Starting CNC router, need some advice

Hi,

I will be starting this month a CNC router. I already got the framework, which is basically a 1/8" thick stainless steel sheet bent around all corners to form a box. The box size is 33.25" long, 24.5" wide, 9.5" high. At only one end (24.5" by 9.5" end) there is a narrow slot near the bottom with no bent sides, this would be a perfect place to slide the parts to be cut into. I plan to put the gantry inside the box, well, as much as I can. I thing the Z-axis will be stick outside the box, depending how big the router is.

I plan to use it mostly for wood, like balsa to oak. Mostly 2.5D engraving and cutting part out. Maybe some 3D wood milling and 3D aluminum. The Z-axis will be go down to 2" to 2.5". The rate of cutting is not important, if it takes all day to cut and so be it. What router do you suggest to use?

The cutting area is uncertain yet, but I am guessing it would probably be around 26" by 18". This is assuming the grantry uses up 6" on the 33.25" axis, and 5" on the 24.5" axis.
1) How short or long should I make these to insure I get a good support for the gantry and the router head platform? Or is the measurement I predict ok? or can it be a little shorter?

I guess I should mention the linear motion system I will be using. Well, I am thinking of using an 1" diameter rod (that polish grinded shaft material). Its better quality than the regular steel rods. 2 pcs going along the 33.25" length, and 2 going along the gantry on the 24.5" length. I was looking at the 3/4" diameter but I think that is too weak for my needs. There is thompson bars but they are expensive. The grinded shaft is expensive but lesser than the thomspon bar. And I plan to use linear ball bearings. I these are a good in between of linear block/rail method, and the regular bearing on rod method.
2) Is this alright? Is 1" strong enough for my needs? Maybe the Z axis for the router should use the 3/4" rod.

Furthermore, I will be drilling holds at either ends of the box in order to put the rods in. On the outside of the box, there will be a metal block maybe around 24.5" x 2.5" with holes in them to support the rods, and this block will be either welded in place or screwed. The rods will be screw tightened into the blocks, in the preparation for future remove of weared out rod.
3) Is this adequate? Should I make th block out of SS or aluminum?

Control system. I plan to get the CandCNC breakout board. I am looking at Xylotex's 3-axis system with 269oz steppers and 24v power supply. I am thinking I will use a belt train to reduce it by 3:1 or something in the range. To make the steppers stronger and better resolution.
4) Is this system alright for my CNC? And is 3:1 ok or should I go for more?

Software recommendations? I really like to use my laptop for the cnc which is 1.8Ghz AMD athlong processor with Windows XP. Mach 2/3 looks good and I hear good things about it, but is there other good windows based software?
I also need software for 2.5D engraving on wood, mostly for hobby airlplane parts on balsa sheets, and engraving on larger wood, like oak, pine, others. But I an hoping that I can use it on aluminum to make some molds for model airplane fuselages. I need something I can adjust the rate of the cutting (ipm).

Thank for you taking the time to read this, this is what I have so far.

If you use linear ball bearings on unhardened shaft, the bearings will quickly wear grooves in the shaft. 3/4" should be fine for the Z, but even the 1" will have some sag and flex if unsupported.

If your mostly cutting wood, and using leadscrews, don't use any reduction at all. All it will do is drastically lower your top speed., and it's very unlikely you'll notice any increase in resolution.

As for software, look at www.meshcam.com for cutting molds and www.sheetcam.com for cutting flat parts. If it's in your budget, www.vectric.com for engraving. You'll also need a CAD program.

So far, I am looking at the linear ball bearing method. Adding supports to it is a good idea. The shaft I mentioned, I dont know if its hardened or not, I'll have to check it. I do know the exterior is grinded to a polished accurate outside surface and it comes packaged in a cardboard tube. I'll ask about the hardness. I realise it will wear out eventually, but once it does, I plan to rotate each shaft by a few degrees to provide a fresh surface for the balls in the linear ball bearings. Thomspon bars seem too expensive, I have ask prices yet.

I also considered using hexagon bar, with a bearing running in the gantry area, at 90 degrees, and have 2 other bearings running on the other side of the bar a 45 and 45 degrees. Any opinions about this method?

It will be mostly for wood. Using 2.5D. Sometimes for cutting radio control airplane parts like wing airfoil ribs from Balsa sheets. But mostly for engraving artworks into wood, like pine, oak, and others. Sometimes 3D in wood and in aluminum, like making model airplane molds for fuselages, but not deep, like a few inches. Time is not important, it can take all day if needed.

From what I read here, I thought people used reduction for 2 reasons, to increase the torque of the steppers, and improve resolution. I dont know if 269oz-in steppers from xylotex is strong enough for hard wood and aluminum, if used directly.

In the future, I plan on building a larger CNC plasma, so I guess the sheetcam/mach3 combo looks ok. Concerning CAD, I have A9CAD, and I have AUTOCAD, but I dont know how to use the autocad yet, but I have been practicing with A9CAD. For engraving, I would like if I could scan in drawing (scratched on paper by hand) and then let the software use it and convert it to something that the CNC can cut.