what gauge for patch work

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PostPosted: Mon Dec 22, 2014 9:40 pm
After taking my goat apart I found an small hole about 1 inch by 7 inches on the floor and a small hole at the window seat by the upper corner and also some rusted metal at the bottom of the front windshield, right where bottom of the windshield ends and the cowl starts. What gauge metal should I use in each of the mentioned spots? I have old fenders kicking around that I can cut patches from if it was adequate gauge for theses areas.



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PostPosted: Mon Dec 22, 2014 10:08 pm
Generally 18 gage, old fender skin will work fine for most small repairs.

I want to order AK or SK sheet but when I call metal shops they think I am crazy.
Dennis B.
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PostPosted: Mon Dec 22, 2014 10:13 pm
I measure the thickness and then try to order the same.
Here's a basic chart for standard steel. As stated above most of the older cars will be 18 Ga.

Ga. Thickness
3 = 0.2391
4 = 0.2242
5 = 0.2092
6 = 0.1943
7 = 0.1793
8 = 0.1644
9 = 0.1495
10 = 0.1345
11 = 0.1196
12 = 0.1046
13 = 0.0897
14 = 0.0747
15 = 0.0673
16 = 0.0598
17 = 0.0538
18 = 0.0478
19 = 0.0418
20 = 0.0359
21 = 0.0329
22 = 0.0299
23 = 0.0269
24 = 0.0239
25 = 0.0209
26 = 0.0179
27 = 0.0164
28 = 0.0149
1968 Coronet R/T


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PostPosted: Mon Dec 22, 2014 10:18 pm
Thanks for the replies, I figured if these old fenders were ok to use, why not make use of them. For the amount of steel I need, there would be still tons left and no sense in driving around looking for some steel, and then having to pay for it, when I have it lying around.



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PostPosted: Tue Dec 23, 2014 5:37 am
'68 Coronet R/T wrote:I measure the thickness and then try to order the same.
Here's a basic chart for standard steel. As stated above most of the older cars will be 18 Ga.

Jim, have you checked the accuracy of your micrometer lately? I believe they used 18ga for outer sheet metal panels in the 1930s and 1940s, and switched to 20ga in the 50s. Some of the panels may or may not be heavier such as rockers, roof, floors and firewall.
A lot of the metal shapers use 19ga sheet metal, but they do a lot of stretching with it.

Using the same ga metal for patches will make welding easier.



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PostPosted: Tue Dec 23, 2014 10:44 am
I was just about to say what I thought was 18 gage doesn't look any were near .0478 thick?
And the old roof Im using for patches is only .021 -,023 depending on how hard I sanded it when cleaning it up and that after marked stuff is thicker and softer but I need to measure it again! wish I could get a source for that after market steel sure is easy to shape and form.
Dennis B.
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PostPosted: Tue Dec 23, 2014 5:01 pm
I don't even know where around my area I could buy steel. If I find that I need steel, I will have to do some research.



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PostPosted: Tue Dec 23, 2014 7:04 pm
If you ever buy any of the after market patch panels and decide to cut them up and only use them partially as I do youl find out that the material is a Little thicker but Softer really soft till you start working it or shape it then it gets harder working it.

Starting with a softer metal in the shaping stage is a great advantage
Dennis B.
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Line Maintenance A&P Mechanic and MOC Tech specialist.

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PostPosted: Tue Dec 23, 2014 8:50 pm
chevman wrote:
'68 Coronet R/T wrote:I measure the thickness and then try to order the same.
Here's a basic chart for standard steel. As stated above most of the older cars will be 18 Ga.

Jim, have you checked the accuracy of your micrometer lately? I believe they used 18ga for outer sheet metal panels in the 1930s and 1940s, and switched to 20ga in the 50s. Some of the panels may or may not be heavier such as rockers, roof, floors and firewall.
A lot of the metal shapers use 19ga sheet metal, but they do a lot of stretching with it.

Using the same ga metal for patches will make welding easier.


Maybe I misread his post but I thought he was working on a window channel area. Either way, I did say "older cars" but since he said "goat" I would assume we're talking mid sixties to early seventies.
My micrometers are fine its the memory that keeps giving me problems. :wink:
1968 Coronet R/T


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PostPosted: Wed Dec 24, 2014 8:01 am
Thats something I can relate to, it seems to be a problem that more and more of us are suffering from as time goes on. Seriously, I'm amazed at your ability to answer so many questions without making mistakes, so I was sure you needed a new mic. I have to reread my posts to see what I have forgotten to put in there, or I fail to see how someone else may read it differently.
Good job, Jim!
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