> Struggling with metal shrinker/stretcher - All MetalShaping <
All MetalShaping

Go Back   All MetalShaping > General Metal Shaping Discussion > Basic questions and answers
  Today's Posts Posts for Last 7 Days Posts for Last 14 Days  

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 11-08-2017, 01:20 PM
WCRiot WCRiot is offline
Member
 
Join Date: Mar 2013
Location: Los Angeles, CA
Posts: 17
Default Struggling with metal shrinker/stretcher

Guys
I am trying to build new corners for the rain water channel for the inside of the trunk. See the yellow arrows in an example picture

This is a C or U Channel, but I am starting with an L. I figure i can always weld the wall on and covert the L to a C/U.
As another example image, I am trying to achieve this:



When i shrink i start to get pretty good movement. But with only shrink on this side I can only get so far. This picture is in process so I am able to get more radius to the bend than what is shown, but not much more.


So last night i tried switching to the streching die and hitting the other side. Thinking that i have done all the shrinking i can. Maybe stretching will help push the metal more to form that "C" shaped radius (from a top view). Is this the correct approach?


The problem i see is that when i stretch, instead of the metal following the contour that formed from shrinking, the side of metal being stretched fans outwards. Create a fan or sea shell shape.

I used a different piece of sheetmetal to help illustrate what the stretching die does.


I will watch some youtube videos to try and learn how to achieve the shape i need, but wanted to get some advice from those on here.
__________________
Todd - Tee Dog

Last edited by WCRiot; 11-08-2017 at 01:24 PM.
Reply With Quote
  #2  
Old 11-08-2017, 01:35 PM
gashammer gashammer is offline
Member
 
Join Date: Feb 2011
Location: Colorado Springs
Posts: 50
Default

From my experience, that will happen. I generally finish the detailing on a sharp edged dolly to get the final shape.

Also, you have a lot of shrink going on. You may consider re-positioning the piece so that your die marks are not directly on top of one another. That could lead to cracking.
__________________
Mike K
Reply With Quote
  #3  
Old 11-08-2017, 03:01 PM
Kerry Pinkerton's Avatar
Kerry Pinkerton Kerry Pinkerton is offline
Administrator
 
Join Date: May 2009
Location: Near Huntsville, Alabama. Just south of the Tennessee line off I65
Posts: 7,153
Default

Todd, I suspect your steel is getting work hardened. Lancaster machines are pretty hard on the metal. It will work great and then just quits like you are seeing. You might try some heat, bend the angle around the radius you want, and hammer down the tucks that pop up.
__________________
Kerry Pinkerton

http://wheelingmachines.com

Reply With Quote
  #4  
Old 11-08-2017, 03:15 PM
crystallographic crystallographic is offline
MetalShaper of the Month October '14 & April '16
 
Join Date: Dec 2010
Location: Western Sierra Nevadas, Badger Hill, CA
Posts: 2,544
Default

Quote:
Originally Posted by WCRiot View Post
Guys
I am trying to build new corners for the rain water channel for the inside of the trunk. See the yellow arrows in an example picture

This is a C or U Channel, but I am starting with an L. I figure i can always weld the wall on and covert the L to a C/U.
As another example image, I am trying to achieve this:



When i shrink i start to get pretty good movement. But with only shrink on this side I can only get so far. This picture is in process so I am able to get more radius to the bend than what is shown, but not much more.


So last night i tried switching to the streching die and hitting the other side. Thinking that i have done all the shrinking i can. Maybe stretching will help push the metal more to form that "C" shaped radius (from a top view). Is this the correct approach?


The problem i see is that when i stretch, instead of the metal following the contour that formed from shrinking, the side of metal being stretched fans outwards. Create a fan or sea shell shape.

I used a different piece of sheetmetal to help illustrate what the stretching die does.


I will watch some youtube videos to try and learn how to achieve the shape i need, but wanted to get some advice from those on here.
Hi WC,
Kerry and I are seeing that your shrink is going well until:
1) your metal gets hard
and
2) your metal gets thick.

You can also shrink when the metal is hot. Heat until it is past purple/blue and goes "black" then shrink 2 or 3 times, and then spray the jaws with alcohol to cool them (no rust).
You will find you can get more shrinking for longer if you do this, and the metal will not crack ..... at least not for me.
__________________
Kent

http://www.tinmantech.com

"All it takes is a little practical experience to blow the he!! out of a perfectly good theory." --- Lloyd Rosenquist, charter member AWS, 1919.
Reply With Quote
  #5  
Old 11-08-2017, 10:20 PM
Jack 1957's Avatar
Jack 1957 Jack 1957 is offline
MetalShaper of the Month Dec. 2016
 
Join Date: Sep 2014
Location: Strongsville,OH
Posts: 469
Default

One basic set of hardwood dies.

aaaaa.jpg
__________________
Jack

Set a Goal So Big That You Can't Achieve It Until You Grow Into The Person That Can.
Reply With Quote
  #6  
Old 11-08-2017, 11:53 PM
BTromblay BTromblay is offline
Member
 
Join Date: Oct 2015
Location: Mukwonago, Wi
Posts: 97
Default

Hi,

In addition to the comments above, I have had good luck with making a pass thru the shrinker with the part at half depth of the die. Once you make a pass at half depth, tucks will form, go back full depth to flatten the tucks.

Bill
__________________
Bill Tromblay
Reply With Quote
  #7  
Old 11-09-2017, 12:44 AM
MP&C's Avatar
MP&C MP&C is offline
MetalShaper of the month 02-11
 
Join Date: Mar 2010
Location: Leonardtown, MD
Posts: 1,128
Default

When trying to shrink or stretch two parallel flanges (the C shape you referred to) I tip the flanges over at about 45* and then perform the shrink or stretch (as needed) until you have the desired radius, then use your flat body hammer to take the flanges over to 90*. This process was used the other day when making the radius corners in our console folds..:

https://www.youtube.com/watch?v=1NdR3c_S8nE


I did some repairs on a Fairlane trunk opening similar to what you are tacking now. Part of this repair had the two folded part that needed shrinking on two opposite flanges. Did the same thing here, bend to 45*, shrink, then fold to the needed 90...:

Quote:
Moving back to the trunk area, the more you look the more you don't want to.
The channel for the weatherstrip seems to have sealed water in as well as out....



It took a few weeks and a few phone calls, but there are still some good junkyard pieces available. We got the corner pieces out of a yard in CO. The rear channel across the trunk opening also has scattered pin holes, so I though I'd give a shot to bending some new ones. First, need a template:





That looks close enough. My press brake dies are only about 18" long, so I'll need to do this in three pieces. The middle one got put in first.





Be sure to check the back side for weld penetration:



The replacement corner was cleaned up, the spot welds were ground off of the adjacent pieces to release the corner with no damage. Looks quite a bit better than the old one.

















Well, on to the next corner. The driver's side was in sad shape:



But in looking at the replacement, although in better condition, it did have issues of it's own.



Time to break out the trusty Lancasters and make some replacement parts.



The replacement corner was left attached to the quarter panel section it came with while remaking the channel in an attempt to maintain the shape.



Note the sharpie "reference lines" in the next picture, to keep the bend in the correct location.













....And a comparison of the "new" part to the old one. That should do the trick!

__________________
Robert

Instagram @ mccartney_paint_and_custom
Reply With Quote
  #8  
Old 11-09-2017, 05:09 AM
Oldnek Oldnek is offline
Member
 
Join Date: Mar 2011
Location: Ulladulla, Australia
Posts: 1,230
Default

Don't go to deep on the Shrinker or Stretcher. It will move more only working about 1/3rd of the flange.
__________________
John
EK Holden V8
Reply With Quote
  #9  
Old 11-09-2017, 09:29 AM
Peter Tommasini Peter Tommasini is offline
MetalShaper of the Month May 2013, Dec 2013
 
Join Date: Apr 2011
Location: Melbourne,Victoria, Australia
Posts: 6,769
Default

Todd
here a simpler way to do that panel
step 1 cut enough metal ( by paper pattern)
Step 2 draw with compass the curve needed + height of Chanel width and lip make sure to have enough panel steel on the other side of you chanel
step 3 bend all the width of the Chanel (height,width and lip) down on the wheel by (kicking the lower anvil up on one side) follow the inside line of your curve (this get's done bit by bit) stretch the side as you go ...you can control the curvature as you go ...in another words......not enough stretching ...the panel will be too round,
step 4 once the panel is at right angle turn the next part (been the width ) back at level plain with the rest of the panel by using a pair of pliers or... back on the wheel, stretch some more in order to keep the now downwards part ( the height) at right angle, once that is done use a piece of steel the width of the Chanel about one inch long or less and simply turn the last piece back up parallel with the height, cut what you need on the top (remember...??????) You had enough panel steel prior to scribe the curve) .....and you will have your Chanel and no welds or shrinking and stretching with machines involved
Peter
__________________
P.Tommasini

Metalshaping tools and dvds
www.handbuilt.net.au

Metalshaping clip on youtube
http://www.youtube.com/watch?v=WEAh91hodPg

Making Monaro Quarter panel:
http://www.youtube.com/watch?v=KIpOhz0uGRM

Last edited by Peter Tommasini; 11-09-2017 at 09:33 AM.
Reply With Quote
  #10  
Old 11-11-2017, 05:27 PM
WCRiot WCRiot is offline
Member
 
Join Date: Mar 2013
Location: Los Angeles, CA
Posts: 17
Default

I tried annealing the original piece and that helped a little. I did a little tune up on the Shrinker dies. Here is a new attempt. Still using scrap metal:

I got better curvature this time. It wasn't as difficult. I just wanted a few youtube videos by LAzze and that got me going.

I tried to figure out a way to make the U Channel then shrink but that was impossible. I then bent an "S" shape and shrunk accordingly. I struggled with that quite a bit. I Might be able to make that work with a combination of Shrinking and Stretching but gave up.

Here is what i am thinking of trying. Shrink one piece to the desired curvature. Then weld a second piece to complete the U Shape


End up with something like this:


No one will really see this piece so if it doesn't look great, i can live with that. I think...

What do you guys think? I don't have a bead roller right now. I've been considering it, but don't have alot of need for it nor the garage space.
__________________
Todd - Tee Dog
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

All times are GMT -5. The time now is 01:12 AM.

Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.