Building a CNC Router

[Grant H.]

Maybe some ideas if you haven't seen them.. A lot of dudes will do a sand drain/fill plug setup for the cavities, to make it easier to assemble/disassemble. Some folks also 3D print plugs for the ends of the extrusions. I did some modeling, and I think lead shot in asphalt may be absolute king shit for vibration suppression. If you're not doing aluminum and expecting a high grade surface finish, I'd guess you might not need it for anything other than noise reduction. Naturally, keep that stuff off the gantry to improve your rapids.

At least to start, given the "pre-used" condition of my extrusions, I am not going to fill the frame. Unless I use pea gravel, it will just pour out with any vibration. I'm more than confident in the ability to machine aluminum based on other similar, however lighter/less rigid, machines I have seen, even without filling the frame. Will it be as good as your Tormach, or a VMC? No. But I don't expect that.

There is a part of me that wants to play with filling the frame with epoxy granite, but I'm unsure how well that will work. If I don't explore that, I will likely go the sand route, with 3D printed plugs for each piece, like you mentioned. Weight is of little concern to me on this, as it will always live on the stand, and it's PLENTY strong...

Who knows, lots of possibilities... Lots to figure out...

ALRECO and K&K is nice for the small remnants, but Xometry has generally better and less beat up remnants boxes for cheap. There's also some dudes on ebay selling Fortnal and 7075 cutoffs. If you're bigger than ~foot by a foot, Midwest will beat ALRECO. Even with shipping. And you'll get new stock. It reflects badly on the local guys.

When it's time to start making parts, I'll take a look at their remnants boxes. I honestly have very little interest in Fortal or 7075. 6061 can be machined just fine if you get it dialed in for the machine, and it has the benefit of still being weldable. Fortal (really just a private labeled 7xxx series aluminum) and really all of the 7xxx series shouldn't be welded. 7xxx "can be" welded, but if inspected it will fail for many reasons, the primary one being stress cracking within the 2 pieces, and the weld bead.

What are you doing for controller? Servo-wise, Clearpath like you mentioned is really nice. And for spindles, people really love those 2.2kw water cooled spindles on ebay

Control is going to be LinuxCNC with a Mesa Electronics 7i96 Ethernet board, fed into PrimoPal 390oz/in Nema23 steppers that I got from Torchmate, of all places. They had a sale on them that made them a good deal, and they come with 4-pin XLR connectors alrady installed. I am building a properly sized/rated unregulated PSU to drive the steppers and their drivers. If they are under powered when this is all built, and maybe just because I can/want to, I will likely upgrade to ClearPath servo's. Necessary vs bigger steppers? No, but more power, no lost steps, simpler control cabinet, and on the list goes.

Yep, I have one of the China 2.2kw Water cooled spindles that is going on this to start. However, I am really starting to ponder Automatic Tool Change capability, which if I am spending that kind of money, it's likely going to be bigger/more power.