget is tight, so I will make use of whatever I have to hand. I have a bench made from Dexion pallet racking. The top rails will support
the MDF bed, which will lay on unistrut(40x40mm channel) cross-rails. The bench is 2 tier, so there is a lower shelf laying on the bottom rails.
The overall lenght of the bench is 2830 x 1m wide. I like the idea of having alu angle rails bolted back to back along the long edges, with the gantry running on v-bearings and chain driven. Similar to buildyourcnc.com. Also having one motor on the gantry seems logical, not just cost wise but also to keep the gantry square.
The plan is to fix a 3050mm x 1100mm x 22mm MR MDF sheet on top of my bench and build from there. Would be nice to do vertical work on one end too.
Any input suggestions would be most appreciated. Will post pics if needed too.

Danny

Hi Dan,

Quite a big machine you have planned there! Any thoughts on what materials and projects you will cut with it - that will help people with suggestions.

How about the electrics side, stepper spec, drive voltage, spindle type (Dremel, router, spindle)? What about the drive systems on the other axes? Any ideas about jog rate?

How much Z travel are you thinking off, considering max work piece thickness plus some clearance to allow easy setup?

For further design ideas have an internet search for:
Joe's 4x4 hybrid
Mechmate
Ironman
Shopbot

Thanks . . .

Hi Routercnc,
I'm a bespoke joiner, so kitchens bedrooms corian fabrication, curved furniture etc. Materials would be MDF, MFC, corian, perspex.

The main thing is to be able to drill, groove, dowel tall carcass sides for bedrooms. Also sink cut-outs and drainer grooves in corian.

Electronics is not my strong point, but looking at other builds I would have thought a Nema 34 with double shaft on the gangry, driving
a sprocket on either end, which runs on tensioned chain running the lenght of the 2 x axis. Similar to buildyourcnc.com.
Same drive system for the y axis, and lead screw for the Z axis. Would Nema 23 do for Y & Z?, not sure, open to suggestions.

Router will be used for cutting. Should I use the cheapest heavy duty one I can find and just replace it often, or go for a more expensive one?

Drive voltage, stepper spec & jog rate will need advice. Would be good to learn from others mistakes?

Most of my cutting would be sheet material, with the occasional tapered table leg. I might want to machine some solid timber but nothing more than 75mm thick.
So Z travel would not have to be more than 200mm. I like the idea of T-slot bed for clamping.

The first machine I wanted to build a couple of years ago was the mechmate, but could never find the time because I was flat out! The only thing I wasn't keen on
with their design was not being able to use the bench for other purposes because of the high sides.

I would like my machine to be able to load from any angle. So that I just had a flat bed that I could just slide boards onto.
Dust is also an issue. The machine will be in the area where the joinery benches are. It will have it's own extraction, but there's always dust coming from the benches nearby.

I have a separate machine room where the 10' x 5' wall saw is. I could always put the cnc next to it, but it means moving other 3 phase machines and their wiring. Time & money
again!

I have looked at some of the other options for linear motion, but the cost would be quite high for a 3m run. Chain and sprocket seems like a good choice. Especially as the tensioned chain would keep backlash to a minimum. Open to suggestions as always...

Danny