Well here goes... Aluminium frame router design

[JAZZCNC]

Hi, TBH I changed because that many people can't be wrong...Can they? :-P
I understand what they are saying, although I don't fully agree because although with the conventional method at miniumum travel it is stronger because the tool tip is about 40mm from the bottom bearing block, at max travel it would be far more flimsy than my design, there must be a 'magic' point on Z where aluminium can be machined ok and if I knew that distance then I could try and work it out in my design.

Well don't be put off by anything we say and always go with your gut feeling I would say. but I'll tell you now thru experience not guessing that your wrong.

There is a magic number.? On my machine.!! It's 0-50mm and past this finish deteriates to point that's not acceptable to me, but that doesn't mean my number will match your machines number.!! . . . . This is essentially the problem in that every machine is different and the finish you get will be a direct results of how strong and how good the design along with many other variables. This also holds true for feeds n speeds to some degree.? Each machine will perform different for same material.!

None of that matters now ( I think!) because I have gone back to the drawing board with a completely different design using a fixed gantry based off a Video Jazz posted in another thread where the Y axis raises and lowers with Z. It may come to nothing and I may change my mind again!

If it's the one I'm thinking about then it's a good layout and very strong. I've got a much larger version part built using 150mm box section for my self just can't get around to finishing it. (Well it's more starting than finishing.!!)

Jazz, I know what you say about jack of all trade machines, it would help if I knew what I intended to use the machine for but I don't! I like working with wood as much as metal, I think now I am leaning more towards metal machining because more practical things can be made but I would also like to have a play with my artistic side with woods and plastics, This was why I was going for a router type build initially but the size required for some of my wood type projects have put a bit of a dampener on that :-( unless I go for a vertical machine like yours.
Cheers, Charlie

If your going for metal then forget the moving gantry design. Go with the design above and make it massively strong. To be honest if your wanting to cut metal then I'd suggest you keep an eye out for a large Milling machine and convert to CNC or look for used or knackerd CNC VMC and convert to Mach3/Linux cnc.
Only few weeks ago there was a Cincinnati CNC VMC on ebay for £1400 24 tool changer and full bag of tricks. At that money even if screws and rails where worn out you could convert control and replace components for same money or not much more than building a DIY machine for cutting steel.!

To give an example I picked this CNC Mill up at scrap value. 1100 x 500 x 500 cutting area. DC servo's, 7.5Kw Cat40 spindle, Was fully working apart from needing PSU for the out dated Hindeman control which at some point around 2060 when get time I'll be replacing with Mach3 and CSlabs Analog controller. DIY isn't always the best option esp when you get into milling steels.!