All,
I've been reading these forums for some time and I was going to buy a CNC ready Taig even though it did not really have as much travel as I would have liked. After seeing one 'in the flesh', I was even more disappointed by the size.
However, while scrounging for parts at a local industrial surplus place, I came across the perfect X-Y axis for a CNC build (sorry for the crappy pics, I only had my phone with me).
It's a Micro-Pax automated packing machine. Unlike a lot of packers, however, it has a cast iron base and arm, so it's very, very stiff.
It's got THK rails and ball screws, all tied to servos. The X axis in 32" with around 28" of travel, while the Y is around 26", with 20" of travel. There is around 10" under the arm, but I could put the whole machine on blocks to raise the Z a bit. The whole assembly probabaly weighs in the region of 200-250 lbs, it took 3 of us to move it easily (two can lift, 'tho).
As you can see from the above image, the connection to the arm is a very, very stout cast iron piece, ribbed on the backside. All the mounting surfaces on the cast iron bits are machined flat, and the arm is also cast.
The machine has 2 servos moving the X & Y axis. They appear to be Minertia RM Series servos, but I don't know the exact power. Everything moves very smoothly, by gravity if tilted. The whole machine has sheet metal covering all the ways, which is nice. Most of it was removed for the pictures.
For the Z-axis, I found an Intelligent Acutator linear actuator. It has two THX linear bearings and a ball screw coupled to a Japan Servo 30v 60w servo.
I'm not sure this motor will be enough to move the head + motor I plan to eventually use (a Sherline Industrial piece + a Surplus Center DC motor), so I might have to change it for a larger servo.
I'm planning on using Uli's servo controller, with fully assembled boards from Manjeet .
The real open question at the momment is what kind of base do I mount all this on? I've been looking at granite surface plates, but they are very, very heavy in the size I need. I could get one for around $200, but the typically have equipment holes in the them (usually right in the middle), which I guess is where coolant would eventually drain. It might not be much of an issue as I plan on having some sort of T-slot holding plate as well. I also priced out MIC6/cast tool plate. It was $350-$450 for 1/2 or 3/4 in the size I need and I'm not sure that's even actually thick enough. At that price, it would almost double my current dollar outlay.
I could really use some guidance here, particularly since I only have access to rudimentary tools (well, and a CNC plasma ) and I don't have ready access to a pickup.
Thoughts, comments, etc. are appreciated. I hope to machine aluminum with this, as well as some plastics. Nothing ultra-precise, mostly car bits, but perhaps I am naive as I've never done anything like this before.
I still need to figure out how to power these servos. I've seen some schematics for power supplies, but I'm guessing that an unregulated DC power supply of the appropriate voltage/amperage would work.
Thx.
Chris.
[PS: I hope I posted this in the right place, please move it if not. Thx.]