Robotic tube mitering/cutting

[Skip Montanaro]

From The Path Less Pedaled, cool application of robots to small batch framebuilding...

https://youtu.be/zQcBCiC4aLU?si=Amn26AU-9NTEip_H

[Jon Norstog]

Very interesting!  If I had one, all I would need is some clients to help me pay for it.

On Tue, Jul 22, 2025 at 7:09 AM Skip Montanaro <skip.mo...@gmail.com> wrote:

From The Path Less Pedaled, cool application of robots to small batch framebuilding...

https://youtu.be/zQcBCiC4aLU?si=Amn26AU-9NTEip_H

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[Mark Bulgier]

Methinks they exaggerate the amount of time you can save. With the typical setup, milling machine and holesaws, it doesn't take long enough for the savings to pay for a six-digit robot, plus the college tuition to learn how to use it...

Yeah I know, you send your specs to the dude with the robot and he cuts 'em. So you pay round trip shipping, and wait and wait, and hope your requirements don't change in the meantime. 

Plus they aren't even good miters. Doesn't it look like the laser remains at a right angle to the tube? Correct me if I got that wrong, but that's not a proper miter shape in my book. I know I'm too precious about miter perfection but it does help at least some for keeping alignment and preserving your design angles, with minimum stress frozen in the frame -- a factor in fatigue endurance, I believe... from scant evidence. 

Plus "water tight" miters look good on insta. ;) 

Not to mention that this is far from a new thing. Several "bigs" were using robotic mitering decades ago. Do these new guys even know that? Or do they think they invented it? I think Panasonic and Cannondale used frikkin lasers, where Co-Motion used a normal cnc mill with a tiny endmill spinning at a million rpm or thereabouts. I watched a video of CM making a tandem mid tube, all 3 miters and two pairs of H2O bosses in about a minute. 

Hell, even at Match (small-batch production shop) in the 90s we had a machine that did all 3 miters on a DT and drilled the H2O holes, in about that much time, but with holesaws and drills. True, a human had to load the tubes and press a button but the machine took it from there. Of course Match went out of business, and spending too much on automation was a contributing factor in that... 

Meh. I actually like mitering, and I pay myself zero, so that means it's FREE! 

- Mark

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From: Jon Norstog <mutton...@gmail.com>
Sent: Tuesday, July 22, 2025 8:06 AM
To: Skip Montanaro
Cc: frame builder list
Subject: Re: [Frame] Robotic tube mitering/cutting

To view this discussion visit https://groups.google.com/d/msgid/framebuilders/CAEasqY38htynRL0T7r1oeKCVEZCqbnJGPXdjTSrEyPddUUVKyQ%40mail.gmail.com.

[m-gineering]

In '95 or so I visited Noell Rahmenbau in Fulda, and he had a laser
with a rotator feed up and running.

On 7/22/25 20:19, Mark Bulgier wrote:
>
> Not to mention that this is far from a new thing. Several "bigs" were
> using robotic mitering decades ago. Do these new guys even know that? Or
> do they think they invented it? I think Panasonic and Cannondale used
> frikkin lasers, where Co-Motion used a normal cnc mill with a tiny
> endmill spinning at a million rpm or thereabouts. I watched a video of
> CM making a tandem mid tube, all 3 miters and two pairs of H2O bosses in
> about a minute.
>
> Hell, even at Match (small-batch production shop) in the 90s we had a
> machine that did all 3 miters on a DT and drilled the H2O holes, in
> about that much time, but with holesaws and drills. True, a human had to
> load the tubes and press a button but the machine took it from there. Of
> course Match went out of business, and spending too much on automation
> was a contributing factor in that...
>

--
Marten Gerritsen
Kiel Windeweer
Netherlands

[Michael F.]

IIRC Trek also had some sort of Laser or Plasma mitering machinery, towards the end of "the steel frame age" in history. 

I bet they sold it for pennies on the dollar once glued and welded Aluminum, not to mention Plastic, frames (sadly) took over the world.

It also seems important nowadays to have some sort of Computer-Aided manufacturing for mitering in order to help with some of the 

overly complicated and questionable designs that younger framebuilders come up with on their 5-axis CAD blueprints. 

Nevermind that they have never picked up a screwdriver, much less a File in their lives. 

On the positive side, I guess, is that it is easier to change designs for the newest bi-yearly changes to BB threading, Headset "standards" and the hundred or so axle widths and diameters.

SNAFU as usual thanks to the bicycle industry stupidity.

MF in SF

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[Eric Keller]

Many of us have bikecad pro licenses, and it will spit out mitering
g-code for a fairly simple CNC mitering machine.
I guess it still miters at 90 degrees unless you build another axis into it.
https://youtu.be/RVZA1H-YKIA?si=wqzNSes2BBCjMoOK

Eric Keller
Boalsburg, Pennsylvania

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