Did a better job than a large granite countertop for a Voron 2.4 350mm. For time I built it, I couldn't quite get every corner square. Square enough to print small parts accurately and precisely, but large parts had enough of a skew to them that the required sanding and a bit of force to assemble. A few other minorz unrelated issues gave me the motivation to tear the printer down to its frame and rebuild it.
Enter the Fystec right-angle holder.
After assembly, every 2020 is perfectly in-plane with it's neighbors, and my machinist square confirms that everything is actually square this time. Still haven't finished the rebuild, so I can't confirm precisely how square via something like a cali-flower, but I can tell it's definitely more square than what it was before.
The only trick to it is that (at least on the Voron frame), it goes on the top and bottom, meaning the screws stick out, which means you can really only use it on whatever the top of the frame is. Because of this, I highly recommend pre-setting all the screws into the blind joints and use something like some empty spring-loaded drop-in T-nuts to support the top pieces while you line it all up and tighten everything. Basically, just set all the pieces, with screws just tight enough for the cross pieces to still slide, and for the verticals to be held just barely against the ends of the cross pieces. From there, use this jig, tighten everything down, and give it a gentle tap with something like a rubber mallet to make sure it's set against the end of the vertical piece, then tighten the screws in the joints. I also recommend something like Loctite 641 (AKA: "Orange" Loctite) for the frame joints, as this will be stronger and more "permanent" than something like Loctite 242 or 243 (you can still break 641 with standard hand tools), without being as tough as a kind of "red" Loctite. This will at least make your grand robust against vibrations, and make it tough enough to handle sensorless homing if you ever go that route.
TL;Dr: I wish I bought this jig the first time around, as it made my frame much more square and made me confident enough to apply threadlocker this time around. When I build my V0 or Saladfork in a year or so, I'll be buying the 1515 version of this jig, too. It's worth it.
