Swage for nesting 1/2" emt conduit

[forhire]

My friend came down today and wanted to build a swage for nesting 1/2" conduit. This has been on the list of things to have for a few years. Sure, he could have bought swaged pipe... but nobody locally stocks it. I've run into this a few times in the past when hanging fabric ducting... now we can make a piece anytime and any length

Found a piece of scrap and a few hours later had this tool.

The tool is simple, didn't want to spend too much time in case it not work. Currently the process takes two pressings. The results are way better than expected. Does anyone have any suggestions to make one that can do it all in one press?

Pic 1: Face the stock. It was 2" thick and 3" wide by 4" long.
Pic 2: Drilled a 19/32" hole through the block.
Pic 3: Chamfer the hole a little.
Pic 4: Drilled the holes for the alignment pins.
Pic 5: Welded the block unto a piece of scrap to facilitate cutting on the band saw.

More pictures on the next post

[forhire]

Pic 1: Cutting part on bandsaw
Pic 2: Cut part
Pic 3: Finished swage with pins installed.
Pic 4: Conduit after first press
Pic 5: Second press. Note the washers to help gauge the final dimension (due to saw curf)

[forhire]

Pic 1: Finished end. Sorry for the fuzzy photo.
Pic 2: Test fitting the two pieces of conduit.

[aevald]

Hello forhire, I have swaged various pipes and conduits using a hydraulic hose crimping machine. Fortunately for me I was able to pick up a portable hand-operated crimping press really cheap, I believe it is a Parker-Hannifan unit. They use die-sets that have vulcanized rubber that holds the pieces together for the two halves, I believe there are 4 sections for each die half. You can slip your part into these and then press them in one shot and reduce the diameter so that it can be slipped into another piece. This is accomplished by having the die tapered and round and the receiver piece is also tapered and round, as the die is pushed into it's mating female part it causes the inner diameter of the unit to be reduced. Your set-up is very cost effective comparibly and even though it takes two reductions it looks like it gets the job done nicely. Since it is always easier to see different ways of doing things once they have been done, here would be a suggestion for a slightly different approach to your design; drill your dowling holes prior to doing any machining, then cut the block in half, using the 4-jaw to hold the two halves together, machine the center hole last, thus you won't need washers to space the unit. Please don't take this suggestion as a criticism, I like your work, simple and effective. Best regards, Allan

[forhire]

Thanks Allen. No criticism taken. After making the part it became very clear it was done out of order. Experience is my best teacher.

[DSW]

Interesting. I'd expected you to make a swage to open up the emt rather than close it up. Guess thats because I'm used too working with copper pipe. I was thinking more of a tool like the ones shown that are usually driven into the end to expand copper to make a socket joint for soldering. With some you need to anneal the pipe a bit to make it easier to expand the tube.

Looks like you idea works fine.

[daddy]

Why would you do this instead of using a coupling with the set screw?

I'm asking because I don't know, not to be a smart azz.

[forhire]

Interesting. I'd expected you to make a swage to open up the emt rather than close it up. Guess thats because I'm used too working with copper pipe. I was thinking more of a tool like the ones shown that are usually driven into the end to expand copper to make a socket joint for soldering. With some you need to anneal the pipe a bit to make it easier to expand the tube.

Looks like you idea works fine.

The emt conduit has a tendency to split when expanded. The pipe is galvanized so we didn't want to anneal it and damage the coating any more than possible.

Why would you do this instead of using a coupling with the set screw?

I'm asking because I don't know, not to be a smart azz.

Those couplers, especially the steel ones may have worked. This method gives us a longer engagement at the junction and hopefully a stronger joint.

This is what they sale at the farm supply. It's designed for hanging curtains. They want $5.90 each. I can buy conduit for $1.97 each. At $4 savings it doesn't take long to make wages
http://www.qcsupply.com/qcsupply/bro...roductId=90258

[RancherBill]

Cool project.

Soon you'll be supplying HF will HEAVY DUTY Engine Stands.

Seriously, there a ton of projects that this would be perfect. A small 8x10 green house comes to mind. Easy to assemble and disassemble. Hey, you could do a proof of concept greenhouse and send it to ME!

All you need is a tubing bender and my greenhouse will be on the way.

[MoonRise]

Interesting project.

Yeah, I would have said the machining order should be:

- drill dowel holes;

- ream dowel holes for dowel press fit;

- split block in half length-wise with bandsaw;

- take one block half and ream the press-fit dowel holes into slip-fit dowel holes;

- press dowel pins into the press-fit holes;

-assemble the block using the dowel pins to align everything;

- put block into lathe and make the desired hole.

I obviously left out all the deburring and such.

Idea to turn your tool into a one-shot and reduce/avoid the squeeze-out into the kerf/gap you currently get:

- add a protrusion into the die to press the tube/conduit inwards as the OD also gets pressed inwards.

Simple way would be to take a length of hard welding filler or drill rod of the appropriate diameter and then carefully weld it length-wise down the hole in the die. As you squeeze the tube/conduit, the 'ridge' contacts the OD of the tube/conduit first and presses it inwards making the 'crimp/dimple' and then the main hole in the die squeezes the OD of the tube/conduit down to the desired new OD size.

[jdh239]

Having a hard time picturing how it actually works. Any video?

[forhire]

Simple way would be to take a length of hard welding filler or drill rod of the appropriate diameter and then carefully weld it length-wise down the hole in the die. As you squeeze the tube/conduit, the 'ridge' contacts the OD of the tube/conduit first and presses it inwards making the 'crimp/dimple' and then the main hole in the die squeezes the OD of the tube/conduit down to the desired new OD size.

I laid some drill rod in the die. It didn't work as expected, it flattened the pipe too much.

I'm thinking I can cut a groove in the top of the die and put a plate in the groove the protrudes above the die, then when pressing this plate will indent the center of the conduit a bit before the die halves start.

I fixed the die this morning. It was simple enough to re-check it in the lathe and bore it to diameter. I then used an adjustable hand reamer to bring the die to the correct finish diameter after a few test parts. Now the fit is nice and snug and no pesky washers to deal with

[forhire]

Having a hard time picturing how it actually works. Any video?

I've uploaded a video here:
http://home.lewiscounty.com/~forhire/emt_conduit.wmv

Enjoy

[forhire]

There are many good ways to make duct. What is the easiest way to do this?

I assume you are referring to fabric air duct? If the duct is on a winch system you'll run a line through the duct and tie it to the conduit every 8 or 10 feet. The conduit supports the duct from the bottom and gives the tube some rigidity, especially when not inflated. We have used pre-swaged pipe, swages our own, and even used steel emt couplers.

I originally made this swage while making some chicken tractors. I can build a 10x12 tractor for around $20 in materials.

[ThorsHammer]

I'm not seeing a way to make this a single press system.

The drill/plate ideas have a fatal flaw, they fill the dimple with another material, thus preventing the pipe from filling said dimple and reducing the diameter of the pipe.

the current set up dimples out making "wings". it would be awesome if you could come up with a way to either shear, or fold over the wings in your first pressing. but I'm lost on how to accomplish this.

Now, onto the tractor, what is the approximate weight? how easy is it to move with 1 person? how much would you sell one for?

[ThorsHammer]

If you've got a mill, and could bevel an edge onto one half starting with the point at the edge of your bored hole, and sloping away from it. then mill out an area for the "wings" to fall into, you may be able to get the desired single press effect.

This leaves me with two concerns though. 1) is the swage made out of hard enough metal to cut the conduit without deforming. and 2) will the conduit retain the swaged shape if the wings are cut off.

I'm not sure you'd have enough room next to your hole to cut the bevel, and have the valley for cut metal before your guide pins on your current set up.

[forhire]

The drill/plate ideas have a fatal flaw, they fill the dimple with another material, thus preventing the pipe from filling said dimple and reducing the diameter of the pipe.

Yep. I tried that and it didn't work.

the current set up dimples out making "wings". it would be awesome if you could come up with a way to either shear, or fold over the wings in your first pressing. but I'm lost on how to accomplish this.

I'd rather not shear anything... I need the strength. A commercial die would fold it in and then press it round. I can be done... but not with such a simple die.

Now, onto the tractor, what is the approximate weight? how easy is it to move with 1 person? how much would you sell one for?

It's really easy with two people but very doable with one. I'd have to weigh some conduit to get a guess at the weight. I've thought about putting wheels on it. Sent PM about sales.

[ThorsHammer]

The only other thing I can think of is a die that pressed onto the conduit from the end. running a dimp up the conduit, then clamping down and pulling off shrinking the conduit as it comes off. it would be a total redesign, and I'm not sure that it would work without tearing the conduit.

You're probably better off sticking with the two step system.

[forhire]

Commercially this would ideally be done with a rotary swage like this:
[ame]http://www.youtube.com/watch?v=3YeItz_9bf8[/ame]

[Rhinodaddy]

Try looking at the problem a little differently. An old timer I knew made a swaging tool for a lathe that was basically a roller ball mounted on the end of key stock. He mounted this ball/key stock where the cutting tool normally mounted, then he chucked the tubing into the lathe. Instead of turning the tubing down, he was shrinking it in by gradually increase pressure from the roller onto the pipe.

Two things to keep in mind. One is, the pressure on the tube is going to deflect it away from the roller tool somewhat, so you need to keep checking your true OD. The other is to keep in mind that your swaged tube is going to elongate a bit. Good luck.

[ThorsHammer]

I wonder, would it be possible/safe to make the roller ball attachment something that the pipe goes through instead of just something that it pushes against? that would eliminate the deflection.

The elongation would be minimal, and moot, as it would slide into the other piece of conduit. as long as your doing your measurements off where the taper starts, and not the overal piece you're good to go.

However, this does seem like it would take longer than running it under the press twice...

[AndyA]

Maybe take one of those scissor-type knurlers and just use smooth rollers. Keep tighening the scissor after each pass of the carriage. I don't know if pressure on only two sides would be enough to make it shrink, or if it'll just squish it in a rolling egg shape without shrinking any.

Definitely seems like it would take longer than the two-hit press method.

[Oldiron2]

Try looking at the problem a little differently. An old timer I knew made a swaging tool for a lathe that was basically a roller ball mounted on the end of key stock. He mounted this ball/key stock where the cutting tool normally mounted, then he chucked the tubing into the lathe. Instead of turning the tubing down, he was shrinking it in by gradually increase pressure from the roller onto the pipe.

Two things to keep in mind. One is, the pressure on the tube is going to deflect it away from the roller tool somewhat, so you need to keep checking your true OD. The other is to keep in mind that your swaged tube is going to elongate a bit. Good luck.

What you're talking about is called "metal spinning" and is explained a bit here:

http://en.wikipedia.org/wiki/Metal_spinning

Here is a link to what it typically looks like: http://www.winward.co.uk/metal%20spinning.jpg

Forhire's project could probably be done on his lathe. I'd try an internal live-center type mandrel in conjunction with an outside roller, perhaps a multistep roller assembly or a single one at an angle, the center to keep the part straight and resist side bending near the point(s) of roller contact.


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[forhire]

Try looking at the problem a little differently. An old timer I knew made a swaging tool for a lathe that was basically a roller ball mounted on the end of key stock. He mounted this ball/key stock where the cutting tool normally mounted, then he chucked the tubing into the lathe. Instead of turning the tubing down, he was shrinking it in by gradually increase pressure from the roller onto the pipe.

Interesting approach. I imagine it would work. I'll have to try it. I've closed tubes on the lathe using one of my metal spinning tools... same idea. Because of the fit the swage was the fastest least trouble method to make the parts. I don't think I can spin them as fast as I can press them... now you have me wondering.

I wonder, would it be possible/safe to make the roller ball attachment something that the pipe goes through instead of just something that it pushes against? that would eliminate the deflection.

I originally tried feeding the tube though a tapered hole on the lathe... it didn't shrink as hoped... galled a bunch even lubed. I wonder it 4 bearings mounted at an angle perpendicular to the pipe could be fed into the taper and shrink.

Maybe take one of those scissor-type knurlers and just use smooth rollers. Keep tighening the scissor after each pass of the carriage. I don't know if pressure on only two sides would be enough to make it shrink, or if it'll just squish it in a rolling egg shape without shrinking any.

It might work. I don't have a scissor knurler to abuse. I thought about taking the cutter out of my pipe cutter and cranking the handle slowly while spinning in the lathe. I image this would shrink the tube... the only issue is the small size... 1/2" at a time.

Forhire's project could probably be done on his lathe. I'd try an internal live-center type mandrel in conjunction with an outside roller, perhaps a multistep roller assembly or a single one at an angle, the center to keep the part straight and resist side bending near the point(s) of roller contact.

Generally the rotation of the work keeps it straight unless you get too aggressive or the material work hardens. Now I'll have to head back out to the shop and play a little.

[Boostinjdm]

What if you cut a slot in your uppper die. Press a strip through the slot to form the dimple. Then remove the strip and continue pressing.