Alright, I'll make this disclaimer upfront. I am 100% ignorant when it comes to CNC's. I have very, very little time with them (spent about 30 minutes playing with a $15,000 router at school many moons ago), despite the fact I've designed hundreds of parts and had several thousands pieces made. I've always passed off the responsibility to someone who had the knowledge to produce a quality product, even the simplest of prototyping efforts.

I've convinced myself that it's time to invest in a small, budget friendly 3D router for the business to do prototype and very short production stuff. I would like to have some feedback on my plans. Majority of the parts will be brass & 7075 aluminum, with some steel parts mixed in, maybe.


6040 Chinese Aluminum Frame - I'd like to have a .375" precision ground steel plate cut to fit under the t-plates, and would tie into the oem bolt holes. My thought is that this will strengthen the frame greatly, in addition to supporting as well as leveling out the bed t-plates, as they're apparently hit or miss in terms of levelness. My biggest fear is the plate sagging after so long under it's own weight. I'd likely need to add some type of support beams under the plate, aluminum u-channels or something similar. I'd add some type of spacer to the gantry to get max Z axis travel back. I think adding the plate would greatly stiffen the frame up enough that I'd be able to run steel through it.

Coolant Spray - Build enclosure and install 12v coolant pump. I'll probably end up running G10 and some Carbon through it, so I'd want to minimize dust. The coolant will help with 7075 and steel parts as well. Control coolant with PMDX-126.

Electronics - PMDX-126, PMDX-134 (may add a 4th axis later), PMDX-107 (to control VFD), Smooth Stepper, Gecko 201x Drivers, Hitachi WJ200-022SF VFD, 2.2kw Spindle (possibly 3kw), 350-500oz/in Steppers (Not sure on specifics, aim for 0.9° variety, insert suggestions), 48V Power supply

My biggest concern is tolerances, and repeatability. I'd ideally like 0.005" (or less) repeatable tolerances. Depth tolerances will matter. My two biggest fears that may not be achievable are based around the chinese frame. a) Is one ball screw and two ball slides on the X and Y axis enough? My fear is quick movements on the x-axis causing the gantry to torque and twist. Would adding 2 additional slides on the X and 1 additional on the Y be worth it? b) Bed flatness, which is probably my bigger concern. I know the extruded aluminum t-plates that come with the chinese 6040 probably aren't super flat nor square. That's why I'd like to add that steel plate, I could even add sporadically placed screws into the plate to pull or shim the aluminum extrusions as necessary to get it flat(ter). If I could find a 20x32" solid aluminum or steel t-plate, that doesn't cost $1000, I'd just scrap both the extruded t-plates and the steel plate idea completely.


If anyone wants to chip in their $0.02, I'd very much appreciate it!