Probably a Stupid Question.

[Electroconducive]

Mix n match isn't a problem but how about giving us a clue to the design and size etc. Also what are you intending to do with this machine.?

Heavy isn't always better.! . . . Done correctly then Mass can help but it's expensive to do correctly because to take full advantage it doesn't just stop at motors. What's the point of having a gantry built like tank when to take full advantage you need 25HP spindle.?
Any machine is only as good as the weakist link and I guarantee there will be more weak links in your design than the gantry, Also if too heavy or not done correctly then it soon can become the achilles heal of the machine.

The motor Calc spreadsheet is useless in the real world of DIY CNC, far too many variables come into play which the spreadsheet doesn't account for. The person who designed the sheet had never even built a CNC machine so couldn't posssibly know all the things which come into play.

I am very much here to defer to the hands on experience of guys like yourself Jazz. So, thanks for prodding me for more details.

The overall size of the machine is currently 940x1200mm. I am hoping for a machining area of 900x600x200mm. I intend to mainly route Aluminium, Copper, Plastics, the occasional bit of wood and I'd like to be able to tickle steel enough to surface it. I am hoping for an accuracy of as much as I can get.

The super wide Z axis is to incorporate a standard 2.2kw chinese spindle and one of the cheap BT30 low 3000-6000 RPM spindles and a servo. I'd kinda like this machine to be as versatile as possible and would want the low RPM for tapping and possible fly cutting. I'd prefer this over a larger machining area. I expect I can shrink the Z width further to increase machining area and reduce weight.

Cheap BT30: https://www.aliexpress.com/item/BT30...ceBeautifyAB=0


The pictures show my current progress. The frame is 80x80x5mm SHS. The Gantry is a single 120x120x5 section with the rail mounts welded on 60x10mm flat bar, and either milled or epoxy levelled. The side sections are 15mm steel plate that will be bolted on and either mill surfaced in situ for rail carriages or epoxied level and in the same plane. The side plates are bolted to make milling the rail supports possible without crashing the mill. I am intending to fill the 120mm SHS with epoxy granite. I am yet to design the router floor stand.

Mass of the gantry+Z is currently 65KG without any spindles or EG. Spindles, steppers and the EG will easily add another 40KG. Hence the question about servo controlling the X axis.