I had to step away from my build for a couple weeks because my wife had surgery, and where I left off I had encountered an issue... the 3 V-rail extrusions for my gantry don't line up exactly. The cuts are off of 90 deg. by small amout, but over a 1000mm the difference is noticeable. What would be the best way to true up the rail ends so that they are as close to square as possible? or am I just making myself crazy over a small detail?
The best way is to bring them to a local machine shop to mill the ends to length together. It shouldn't cost anymore than 20-30 dollars. With that said, a machine shop isn't always an option. If you have a chop saw or know a buddy that has one then that should do the job. A finer tooth is recommended, but if you need it done you try with what's avail. Another method is with a miter box and a solid stop. Since it can be quite difficult to take only a hair off of the end with a hand hacksaw you may want to take off a full blade width of a cut plus a small amount for cut off. If you're really strapped and have a hand file you could use that to draw file the ends square together. You may have to make a square of you don't have one of those laying around. Just some ideas. I'm sure there's more. Joe.
I talked with a buddy and I may have a solution (if you don't mind giving your opinion on it) I picked up a table saw balancing blade and some matching fine grit sandpaper for it... I was going to carefully calibrate the miter gauge and blade angle with a machinist square, then carefully sand true the 3 members... if that doesn't work, I figure I can sacrifice 20mm or so of width and cut them true with the metal cutting blade I got for my chopsaw... My only concern is getting the same length on all 3 extrusions... but with a little fiddling, I am pretty confident that I can figure that one out... I guess I could make a sled with a fixable stop for the saw, that could be the next attempt I guess.
Best solution would be getting a non-ferrous metal cutting blade for your table saw, ganging the pieces together and running them through on a sled. If you're just shaving the ends slightly, any carbide tipped high tooth count panel cutting blade should also do the trick, saving you the $$ of buying a blade for such a small number of cuts. As an alternative (as I don't have a decent table saw), I set up a simple V-slot jig to trim ends with. The plate you see at the far end was used to gang multiple similar pieces together so all would be trimmed to the same length. I'd trim one end and then rotate the whole piece and do the other.
That is a slick idea right there... I just used my chop saw with a 40 tooth carbide tip blade and lubed the blade and vslot with wd40 between cuts.
doh! lesson learned, always measure for yourself before you build it... After I took the whole mess apart I checked each end with a machinists square... they all were nice and strait... but when I lined up the 3 beams, one of the 20601000s was 1mm longer than the other two.... so I asked a machinist buddy what he thought the best way to remove just 1mm from the extrusion was (given my toolset) and we decided to use the tablesaw as a disk sander... (since I had the parts)... 15 minutes of setup, 1 minute of sanding and I got this: I reassembled and Huzzah! so... given that my toolset is mostly woodworking and I have a fairly nice 10" table saw (not one of those really sweet ones that cost a mortgage payment... just a workable Rigid) I installed a truing/sanding blade and used a disk of 240 grit paper designed for sanding aluminum... I kept the pieces ganged together and attached another piece of extrusion to my miter gauge ( a 2060250 that I broke a tap off in... it's going to stay there... it's much better than the wood extension I had on there before) and took my time removing the angry millimeter... about a minute Thanks for your input though and maybe my mistake and bad assumption will help someone in the future. Lessons Learned: 1) always measure everything for yourself 2) always measure everything for yourself before assembly 3) always measure everything for yourself before assuming you know what the problem is 4) always measure everything for yourself before wasting time to try to fix a problem that doesn't exist. 5) always measure everything for yourself before wasting (other people's) time to try to fix a problem that doesn't exist. Also Learned: 6) don't over tighten screws... its a router, not a tank. 7) Don't Panic... Other people are awesome and will have good advice if you ask the right questions
