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Need to flatten thinwall pipe ends for structural use. Ideas on methods?

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  • Dave C
    replied
    What you are trying to accomplish is essentially creating a Z bend in the pipe while forming the flattened section. You cannot do that without holding the rest of the pipe securely to prevent it from lifting and squirming back out of the die. I could be wrong, but 30 years of designing and building metal stamping dies says probably not.

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  • J Tiers
    replied
    Got up early and tried a simple piece of half inch plate, with a half circle cut in it at a larger diameter than the pipe. Worked great, flattened the end just as I want, formed a good rounded transition to the flat.

    One problem.... the flattened part is still at an angle.

    Originally posted by Dave C View Post
    You need a longer hold down. The one you are using is letting the ass end of the tube lift, and that is where your angle is coming from.
    So, back to this issue. But the stated fix is NOT a fix.

    The end is not lifting up, the problem is the pipe is flattening on the bottom, the part resting on the flat bottom plate, because of the force of flattening the end to one side. Holding down the back of the tubing does NOT help with that, the bottom still flattens near the end.

    I suppose the next step to fix that would be a sized round clamp to hold the tube, so it cannot spread, which might help with the flattening, but it would have to be a pretty tight fit to avoid the tiny amount of spread that goes with the flattening. And there has to be SOME spread allowed, in the transition.

    I kinda like the result that KMoffet showed way earlier in the thread, but I do not see that sort of result. I HAVE seen the right result on commercial products.

    I like this OK as far as the not completely straight-across transition.




    I do not like this. The flattening of the back gives the undesired angle.




    Holding down more, or farther away, seems to convert the last pic into something with a longer flattened back, but there is still an angle.



    Kmoffet showed a result which may be fine, but I don't know why a similar setup gives different results. The pipe ends up arching up to still give the flattened back and angle. In fact, it actually looks as if his actually did the same thing I am finding. Possibly a bit less of it

    The ideal result is to get the pipe so when laid down, the flange on each end is flat down on the surface, and the pipe contacts the surface all along. I have seen it in products, but have not seen their process.

    His result looks as if there is still some flattening of the back, and still some angle.

    https://bbs.homeshopmachinist.net/fi...3&d=1597936923

    His setup

    https://bbs.homeshopmachinist.net/fi...2&d=1597936923

    Last edited by J Tiers; 09-12-2020, 10:35 AM.

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  • J Tiers
    replied
    I'm in a desert of yuppies..... Example: one neighbor did not know how to assemble his new lawn mower (with a manual, and his mother-in-law looking on), so he came over and had to ask my wife how. (She rebuilt cars with her father, and can be trusted to bring the right tool, etc, etc). My wife showed him what to do and had to remind him it needed oil in the crankcase. He was a lawyer, and it showed. He moved out, we have nice musicians in there now. Well, one of the musicians decided to switch careers, and she is a senior purchasing agent at the nearby AFB as the day job, but they are still nice.

    So, no shop buddies around here. The only one moved away years ago.

    I need to get a 20 ton (or more) press, you are correct.

    But I do not think the die I made is really right for the job, it is doing too much forming, and I should have seen that straight off. I knew perfectly well that the tool should be simpler back when I started on it......... The idea did not feel right, but I figured the hydraulic press was "obviously" going to give more force, and "should take care of that".

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  • The Metal Butcher
    replied
    Got a friend with a bigger press? Seems like an easy solution. I've got a 40 ton that would make quick work of that, maybe someone near you has one?

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  • J Tiers
    replied
    Fixed the ram retraction issue (the spring had actually become unhooked as the end plug was screwed in). Now it retracts almost the full distance, it is just not quite powerful enough at the end of spring travel when almost relaxed.

    It seems the press has not got the power to do the full forming, but it can flatten the ends before the pressure goes off scale (max 5000 psi on the gauge). So, I'm going to try a couple things using pieces and parts I have available, because I really do NOT want to do a straight across "squash".

    Before I take a saw to the existing die, I need to prove that I either can, or cannot, use a rounded end slot in a piece of metal to get something better than the straight across crimp. Really not even a slot, just a rounded edge.

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  • J Tiers
    replied
    Originally posted by Dave C View Post
    You need a longer hold down. The one you are using is letting the ass end of the tube lift, and that is where your angle is coming from.
    Mostly that the die is not guiding down flat, partly that it is not getting flattened. The bottom of the pipe is getting squashed a bit as the die comes down, so the pipe ends up at an angle to the end even though the back of it does not come up.. I can look at it and see that the pipe does not raise up.

    It's maybe also the die not coming down straight, and maybe not being forced flat buy the ram (4 tons not enough). If it was, the end would be forced straight.

    Maybe I look at this some other time, right now I need to do what this was supposed to facilitate. Executive decision time, and this rat-hole isn't worth the time for the moment.

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  • alanganes
    replied
    Originally posted by Mike Amick View Post
    No, I take your point Jerry, definitely wouldn't have an electrical use. But it would
    be something that you could take a bunch of conduit and make a little table or book stand, whatever.

    People do it all the time with PVC .. just saying it might be cool if you could do it with conduit.

    I have actually made couplers AND T's welding up lathed to size steel rod. But I wouldn't want to
    have to make a bunch of them.
    OK, just to slightly derail (lame train joke there, Mike...) again, it seems that someone heard you. Not especially cheap but they exist:

    https://makerpipe.com/
    Last edited by alanganes; 09-10-2020, 11:05 PM.

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  • Dave C
    replied
    You need a longer hold down. The one you are using is letting the ass end of the tube lift, and that is where your angle is coming from.

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  • J Tiers
    replied
    Well, I relieved the die and did not get sufficiently better results to make further work worth while. And, the 4 ton ram seems as if it is just not good enough, never mind the fact that there is too much friction with the new seal for it to retract. With 4000 lb on the dial, which is 2 tons pressure, the result is not better than what I get with the blacksmith vise, i fact the vise seems to do better.. The press is not big enough for this small job. Dial only goes to 5000 lb, ram should go to 4 tons.

    Looks as if I ought to stop wasting time on this and get the job done in some other way, possibly with other materials.

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  • J Tiers
    replied
    Since the new parts were installed in the hydraulics, I tried the die again.

    The die does not flatten the pipe at the pressures that I am willing to put on the frame. I went up over 3000 lb pressure, and the pipe was not flattening sufficiently, plus the angle is still present on the "flattened" part vs the axis of the pipe. The frame was starting to flex, so I stopped there. Looks like the vises actually may have applied MORE force than the hydraulics have.

    It got this far and quit at the pressures I was willing to use.





    The angle is still present.



    This may not be the way to go, or the die may just be holding the pipe from deforming. I was concerned about that but did not have a way to relieve the die as might be needed. I have a couple things I can try still, like drastically simplifying, and not trying to control the profile in the transition from round to flat.

    I wanted a rounded end to avoid the sharp bending point and stress riser that would result from a straight-across edge. I'm getting that, but the rest of the die may be holding up the forming. Trying for less control of that, and retaining the round end may do the trick. I have a zoom meeting (City business) coming up in a half hour and have to get ready for it.

    Well, I DID get the hydraulic press done.... now I need to make a better frame.
    Last edited by J Tiers; 09-09-2020, 08:03 PM.

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  • J Tiers
    replied
    That's basically why I chose that approach. But I have never seen those but once, several years ago, and flea markets are not happening much around here. There is also the question of whether the one they do is any better than mine.

    I tried a change...I did a hold-down separate from the die, so that the hold down and a base plate are together, and the die is pressed down over the tubing that is sticking out over the baseplate beyond the hold-down. When closed, the die cavity is be an extension of the hold-down profile, then curved toward the baseplate to do the forming of the "nose". There is a clearance space when closed, that is 2x the metal thickness, to get the tubing flat.

    The result is considerably better, but is still not perfectly flat, there is a couple degree angle on the flat. Sounds like nothing much, but at the end of a couple feet of tubing, it's a bigger deal, not to mention the fact that the other end will have the same issue. The combination gives a 4 to 6 degree error off a flat plane, which is not good.

    But, I do not at the moment have the press power to bottom the die. The Porta-Power was supposed to do that, but it decided to fail before I actually got any pressure out of it.

    The vises I have available are not doing the job, I have about 1/8 or a bit more to go before the die is bottomed, even basically hanging on a 16" lever. I do not want to use a piece of pipe, since I will either break something, or bend the lever.

    The arbor press is too small, it is really a joke, a JET 1 ton that I picked up many years ago. Talk about "chinese tiny horses", their units of measure must be pretty small also. I doubt this one will do a half ton without something breaking. It's OK for actual arbors, so long as they are not too long, as it has about 7" daylight.

    So it looks like I need to fix the press setup to get any farther along.
    Last edited by J Tiers; 08-31-2020, 11:08 PM.

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  • Lew Hartswick
    replied
    Re the weird angles for EMT; I've seen at "flea markets" the use of it for the "sunscreens" a lot of vendors use and even the sale of those angle pieces that form the corners and ridges both along the ridge and at the ends. So people are making them and selling them. Just go to a flea market and look . :-)
    ...lew...

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  • J Tiers
    replied
    The die, even as -extended, is just not doing the crimp. The flat ends up at an angle to the axis of the pipe, and that is just plain not acceptable. The crimp is GOOD, but it is at the wrong angle.

    I probably should not have tried to do a single piece die, and ought to have set up a clamping piece, with the pipe held in it, and then had the die come down on it.

    At this point I need to evaluate whether to bother continuing to throw time at this idea, or whether to drop it. Solving the angle issue may not be a possibility with this design.

    I seem to be at the point where the "sunk cost" trap appears, and I may just need to use angle (which I do not have in stock at suitable lengths) instead.

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  • J Tiers
    replied
    Since I found that the die needs more pressure, althugh maybe not a lot more, I decided to adapt the Port-o-Power to the frame it came with from the previous owner, in a new way. So I made a 1 1/2-16 nut , secured the nut to the top of the frame, with a clearance hole through for the cylinder to pass through. The frame is not good for all 8000 lb, but will do this, the PO used it for material testing at a couple tons.

    The nut, faced, bored, and threaded, just trimming down the plugs I inserted into some side threaded holes so the inside could be threaded without an interrupted cut, which never goes well on a small lathe.


    The nut, with the mounting holes having transfer screws in them to mark the drill holes (and bounce marks from the interrupted cut)


    Mounted, with cylinder


    Mounted nut from below. I can face off a fair amount of it if any rod tooling does not fit. The first bit is not even threaded and the threads on the cylinder do not go that far anyway.


    Sometime when I get a round-tuit, or need to, I can move the nut and cylinder to a new and better frame. This one should do for now.

    It is welded of flat bar and 12" or so channel iron.
    Last edited by J Tiers; 08-27-2020, 04:58 PM.

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  • J Tiers
    replied
    Eased the edges, and lowered the area to accommodate the flattened part, but I am not yet happy with the results. The EMT is so strong that it is difficult to flatten in a vise, and very difficult to get formed in the die. The conduit flattens in the wrong places, and the forces are considerable.

    I think I need to ease it more, and allow more space for the tubing to widen out.

    So I am taking a side-trip to set up my Port-o-Power as a press. I got a frame with it that ought to stand up to some force, since it was what the thing was used with. The Port-o-Power cylinder has an inch of 1 1/2-16 thread on it for attaching fixtures, which apparently can be used as a mount, so I can make a flange and then mount that to the frame. it will take the whole 4 tons, more than I expect the frame can, but I don't think it will take 4 tons to squash EMT.

    Noitoen:
    The threaded material is what is called "conduit" in the US. There is a lighter material that is also threaded, known as "IMC:: "Intermediate metal conduit", and a light tubing "EMT": "Electrical Metallic Tubing". The EMT is what I am looking at, wall thickness about 1.1 mm. The "IMC" is not widely used for normal purposes.
    Last edited by J Tiers; 08-26-2020, 01:47 AM.

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