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Old 02-19-2021, 11:55 PM   #1
Driver_WT
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Hammer and Dolly Basics

I have slightly warped a sheet metal piece for my fabricated console (goes around the shifter and up to the dash. The weld is up the middle of the piece and it now has a slight dip in it. Can someone provide or point me to some hammer and dolly basics for getting the dip out?

Thanks.
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Old 02-19-2021, 11:59 PM   #2
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Re: Hammer and Dolly Basics

heres your pic to go with your question with the bowed area

and the other thread.. http://67-72chevytrucks.com/vboard/s...d.php?t=818565
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Old 02-20-2021, 12:17 AM   #3
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Re: Hammer and Dolly Basics

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Originally Posted by mongocanfly View Post
heres your pic to go with your question with the bowed area

and the other thread.. http://67-72chevytrucks.com/vboard/s...d.php?t=818565
Thanks for the help Greg.
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Old 02-20-2021, 05:41 AM   #4
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Re: Hammer and Dolly Basics

Anytime you weld a seam, the weld and adjacent area which is called the HAZ (Heat Affected Zone, the area that has turned blue/discolored) is going to shrink as the weld cools. So as an example, in looking at a quarter panel side profile (red line) :

Name:  crown loss from welding.jpg
Views: 184
Size:  5.0 KB


...if we were to weld a vertical seam top to bottom, as the weld cools and shrinks, it gathers up/becomes shorter in length (arrows) along the entire length of the weld. So in essence, the linear length of the weld gets shorter; it becomes a shallower arc, or towards a straight line.. (blue line) This is why ALL welds in a crowned panel, absent any planishing, will pull into a valley. The arc is becoming a straight(er) line. You combat this issue by planishing using a hammer and dolly. You want to stretch the weld to regain the linear length it was prior to welding.


For "sizing" your dolly for the concave back side, you want to match the inside of the crown as closely as possible without the corners touching. (to prevent marking/coining the metal). The convex outside of the panel you would want to use as flat a body hammer, or a slapper, etc as you have. Hold a slight upward pressure on the dolly as you hammer to coax it to move outward.
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Last edited by MP&C; 02-20-2021 at 05:49 AM.
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Old 02-20-2021, 09:07 AM   #5
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Re: Hammer and Dolly Basics

Quote:
Originally Posted by MP&C View Post
Anytime you weld a seam, the weld and adjacent area which is called the HAZ (Heat Affected Zone, the area that has turned blue/discolored) is going to shrink as the weld cools. So as an example, in looking at a quarter panel side profile (red line) :

Attachment 2083119


...if we were to weld a vertical seam top to bottom, as the weld cools and shrinks, it gathers up/becomes shorter in length (arrows) along the entire length of the weld. So in essence, the linear length of the weld gets shorter; it becomes a shallower arc, or towards a straight line.. (blue line) This is why ALL welds in a crowned panel, absent any planishing, will pull into a valley. The arc is becoming a straight(er) line. You combat this issue by planishing using a hammer and dolly. You want to stretch the weld to regain the linear length it was prior to welding.


For "sizing" your dolly for the concave back side, you want to match the inside of the crown as closely as possible without the corners touching. (to prevent marking/coining the metal). The convex outside of the panel you would want to use as flat a body hammer, or a slapper, etc as you have. Hold a slight upward pressure on the dolly as you hammer to coax it to move outward.
Thanks for the explanation Robert. So do I hammer "on dolly" or "off dolly" to move the metal outward.
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Old 02-20-2021, 09:45 AM   #6
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Re: Hammer and Dolly Basics

When planishing welds I do on dolley..
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Old 02-21-2021, 01:16 AM   #7
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Re: Hammer and Dolly Basics

On-dolly gives you a stretch and you should hear a ping like striking two hammer faces together. Off-dolly gives a shrink or a metal bumping without stretching.
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Old 02-21-2021, 08:07 AM   #8
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Re: Hammer and Dolly Basics

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Originally Posted by MP&C View Post
On-dolly gives you a stretch and you should hear a ping like striking two hammer faces together. Off-dolly gives a shrink or a metal bumping without stretching.
Very helpful. thank you. I will try this today.
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Old 02-25-2021, 09:27 AM   #9
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Re: Hammer and Dolly Basics

Thanks for all of the replies and info. I have got the console pretty much flat where the stereo will go and the rest of it looks pretty good. There is still a bit of dip in the middle at the top, but that piece will be under the dash so I am not too concerned with that part.

And I learned a bit more about hammer and dolly so thanks for that.

Wade
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