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When you’re coping a piece of round tubing to make a strong welded joint, you usually need a pretty expensive, dedicated tube-notching rig — or the willingness to eyeball it and hope for the best. Hal at MetalGeek.com offers the world a nice compromise: the Tube Coping Calculator. Just plug in a few details about the tubing that needs to be fitted, and the program generates a handy pdf template that shows you where to cut.

Print out the template and wrap it around the tubing, then cut along the line with a grinder or even a hacksaw to make a nice-fitting joint. The Tube Coping Calculator can make free templates for simple two-piece joints, for tubing from 10″ down to .1″. (If your joints are more complicated, they’ll ask you to pay for the software.)

The templates can be output in several different file formats including pdf, png, postscript, HPGL, and G code. Hal also links to a standalone DOS program that does a similar job, for when you don’t have access to the interwebs.

The Tube Coping Calculator [MetalGeek.com]


7 Responses to Just A Little Help Coping…Your Tubes

  1. BC says:

    This could be handy in other places too. Neat. I’ll probably never use it, but I’m bookmarking it just in case.

  2. tmib_seattle says:

    I used a program similar to this (tubemiter.exe http://www.ihpva.org/people/tstrike/building/tubemit.htm) when I built my chopper frame. Pretty handy. Trace it with a good sharpie or fat max marker, and then you can cut with an angle grinder to get close. Follow with a die grinder to get right to the line. Works well.

  3. Chaim says:

    I do wood and I have no idea what this is talking about, will someone enlighten me?

  4. Chris says:

    @Chaim: Imagine coping a wooden dowel to fit flush at a 90º angle in the middle of another wooden dowel of the same diameter (so the end result is a big wooden T made of dowels) and you should have some idea of what’s going on here.

    Alternatively, take a look at any of the welds on a typical bicycle frame next time you’re out in the garage/shed/basement (or wherever else you might keep a bike).


  5. Chaim says:

    Got it, like coping baseboards. kewl, thanks Chris! But it would drive me crazy if I had to do that as the major part of my work like making a bike!

  6. Hal Eckhart says:

    I noticed the mention above of the tubemiter program. That’s what I first started with, but it was a little awkward to use, and only produced the theoretical outer intersection of the cope. This meant you usually had to trim a bunch of excess off the cut. I believe tubemiter simply packaged Eric Fahlgren’s original script and ran it in Windows. Eric kindly talked me through the nitty gritty of his script. At least it was enough for me to hack together my PHP version to where I was happy with it.

    Thanks for the traffic!

  7. Fred says:

    We recularly cope round wood stock to fit into other round stock. This is trivial (we just make us a jig out for scrap to hold the dowel tigihtly and gude a holesaw or forstner bit to slice through the end.

    For welding tubing – especially high pressure fluid or gas lines – the coping needs much more precision – and eyeballing may not “cut it”

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