deep shrinker/stretcher

  1. optima21 Forum Supporter

    Messages:
    2,543
    Location:
    halifax, England
    a couple of years ago I got a cheap Metz shrinker / stretcher off ebay

    http://www.ebay.co.uk/itm/261620178141

    and then saw some lazze videos about using a deep shrinker / stretcher to create compound curves like this one



    so rather than buying one, I thought I'd make a new body for one, as the jaws on the standard and deep shrinker stretchers are the same.

    so here are a few pics from me building it.

    the sides of the body were made from 12mm thick steel plate, I decided that that it was a bit thick for cutting out with hacksaw and file, so decided to cut the shape out in my milling machine, using 6mm carbide slot drills. the holes in both plate were drilled at the same time (both plates clamped together), then the plates were separated and the slots were cut (like doing a dot to dot with a milling machine). the bolts and washers in the slots on this pic are to clamp the centre being cut out

    DSC03219.JPG

    and one plate after being drilled and one with the slots cut out, I guess it could be done quite cheaply by other methods but took a few hours moving the plates about,but the carbide cutter was only £3.00, and time is free to me.

    DSC03222.JPG

    I then had to mill the recesses for the shrinker/stretcher jaws, I wouldn't have needed to do this if I had used 10mm plate (I wouldn't have needed to make new pivots if I'd used 10mm plates too) its not an issue with a milling machine but without one I would have been stuck. ohh and I'm using large lolly sticks for packing to save the milling machine table as the plates are hot rolled plate.

    DSC03226.JPG

    then it was time to weld the two sides together, with 4 plates in stategically located places, I already drilled some holes in the corners so the plates could easily be aligned using studs and nuts

    DSC03231.JPG

    and the welding completed, showing my poor attempt at tig welding (we all have to learn by practicing), but its not structural so it should be ok. there is also a plate on the base with the mounting holes and a small plate on the back too.

    DSC03238.JPG

    then first assembly of jaws and operating lever.

    DSC03230.JPG

    I had already decided that if I made some new levers and pivots I could use the old body for the stretcher (and saves having to keep changing jaws which can be a pain). At this stage I was wondering why they were so hard to use as I'm not the world strongest person, but then realised its all about the leverage, so thought that if I moved the point of contact with the shrinker jaws back towards the pivot hole, I would need to use less force, with a smaller jaw opening which is a trade off I can live with, so on my new lever I cut some slots so that I could use some round bar to change the leverage ratios. so here are my new and old levers. Im not sure how long mine will last as the old (black) ones are definately tougher, so I may need to case harden mine.

    DSC03244.JPG

    and the completed assembly. the cover that holds the shrinker jaws together was just cut in two and and a couple of extra mounting holes were cut in both halfs

    DSC03253.JPG

    and a test piece shown in front of the new body. I'll still be hand operated instead of foot operated. I started of with a 20cm dia disk of 1.0mm zintec, after shrinking its 160mm dia at the base and 45mm high. the finish is a bit rough though, but its a start

    DSC03260.JPG

    so he is the new body I've made on the left with shrinker jaws in and the original body with stretcher jaws in. the body in the background is one that I made earlier and turned out to be a failure due to being to flexible. it was made from 250 x 250 x 6mm sides (this was cut with a hacksaw and filed by hand), so when I made the one with 12mm sided I started out with plates that were 200 x 200 x 12mm. the hole in the middle was smaller too to help increase rigidity.

    DSC03263.JPG

    I've started using BEJ steel for material, as I cant get to the local steel suppliers as Im working (so have it delivered to a relative who lives close by. they also have more items on ebay, but you can email them by their site they will send you a paypal invoice which works out cheaper than buying through ebay, and the combined postage prices help too if you have a few items

    http://bejsteel.co.uk/

    http://www.ebay.co.uk/sch/steel2go/m.html
     
  2. Excellent!
    I had thought about doing that myself with my shrinker/stretcher set but managed to do what I needed with the standard bodies.
    I will bookmark this for future reference though, thanks for posting.

    I need to do some maintenance on my Shrinker as the spring holding the bottom jaws apart has become knackered, it still works but I need to source a replacement.
    Do you thump your handle in use, I find a jerking action with the handle is more effective than just pulling on the handle. (No puns please!).
     
  3. Wallace

    Wallace Member

    Messages:
    6,244
    Location:
    Staines, Middlesex, England.
    Top notch job. I made a foot pedal operated stand for my shrinker stretcher and I have found the pressed steel jaw casings are starting to get a little out of shape, how are yours coping?
     
  4. optima21 Forum Supporter

    Messages:
    2,543
    Location:
    halifax, England
    I've only used it for a couple of jobs, so its holding up well, I did this as I'm wanting some new inner rear wheel arches for my herald, which can probably be made in 2 peices welded together.

    Tuck forming seems to be a bit brutal to get consistant results until you've been doing it for a while, so my thinking was that this would form the curves more gently.

    as for usage, I've just applied firm pressure, on smaller pieces you dont see much happening, but on larger items a tiny amount of shrinking or stretching makes a big difference (like on the flange on my heralds boot lid as its almost flat to begin with)

    I didnt know about the jerking action until I saw this video a few weeks ago



    and another video below is pretty informative if you've got an hour to spare



    ohh and Im pretty much a beginner at this panel beating lark, but there are some parts I need to make so I'll have to learn slowly but surely
     
    james butler likes this.
  5. Kent

    Kent Member

    Messages:
    10,002
    Location:
    Bowland, Lanacshire,UK
    well worth the time to watch and listen to the last guy
     
  6. bigbadbugga

    bigbadbugga Member

    Messages:
    1,006
    Liverpool uk
    I just watched that last video, very good and informative thanks.

    I also watched another video taken at the same stand, about how to paint your car at home. About 3/4 of the way through and spotted good old Ed China in the background with his pet Brewer. :)

    Here, 49:50 onwards, or watch it all its a decent video.

     
  7. MattF

    MattF Forum Supporter

    Messages:
    9,874
    Location:
    South Yorkshire, England
    I prefer the look of the one you've made over the original. :D Very nice work. :)
     
  8. MattF

    MattF Forum Supporter

    Messages:
    9,874
    Location:
    South Yorkshire, England
    Those seem to leave quite a lot of marks on the metal. How bad is it to tidy up afterwards? Btw, I'm blaming you for the fact I've just been watching this. :D Linked to from one of those vids.

     
  9. optima21 Forum Supporter

    Messages:
    2,543
    Location:
    halifax, England
    the professional ones do cause less damage to the metal, as the seartions in the jaws are better quality. the shrinkers cause a ripple in the metal because of the way they work
     
    MattF likes this.
  10. MattF

    MattF Forum Supporter

    Messages:
    9,874
    Location:
    South Yorkshire, England
    It was the serrations which I noted. The shrinker obviously needs to distort somewhat to do its job, so I expected that. How do you handle the serrations left by the stretcher? Looks like they may need some fair work to clean up without serious filing/grinding?
     
  11. optima21 Forum Supporter

    Messages:
    2,543
    Location:
    halifax, England
    I had read that you can put emery cloth between the shrinker jaws and sheet metal to give a smoother finish...I tried that tonight and it doesn't work with mine, it doesn't shrink.

    just for scale this is a peice of 0.9mm that I tried it on tonight, the ruler is showing the mm markings

    DSC00659.JPG

    DSC00660.JPG
     
    MattF likes this.
  12. Maxakarudy

    Maxakarudy Member

    Messages:
    322
    Location:
    West Mids
    I wouldn't use Lazze as the best instructor for metashaping, he's self taught, lurks around the metalshaping sites looking for ideas to claim as his, never seen him weld either! He over uses the shrinker/stretcher tools, shrinking is usually kept to edges where the weld join is, so the marks are taken care of in the metal finishing stage. Stretching edges or anything else is better done with a wheel as there is no marking.
    Also all these shrinker/stretches leave flats the deeper you go, so deep throat machines are not that essential for metalshaping.
     
    Wallace likes this.
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