My first ever built CNC router.

[JAZZCNC]

I've been working on a design for a DIY CNC Router for a little while and recently I said damn it, I need to build it. I've kinda gone headlong into it and started to order bits (probably a mistake) but I wanted to get some professional feedback to hopefully put my mind at rest a little.

Ok well saying don't buy anything yet would be saying it after the horse as bolted so instead I'll say SEND IT BACK.!!

The rails and ball-screws are ok-ish thou they are the budget range but still better than round rail so your ok there.
However the drives and motors you need to dump as they will cripple the machine, esp if using parallel port.

The spindle is open to debate, some like Air cooled for it's simplicity. Me personally I prefer water cooled not so much because of the noise, which they are much quiter, but for the fact I can run jobs that are 20-30hrs and not worry. Try running a cheap air cooled spindle for more than 8hrs continuously and it will melt down.
Now your thinking aghh but I won't ever cut that length of time.!!.. … But you'll probably find you will at some point, esp if you ever want to cut 2.5D/3D ie: relief carvings etc which even a small-ish job can easily take 8hrs if it's detailed.

Regards the controller, if your going with a parallel port then go with Linux CNC. Mach3 is rubbish with a PP and flaky.
My advise is spend a little more and buy a decent ethernet motion controller like UC300 or AXBB because parallel port is slow and frustrating. The motion controller is the heart of the machine so it needs to be good.
Regards the Stand alone DDCV controllers then all I'll say is I know lots of people who have taken that route only to still end up fitting a PC based controller because they find them restrictive or don't like the fact they can't do the things a PC based one can.?

I have one cost nutral tip.

Swap the bearing blocks and rail on the z axis.
So the rails are on the moving part of the z axis.

No that's the case with this design and it will restrict the machine rather than make it better unless the whole gantry is re-designed to account for it.!

I've said this several times now but there is very little difference between the two methods in real world use depending on gantry design. The type and design of machine/gantry is a better selector for which method is best.
In this case it would restrict the travel of the Z axis which would require the gantry is made taller to get the travel back. This negates any advantage that rails on the front plate would have and actually turns it into a disadvantage because tall gantry sides introduce more vibrations at the spindle which negatively affects finish quality and tool wear.

Also because the gantry is short n stubby with a short front plate, which is a good thing, the cutting forces are transferred straight back into rear plate at all times.
Yes there is a constant length lever affect but it's short and not an issue when cutting, however the advantage in cutting height it gives is well worth the tiny difference.
The short stubby gantry makes this possible.