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hiya,
i just bought a brazing rig and other than doing some small modifications to a frame or two i have on hand i want to give stem building a go. does anyone have any recommendations for relatively inexpensive stem jig? should i diy something from aluminum extrusions?
thanks!
I would recommend fabricating a simple tool steel fixture for stems...will be an excellent machining exercise for you with little financial outlay. I would avoid using AL extrusion if you are brazing,
Best wishes,
Rody
Jeff at Sputnik tool makes a nice one.
http://www.sputniktool.com/small-tooling/stem-fixture/
thanks for the responses. after brazing a disc tab and a few other little things to my 90s univega mtb that's now my bikepacking rig, i think i've realized i'm gonna need to keep practicing before i buy or build a stem jig. i've got a lot to learn before i can justify a jig to make stems haha
If you limit your making stuff to the smaller things (racks, stems, seat post things, lighting bracketry) I would suggest getting a smaller surface plate. 12"-18" on edge surface plates are routinely listed for sale via FB Marketplace and Craig's List, or are here in NY State. Basic Vee blocks, squares, height measuring thing (I used a 6" caliper for years before getting a proper height gage) and a handful of clamps are all one needs for stem work. But a basic plate will also work for many other devices too. Andy
Sounds like your post shows the wisdom to know when something is too difficult for your current skill level. Stems are quite safety-critical, second only to forks. Maybe get a second-opinion from a trusted mentor who can inspect your work in person, before trusting yourself to make a stem. I also strongly recommend making a lot of test joints and breaking them with a vise and cheater-bars.Quote:
Originally Posted by floppywonka
Precision alignment on stems is nice but over-rated imho. As Jimmy Diresta says, "if it looks straight, it is straight". Holding together (not breaking in use) is a bit more important than precision alignment. I'll go so far as to say no jig is needed at all if you have a way to clock your miters precisely — then let the miters determine the alignment.
Paul Brodie has a recent youtube where he complains about a customer who measured the alignment on one of his stems and found it to be off, I think one side of the handlebar was a couple mm lower than the other side, I forget. He basically said it's a hand-built part, what do you expect? I can't comment on how precise the customer deserves to demand, but it is good to keep in mind that any brazed or welded tubular structure will have some distortion, no matter how good you are.
The ability to measure the alignment, to see how well you did, would be important if you were selling them. But if making one for yourself, just ride it and be happy. You're not likely to be able to cold-set it if you're off, so maybe it's better not to know.