Cheapish CNC machine

Delrin anti-backlash nuts will wear faster than ball nuts or ACME spring nuts.
Not an issue, unless you don’t check your run-out till you start ruining work pieces.

Another key aspect I failed to mention was the frame construction, which impacts pretty much everything. Routers are a complicated thing.

There’s also a major difference between using a standard woodworking router or an industrial spindle. The ShopBot FAQ has a good explanation of this.

Yeah, the description of the machine says just that. I figure I could replace them with a better nut.

Take a look at what Brandon Satterfield is doing at I built an OX using his kit of parts and the quality is outstanding. He also has some ther devices that are more comfortable with aluminum.
Plus, he supports FIRST teams with a discount.

We’ve had pretty good experiences with our X-Carve, as others have said it’s great for wood and polycarbonate, but you have to take it slow with aluminum (and use cutting fluid).

Really it all depends on what you want to build. In our case we built our chassis out of 3/8" polycarbonate so using it to cut our chassis side panels is no problem, and the tolerances are more than enough if you’re building a chain drive; however when we cut some custom 1/8" aluminum gearbox mounting plates for our 3-CIM Ball shifters, we had to intentionally undersize the holes and then finish them on our Bridgeport CNCs.

Basically our X-Carve is pretty good at positioning accurately, but not great at making round pockets consistently. If all you were doing was drilling straight holes and not doing any pockets, you could likely do it all day long and not have any issues with accuracy.

I don’t think I would try to build an entire robot out of aluminum using an X-Carve, but using it for mostly polycarbonate parts with only a few, small aluminum pieces is certainly doable.

One thing to note for these machines is that you either have to babysit them with a vacuum or construct some sort of dust collector for it, because even the slightest bit of material flying off the part can get lodged between the tracks and the wheels and throw off the positioning of the entire unit, ruining the part. If you wanted to get really creative, adding a closed-loop control system to it would also solve the problem, and improve accuracy.

The frame looks very similar to the common chinese 3040 CNC router/mill you can find on eBay. I too would be very interested in plans/sources for the frame parts. I can’t wait for the build log!