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Does anyone here with experience in plumbing or piping know if a 3/4" pipe can fit inside a 1" pipe to the point where you can slide it in and out like a telescope to make an adjustable stand post?

According to this link and if my math is correct, the inner diameter of a 1" SCH 40 pipe is 1.049" and the outer diameter of a 3/4" SCH 40 pipe from the chart is 1.05" which is .001" too big. If I were to go to Home Depot would this difference matter?

Also I have a random question, are "all-purpose" drill bits able to drill through galvanized steel piping and is there a good method for drilling on round surfaces?

The reason I'm doing this is because I'm trying to build a DIY bike repair stand with an adjustable height. It's loosely based off this, but with a "Quik Klamp 3-Way Open Corner 1" (sorry I couldn't post another link) acting as the base-support piece mainly because the whole thing could be disassembled and I'm hoping a bit more solid.

  • I doubt it will work. Get the largest pipe small enough to fit in the larger then drill out three spots for set lugs that will go into a threaded hole in the larger to hold the smaller. You can check at the store. You should be able to use any metal bit. The newest-sharpest will work the best. To get it going on a round surface - mark your spot and use a punch to set a starting point. From there, depending on the whole size, you can use a smaller bit to get a starter hole, or just go for broke. – ChiefTwoPencils Feb 2 '15 at 20:14
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    You might want to try PVC - it's a lot easier to work with. – mbeckish Feb 2 '15 at 20:34
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    I already bought a 3/4" galvanized steel pipe as the inner adjustable pipe. Would a commonly sized PVC pipe fit nicely around that specific pipe and also fit in the base-support piece ? Or should return a bunch of things? – Baldemy Feb 3 '15 at 2:07
  • You might have some luck if you mix trades (i.e.; electrical instead of plumbing/gas). I don't see pvc being of any use unless you substantially up the size, certainly nothing less than 2". – ChiefTwoPencils Feb 3 '15 at 5:18
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Right copper tubing of 3/4" size telescopes nicely inside 1" right copper tubing. It is not a near interference fit like other styles of pipe and thus does not bind up. This is nice because copper is easy to work with (it solders) and is strong but light weight. Rigid copper fittings of all sorts are available to allow making all the corners of your stand.

  • Do you know about about galvanized steel piping? I haven't bought the bottom joint yet but I bought basically everything else and didn't take copper into consideration because the pipe clamp I'm using says to use black iron piping and it was easy to connect that via an elbow to a 3/4" galvanized steel pipe. If galvanized piping doesn't fit like that would a common home depot 1" copper or PVC pipe fit around the existing 3/4" pipe I bought already? – Baldemy Feb 3 '15 at 2:01
  • @Baldemy - Iron or galvanized pipes vary some. In addition, since most iron type pipe is hot formed from a flat strip into a tube that creates a seam all along one edge. I have seen some pipes where this seam leaves a ridge on the inside of the pipe. Such ridge could keep another pipe from fitting inside. Best thing that I can suggest is that you go to your home depot and simply see if the pipes that they have there will fit. – Michael Karas Feb 3 '15 at 3:23
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    BTW, I looked at the stand picture that you said you are working to and I think that you should use iron pipe for that application. The copper pipe idea is better left for a type of stand that would have several "legs". – Michael Karas Feb 3 '15 at 3:24
  • ok sounds good. – Baldemy Feb 3 '15 at 8:12
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If this is PVC, 3/4' will slip inside 1" Class 200. The class 200 has a thinner wall, so is larger inside.

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I would look at the twist lock connectors that you get for tent poles, they are quite strong and you have no limit to the length settings. twist lock adapter

Otherwise the most reliable route would just be to drill lots of holes and used pins through the tubing.

  • Yes I think I going to used pins like that. I think I'm going to stick with piping because I can get spare parts really cheap and pipe clamp I'm using fits nicely but thanks for the advise. – Baldemy Feb 3 '15 at 1:59
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I hand drill water wells in Africa and design hand pumps from whatever pipes are available locally. We do this all the time. You can fit a 1/2" into 3/4" or 3/4" into 1" etc. Just use a torch to evenly heat the last inch or two of the larger pipe. When it is soft enough, twist and push the smaller pipe into the larger. If you want to glue the two together, as it cools, keep wiggling and twisting the smaller pipe or the larger will shrink so tight it is difficult to get apart. Then take the two apart, glue and push back together.

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I used a threaded pipe coupling on a base. I found a pc of plate steel or an old industrial fan base. Weld the coupling to the base, I used 2". Then find a used piece of @" threaded on one end, I cut mine about 2' long and screwed it into the coupling on base. Find a piece of scrap 1 1/2 in pipe about 2-3' long and it will fit easily into the 2". About 3" down from the end of the 2" pipe drill/tap for 5/16 bolt in 1 or 2 places. This will lock it into any position up, down or rotate. Put a 1 1/2" tee or 90 on the end of the 1 1/2" and put a padded clamp or something on it to secure your bike. You could thread or glue 1 1/2" pvc into your 90 or tee to hand your bike on for a no scratch mount. Or cut the top out partially for a "U" to drop your bike or seatpost into.

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