Steel Tube Joint - Need your help

JDishong · May 3, 2013

I need some advise from you machine-shop types ...

Problem: I need to join 2 identical OD/ID steel tubes ( end-to-end ) so the total length of the combined tubes is adjustable by a few inches. This would be similar to telescopic tubes but I must use identical tubes in this application.

Idea#1: Machine shop to create swedge end on one tude so it becomes like a telescopic joint. This is not ideal since it adds cost to the manufacturing.

Idea#2: see drawing below. This is a concept I thought might work but lack the knowledge of what it is called. It looks like a possible solution but I would like to research it by name .. any advice on what this style/type of joint is called ??? any other suggestions on how to make a similar combiner joint?

Thanks!

metaleltr · May 3, 2013

What about a sleeve? It could be either internal or external. Close fitting piece which could be welded in place to join them, unless it need to be removable. Then you may be able to just weld half the sleeve and slip fit the other half.

1320stang · May 3, 2013

Sleeve and plug weld it.

JDishong · May 3, 2013

I probably should have stressed the point about cost-sensitive .. these are $2 - 3 dollar tube pieces. Welding not an option due to price.

Thanks for your thoughts though

Elvenhome21 · May 3, 2013

looks identical to chevy oil pump drive

619DioFan · May 3, 2013

Not sure what guage tubing you are using but if it is similar to exhaust pipe p/u an exhaust pipe expander tool ( harbor freight has them ) slips into one end , crank down on it to expand the tube so the other one can slip inside.

retrobuilder · May 4, 2013

sleeve it on the inside or outside. Rivet one end with 2-3 rivets around the tube or braze (diy).

What size tubing?? material? aluminum or steel

We do this method on low cost aluminum towers for boats. www.fishmaster.com

theoldwizard1 · May 4, 2013

JDishong said:
I probably should have stressed the point about cost-sensitive .. these are $2 - 3 dollar tube pieces. Welding not an option due to price.

Swage.

The best "home made" one I've seen used a 2 piece die set (2 pieces of 1/2" steel) attached to an air hammer/chisel in some kind of frame. Lube the tube. one person runs the air hammer while the other turns the tube.

Flatland Dave · May 4, 2013

I'd say this is a problem in a mfg situation, not a garage project problem if time to weld two pieces together is a concern?

I'd guess friction welding is out too?

theoldwizard1 · May 4, 2013

Flatland Dave said:
I'd say this is a problem in a mfg situation, not a garage project problem if time to weld two pieces together is a concern?

I'd guess friction welding is out too?

You guys keep missing the key point

... so the total length of the combined tubes is adjustable by a few inches ...

Tink · May 4, 2013

Probably need more information. Do the inside and outside diameters have to be the same size? Would it be possible to let us know the application of this product?

Flatland Dave · May 4, 2013

theoldwizard1 said:
You guys keep missing the key point

Ok, so how about a thread-able insert, or must it be the same diameter the whole length of the piece. and the ends are fixed.

Another thought would be to have a sleeve with a pin through the inner piece which rides in a slot in the outer tube.

Details, we need details!!! :lol:

bczygan · May 4, 2013

You are getting answers all over the map because you haven't defined the parameters closely enough. What forces are acting on the joint? From what directions? What materials? What actuates them? What size tubing (Diameter and wall), what are they connected to? How are they supported? Etc...

vhol5 · May 4, 2013

bczygan said:
You are getting answers all over the map because you haven't defined the parameters closely enough. What forces are acting on the joint? From what directions? What materials? What actuates them? What size tubing (Diameter and wall), what are they connected to? How are they supported? Etc...

^^^^^^this^^^^

bobadame · May 4, 2013

Machining is much more expensive than welding.

egnorant · May 4, 2013

Details...Can the ID and OD be altered? Will this joint be subject to different forces...rotational, compression, traction or what?
Movable joint? Does this mean moved once for manufacture then locked into a setting or will it be adjustable as part of the tolerances of its operation or will it be variable as a function of the operations?

What are your capabilities? If we are not allowed to use welding, swaging, splines, pins,sleeves, inserts, glues or whatever it would help.

Bruce

JDishong · May 4, 2013

Thanks to all who contributed - your inputs now have me going in a new direction. I like the sleeve idea because its simple and low-cost ..

This is 1" OD steel tubing project, 16GA. It's basically a concept at this point, hence the lack of details.

Loading is insignificant.

Thanks again to you all!

bczygan · May 4, 2013

Wait a darn minute there BUSTER BROWN!!!

...you owe us further explanation...we gave you help. Now we need to be entertained.

JDishong · May 4, 2013

egnorant said:
Details...Can the ID and OD be altered?
** NO

Will this joint be subject to different forces...rotational, compression, traction or what?

*** I only need to adjust the length and then secure so it can't slide anymore. Rotational - NO, Compression - NO

Movable joint? Does this mean moved once for manufacture then locked into a setting or will it be adjustable as part of the tolerances of its operation or will it be variable as a function of the operations?

**** Variable as f(op), yes.

What are your capabilities? If we are not allowed to use welding, swaging, splines, pins,sleeves, inserts, glues or whatever it would help.

Unfortunately, only a chop saw at this time...

Bruce

see note above

JDishong · May 4, 2013

I asked for help naming the joint type I posted in the drawing ... still not sure what to call this type of joint ... inter-digitized sleeve ??

bczygan said:
Wait a darn minute there BUSTER BROWN!!!

...you owe us further explanation...we gave you help. Now we need to be entertained.

JDishong · May 4, 2013

Tink said:
Probably need more information. Do the inside and outside diameters have to be the same size? Would it be possible to let us know the application of this product?

No application, conceptual question. but to answer your question, YES.

bczygan · May 4, 2013

Ahhhh....we have your answer.

Get two guys.

One holds each tube.

When you need them pulled apart, holler at them, "MOVE APART".

Reverse is same, except with command, "MOVE TOGETHER".

The joint you are showing is a spline joint. And the drawing is wrong. If you look at the part on the right, the ends are square, not radiused. The part on the left has slots that are radiused to accept it. This would be a great joint for a solid rod or a tube with a thick wall, not so good for thinner wall. Creating a rounded edge on one mating edge and a rounded slot on the other would help them mate if sufficiently thick. More fingers would also help, ...to a point.
And when the joint is open, the pipe or tubing is open. Is that OK?

retrobuilder · May 4, 2013

Joint terminology- simple internal swaged joint- no new I.P. here.. unless the slot is to prevent rotation some how- I'd reverse the slot to opposite part.

bczygan · May 4, 2013

If the pipe is thick walled enough you can turn down the OD on one and turn up the ID of the other, for the specified length you want to move them, plus enough for adequate support.
That will give you complete coverage, but when open, the pipe on each side will have a portion exposed that has a wall of half the thickness.

A lathe or some other method for reducing and increasing diameters would be required.

JDishong · May 4, 2013

Love this idea .. except I need to design a built-in language translator for politically correctness !

Spline joint - that is what I was after, thanks! Understood on the radius issue.

bczygan said:
Ahhhh....we have your answer.

Get two guys.

One holds each tube.

When you need them pulled apart, holler at them, "MOVE APART".

Reverse is same, except with command, "MOVE TOGETHER".

The joint you are showing is a spline joint. And the drawing is wrong. If you look at the part on the right, the ends are square, not radiused. The part on the left has slots that are radiused to accept it. This would be a great joint for a solid rod or a tube with a thick wall, not so good for thinner wall. Creating a rounded edge on one mating edge and a rounded slot on the other would help them mate if sufficiently thick. More fingers would also help, ...to a point.
And when the joint is open, the pipe or tubing is open. Is that OK?

JDishong · May 4, 2013

bczygan said:
If the pipe is thick walled enough you can turn down the OD on one and turn up the ID of the other, for the specified length you want to move them, plus enough for adequate support.
That will give you complete coverage, but when open, the pipe on each side will have a portion exposed that has a wall of half the thickness.

A lathe or some other method for reducing and increasing diameters would be required.

I've seen the joint you are describing. I think I like the spline joint though - thanks

theoldwizard1 · May 4, 2013

I would not call that a spline joint ! This is a spline joint

It looks closer to a lovejoy coupling without the inner rubber spider

or possibly a dog clutch.

All of these are designed to transmit rotational force.

Some one already mentioned it. Internal threads and a piece of all-thread in between. Drill and tap the tubes on the side and use a set screw or button head screw to lock it. The tube would need to be at least 0.080 wall thickness. 0.100 or 0.125 would be better.

JDishong · May 4, 2013

theoldwizard1 said:
I would not call that a spline joint ! This is a spline joint

It looks closer to a lovejoy coupling without the inner rubber spider

or possibly a dog clutch.

All of these are designed to transmit rotational force.

Some one already mentioned it. Internal threads and a piece of all-thread. Drill and tap the tubes on the side and use a set screw to lock it.

Thanks TheOldWizard - 16GA steel tube is too thin to tap threads... I have tried a flow-drill but not enough metal using 16GA.

theoldwizard1 · May 4, 2013

Cheap, simple.

Get some rod/tube that fits the ID of the tubes that you want to join. Drill and tap the outer tube for set screws/button head screws. I would use 2 or 3 set screws on each tube.

JDishong · May 4, 2013

theoldwizard1 said:
Cheap, simple.

Get some rod/tube that fits the ID of the tubes that you want to join. Drill and tap the outer tube for set screws/button head screws. I would use 2 or 3 set screws on each tube.

I think the inner tube that fits the ID is the simplest approach too. - thanks. I need to test out how many threads will fit in 16GA outer tube. If I can't fit more than 3 threads, I'll just drill through both tubes (inner and outer) and secure.

Thanks

theoldwizard1 · May 4, 2013

JDishong said:
I think the inner tube that fits the ID is the simplest approach too. - thanks. I need to test out how many threads will fit in 16GA outer tube. If I can't fit more than 3 threads, I'll just drill through both tubes (inner and outer) and secure.

Ahhh ... then it is no longer adjustable !

LG63 · May 4, 2013

JDishong said:
.. any advice on what this style/type of joint is called ???

I would call it a "slip tang-yoke joint"

theoldwizard1 · May 4, 2013

LG63 said:
I would call it a "slip tang-yoke joint"

I'll buy that !

No way to lock it at its desired length. In order to transfer rotational force the walls of the tube would have to be thicker than 16 gauge.

I would not feel safe with loads that are perpendicular to the tube length unless there was a slip tube covering the joint. The outer slip tube could have set screws to lock the desired length.

The tang and yoke could be designed so that they were identical, just rotated 180°.

BD1 · May 4, 2013

Just for info, if that's 1'' OD, standard 1'' schedule 40 pipe is 1'' ID. Will be perfect to slide over.

JDishong · May 4, 2013

theoldwizard1 said:
Ahhh ... then it is no longer adjustable !

So true!

racer-john · Dec 5, 2015

On my computer the drawing the OP said he posted, did not show.

racer-john · Dec 5, 2015

Now it's there. What gives?

bullnerd · Dec 6, 2015

If your going to manufacture that part in quantity, there's only one way...CNC laser tube cutting machine, no brainer.

RobSmith · Dec 6, 2015

JDishong you have not told us what you are making...if we knew that we might come up with an entirely different os simpler way of doing the job.

ishiboo · Dec 6, 2015

Racer dug this thread up from 2003.

Steel Tube Joint - Need your help

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