I have just ordered a shrinker stretcher online, has anyone used them? Got any tips before I start? I am intending to fab screen surround repair sections and general covex/concave pieces
Incredibly simple/easy to use things, just have a play with some scrap to get a feel for it. Harder you pull the handle the more it'll stretch/shrink a given spot, leave a little space between shrinks and you get a very large radius. For tight radii you may be making several passes, using the full depth of the jaws initially and maybe only about half the jaw depth with light pressure as it gets closer.
i had a job in last week where i was using this sort of thing, it was a cone with a sort of flange on the end of it, made the cone slighty longer then used a handheld thing to form the flange and used a motorised shrinker/strecher to take out the creases very useful thing to have
I haven't used it a great deal but the curved bits i have used it for turned out fine.
I bolted mine to a bit of angle and stick it in the vice....the only trouble is you then have to hold the work with one hand and press the lever with the other.
One of those stands so it can be foot operated is on my "to do" list.
For the most part they don't really do anything that can't be done with hammers, dollies and a few bits of hardwood. Just make life easier and a lot faster (and leave a bunch of nasty marks). What exactly is the job at hand v8mini? Various methods for shrinking, stick 'tuck shrinking' and 'stump shrinking' into youtube or google for one method
Yep, you are right ............. but if you want to get results out of the box so to speak they are much easier than tucking and using stumps. As for marks, thats what flapper discs and wheels are made for
I'm just bidding on one now, I've tried to follow various techniques with a hammer and not had good results. Stretching is no problem, unfortunately I can't master shrinking at all - it just keeps going back to a straight piece. I guess the machine lets me get the job done much quicker and is probably worth it for that.
Quick and dirty demo of another way to shrink with minimal tooling...
First step is to put some tucks into the area that needs shrinking. Spacing of the tucks effects curviture as does size but tighter radii will need a couple of rounds of tucking and bashing
I just layed the piece across open vice jaws and bashed it with a ballpein- not the best way as the vice marks the metal excessively and causes more stretching than if a tucking fork or similar is used
Locking the curvature in with a strip of metal and some vice grips. Next bash the tucks down over a suitable dolly (i used a piece of barstock in a vice and a heavyish planishing hammer). As in the videos best to work the tucks down from the middle out. Best to work 'em out evenly too or the radius can vary
The slight twist in the piece is because it started out with a radius bend and the chunk of bar i used was sharp edged. With a bit of thought and care over tool selection you can get much cleaner results
I note that the thread has moved to shrinking & stretching on a curved face.
For wrinlkes and gouges on flat metal sheet up to 3 mm thick.
In the past I have used a home made tool from an 18 inch hand safe edge bastarflatfile, heated and made into a slight question mark shape brazed a bit of pipe on for the handle .
Simply heat the affected area to bright cherry and knock the file teeth into & along the metal it will raise edges, shrinking stretches and also allow you to manipulate the area .
Once you get it nearly flat ... re heat & GENTLTY planish it flat between two hammer faces etc...the raised bits will recombine and you should, with little effort end up with a nice clean flat surface as good as the day it was first built.
You can use the same stuff /idea to also stretch all sorts of surfaces with out rupturing wrinkles & crinkles.
I don't have any pictures or still have the tool as computers & digi cams were not invented back in those days of the last century , but any decent mechanic/engineer should be able to do it.
The particular shrinker I bought turned out to be unsuitable for the 18g I want to bend, so unfortunately it's gone back. Pity really, now I don't know whether the basic one at Frosts, which is more expensive than the one I bought, is actually any different or just dearer. I can't justify nearly £500 for the more expensive one, so I'll practice some more with the hammer techniques here and elsewhere.
The basic frost one will shrink 18swg OK. CR4 relatively easy going, zintec takes a bit more grunt. It'll shrink 0.8mm stainless too but that'll probably wear the jaws faster. Biggest drawbacks of it are the small handle (easily fixed, especially if swapped to foot control) and lack of throat depth.
The difference between the cheaper and proffesional versions is staggering, the basic Eckold... different league doesn't do it justice, completely different game closer to the mark. Just don't ask how much they cost . Not sure about the smaller one but 'No mar' dies are available for the bigger kraftformers