[GME]

It's the same as my machine.

George is right about a tig welder being better, you still can use a mig if you drill out the holes so you are only drilling into the weld it's just going to be harder to drill through. Another option is to drill out the suspect holes oversized tap them with a bigger size use a long bolt that you can thread in to where it bottoms out in the tube, apply loctite cut the head off the bolt and grind it flush, then drill and tap the bolt aka plug. No heat involved no welding just a drill, tap, grinder, loctite some labor and some choice words for fineline that you will be thinking about while working on it. .

Some of the mounting holes look like they are off enough that it would take a pretty large oversize bolt to be able to then drill and tap it.

Ditto on the MIG weld plug being a beast to drill and tap. Without a magnetic drill press, (or maybe even with one) I question whether you could pull it off.

TIG is definitely a better option, but it takes practice to do it right. If you've never done it, you'll spend most of your time on a grinding wheel cleaning and sharpening your tungstens. If you have a friend with a TIG and willingness to help you out, I wouldn't be inclined to use stainless rod. (Sorry Bill, and no disrespect meant. I suspect you and I have probably had different experiences). Stainless is a dog to drill and tap. It work hardens something awful. I've filled my share of holes with my TIG, but I have to admit that I've never tried creating a plug to be drilled and tapped. So, I can't say whether you would get the same hardening problems problems with the TIG as with a MIG.

I guess I'd be inclined to go back to suggestions made on my Saturn 2 build thread. Forget the existing threaded holes. Add a plate, whether it's steel or aluminum, drill the rail mounting holes in it, and create slotted holes closer to the edges of the plate for mounting it. The slotted holes will give you lateral adjustability for mounting the plate and getting the linear rails parallel to each other. I believe Dan (NTL) suggested adding set screws get the plates in the same plane. Were I doing it, once I had the plate where I wanted them, I would inject a special epoxy under the plates to fill any gaps and provide more support - like the expanses between the set screws where you would experience flex. This is way different than epoxy leveling, which is more likely to fail than succeed. This is just using epoxy as a filler material between two fixed surfaces. You would leave the set screws in place to continue fulfilling their support duties.

Another thread to look at is Jack/Ponder Labs Saturn 2 build thread. Lots of suggestions there too and you reading them will save having to repeat them here. Here's the link: https://www.cnczone.com/forums/finel...cnc-forum.html.



Erik, I see what you mean about the aluminum angle braces. I would have to try really hard to mess them up as badly as yours. The size of the burrs is considerable, and are probably enough to cause some degree of binding them the brace is tightened down. They are clearly indicative of the holes in the braces not lining up in either the holes in the gantry, holes in the interface plates, or both. It might help to file off the burr back to flat surfaces, but you shouldn't hold your breath. Cannot hurt to try, though. No out-of-pocket costs and minimal effort involved.

I'm still thinking you may be better off scrapping the steel gantry and going with a 3060 80/20 extrusion. the 3060 profile is pretty pricey, but in the aluminum extrusion world, it's about as good as you are going to find. The metric counterpart is slightly larger (80mm x 160mm) in most every way. Although marginally so, it should be a bit stiffer than the imperial. I went with the 80mm x 160mm extrusion, but for reasons unrelated to stiffness or strength. I'd add a 3/8" interface that mounts to the underside of the gantry and mounts to the top of the interface plate that mounts to the linear rail bearings. If you do it like I did, you have a huge amount of adustability for square. It also allows you to fabricate angle bracing that is far superior than the 1" x 2" braces yours came with. Your angle braces might actually work with an extrusion gantry. That's what they were used on originally.

Gary