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

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  • J Tiers
    replied
    Originally posted by nickel-city-fab View Post
    Wow, nice clean work. I imagine that solar parts are very overpriced and it's better to make your own.
    Not really, I just want to mount it in a way that there are not parts made for.

    It looks lot's cleaner at the photo distance than up closer. And the die is a bit of a hack job.... But thanks anyhow!

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  • nickel-city-fab
    replied
    Wow, nice clean work. I imagine that solar parts are very overpriced and it's better to make your own.

    Leave a comment:


  • J Tiers
    replied
    Originally posted by Jim Stewart View Post

    Not seeing anything...

    -js
    You were too quick.....

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  • Jim Stewart
    replied
    Originally posted by J Tiers View Post
    Number one
    Not seeing anything...

    -js

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  • J Tiers
    replied
    In the last pic of previous post, you can see the new bottom piece (base) is quite thick and stiff.

    Here is the other side of the setup, with the piece of aluminum functioning as a guide to locating the die and pipe, shown just before applying pressure.



    The die, and the hold-down piece, upside down. Both were made on the horizontal mill, first cutting the slot for the pipe with a convex cutter, as shown in the other thread linked in a prior post, and then the cutouts were made later using a side cutting plain milling cutter. going across the part.

    For scale, which I forgot to put in a ruler to show, the milled recess is a 0.75" wide recess. It that size because it is big enough, and I had a cutter for it, not because I had any special calculations of recess size, etc..

    The recess was then eased off to allow more space for the spreading of the pipe as it is "squashed". There is a shallower part to press the flattened part of the pipe, and a deeper portion to allow for the pipe to spread out as it transitions to the squashed part. The deeper clearance area did not go back far enough toward the place the pipe comes in, so I had to get out my Swiss riffler and die sinking files, after roughing with a coarse file. The deeper part could have been cut a little farther toward the end of the pipe recess, and then that might not have been required..





    Last edited by J Tiers; 09-13-2020, 10:41 PM.

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  • J Tiers
    replied
    So the first lot of struts is done. These are not for awnings (that is the future task) these are to support a solar panel. There is one more to be made, a sway brace, but these are the supports to hold it up on a wall (they are "structural" enough for that!). In the pic, they have not yet been drilled, and the ends are not rounded as they will be.



    For Anton Largiader:

    This is the general setup, with the die fully down on the pipe, finished forming the end. The marked circle is the approximate pressure point for the ram



    This is the die in place, before pressure is applied. The end ridge of the die is just beyond the end of the pipe, which is 1/2" EMT, 0.715" OD.





    Continued in next due to pic limit
    Last edited by J Tiers; 09-13-2020, 10:35 PM.

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  • Dave C
    replied
    Glad you got it worked out. As you discovered, a lot of die design involves trial and error. Many jobs that I was asked to bid on would have the phrase: "Develop the blank" in the part description.

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  • AntonLargiader
    replied
    It sure looks like you are putting spring tension into it when you form it, and then when you release it the part curls. I don't think holding it down any "better" will help unless you hold it down with the right amount of counterbend.

    Super interesting to see your results; thanks for posting. I would have thought this was more straightforward.

    I guess we know why the people in the video were using a secondary op.

    And BTW it's cool that you are making awning frames. I have a few sticks of new conduit in the garage for the exact same reason. I do have a stronger press, but I can see that that is not necessarily the solution. But in my case I think I can flatten to the centerline of the pipe; no need to be perfectly offset to one side.


    EDIT: didn't see your last results. Nice! Maybe I WILL go for the offset on my own frames. Can I borrow your dies?
    Last edited by AntonLargiader; 09-13-2020, 09:46 AM.

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  • J Tiers
    replied
    I do not think there is any forming of the top being done. The curve of the tube is way different than the end of the recess left by the convex cutter except right at the lip where the curve meets the flat. ( https://bbs.homeshopmachinist.net/fo...he-forming-die )

    As far as I know, the flat is being formed, and the curved end of the tube where it hits the flat is being formed, but that's about it. The die is only hitting those areas, the rest is to clear, and to stop at the right point when the surface hits the bottom backer.

    The cuts are to clear, and allow the tube to spread out. In fact, I need to do more where you can see the heavy rounding over, because that point is marking the tube, and shouldn't be.

    It's mostly working as I expected, and it seems capable of doing what I want, since it just did.

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  • Astronowanabe
    replied
    That looks really good.
    I have only made straight line bores with a mill or hole-saw
    for relief in my dies, which may work with less pressure,
    but I think your forming die produces a nicer looking crimp.

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  • The Metal Butcher
    replied
    That looks pretty damn good from here.

    Sucks to take the die grinder to a nicely machined tool, but we've all been there. If it gets the job done... it's the right answer. But now you'll have to make 2k to justify your time haha.

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  • J Tiers
    replied
    If I can reproduce this, I've got it licked......

    Did everything the same as before, but with a more rigid base, and the result is essentially exactly what I want. Same die as originally planned, hold-down, etc, but the base below the die is a thicker piece.

    I need to ease a couple edges on the modified die, but if I can reproduce this, it will be good to go. I think I know where the ram was hitting the die, maybe I can check for the marks.

    I did not see enough movement with the old base piece to make the difference, but I cannot argue with results. Took about 3000 psi.

    Top views of part, base, hold-down, and die (face-up), aligned as used.




    Result lying along flat surface of the base piece. Just a hint of a tip-up, easily adjusted in a vise in 5 seconds.



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  • J Tiers
    replied
    Originally posted by Dave C View Post
    ........... If you want to get into the business of doing the parts commercially, PM me to discuss consulting fees and royalties.
    Not hardly, thanks. I've a dozen or two to make now, that really need to be flat and in-line with one side. Basically custom awning frames for the property.

    I figured it was going to come out to more than one piece for the die, or a lot more force than 3 or 4 tons, and I may do a different approach if I don't get good results. looked at just using the centered flange, and may do that, but I'd rather not.

    I could possibly deal with the form the Pakistani video showed for most, but there are places where two or three need to stack, and theirs do not stack because they are not fully flat, they have a bulge on each side. .

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  • Dave C
    replied
    Well I've been responding off the top of my head without getting too deep into the issue. That said, I don't think you are going to get the result you want by using a single die. If I were to take this on in a factory environment, I believe it would take at least two dies and possibly a third to get the required result. The last station would be one that squares the end of the flattened section. If you want to get into the business of doing the parts commercially, PM me to discuss consulting fees and royalties.

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  • J Tiers
    replied
    Her is another, and yes, the back of the tube has again been held down with little change. I totally understand what you are saying, and took what appear to be provisions to avoid the "squirming and lifting".

    Here is the flattening. Very simple straight line, no fancy variables.




    Here is what actually happened. Numbers are inch marks. The two lines at the 5 inch mark are the location of a hold-down, a piece of aluminum clamped to the platen, which is milled to 0.75 diameter, slightly less deep than the pipe diameter (0.715"), so it held tight. The dotted line is the outline of the actual flattening of the tube along the bottom, it extends just past the 3" mark, the flash washed the marks out on the picture.




    The result was that regardless of a hold-down that absolutely did not allow the pipe at that point to lift, the actual flattened part of the pipe ended up nearly on-axis because the pipe itself flattened at an angle under the force of forming. I strongly doubt if any amount of hold-down further out than the one indicated could have made any difference, since the pipe itself would just bend (asa beam) under the forming force. You can see the flattened flange is maybe 1/8" off axis.



    I watched the pipe and there was NO lifting, the hold-down held it down, but I could see the pipe being deformed between the hold-down and the forming piece.

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