Simple Inside Pipe Clamp

This Instructable will show you how to make a simple pipe clamp.

While working on a Vapor Mod I needed to thread a piece of copper pipe to accept a brass NPT fitting. I needed to be able to clamp the pipe with enough force to be able to cut threads but without damaging the exterior. This is what I came up with. If you ever took your bike apart as a kid you will notice that this is the same design used to mount handlebars.

Find a piece of steel tube that fits inside the pipe you need to clamp.

You want the fit to be loose enough to slide in and out easily but without a lot of play. The copper pipe I am working with is 3/4 inch O.D. I used a ~1 1/2 inch piece of hot rolled steel that was slightly too large to fit inside my copper pipe. You want the clamp to be able to take a lot of stress so select a piece of tube with a suitable (large) wall thickness.

If you need to reduce the diameter of the steel tube as I did, you can do the following:

1. Find a sturdy bolt that fits inside of your steel tube. It should be about 1 inch longer than the steel tube.
2. Find a rubber hose that will fit over the bolt and inside of the steel tube.
3. Cut a piece of rubber hose the same length as your steel tube.
4. Push the rubber hose onto the bolt.
5. If your hose is too large to fit inside the steel tube, put the bolt in your drill press. Use a file to remove the outside of the rubber hose until you get a nice snug fit.
6. Push the steel tube over the rubber hose. What you end up with should resemble the picture.
7. Put the bolt back in your drill press. Now use the file to reduce the outside diameter of the steel tube until it slides into your pipe.

Use an abrasive metal cutting saw to cut the steel tube at an angle.

I cut the pipe at about 45 degrees. Decreasing the angle used will increase the holding force but require a longer piece of steel tube.

Try to leave a small section of uncut tube on each end similar to the piece on the left. I cut the piece on the right a bit short but I am going to weld a nut to it so it will still work.

In this step we will prepare the pipe clamp for use.

1. Place the steel tube back on the bolt using the rubber spacer.
2. Tack weld the nut to the steel tube.
3. Remove the steel tube from the bolt and complete the weld.
4. Grind your weld flush with the steel tube.
5. Discard the rubber spacer.
6. Place a washer on the bolt followed by both pieces of steel tube. I ground two flat spots on the washer (not shown) to allow it to be held with an adjustable wrench.

Place the clamp in the end of your pipe. Use an adjustable wrench to hold the washer while tightening the bolt. You can now use a vice or an adjustable wrench to hold the washer while you work on the other end. To remove the clamp, first loosen the bolt. Tap on the bolt to separate the two pieces of steel tube. The clamp will slide out easily.

Caution: This clamp develops a lot of force. If you closely at the image above, you will see a perfect outline of the clamp has been impressed into the face of the copper pipe!