Have any of you guys used this kit before? what do you think of it? what kind of performance can I expect on a 2' x 4' cnc router acme 1/2-10 lead screw of jgro design? Any suggestions?

It should be good for at least 30ipm, possibly up to around 50ipm.

I agree with Gerry on the speeds, I use a 1/2-5 lead ball screw and cut at 45 to 60ipm with rapids of 100 ipm, so half of that would be appropriate on a 1/2-10 lead screw.

I'm happy with the Xylotex setup. I have burned up my boards a few times during the learning process. It seems that I can't follow directions properly. But they are cheap to repair and haven't had any problems once the board is setup correctly.

Buying the motors, cables, and board as a set will simplify your installation. I recommend going that way for a beginner.
Trent

Gerry, do you think I should leave the lead screw pitch at 1/2-10 acme or goto something like 1/2-8 or 5? any suggestions?

I have been running an older Xylotex board on 24V with 116 oz. in. steppers. I use ACME 3/8-12 with UHMW nuts. I get 72"/min rapids on this set-up. If you can find a 30V power supply, that will increase your speeds.
I use the 3/8-12 for a couple of reasons. Less material to take off when turning down the ends, it is the cheapest by far at Mcmaster carr, and, I guess, that the smaller diameter would offer some mechanical advantage and may make missing steps less likely. Mainly because it is the cheapest though.
Colin

Keep in mind that Colins machine is a lot smaller than 4ft, though. I'd go with the 1/2" at that length. 5/8 or 3/4 would be even better, but then requires bigger motors and drives and lots more $$$$$$$$. That's why you usually see 1/2" as the standard.

I went ahead and ordered 1/2 x 8 2 start acme it seemed like it was a good happy medium and I order a set of lead nuts from dumpster man.

I have a 28"x28" drawer slide design and was looking at this kit also and was wondering if the steppermotors would be large enough for my application. It is going to be a router. The table slides pretty easily, it don't slide perfectly free but it isn't too bad. I have included a pic so you can kinda see what I have going on...its a dual slide per side design, but anyway wondering if you guys think this board would be a good choice for the application and if you have any suggestions on lead screw sizes. Thanks the help would be much appreciated!