Steel frame cnc router design/build

[JAZZCNC]

Ok I'm back with my wrecking ball . . Get ready.!!. .

So I see you've been paying attention with using the high sides and gantry sat on rails design which is great for twin screw machines but in this case it's actually hurting your design badly.?

Because your wanting to use single screw (with option to upgrade) this means having gantry cross brace but with those high sides it means having long gantry sides which are acting has levers. They will flex, twist and stress the bearings, they will also resonate like crazy, this all transfers back to the work or like Matt hinted at make the bloody thing dance around the room if bad.!!. . . Not good design for this way of doing it.!

Really because of your budget restrictions then your going to have accept a bit of compromise on design.? In this case it's flexibility regards cutting height and materials you'll be able to cut. The high sides with gantry on rail design works very well if you want strong rigidity and flexibility of lifting the bed but it just don't work for use with single screw.

So your going to need a way to keep Gantry sides short has possible but yet high enough to give clearance you'll need for cutting what you want to cut.? . . . . It's simple enough you can't have high clearance and high strength,it's always a compromise with this way of doing it.
So best thing is first decide the lowest clearance you can work with a build frame that allows gantry to be kept short and strong.!

There's several ways to build frame to allow this and I'm not going to try telling them all I'm just going to show the sort of thing I'd build for this Budget and upgrade has you can afford way of doing things. (It's just something I knocked up to show principle not finished design)

This gantry/frame design will be very strong and use's roughly 2.5 x 7.5mtr lengths of 80x40x3. It can easily be converted to twin ballscrews.
It's shown has desktop machine to keep cost's down but making it free standing would be simple enough just cost more.

Hope this helps and carry on it's perfectly do-able to build strong machine even on budget.

Oh one more thing or Tip with modelling.? . . Get accurate dimensions or better still Cad models for the things you plan to use, like ballscrews, motors etc has it's easy to think I'll use this or that like this and then it doesn't fit or interferers with something else.