First design - Few questions

[JAZZCNC]

Some general questions from reading and looking at some of the designs.... What strikes me is there is a lot over engineering in frames etc. Ok that's needed in context of cutting duty.
I'm thinking MDF, Plywood and Aluminium plate, with 3- 10mm cutters I assume.

Some of the frames are huge steel welded section, the likes which I've made/designed in the distant past to hold large diesel generating sets.... Then heavy steel gantries on top.... Seems OTT for such cutting duties.

Yes they are well OTT has my recent little rant tried to highlight for new users just like you.
If your into engineering then you'll have a good idea of whats required material strength wise so just apply common sense. The things to think and design around are resonance, flex along with plenty of adjustment built in to account for the DIY factor.
The most important area and under estimated is the Z axis. It's at the sharpe end taking all the cutting forces directly so any weakness here will show in the finished work.

I'm not expecting to machine steel billets, for a start I'm thinking of a Kress 1050 spindle, which I guess could be the limiting factor on loads.
I also want to use 3 4mn Nema 23's... So I have an eye on the weight.
Having looked at the designs here I'm reluctant to post my CAD design now, as its a way off what I see. For example running FEA analysis on say a single 1200mm length of 25mm x 200mm Marine plywood gives 0.0X range of deflection with a 50 Kg load.

Going back to the Z axis and cutting forces. The spindle power is key to balance and all those OTT engineered machines you've seen are under powered in the spindle department, by long mark in many cases. That is just waste of money, resources and time IMO which actually reduces the machines capabiltys not improves. IE: Lower acceleration or rapid feeds.
For a serious DIY machine that will cut everything upto aluminium and do it for lengthy periods then don't use a Kress spindle. They are toys in comparison to the chinese Water cooled spindles and not much cheaper.

Weight wise then 3 or 4Nm nema23's with the correct drives and voltage using ballscrews and profiled linear rails will be ok upto 70-80Kg Gantry and give good speeds with correct pitch.

Regards your design then don't hold back post it up for us to see. It's the best way to iron out any grey areas.
I'm not a fan of wood machines for several reasons which have been said but what you have to consider is the main use of the machine. If soley or mostly Wood use then it will be fine if designed correctly. It won't be cheaper than steel thou and much weaker.

If your thinking to cut aluminium then just plane forget using wood it just won't work reliably over time and be repeatable. Cutting Aluminium correctly takes the machine into another level. Yes most any machien will scratch it away but thats not cutting and does take it's toll on machine and tool life if not designed for it.
For a first machine I'd recommend you concentrate on the wood use only and build it the best it can be to do that.

Go for it and DONT let those Massive builds put you off it's NOT REQUIRED.!. . .