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-   -   Damn the torpedoes....my first miter ever. (http://www.bikeforums.net/framebuilders/713920-damn-torpedoes-my-first-miter-ever.html)

daddybland 02-16-11 09:03 AM

Damn the torpedoes....my first miter ever.
 
5 Attachment(s)
What do you guys think?? This is gonna be FUN!!!
Attachment 190151
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Attachment 190152

NoReg 02-16-11 03:13 PM

Couldn't tell, but it looked loose on the side, so just deepen it, if that is the case, and you have the room to move. Are you using a tube miter program? They are free, and should make getting a fit pretty automatic.

unterhausen 02-16-11 06:57 PM

you can see he's got the tube wrapped up in paper that is the output from a program.

The miter isn't quite there yet. Right at the ears, there would be a very large gap on the inside of the tube. A perfect miter will have very thin sections at the outside, you want to avoid that. You want the tubes to be touching each other on the ID of the mitered tube.

daddybland 02-16-11 08:08 PM

How much, if any gap is acceptable? I checked with feeler rods and couldn't find any gaps larger than .3mm. Is that to much?

daddybland 02-24-11 07:01 AM

^^What?^^

sannerbikes700 02-25-11 12:00 AM

Quote:

Originally Posted by daddybland (Post 12237197)
How much, if any gap is acceptable? I checked with feeler rods and couldn't find any gaps larger than .3mm. Is that to much?

Depends on what your are going for...

Look at these miters. And the joints probably didn't break. http://wjc.fidean.net/log/2008/09/01...t-tube-miters/

I saw Bernie Mikkelson at a frame builders show a few years ago displaying some bad lug work. There was a joint he pulled apart from an old Sears frame, where there was no miter at all. The ends of the tube had been bashed in with a hammer, shoved into a lug and brazed together. And the joint held up.

I have an old Raleigh Record frame lying around, and if you look into the BB shell you can see none of the tubes were mitered at all. Stays, ST, DT-- all straight cuts. The ST and DT were just jammed together in the shell, no cuts.

I'm not suggesting you start mitering with a hammer, but if the miters on your first frame turn out to be slightly off, don't lose sleep over it. Assuming you braze them well, you'll be fine, and you can work to improve the miters on future frames.

unterhausen 02-25-11 12:08 AM

pressed steel lugs were much more forgiving of this sort of thing than IC lugs -- especially on the top tube which is generally under compression.

sannerbikes700 02-25-11 11:55 AM

Quote:

Originally Posted by unterhausen (Post 12277146)
pressed steel lugs were much more forgiving of this sort of thing than IC lugs -- especially on the top tube which is generally under compression.

Definitely...

Maybe I got the wrong point across... Good miters are are of course very important.

unterhausen 02-25-11 03:14 PM

Back in the day of pressed steel lugs, I saw a bike made by one of the big name U.K. builders that had been cut apart as a display. The top tube was clocked like the Huffy in your link. I laughed and laughed. The sad thing is that the bike would have worked fine for anyone that it fit. For some reason they were trying to hype this builder like some other builders had been hyped. I don't think it worked, but not because of that display.


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