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Aluminum wall thickness and welding [message #286560]

Fri, 04 September 2015 08:41

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

I have completely redesigned the interior of my coach, meaning I have a lot of holes to patch (fridge vent, bathroom vent etc etc)
I will be welding in fillers, but I'm curious if anyone has done it and if anyone knows what aluminum alloy the factory used?

Before everyone chimes in I will be tig welding it, not botching it.

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Aluminum wall thickness and welding [message #286569 is a reply to message #286560]

Fri, 04 September 2015 09:40

Olly Schmidt

Messages: 1265
Registered: February 2014
Location: Germany and Scottsville, ...

Karma: 8

Senior Member

Justin,

is the GMC Assembly Manual of any help?

--
Best regards

Peer Oliver Schmidt
the internet company
PGP Key ID: 0x83E1C2EA

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Olly Schmidt
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'76a Eleganza II, VA
'73 Sequoia, SH, Germany

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Re: [GMCnet] Aluminum wall thickness and welding [message #286578 is a reply to message #286560]

Fri, 04 September 2015 10:20

powerjon

Messages: 2446
Registered: January 2004

Karma: 5

Senior Member

Justin,
Tig welding here is probably not the first choice that should be used here as no matter how good or careful you are you will be dealing with warping of the panels as they are not flat but on curved surfaces. A better choice would be to use the body adhesive that GMC used in assembly.

Such as the one in the middle:
http://www.gmcmhphotos.com/photos/fixing-the-front-end-bulge/p11516.html
Summit Racing
http://www.summitracing.com/parts/trm-8115

An alternative is to use JB Weld as the Adhesive as it can provide almost the same bonding and the #M 8115 adhesive and you don’t have to clean out the adhesive from the seam points as you could just sand it.

Cut hole patch to correct size and then make an another ring piece that is 1 inch bigger and 1 inch small that the patch size using the same thickness material (.060 as measured from a piece I had cut from a new vent in the bath) as the body. Clean both the underside of the body and all other aluminum pieces with acetone to remove any oils. You may need to slightly bend the patch to fit body curvature before fastening as the top of the coach is not flat anywhere. Using the adhesive and pop rivets install the support ring and then the patch using the adhesive and rivets. Clean the excessive adhesive out of the seams between the body and the patch before it sets unless you're using JB Weld. After every thing is set, sand off the rivet heads and the area where the body part meet and I would use JB Weld type as a filler for both the seam and ground off rivets as it doesn’t expand or contract as much as automotive body fillers can and bonds better.

or
http://tinyurl.com/o7rclsq
And regular JB weld would work OK too!

Just how I have done it in the past with good results and if done right you can’t even see the patch from the outside. Yes, I do have a Tig unit in the shop! If your that good on 0.060 thin aluminum body panels then go for it. JMHPO

JR Wright
GMC Great Laker MHC
GMC Eastern States
GMCGL Tech Editor
GMCMHI
78 GMC Buskirk 30’ Stretch
1975 GMC Avion (Under Reconstruction)
Michigan

> On Sep 4, 2015, at 9:41 AM, Justin Brady wrote:
>
> I have completely redesigned the interior of my coach, meaning I have a lot of holes to patch (fridge vent, bathroom vent etc etc)
> I will be welding in fillers, but I'm curious if anyone has done it and if anyone knows what aluminum alloy the factory used?
>
> Before everyone chimes in I will be tig welding it, not botching it.
> --
> Justin Brady
> 1976 Palm Beach 455
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan

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Re: [GMCnet] Aluminum wall thickness and welding [message #286582 is a reply to message #286578]

Fri, 04 September 2015 10:25

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

Another thing to consider before welding is that the sprayed in insulation is flammable. Welding could cause a fire. One would have to remove the inside ceiling panels where you are welding and scrape out the insulation. Then you should have a person stationed inside the motorhome with a fire extinguisher in hand!

Emery Stora
77 Kingsley
Frederick, CO

> On Sep 4, 2015, at 9:20 AM, John Wright wrote:
>
> Justin,
> Tig welding here is probably not the first choice that should be used here as no matter how good or careful you are you will be dealing with warping of the panels as they are not flat but on curved surfaces. A better choice would be to use the body adhesive that GMC used in assembly.
>
> Such as the one in the middle:
> http://www.gmcmhphotos.com/photos/fixing-the-front-end-bulge/p11516.html
> Summit Racing
> http://www.summitracing.com/parts/trm-8115
>
> An alternative is to use JB Weld as the Adhesive as it can provide almost the same bonding and the #M 8115 adhesive and you don’t have to clean out the adhesive from the seam points as you could just sand it.
>
> Cut hole patch to correct size and then make an another ring piece that is 1 inch bigger and 1 inch small that the patch size using the same thickness material (.060 as measured from a piece I had cut from a new vent in the bath) as the body. Clean both the underside of the body and all other aluminum pieces with acetone to remove any oils. You may need to slightly bend the patch to fit body curvature before fastening as the top of the coach is not flat anywhere. Using the adhesive and pop rivets install the support ring and then the patch using the adhesive and rivets. Clean the excessive adhesive out of the seams between the body and the patch before it sets unless you're using JB Weld. After every thing is set, sand off the rivet heads and the area where the body part meet and I would use JB Weld type as a filler for both the seam and ground off rivets as it doesn’t expand or contract as much as automotive body fillers can and bonds better.
>
>
> or
> http://tinyurl.com/o7rclsq
> And regular JB weld would work OK too!
>
> Just how I have done it in the past with good results and if done right you can’t even see the patch from the outside. Yes, I do have a Tig unit in the shop! If your that good on 0.060 thin aluminum body panels then go for it. JMHPO
>
> JR Wright

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Re: [GMCnet] Aluminum wall thickness and welding [message #286590 is a reply to message #286582]

Fri, 04 September 2015 11:05

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

I will do a good bit of practice before welding, I have welded .06 alum before with good results, you just go really slow.
The insulation will all be removed before patching.
It may turn out horribly! But I don't like rivets and patch panels, when the next owner repaints I'd prefer they not be able to find the patches!
We shall see.

Does anyone know the alloy used? It would be easier welding if I can match the alloy

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Aluminum wall thickness and welding [message #286598 is a reply to message #286590]

Fri, 04 September 2015 11:22

sgltrac

Messages: 2797
Registered: April 2011

Karma: 1

Senior Member

I've patched the roof both ways mentioned , welding and adhesive patch with
aluminum sheet. The results were MUCH better using an adhesive to patch
with an oversize sheet from the interior. There is a lot of stress in the
roof sheet and it quickly deforms with the introduction of weld heat. And
if you pull that off you need to be REALLY careful while finish sanding and
grinding for the same reason. If the hole is carefully beveled on the
outside then a patch placed on the inside the repair area is much more
stable leaving only a slight depression on the visible side which is easily
filled and contoured.

My 2 c

Sully
77 royale
Seattle

On Friday, September 4, 2015, Justin Brady wrote:

> I will do a good bit of practice before welding, I have welded .06 alum
> before with good results, you just go really slow.
> The insulation will all be removed before patching.
> It may turn out horribly! But I don't like rivets and patch panels, when
> the next owner repaints I'd prefer they not be able to find the patches!
> We shall see.
>
> Does anyone know the alloy used? It would be easier welding if I can match
> the alloy
> --
> Justin Brady
> 1976 Palm Beach 455
>
> _______________________________________________
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> Unsubscribe or Change List Options:
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>
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Sully 77 Royale basket case. Future motorhome land speed record holder(bucket list) Seattle, Wa.

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Re: [GMCnet] Aluminum wall thickness and welding [message #286603 is a reply to message #286590]

Fri, 04 September 2015 11:44

bdub

Messages: 1578
Registered: February 2004
Location: Central Texas

Karma: 5

Senior Member

Justin
I'm sure you've checked for yourself, but the insulation on my '76 will burn
if you hold a torch to it but will go out as soon as that source is taken
away. It will burn, but will not support combustion. Trouble is, I've
heard that it puts off cyanide gas when it does burn. (yikes!) Probably
about like burning or trying to weld galvanized metal.

bdub

-----Original Message-----
From: Gmclist On Behalf Of Justin Brady
Sent: Friday, September 04, 2015 11:05 AM

I will do a good bit of practice before welding, I have welded .06 alum
before with good results, you just go really slow.
The insulation will all be removed before patching.
It may turn out horribly! But I don't like rivets and patch panels, when the
next owner repaints I'd prefer they not be able to find the patches!
We shall see.

Does anyone know the alloy used? It would be easier welding if I can match
the alloy

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bdub
'76 Palm Beach/Central Texas
www.bdub.net
www.gmcmhphotos.com
www.gmcmotorhomemarketplace.com
www.gmcmhregistry.com
www.facebook.com/groups/classicgmcmotorhomes
www.facebook.com/groups/gmcmm

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Re: [GMCnet] Aluminum wall thickness and welding [message #286605 is a reply to message #286598]

Fri, 04 September 2015 11:50

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

So what you're suggesting is just placing a patch on the inside?
What about the .06" depression you're going to have leftover? Filler?

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Aluminum wall thickness and welding [message #286608 is a reply to message #286605]

Fri, 04 September 2015 12:21

Harry

Messages: 1888
Registered: October 2007
Location: Victoria, BC CANADA

Karma: 3

Senior Member

Do both.
An inside sheet and a filler sheet on the outside.

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Re: [GMCnet] Aluminum wall thickness and welding [message #286612 is a reply to message #286608]

Fri, 04 September 2015 12:52

sgltrac

Messages: 2797
Registered: April 2011

Karma: 1

Senior Member

Only a patch on the inside then filler on outside. If you put a sheet on
the outside you will never get the contour cosmetically correct.

Sully
77 royale
Seattle

On Friday, September 4, 2015, David H. Jarvis wrote:

> Do both.
> An inside sheet and a filler sheet on the outside.
>
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Sully 77 Royale basket case. Future motorhome land speed record holder(bucket list) Seattle, Wa.

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Re: [GMCnet] Aluminum wall thickness and welding [message #286615 is a reply to message #286612]

Fri, 04 September 2015 13:41

Ken Henderson

Messages: 8726
Registered: March 2004
Location: Americus, GA

Karma: 9

Senior Member

Todd,

I suspect that most folks on the 'net don't know that this is you:

http://www.yelp.com/biz/seattle-collision-center-seattle

Y'All pay attention to what he says!

Ken H.

On Fri, Sep 4, 2015 at 1:52 PM, Todd Sullivan wrote:

> Only a patch on the inside then filler on outside. If you put a sheet on
> the outside you will never get the contour cosmetically correct.
>
> Sully
> 77 royale
> Seattle
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Ken Henderson
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach

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Re: [GMCnet] Aluminum wall thickness and welding [message #286616 is a reply to message #286569]

Fri, 04 September 2015 13:46

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

Ken, I second that.
Jim Hupy
On Sep 4, 2015 8:42 PM, "Ken Henderson" wrote:

> Todd,
>
> I suspect that most folks on the 'net don't know that this is you:
>
> http://www.yelp.com/biz/seattle-collision-center-seattle
>
> Y'All pay attention to what he says!
>
> Ken H.
>
>
> On Fri, Sep 4, 2015 at 1:52 PM, Todd Sullivan wrote:
>
>> Only a patch on the inside then filler on outside. If you put a sheet on
>> the outside you will never get the contour cosmetically correct.
>>
>> Sully
>> 77 royale
>> Seattle
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Re: Aluminum wall thickness and welding [message #286619 is a reply to message #286560]

Fri, 04 September 2015 15:21

kerry pinkerton

Messages: 2565
Registered: July 2012
Location: Harvest, Al

Karma: 15

Senior Member

Justin, I shape aluminum basically for a living.

http://www.gmcmhphotos.com/photos/data/6130/D-012s.jpg

http://www.gmcmhphotos.com/photos/art-deco-roadster/p45004-d-012s.html

http://www.gmcmhphotos.com/photos/data/6130/V_0023.jpg

http://www.gmcmhphotos.com/photos/art-deco-roadster/p49529-v-0023.html

I can, with some authority, promise you that the weld will shrink. It is absolutely going to pull and distort. Going slow won't make any difference.

Since you'd have access to the back side, you COULD planish out the welds and get it in the proper shape...but it's not as easy as it sounds. I've seen vastly more attempts messed up than successful.

If it were me, I'd make an oversize patch with the appropriate simple roll (the aluminum curves in one direction only) and panel bond it to the INSIDE with at least a 2" overlap. I'd then cut a patch that is just smaller than the hole and bond it to the first piece. I'd fill the resulting small crack with quality filler and block smooth.

I'll be glad to help you make the aluminum panels if you like. If you have a slip roll, or access to one, I can tell you the radius you need or you could trace the door frame onto a piece of plywood and make a template.

I'm not sure of the alloy but the aluminum is .063 thick. I suspect it is 5052. I would use 3003 H14 because that is what I have on hand and it will not make any difference structurally. 5052 is not as workable as 3003 but either will easily take the small roll needed.

The "RIGHT" way to do this would be to pull the old siding off and replace it with a new sheet from seam to seam. Lots of work but it's probably the only way to ensure you won't be able to see the repair. The problem is that the patch will expand and contract at different rates and show up in the paint. A big filler patch will do the same thing.

Kerry Pinkerton - North Alabama Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L

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Re: Aluminum wall thickness and welding [message #286824 is a reply to message #286619]

Mon, 07 September 2015 15:28

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

Kerry,
First off Amazing work!

I guess I should take your advice and use a filler from the back side.
I was planning to planish the welds but you're probably right, more trouble than it's worth!
Thanks for the input!
Justin

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: Aluminum wall thickness and welding [message #288630 is a reply to message #286824]

Tue, 13 October 2015 11:14

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

Okay guys getting ready to do this, what's the preferred sealant to use to bond the new patch panels to the old aluminum?

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Aluminum wall thickness and welding [message #288635 is a reply to message #288630]

Tue, 13 October 2015 11:37

sgltrac

Messages: 2797
Registered: April 2011

Karma: 1

Senior Member

Any cross bonding 2k adhesive.
3m 8115
JB weld
Fuzor cross bonding adhesive

All are toolable and will cure quicker with the introduction of heat.

Sully
77 royale
Seattle

On Tuesday, October 13, 2015, Justin Brady wrote:

> Okay guys getting ready to do this, what's the preferred sealant to use to
> bond the new patch panels to the old aluminum?
> --
> Justin Brady
> 1976 Palm Beach 455
>
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Sully 77 Royale basket case. Future motorhome land speed record holder(bucket list) Seattle, Wa.

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Re: [GMCnet] Aluminum wall thickness and welding [message #288637 is a reply to message #288635]

Tue, 13 October 2015 11:48

Loffen

Messages: 1087
Registered: August 2013
Location: Norway

Karma: 1

Senior Member

I did my drivers side chipmunk with 3M 08115, strong stuff and holding, will do the same with some other panels and do not worry about them coming off.

I did also use the 3M 08115 to glue one of the handles on my brake lathe to the axle, works like a charm Smile

Smile

1973 23' # 1848 Sky Blue Glacier called Baby Blue and a 1973 26'-3 # 1460 Parrot green Seqouia Known as the Big Green, And sold my 1973 26'-2 # 581 White Canyon lands under the name Dobbelt trøbbel in Norway

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Re: [GMCnet] Aluminum wall thickness and welding [message #288638 is a reply to message #288637]

Tue, 13 October 2015 11:51

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

Karma: 11

Senior Member

Sounds good guys, I'll get some.

So next question, do you guys recommend using only the sealer or should I use rivets as well?
I am thinking put down a good layer of adhesive, then rivet the panels on to hold them tight while it cures, then I'll sand the rivet heads off flush once it's cured.
This sound like a good plan?

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Aluminum wall thickness and welding [message #288640 is a reply to message #288638]

Tue, 13 October 2015 12:18

sgltrac

Messages: 2797
Registered: April 2011

Karma: 1

Senior Member

I would avoid rivets.
I would
1. Prep the inside and outside of the repair area with 80 grit or
courser to at least 2" past hole. Re -Abrade immediately prior to bonding
to prevent surface oxidation.
2. Cut the patch material and carefully arc the patch to match the panel
arc.
3. Mix and apply x bonding adhesive to patch and panel. Apply a thick
enough layer to allow some squeeze out when patch installed to eliminate
voids
4. Install patch panel and support from inside with a brace clamped onto
surrounding roof stringers, prop stick to floor/counter etc.
5. Heat with heat gun for 5-10 minutes ( just hot not burning. Hot to the
touch but still touchable)
6. Allow to cool naturally and check for cure. Bracing can now be removed
if it's in the way(prop stick to floor etc.)
For finish surfacing and shaping wait 12 hours.
7. Plane top surface to original contour and bevel perimeter of hole
8. Fill for final contour with plastic filler.
Above times assume ambient air temps above 60 degrees.

Sully
77 royale
Seattle

On Tuesday, October 13, 2015, Justin Brady wrote:

> Sounds good guys, I'll get some.
>
> So next question, do you guys recommend using only the sealer or should I
> use rivets as well?
> I am thinking put down a good layer of adhesive, then rivet the panels on
> to hold them tight while it cures, then I'll sand the rivet heads off flush
> once it's cured.
> This sound like a good plan?
> --
> Justin Brady
> 1976 Palm Beach 455
>
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Sully 77 Royale basket case. Future motorhome land speed record holder(bucket list) Seattle, Wa.

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Re: [GMCnet] Aluminum wall thickness and welding [message #288661 is a reply to message #288640]

Tue, 13 October 2015 16:29

Loffen

Messages: 1087
Registered: August 2013
Location: Norway

Karma: 1

Senior Member

Did just clean the surface and 80 grit, no rivets, bolts or screws, just clamps to give it pressure, no large gaps between the surfaces, the closer (thin layer of 08115 is better than thick )heat and time, 24 hours is good

1973 23' # 1848 Sky Blue Glacier called Baby Blue and a 1973 26'-3 # 1460 Parrot green Seqouia Known as the Big Green, And sold my 1973 26'-2 # 581 White Canyon lands under the name Dobbelt trøbbel in Norway

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