Rack Building Basics — 90 degree miter

This is mitering for a basic 90 degree joint with 3/8″ tubing.

The tube directly after cutting with a hacksaw. It’s a little messy:

Make a notch in the centerline of the tubing using a file or hacksaw. This keeps the file centered in the next step:

File. A handy hint is that a 12″ Nicholson bastard file has a 3/8″ diameter, so it makes a nice miter into 3/8″ tubing. A 10″ file works for 5/16″, a 8″ for 1/4″ tubing.

Once filed you have a miter, but it’s pretty ugly:

Clean up the inside of the miter with production cloth wrapped around a piece of tubing:

Then clean up the outside with production cloth:

Check the miter. It looks pretty good to me:


  1. Jim G says:

    Any tips for keeping the file square to ensure that the final miter is exactly 90 degrees?

    Any recommendations on tubing sources? And when to use what diameter for what rack part(s) — 3/8inch everywhere, or do you use a mix of sizes?

    Thanks also about the file-diameter tip (12inch round file for 3/8inch dia, 8inch round file for 1/4inch) — I didn”t know that!

  2. AlexWetmore says:

    I have a entry planned on how to pick tubing sizes. I want to do some more research into it before just offering up what I use.

    To get the miter at 90 degrees just takes checking as you go along. Another tricky thing is keeping miters at two ends of a stay parallel with each other. Last night I took some photos that show how to do this, and they”ll appear in the next entry.

  3. wackor says:


    I bought a 12″ Nicholson bastard file to make my racks. But I wonder my file diameter isn”t 3/8 inch, but about 7/16 inch. Interesting…

  4. Alex Wetmore says:

    I wonder if that is why Nicholson doesn”t list the diameter of the file in their materials. Perhaps there is enough variation. Both of my 12″ round files have been close enough to 3/8″ to work well for me.