Newbie questions about mitering stays to dropouts and bb? Order of tack?

[J Alsvig]

Hello all,

Started thinking about/wanting to build my own frames when I was cracking and breaking my Haro Masters back in the 80's. Really wanted to start building my own stuff when S&M, Standard and others started selling to the public. Went to UBI (tig) about six years ago and have finished nine frames since then. Mtn bikes, bmx, dirt jump, and a severely crooked 29er cruiser that just won't die. I've got a few friends who agreed to be test monkeys and are riding mtb frames I built. No disasters yet. All fillet brazed because I couldn't afford a tig. I finally got a tig about two years ago but I just haven't had the time to practice. Been lurking around this site for awhile now. Tons of great into and advice! I figure I'll try to tap into that a bit...

First: I'm still doing all mitering by hand including the slots in the stays for the do's and the miters to the bb/tt. I'm currently using the attachments on my jig (Bringhelli) to hold stays in place while I use a square to get lines drawn on the stays to cut the slots for the drop outs via hack and a bit of dremel. What is/was your method for getting those slots near perfect by hand? I almost always end up having to cut more material out of the slot than I should to correct the angle vertically or horizontally. Usually results in a stay that droops a bit, and that is really, really annoying to me.

Second: What is/was your order of tacking the stays to the front tri and do's? Do you braze the chain stays to the drop outs first or tack to bb first? I've done it both ways and on the last two frames tacking to the bb first has worked the best. I like it because I can add a tack or two if I need to pull the stay side to side to line it up to the drop out.

Third: I've been wanting to get a bench top mill for work on stays only. Anyone have a setup like this? Any recommendations?

Any advice or info will be very appreciated.

Thanks,
Jason

[Andrew R Stewart]

1st- I cut the stay's slot narrower then the drop out tab needs. Then judge where on the slot should be filed further to achieve the slot's needed placement. As I use brass for these joints there can be a bit of slop.

2nd- This is the hardest part of building alignment as far as I think. I usually tack, check, correct if needed and then fully braze the CS on to the shell (the drop outs having been done already). File and align then set up the SS. I'll do the top of both SS next and fully braze one Ss/drop out leaving the other to adjust the SS alignment. Check, correct and tack. Check again and hopefully not need correction before full brazing that second SS/drop out. I usually have to do a little slot filing to get spot on alignment.

3rd- There's a lot of threads about using a mill and fixture for stay mitering. I have a fixture sitting on a mill in my garage. Both haven't been set up yet... I will say that with care and skill a hand filing of stays can be very well mitered and very low cost. But you knew that already... Andy.

[custumfab]

Jason - Slotting has always given me trouble. My brazing and filing skills bail me out, but wastes time. Are you doing fastback stays? I was really happy when I got a Sputnik seatstay fixture. That along with basically the same technique you describe at the drops works for me. I have an anvil fixture that has a platform you rest the stays on. The center line is drilled for a dowel pin. I stick a dowel pin in the center and have machined a cylinder that mounts on the dowel pin. then I push the stay against it while they are lying on the platform. They stay in plane and it is very easy to see length discrepancies.

One other note. 99% of the time I do not slot the stays in the middle but notch out the inside to make a right angle. This keeps the stays away from the chain and cogs and it's easier to fit to the drops. If your rotation is off a little it's easy to file on one side and fix it. Often on road bikes to save weight I braze it in and leave it hollow. That's handy for venting, frame saver, and drainage.

hope that helps,
rich adams

[Jamie Medeiros]

To answer your question about a table top mill for stays, here is a photo of what I use to slot XCr chain and seat stays.



tumblr_lfl4bugJ5Q1qgwe7to1_500.jpg

Rouse Mill

[J Alsvig]

Hi Rich,

No fastbacks. S-Bend as far out to the sides of the seat tube as I can get them within reason. The more tire (mtb) clearance the better. I'll give that Sputnik fixture a lookover. Maybe make something similar that wouldn't be as expensive, or accurate, but would assist in the process.

I slot the stays to the inside as well. Clearance is key. Getting the notch dead on as far as angles is the issue. I fillet braze so I know that filling in a bit of a gap is no biggie, it just bugs me. I'd like to start tig welding frames one day and that gappy notch might not be very easy to deal with. Hopefully by then I'll have a proper notching process figured out.

James, that is exactly what I was looking for. Thanks!

Andrew, sounds very similar to the way I do stays. I know that there is no reason for me to have a mill or a lathe...I just like to tinker with machines...

Thanks for the advice everyone!
Jason