MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Shrinker / stretcher

I know that this topic will be of amusement to some,though I cannot think why !

But, Has anyone used one or got any advice on where to buy one at a reasonable price?
Guy Weller

No, but if you are going to be using it much you should consider a foot operated model.
Trevor Jessie

Yes, good idea!
There is stuff on the internet about this, with some ideas on how to make a stand and pedal operated linkage to convert a hand operated (i.e.cheaper) model. First find a unit that I can afford!
Guy Weller

Guy,

I have some experience with shrinking jaws and would suggest you try the lower end ones first to make sure you're happy with the surface they produce. I have a set made by DFS, not the furniture company but named after Douglas Frank Salt the patent holder see http://worldwide.espacenet.com/publicationDetails/biblio?FT=D&date=19650120&DB=worldwide.espacenet.com&locale=en_EP&CC=GB&NR=980790A&KC=A&ND=4 , and when I worked at RML I and the workshop manager compared mine to the companies US made shrinker and it was like night and day the surface quality difference. The shop manager said they didn't like to use it due to the surface damage it produced potentially causing later cracking. Worth looking for opinions elsewhere though. There seem to be US made ones and German which I think Frost may sell. A quick look seems to show the Frost ones are US made so not sure where I saw the German company but did find it on the net, the company name was visible in the image where they were being sold. I have been told that you can still or could get quality UK made ones but the guy that said that wouldn't say who as he'd lose his cut. Eckold http://www.eckold.co.uk/sheetmetal.php do or did make some good stand alone small shrinkers but like mine they're not cheap when I've seen the price. On the Eckold site look under Kraftformer and the Handformer HF 100, one of those anoying sites where you don't seem to be able to provide a direct link.

For stretching the stretchers are a convenience but stretching can be done quite easily with a hammer a dolly or similar.

A good book worth getting is a copy "Metal fabricator's
handbook/race & custom car" by Ron Fournier ISBN 0-89586-171-2.
David Billington

I think the German lot was these guys http://www.dinohome.de/ and they seem to have quite a range of shrinkers/stretchers and likely as wide a range of prices and capabilities.
David Billington

A bit off topic, but you should watch some of this guy's metal shaping videos on you-tube.

He has an interesting technique that keeps the metal deformation to a minimum that results in more uniform thickness.

http://lazzemetalshaping.com/
Trevor Jessie

Some interesting and very informative videos there Trevor. Thanks for that link!

And David, thanks for your info too. Beginning to get more of an idea about what to look out for.
Guy Weller

Guy,

My mate has one - using it on his TR2 longdoor.

Not sure of the make but will ask him and report back.

Not cheap I seem to remember.

Regards,

R.
richard boobier

I've spent the last hour watching videos on using these things. They are much more versatile than I had realised! I was just thinking of a small-jawed one to add curves to flange edges but deeper throated ones seem to open up all sorts of other possibilities! Still, I mustn't get side-tracked at this stage from what I want to do! Its interesting stuff though!

Richard, did you go on the MASC outing to the Atom factory visit?
Guy Weller

Guy,

You might look here for an idea of the surface http://www.tinmantech.com/html/lancaster_modified.php under "more photos" tab
David Billington

Some information I posted back in 2005 in the Metalworking.com dropbox now mwdropbox.com as the previous URL was quite valuable in the end.

the content of the associated text file describing the images.

"DFS shrinking jaws test samples

All samples are 18swg and the shrunk surface is 1" wide.

dfsshrinksample1.jpg from left to right aluminium, brass, copper, steel, stainless steel showing single impression.
dfsshrinksample2.jpg from left to right aluminium, brass, copper, steel, stainless steel showing worked surface after multiple impressions.
dfsshrinksample3.jpg show brass and copper closeup of worked surface."


http://www.mwdropbox.com/dropbox/dfsshrinksample1.jpg
http://www.mwdropbox.com/dropbox/dfsshrinksample2.jpg
http://www.mwdropbox.com/dropbox/dfsshrinksample3.jpg
David Billington

Details for the shrinking jaws.

the associated text file content

"Details of DFS shrinking jaws.

dfsshrinkpatentpic.jpg - scan of diagram of shrinking jaws from british patent 980790
showing basic layout

dfsshrinktop.jpg - top view of shrinking jaws. Diameter of items shown is 1.75" (44.5mm)

dfsshrinkside.jpg - side view of shrinking jaws. Items intended for use in a fly press
hence common 1" (25.4mm) mounting stem"

http://www.mwdropbox.com/dropbox/dfsshrinkpatentpic.jpg
http://www.mwdropbox.com/dropbox/dfsshrinktop.jpg
http://www.mwdropbox.com/dropbox/dfsshrinkside.jpg

I might have tried posting as one post with all the links but ran into problems with many links some years back but I think it has been relaxed but not sure what the limit is.
David Billington

ive been wanting to buy a stretcher / shrinker ...the look cool, im just not sure offten id use it, but a foot operated model is a must have

harbor freight has them

prop
Prop and the Blackhole Midget

David,
Thanks for all your replies, and the time you have taken to search out and post those links. Interesting stuff!

Probably going beyond what I am likely to be able to justify for home DIY use, but it helps to know what to look out for and what the principles are. The Lancaster ones do seem to be the ones rated best, for the small edge shrinkers that I am looking at. Looking in the various versions available they look to be either all out of the same factory, or at least pretty close copies. I suspect they are being produced by some enterprising capitalist in the PRC. Maybe I just need to wait for Aldi to stock them!
Guy Weller

In the US HarborFreight sells them, so they are obviously some "cheap" ones being produced: http://www.harborfreight.com/catalogsearch/result?q=shrinker
Trevor Jessie

That is cheap. Well at current exchange rate that is around 100 GBP. In the UK the cheapest sets are around 175 GBP. ($260) I wonder what postage (& tax ?) would be on those.
Guy Weller

I bet it would be expensive... thats alot of steel to ship by air or ship

try your machine mart/halfords...I think there simalar to our harbor freight

prop
Prop and the Blackhole Midget

Guy,

The stuff of dreams on ebay at the moment http://www.ebay.co.uk/itm/ECKOLD-PICCOLO-KF310-SHEET-METAL-POWER-SHRINKER-STRETCHER-SHRINKING-STRETCHING-/121090052081?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item1c31878ff1 . I suspect it'll go for a bit more than that in the end.
David Billington

Wow! that would be fun to use! You really should have kept quiet about that one! I promise not to bid against you, but who can tell who else might!
Guy Weller

Guy,

While it would be nice to have I doubt I'll place a bid as it'll likely go for far more than I would be willing to pay considering I already have the shrinking jaws and such a machine could only be justified if used with some regularity or I won the lottery (must check tickets before auction ends). I will keep an eye on it though to see what it goes for. I don't know what they cost new but I wouldn't expect to get much change out of £10k considering the bits that are shown with it.
David Billington

no longer avialable...I bet it was cool
Prop and the Blackhole Midget

It was one of these http://www.youtube.com/watch?v=tNBuIArTmSY . Maybe someone made an offer that couldn't be refused. Shame as it would be been interesting to see what if would fetch. In the video I don't like the running of the jaws together without any material in between but then it's not my machine.
David Billington

Guy,

Checked with my mate - its a Frost / Eastwood unit - used mainly for the wheel arches etc.

No didn't know about the Atom visit - I'm not very well connected to any local groups.

R.
richard boobier

Well, took the plunge, spent some pennies and got one of these from Frost. Now I just need to design and build a foot-operated stand for it.

Richard, only just seen your answer to me on this thread. Sorry! I only asked as my mate that you met up with once, Greg the Dalek keeper - went on it. Not that he is a MASC member; he got invited by another friend. He said that the Atom factory visit was excellent.

Guy Weller

Guy,

Have you had an opportunity to try them yet? and can you post a pic of the resulting metal surface.
David Billington

David,
I went for the Frost ones as after negotiating a discount, and with free delivery, the set worked out at less than a single well used second hand one that I was watching on e-bay went for at the same time!

I have only used it on one flange edge so far. I am doing a bit of "fine tuning" of the curved edges of my Frog bonnet where it joins to a new front wing panel. The curves down towards the indicator lamp position were quite different but I have now managed to match them quite well. The shrinker jaws that I have been using have some quite fine serrations that don't seem to mark the metal too badly. But the surface of the flange is already a bit pitted from where I have chemically cleaned surface rust off it with phosphoric acid. On a new piece of bright steel the marks would show more.

Next thing is to use it to put a curve into the "T" shaped bead to go down the same joint. When I have done that I will post a photo of the markings on that which is bright steel to start with.

I wouldn't say that the stretcher/ shrinker is top quality. It has the hall marks of the far east - reasonably heavy castings and components but a bit shoddy in terms of finish and machining. Probably OK for the level of use I will make of it but not right for professional quality.
Guy W

Guy,

Will wait for the pic. The Lazze guy mentioned earlier in the thread had some tips in one of his videos about some tuning that could be done to the shrinker/stretcher bits if you haven't seen it already.
David Billington

Yes I saw that Lazze stuff, and his tips on fine tuning. Looks worthwhile, and I think I will try some of those ideas. I thought his other videos were really interesting too. Very clearly presented and informative without labouring the obvious as so many U-tube videos do.
Guy W

This thread was discussed between 01/04/2013 and 17/04/2013

MG Midget and Sprite Technical index

This thread is from the archives. Join the live MG Midget and Sprite Technical BBS now