CNC Router V1.0 (For Cutting Multiple Materials)

[Wobblycogs]

Just my 2p worth... I'd say you have a lot of designing still to do. My guess is that you will replace some of that extrusion with plate and you'll probably add more (machined) plate into the design. Any guess at a machining cost at this stage would be unrealistic I think. You might also like to consider whether your design will require machining on both sides of any plate as that will increase the cost due to the set up time needed to machine one side, flip the plate and align it accurately for machining on the other side. If you have a look at my design I've specifically made it so that it can all be machined from one side with the exception of some counterbores that I'll do myself. Lets put it this way, I spent a lot more on parts than I did / will on machining costs.

[biketrialsdave]

Thanks for the help, I will try and keep all parts machined one side only.

Slowly but surely I'm starting to make some progress...

[biketrialsdave]

My thread moved?!

[biketrialsdave]

Small update...



Now I've mounted the FF blocks on the outside of the plates I don't think I'll get an off-the-shelf motor mount which will fit over them? So I might need to use pulleys?

[Wobblycogs]

Pulleys are the way forward, they give you flexibility in the final machine and generally make the design simpler. It's slightly more expensive to use pulleys rather than a direct connection and there are more moving parts which means more points of failure but I think that's a small price to pay.

One thing I would say about your design is start pricing it up. I'm guessing those corner connection blocks are the 90x90 ones - they are quite expensive if you need a load of them and they don't result in a machine that is all that stiff (they are great for display stands, not so great for machines). Once you start getting into the nitty gritty of placing components and pricing up I think you'll begin to consider using aluminium plate and box section more.

Looking good though.

[biketrialsdave]

You are very right. I have been keeping an eye on the cost and realising that it soon adds up. The reasons why I am not leaning towards a steel box section frame; the first is I don't have a MIG welder! The second is that even if I could justify purchasing one then I cannot see how people manage to weld everything so that it is all square and flat? In my mind that would be quite a hard thing to achieve?

[Wobblycogs]

I was meaning aluminium box section, you can get some really large sizes if you shop around. It's more expensive than a frame made from steel box sections but it's easy to work with and the supplier will cut it to length normally (I used aluminium warehouse iirc).

My first CNC design included a steel frame and I actually rushed out and bought a halfway decent MIG welder. I never actually built the frame in the end though, doh! Anyway, you don't need a fancy MIG to weld the steel frame together - a cheap and nasty stick welder from ebay will do the job, there's one up for £26 at the moment. The trouble with MIG is unless you go for one with some grunt it won't handle the 4mm thick box you'd want to build the frame from. As for keeping it square and level if you look around you'd be amazed what can be done with epoxy resin. Basically you weld up the frame as square as you can (lots of small welds + clamps) and then pour very thin epoxy over where you'll mount the x-axis rails. The epoxy will self level and should leave you with two sides that are in exactly the same plane. Check out this thread as Neil will be doing another epoxy pour any time soon (actually the technique in the first pour was fine he just fluffed the mixture).