Hey guys!
It's been quite a while since I posted!

My last machine was a Probotix Fireball V90 that has since gone to a new home (and they've put over 500 hours of 3D carving on it since! wow!). I have been without a CNC machine for about a year, and have been finding more and more jobs in my new workshop that would be well suited to a smallish CNC router.

I currently make quite a number of semi-custom knives for customers all over. A new CNC router would be very handy in my shop for engraving (I used to do that on the V90) as well as 3D carving G10/Carbon fiber for knife handles... Currently I do basically everything by hand but I'd like to start looking at automating various parts of my process.

The materials I'd like this machine to work with are: wood, G10/FR4, Carbon fiber, aluminum. I'll also be using it quite a lot to engrave my logo and serial numbers into the knife blades after their completed. I've done this in the past with a carbide v-scoring bit and it's worked out very well so far.

One other potential use that I have for this machine that's a little outside the box is abrasive machining. Carbide tools don't last very long when cutting G10, but I run ceramic belts on my belt grinder that will last a very long time when cutting G10. For my handles for instance I think that it might work well to mount a small belt grinder in place of the spindle and use the abrasive belts to machine some of the simple contours on the handle. Kinda hard to explain just in text, but I think it has the potential to work out well.

The machine I have in mind would be fairly small with a work envelope of 12x24" to 24x48". I haven't decided yet whether I should concentrate on going small with the aim of getting extra performance out of the machine, or go a bit larger and hope the the extra flexibility will pay off.

Features I'm looking to incorporate:
* Ballscrews on all axis
* Profile rails on all axis
* Router frame constructed of aluminum extrusion and MIC-6 plate
* All rails/screws fully shrouded to protect from dust created by abrasive machining
* Water-cooled 80mm spindle and VFD
* Ability to use tooling up to 1/2"
* Home/limit switches on all axis
* 2x ballscrews and 2x steppers on X axis
* Gecko G540, NEMA23 steppers, and LinuxCNC for control

So, the questions I have for you guys:

1) Should I go big (24x48") or stay small (12x24"). My shop isn't large. Having the extra work envelope is nice, but if I can build a smaller and stiffer/more performant machine then that is also attractive as this machine *will* be used for production runs. The parts I'll be making will generally be small (on the order of 1.5x5x.25"), and the materials they're made from generally only come in small sheets (12x24" usually).

2) What kind of extrusions should I use for the machine frame? I can either get t-slot extrusions from Misumi, or I can simply use extruded rectangle tube from my metal supplier. I have a mill and lathe, so machining the tubing should be ok. The simplicity and cut-to-size nature of the t-slot is appealing, but at the same time I'm sure I can get more stiffness from 2x3" (or larger) rectangular tube.

If you guys think any of this sounds nuts please do speak up! The primary goal for this machine is to be performant and long-lasting. I'm less worried about it being the cheapest possible build as I know that once I get it running it will make my life better and help me get more product out of the shop.

I have a reasonable amount of experience fabricating parts, but I'm not an expert machinist by any stretch of the imagination. I am very familiar with all the parts necessary for the CNC though, as well as the required CAD/CAM workflows as I've built and run several kit CNCs in the past. I want this one to be a good deal more serious!

Any input it appreciated! Drawings and CAD mockups will start coming soon.
-Aaron