I would like to a hole drill into the outside of 1 1/2" NPT elbow so that it lines up with the center of the pipe. I need to introduce a propane jet and this seems like the neatest way to go. How do I control the drill bit so that it doesnt walk around on the curved surface? I have thought of welding on a small piece of flat bar so that it would be normal to the bit in the hope that drilling through the strap would serve as a guide. Is there an easier way to do this?

Thanks

That might work, as well as making a guide that threads into the fitting, and comes close to touching the back of the elbow. You then drill from the inside out.

If it was me I would clamp it up on the mill, or drill press. Use a center drill , or endmill to pop the hole in. Use a short drill to maximize rigidity.

How big of a hole?

center punch.drill pilot hole,then. drill out to finished size..

Make a drill guide jig. Get a short scrap of angle iron, drill thru the corner from the inside of the 90 with a 1/8" bit, then take that and strap it to the pipe with a hose clamp or two. Once the pilot hole is done, the rest is easy.

Viola! Self-centering pipe jig.

I would like to a hole drill into the outside of 1 1/2" NPT elbow so that it lines up with the center of the pipe. I need to introduce a propane jet and this seems like the neatest way to go. How do I control the drill bit so that it doesnt walk around on the curved surface? I have thought of welding on a small piece of flat bar so that it would be normal to the bit in the hope that drilling through the strap would serve as a guide. Is there an easier way to do this?

Thanks

Last time I did that I welded a sleeve onto the pipe elbow that would receive and hold the propane supply tube. The sleeve had a set screw for to hold the supply tube. The set screw allowed easy removal of the supply tube, hose, and regulator. So I prepared the sleeve, with the pre-machined hole, welded the sleeve to the elbow and used the sleeve as a drill guide.

I will post a photo of the assembly in the gallery section. and here if I can figure out how.

I used a hose barb threaded into the opposite end to drill a Tee, I bet something similar may help with an elbow. If you have a lathe then boring it would be best.

Phil

I did the same process when I built my gas forge, if you drill the hole in the centerline of the pipe, it's going to be difficult with out a milling machine and end mill. The local pipe supply company will have these nifty doo-dads called Thread-o-let, or Weld-a-let, which is a lump of steel with a pipe thread running through. your hole in the pipe can be a bit rough, the thread-a-let will give you good threads to adapt to.

Bush down one side of a "T".

At a good plumbing supply you can buy a tee that it 1 1/2 x 1 1/2 x1/2 with the 1/2 in either position you need. Should be easy to handle from there

At a good plumbing supply you can buy a tee that it 1 1/2 x 1 1/2 x1/2 with the 1/2 in either position you need. Should be easy to handle from there

A lot of clever ideas. I must try the angle iron jig. I think I can use all of them in different circumstances. Thanks everyone.

Currently, I have a T with a drilled out bushing. I am trying to cut down on the weight of my air piping and reduce the number of sharp corners. Also, I face a similar problem in a number of other projects that I am planning so it's good to have some tricks up my sleeve.

A lot of clever ideas. I must try the angle iron jig. I think I can use all of them in different circumstances. Thanks everyone.

Currently, I have a T with a drilled out bushing. I am trying to cut down on the weight of my air piping and reduce the number of sharp corners. Also, I face a similar problem in a number of other projects that I am planning so it's good to have some tricks up my sleeve.

Punch it carefully and exactly where you want the hole, clamp it solidly so it's nestled between two V-shaped objects, then very slowly with a sharp drill bit start drilling a small pilot hole, then it'll be easy to drill the larger hole.

I think the Tee maddog is talking about would be a 1 1/2 x 1/2 x 1 1/2 it should be common for fire sprinkler use. The first two numbers are the top of the tee (the straight through hole) and the 3rd number is the leg or the 90 degree hole. I used to do industrial pipe work and had to have the right numbers on these things to get what we needed. Hope this helps a little
Rob

I think the Tee maddog is talking about would be a 1 1/2 x 1/2 x 1 1/2 it should be common for fire sprinkler use. The first two numbers are the top of the tee (the straight through hole) and the 3rd number is the leg or the 90 degree hole. I used to do industrial pipe work and had to have the right numbers on these things to get what we needed. Hope this helps a little
Rob

That's what I used. It worked great. Then I used a bushings on the inside to reduce it down to 1/4 - 28 and put a mig tip in it. The mig tip is copper (not affected by propane), and I can change sizes. Right below the elbow I made a cut 1/2 way thru the pipe, took a thin sheet of SS, and made an air gate with a hinge.

Nice, sounds like it will work good. Have you fired it up yet?
Rob

When I built mine, having a nice forged steel tee, rated to 2000psi (means nice wall thickness) I just used a sharp punch, drilled with a short small bit to get a good start and then drilled to size. Been using that ABANA pipe forge for at least 10 years. I did the drilling in a small drill press.
Nice part about the forged steel fitting besides it having been free from work as scrap, but that forged steel is soooo easy to weld to.

I put a hole through a rounded end cap by using a dremal first to flatten, then make a concavity. After that, I could clamp the cap in place and drill in.