The main problem that I have found with CNCZone is the number of people on here who make building these things look easy. Spend enough time on this forum for example and you start to wonder how hard it could possibly be ? And down that road lies madness.
A bit of background. I'm an architecture student and I have exactly zero experience machining anything. I build models out of basswood. Actually until last night I had never even taken a drill to anything but wood.
Long story short I run across the Solsylva stuff, I see a few examples on Youtube, I recall an experience watching one of my models get cut out on a Zund machine, and I figure I can do this. And I buy the plans.
So here's what I want to achieve. Build the rack and pinion router table with the aluminum gantry straight out of the plan book but make it cut model materials like chipboard and cardboard. This requires a knife rather than a router. (see this machine for inspiration: http://www.comagrav.com/oscillating_...ial_knife.html )
This knife needs to rotate around its axis (parallel to z) so that's a 4th motor, size unkown. I also want to be able to swap a router on to this and create 3D contours on site models. This is a lot of routing so I want it to be fast. So some 425 oz-in steppers on x,y and z should just about do it.
Until I figure out what motor size I need to turn the knife (not a clue but probably not big) I'm holding off on sourcing the motors.
First off these materials come in 36" wide sheets so I need to increase the y axis. No problem according to David Steele. I figured I could use 4 foot racks everywhere. DS lets me know in a very informative email that I'm better of with 3/8" leadscrews on the y if I want to avoid excessive backlash. But now I need to cut my leadscrews from a 6' length.
Interesting thing, the 6' x 3/8" screws at McMaster do not come in plain steel. The 1/2" ones do. So 1/2" at 10-2 is cheaper than 3/8". However I am sure that that difference will be offset by the cost of 1/2" leadnuts and bearings. So 3/8" or 1/2" ? Decisions, decisions. Whipping isn't really going to be a problem over 4 feet and apparently neither is z axis drop.
David evidently got good results with 1/2" 10 - 2 ACME Precision rods (in the drive systems comparison table in the plan book) so I'll just go with those. Maybe it's overkill ? What do I know ? At this point the anticipation is making my palms itch.
Summary: my final machine spec will be something like a 36" x 48" cutting surface with racks on x and ACME Precision 1/2" 10-2 rod on the y and z. Then I'll be putting 425 oz-in steppers on all 3 axes.
This leaves the cutting head design. I'm still stuck on that. But this can wait. Like I said, I'm getting antsy. I need to start building something.
So on Friday I went and got all the aluminum from our local Alro Metal Supply here in Sarasota. Total 112 $. On Saturday I went and got the hardware and gas pipe. On Monday evening I chopped the 3/8" x 6" aluminum plate for the gantry ends and put in the order for the bearings. And last night I broke out the Craftsman benchtop drill press I got specifically for this purpose a year ago (50$ on Craigslist), checked the supplied templates for accuracy (they are way more accurate than I am) and started drilling the y gantry end plates.
Halfway through making the 5/16" holes I get over enthusiastic, push too hard, stall the bit in the aluminum, yank the chuck straight off the arbor and bend the bit into new and interesting shapes.
Open fridge, extract beer, close fridge, drink beer, go to bed.
Today I receive delivery notification that the skate bearings have arrived and so am flush with a renewed sense of purpose.
Need new drill bit.