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
|
|
|
|
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:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
|
|
|
|
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
|
|
|
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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
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
|
|
|
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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
|
|
|
|