mitering

[jpogge]

im a relatively new frame builder. i am currently building my 4th frame(all tig welded thus far, i am currently practicing with a torch to make lugged frames.

ive been using an inexpensive tube notcher using bimetal hole saws with a hand drill to make my miters. i have now aquired a vertical milling machine and i invested in some anvil tools(seat, chainstay and main tube mitering fixtures).
with my cheap hole saws the miters come out ok, but not perfect. i can invest in nice hole saws but im wondering how long they last(can they be sharpened?)
or is it possible to use end mills?
what will come out better or be more cost effective?
ive also seen people using abrasives to notch tubing and belt sanders with different diameter pulleys for notching.
whats the best mode

e

[Nessism]

There is no "best" method. Many excellent framebuilders, like Carl Strong, use simple bi-metalic hole saws while others use high-end heavy duty, sharpenable whole saws like those sold by Strawberry. Both have their pros and cons with cost being the number one consideration.
http://www.strawberrybicycle.com/gal...e=Store&page=4

[velonomad]

I agree there isn't a *best* way. I think everyone figures out what works for them and goes with it. I made my first couple of frames using a hole saw chucked in a borrowed Atlas MFC mill. I still had to file the notches to get a perfect fit. After a couple of frames I figured I was spending more time fiddling with the mill than I would be if I just filed the notches by hand.

[Nessism]

I agree there isn't a *best* way. I think everyone figures out what works for them and goes with it. I made my first couple of frames using a hole saw chucked in a borrowed Atlas MFC mill. I still had to file the notches to get a perfect fit. After a couple of frames I figured I was spending more time fiddling with the mill than I would be if I just filed the notches by hand.

My understanding is that some professional builders, Richard Sachs for example, hand file there miters instead of using machines. A proper, close tollerance miter can be made many different ways.

My favorite low budget method is to use a program called miter.exe. This small program makes a paper pattern of the miter which you can print out on an ink jet printer, cut out, and wrap around the tube to describe the outer edge of the miter. A few file strokes to bevel the inner edges and fine tune the fit, and away you go.

Ed

[velonomad]

I was searching a couple of days ago for miter .exe and haven't found a copy yet. I am going to take a try at building a LWB recumbent tandem in a few weeks. I will have a cluster of 4 tubes around the front BB that is going to be difficult for me to get right by eye.

[atombikes]

velonomad,

I've used it many times, it's called tubemiter.exe. You can find it on the International Human Powered Vehicle Association website. Here's a link to all the tools (scroll down to tubemiter.exe):

tubemiter

[Nessism]

velonomad,

I've used it many times, it's called tubemiter.exe. You can find it on the International Human Powered Vehicle Association website. Here's a link to all the tools (scroll down to tubemiter.exe):

tubemiter

That's the one!

[potus]

I'm going to go out on a limb and say an abrasive/sanding belt set-up is the best for bicycle tubes.

bicycle tubes are too thin for end mills.

hole saws work well but still require a little clean-up.

hand filing is the most affordable and is only as good as the person doing it.

[velonomad]

Thanks for the link to the miter program!

I know a guy who built an abrasive miter, it works well for him but the the long edge of the miter is always a little too large, But he is building racing kart frames and working with 1.25 x.083 wall tubing so he just pinches the long side of the notch a little in a vice and welds it. I tried his miter on some old bike tubing and still had to do some handwork to get a perfect fit.

Maybe I am fussing too much over the fit? I file the notch till I can get prussian blue to transfer to the abutting tube all the way around.

[potus]

semi-related... why do bicycle builders call them miters instead of copes? to the rest of the world a miter is a straight cut.

[jpogge]

a guy i know is working on a cnc plasma torch. he is planning on setting it up to also miter tubes. i am not sure what he plans on using to turn the tubing, but it seems like an interresting idea. im going to stick with the hole saws i have for now. the hand filing thing sounds like a load of work.
thanks
justin

[bellweatherman]

semi-related... why do bicycle builders call them miters instead of copes? to the rest of the world a miter is a straight cut.

Technically, you are correct. A miter is an angled cut. A cope is a "saddled" cope and can also be angled. That is, that is what the motorcycle bike framebuilders call it. So, technically framebuilders should use the term cope instead of miter. It probably arose long ago from. One guy said it and the rest of the sheep followed.