Heat warpage? - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Body - Exterior
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 01-10-2007, 07:06 PM
Gearhead forever's Avatar
Member
 
Last photo:
Join Date: Jan 2003
Location: Elora, Ontario, Canada
Age: 46
Posts: 458
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Heat warpage?

I have experience with heavier gauge materials for the most part. With welding in new body or patch panels, would a slight gap on the seam help control warpage better that a tight fitting seam?

Thanks in advance

Gear

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 01-10-2007, 07:22 PM
Member
 
Last photo:
Join Date: Jan 2005
Location:
Posts: 3,707
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
tight with no gap is better, make sure your panels are well fitted and relaxed-if there's a lot of pressure making them conform to shape then expect some serious warpage. The rule is if there's a gap then there's room for the panel to move-pull when it cools and shrinks.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 01-11-2007, 07:24 AM
Bee4Me's Avatar
Problem Child,Hard Case
 

Last journal entry: Strangest job I've ever done
Last photo:
Join Date: Jan 2005
Location: ARK.
Age: 57
Posts: 1,773
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
I agree,Little or no gap but the no gap is next to impossiable as your cutout is going to waver "some" but IMO the bigger the gap the MORE shrinkage you get. I'm patching a firewall/cowl box now and having to fab my own pieces has been a trick. I'm almost finished now and when welding,just use a series of spot welds and continue this till it's done. Trying to run much of a bead on sheet metal is a sure way to warp it.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 01-11-2007, 09:22 AM
gator412's Avatar
1955 2nd series Chevy Pick Up
 

Last journal entry: Body work and U bolts
Last photo:
Join Date: Feb 2005
Location: Santa Maria, Taxifornia
Age: 54
Posts: 282
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I had a lot of patch panel to weld in on my 55 Chevy truck. Most were hand made. If you look at entry # 92, 93 and 94 in my journal it shows how I did the patch panel I made for the inner fender-well. If you look else were in my journal I show using a piece of copper to back up some of the holes I had to fill. weld won't stick to copper and can help you fill in some difficult holes some times.

I cut the patch it fit as tight as possible. Run a series of spot welds and cool them off with air as I go. I hammer them down also when I can get to both side easy. I back it up with a dolly to flatten the weld. I then make another pass of spot welds and just keep cooling and hammering till the patch is completly welded in. It really is a fast process if you keep the heat down. Mind you I an no expert, but this has worked for me. I still have some more patch panels to weld in on the cab. One fender had 9 patch panels I welded in! I have more time than money and time is short too!
Hope this helps

http://hotrodders.com/journal_photos...1595427360.jpg
http://hotrodders.com/journal_photos...1595432981.jpg

These two pics are from my journal and show the beginning of the spot welding and the final product. They are of the inner fender-well that had a bead area rusted out.

Last edited by gator412; 01-11-2007 at 09:33 AM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 01-11-2007, 10:38 AM
Gearhead forever's Avatar
Member
 
Last photo:
Join Date: Jan 2003
Location: Elora, Ontario, Canada
Age: 46
Posts: 458
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks guys.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 01-11-2007, 11:05 AM
35WINDOW's Avatar
Member
 

Last journal entry: Dash Mock-up
Last photo:
Join Date: Dec 2004
Location: utah
Age: 59
Posts: 1,395
Wiki Edits: 0

Thanks: 7
Thanked 21 Times in 19 Posts
In my experience, if I MIG a Patch Panel in, is to grind both sides of the Weld down to about .040-.060 proud of the Metal-if I am gong to Hammer the shrink (Welding heat) out of the Metal (stretch it back to normal)-there is just too much Weld material if I try to just Hammer the Weld flat. What you want is for the Weld to disappear-
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 01-11-2007, 06:04 PM
Bee4Me's Avatar
Problem Child,Hard Case
 

Last journal entry: Strangest job I've ever done
Last photo:
Join Date: Jan 2005
Location: ARK.
Age: 57
Posts: 1,773
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
35 is right and using anything to help cool the weld will increase shrinkage.
Leave it ALONE and do another away from it.Then,quit for a short while and have at it again. Like paint,Getting in a hurry to weld WILL give you grief.
Same with grinding. Take it easy and Blue is Bad.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 01-13-2007, 06:32 PM
Registered User
 
Join Date: Nov 2005
Location: NJ
Posts: 84
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The rule is every weld is a shrink point. Basic physics of metal.

The amount of shrink is more dependant on the size of the heat affected zone. The heat affected zone is the area where the metal is hot enough to become plastic. The surrounding metal that has not turned plastic expands pushing in on the plastic metal forcing it in on itself. The surrounding metal keeps pressure on the metal long after the area is no longer plastic causing the metal to keep the smaller size.

The shrinkage is kept smaller with less heat.

The fix is easy. Hammer on dolly hits until the panel back to the correct conture.

Changing the gap between the metal has more to do with expect fit of the patch. If you set an even gap and just weld from one end to the other, by the time you are at the other end the metal may be overlapping. This is way you need to do a tack weld and then do some hammer on dolly hits on the tack weld and then move to the opposite end and do another tack weld.

Try putting a patch in with zero gap and a tig welder. If you do it right, very little grinding is needed- if any.

If you want to surprise yourself take the time to read about shrinking metal and how metal reacts to heat. A book and several videos later I found substantial improvement in my metal work.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 01-13-2007, 07:56 PM
Member
 
Last photo:
Join Date: Jan 2005
Location:
Posts: 3,707
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Another trick to control warpage while welding is to use a heatsink, a large piece of copper held on the backside to absorb some of the heat while welding will limit the size of the heat effected zone-just be sure the actual weld is hot enough to get good penetration.
Reply With Quote Quick reply to this message

Recent Body - Exterior posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Effects of paint on cooling components Animal General Rodding Tech 7 03-12-2006 05:10 PM
Sandblast warping heat MYTH. MARTINSR Body - Exterior 55 02-06-2006 08:45 AM
Heat shrink, routing wires, etc. Blackdog Electrical 4 10-16-2005 07:18 AM
over heating delsman Engine 38 09-14-2005 08:32 PM
How are you going to heat your house this winter? CrashFarmer2 Hotrodders' Lounge 29 09-05-2005 06:11 PM


All times are GMT -6. The time now is 08:34 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.