Notching the fancier harder steel tubesets...

Hello everyone.
I think this might be my first post. I'm a long time reader though, so I feel like I'm part of the community. Even if my stats don't show it.

I've built a handful of frames for myself over the last few years. And I've been using some of the basic tubesets that I think are vanilla 4130 butted materials. Things like Columbus Zona, and Some Nova Tubesets. Great tubes for learning. But I recently started on a new frame and decided to step up to a Columbus LiFe Niobium tubeset. All the trade names are a bit lost on me. But from my years of fabricating on a bunch of different materials, this stuff feels alot like stainless steel in it's "hardness". It seems much harder and tougher than the standard 4130 tubes. And is causing me some tooling problems.

I've been using a tube notcher and hole saws to cut my tubes without any trouble until now. But the first time I tried to cut a 34.9mm Niobium tube I was shocked at how hard the material was. I had a fresh Milwakee hole saw in my nother and it would hardly scratch the surface. I pushed so hard that I ended up damaging the tube. I could not get the saws to cut into the surface of this stuff even with really extreme amounts of force. I ended up damaging a downtube.

I'm looking for some advice for cutting these harder materials. I'll probably go back to miter templates and hand grinding with files to be safe. I don't want to waste more precious tubes.

Here is my setup. Please advise...
Attachment 111399

-Ken

Quote:

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Originally Posted by ken377lx

Hello everyone.
I think this might be my first post. I'm a long time reader though, so I feel like I'm part of the community. Even if my stats don't show it.

I've built a handful of frames for myself over the last few years. And I've been using some of the basic tubesets that I think are vanilla 4130 butted materials. Things like Columbus Zona, and Some Nova Tubesets. Great tubes for learning. But I recently started on a new frame and decided to step up to a Columbus LiFe Niobium tubeset. All the trade names are a bit lost on me. But from my years of fabricating on a bunch of different materials, this stuff feels alot like stainless steel in it's "hardness". It seems much harder and tougher than the standard 4130 tubes. And is causing me some tooling problems.

I've been using a tube notcher and hole saws to cut my tubes without any trouble until now. But the first time I tried to cut a 34.9mm Niobium tube I was shocked at how hard the material was. I had a fresh Milwakee hole saw in my nother and it would hardly scratch the surface. I pushed so hard that I ended up damaging the tube. I could not get the saws to cut into the surface of this stuff even with really extreme amounts of force. I ended up damaging a downtube.

I'm looking for some advice for cutting these harder materials. I'll probably go back to miter templates and hand grinding with files to be safe. I don't want to waste more precious tubes.

Here is my setup. Please advise...
Attachment 111399

-Ken

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Any chance your drill was in reverse? Maybe bad holesaw? Is it 10tpi?

When machine cutting heat treated tubes, rigidity is your friend.Tube notchers are not particularly rigid, and I can imagine things skipping/ chattering before a clean bite. Thin tubes can also deflect some as well as work harden.

It looks like that is a hand drill- my guess is that it's moving too fast for the saw and cutter set up.

I've pretty well landed on Lenox for my saws- I'll use others from time to time, but for the quality/ availability/ value, I have best luck with these. I've not used everything, but they are by no means all created equally.

So- check your rotation speed, figure out how to get consistent feed, and quite possibly just ditch the notcher. If you are only building the occasional bike for fun, cutting these with a decent hacksaw and good files doesn't take that much time and can well be an enjoyable part of the process.

Quote:

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Originally Posted by Eric Estlund

When machine cutting heat treated tubes, rigidity is your friend.Tube notchers are not particularly rigid, and I can imagine things skipping/ chattering before a clean bite. Thin tubes can also deflect some as well as work harden.

It looks like that is a hand drill- my guess is that it's moving too fast for the saw and cutter set up.

I've pretty well landed on Lenox for my saws- I'll use others from time to time, but for the quality/ availability/ value, I have best luck with these. I've not used everything, but they are by no means all created equally.

So- check your rotation speed, figure out how to get consistent feed, and quite possibly just ditch the notcher. If you are only building the occasional bike for fun, cutting these with a decent hacksaw and good files doesn't take that much time and can well be an enjoyable part of the process.

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Sounds about right from what I am experienceing. The thinner tubing was deflecting like a slippery spring and the teeth were not cutting in, even when running at a low speed on the 2 speed drill. I do like the accurate easy fit up with hole saw cut tubes. My hand filed tubes never seem to be quite that tight fitting. But I do remember how to hand file tubes. I'll probably go back and dust off that skillset. It's certainly a known entity. I did quite a few that way on my first couple frames.

I guess I'm understanding why people fixture tubes in a Mill with a rigid fixture holding very close to the cutting tool... The mill runs at a nice slow speed and everything very rigid.... I always thought a mill seemed like overkill for running a hole saw. But there must be something to it.

When I went from an 800lb mill drill to a 4000 lb mill, even with the same fixture, it was an amazing difference. I think I'd rather do it by hand than a tube notcher. Different story if you are making roll cages or furniture, but thin wall tube is a totally different animal.