Airburst

I've been thinking of building my own bike frame for a while. I think I have (or can get hold of) most of the tools and parts. The only thing I still need is some way of cutting the mitres. What tool do most builders use for this? More importantly, how much will one cost?

Thanks

Amani576

You could do it yourself with a small cutting tool (I.E. Dremel) and some files. It's not rocket science, but the tubes need to seat with the tube they're connecting with fairly evenly.
If anything, for practice, get some round mild steel tubing and mitre them over and over till you feel you can do it well with the thin walled tubing you'll use on the real thing.
-Gene-

Cassave

Hacksaw and a few half round files of various sizes.

Nessism

I use tubemiter.exe and print out a paper cutting template for the angle needed. Rough cut along the line and then use half round files to dress the cope joint to achieve a close fit. https://www.ozhpv.org.au/shed/tubemiter.htm

Six jours

Many very good framebuilders over the years have used nothing but a hacksaw and files. I like a 12" half-round bastrad cut (yes, I know how to spell it but the forum censorship software isn't too bright) for typical "soft" 4130. It takes me an average of 15 minutes to finish a miter.

Tom Stormcrowe

So, you want to talk about a bastard file or other tool? Odd, bastard is working just fine for me....

(Actually, I removed bastard from the censor some time ago so no need to misspell it....that was a word I inherited on the list)

Allen

Thanks Tom

scbvideoboy

I have been using a drill press, heavy vise and bi metal hole saw. The problem with the vise is holding the work and if tubes need to be turned to a certain angle too. I knew a pro bike builder and they had machined super precision tubing clamps for the common sizes and I think they were milling the mitres. Super nice and $$$ in time/setup. I have used half round files too.

Six jours

Thanks, you old bastard!

Shimagnolo

Thanks!
This could be useful for responding to Pcad's posts!

PaPa

Perfect tube miters can be made with ONLY a hack saw and a flat file (or brief touch-up on a bench grinder). However, I can make perfect miters in less than 90 seconds using one of these:



HERE'S HOW: (The example below will create a miter for a 90 degree joint):

A - Unmodified tube
B - First 45 degree cut
C - Second 45 degree cut
D & E - Round-off both points
F - Finished tube viewed at 90 degrees

Ferrite

How would you apply that to a compound miter? Since most miters on a bike frame are compound.
I got one of those saws and would love to know. I'm not really a hack and file type of guy (not to kick the method, just seems time consuming considering the time it takes to put a bike frame together).

zzyzx_xyzzy

Play with tubemiter.exe or similar, you will see that most compound miters can be done with 2 rough cuts on whatever saw and about a minute or two with the appropriate bastard file.

Put your tube in a block in a vise, use cutting oil, remember to press down on the push stroke not the pull. A good file takes off material quickly and automatically makes the right profile (one file has the right radius to join to 28.6 tubing, the next one up has the radius for 31.8, etc.)

If you want really close joints for fillet brazing etc. you're going to be test-fitting and filing no matter what initial method you choose.

Pete359

Spend more time looking at bike building blogs. You're not ready to miter tubes yet.

scbvideoboy

Who is that for? Yeah to OP, you'll be spending lots of time cutting and test fitting. If you don't kave a waist high work table, bending down and crawling on the floor and then getting up every few minutes gets "old" fast.

DH

Airburst

Thanks for all the help guys!