This part of the welding technical article is in final draft form. Please read and make any comments you wish. We need to fully cover this topic and do not want any mistakes or misinformation.

You can read the 1 page (short) section at http://www.old-fords.com/welding/glue.htm.

Use the user name "fte" and the password "weld"

Thanks for your help, this is a group effort -

 

WillyB -

Mongo likee!! Excellent article. I like the approach. It is very readable, has a good example (Go Irondragon!) and good instructions, especially the surface prep info. Very good.

Input:

Acetone, naptha and MEK are also excellent surface cleaners prior to adhesive application. As with Lacquer thinner, a clean rag wetted with the solution should be washed over the surface to remove debris. Follow the wetted rag by a dry one to remove all traces of the solvent. Some debris is left on the surface if you just let the wet surface air dry. You'll still get a good bond. You'll get a better one by drying the solvent off the surface.

I sure would like to see more than one product name and number. Maybe a table of products by type (acrylic, urethane, epoxy) and their working times (fast, medium or slow setting). Or, at least manufacturer's website addresses to research further and find supplier locations.

Ultimate adhesive joint strength is determined by good prep and the amount of seam overlap. When you say "3000 lbs", you should say 3000 psi (pounds per inch). The 2" overlap then would yield a strength of 6000 pounds per linear inch of seam (in tension/shear). That's a pretty structural joint by itself.

Never rely on an adhesive only joint where there are peeling forces trying to pry the parts away from each other. No adhesive does well with that kind of load. A 3000 psi adhesive will typically come apart with an edge load of less than 500 lbs, depending on temperature. Always also use fasteners where that kind of load may be present. These fasteners are referred to as "peel stop" fasteners in aircraft design. Countersunk blind rivets work well. McMaster-Carr sells tons of them. The countersunk head can be filled over before paint and the fastener stays there to do the work A fastener spacing of 4D (4 times the rivet diameter between rivets) is the usual in aircraft work for a structural joint (ex: 1/8" rivets on 1/2" spacing). Larger dia rivets have higher shear and clamp-up strengths. The soft 1/8" pop rivets generally available to us have a shear strength in the area of 200 pounds and a clamp-up strength of about 60 pounds.

You gave acrylics and urethanes a description, but not epoxies. Epoxies can have shear strengths over 5000 psi, although most room temperature cure compounds in your local parts house are in the 1800-2400 psi range. These are also excellent for filling gaps between the panels. However all adhesives yield lower strengths when the gaps get bigger. Basically, the smaller the gap, the better the adhesive strength. A nominal bond line thickness of .005 is usually what the adhesive strength is based upon. So, it helps to work the part edges (hammer and dolly) to minimize the gaps before installation.

UV light kills every adhesive. Generally, all glued seams will be covered by paint eventually or be inside the vehicle, maybe under carpeting or such, so the problem is eliminated. But it may be worthwhile to mention that a glued seam should not be exposed to sunlight for long periods during the build as that will deteriorate the adhesive strength.

Also, since they are thermosets, most any adhesive joint can be disassembled after cure by using extreme heat or cold. Heat can be applied using a torch. This method, of course, can warp the metal if you're not careful and that makes it problematic. A better method is to use liquid nitrogen. It crystalizes the adhesive and the joint can be separated using a panel knife or scraper. Either method will destroy the bond permanently. For that reason, I would never recommend using adhesives near a source of extreme heat, like headers. (Winter temperatures are not cold enough to worry about).

That's my 2 cents...

 

VERY nice job!

I have never thought about adhesives for joining body parts... (except maybe epoxy!)


I have a couple suggestions for the mechanics of navigating around in the article.

If possible put "NEXT PAGE/PREVIOUS PAGE" buttons at the top and bottom of every page. It's very convenient when the page is large enough for scrolling>

That's something that could be added "globally"........ Here's an example of how it could look: http://www.tldp.org/HOWTO/3-Button-Mouse-6.html

This is a standard all through the Linux Documentation Project which is completely written by users all over the world.

It's also very nice to have lables on each button that tell the reader where the button takes them.



Thanks for the outstanding article!



Rick



btw......Where in Central Ca are you? I used to live in Taft. We called that Central Ca also!!

 

[QUOTE=HT32BSX115]VERY nice job! . . .
I have a couple suggestions for the mechanics of navigating around in the article. . . .Thanks for the outstanding article!
QUOTE]

Rick, Thanks for your kind words and encouragement. We are not sure of the final form of the article, except that it will not be hosted on the website it is now on. It has to meet FTE guidelines and will appear on this (FTE) website. I used old-fords.com just as a working area for the group doing the article.

In addition, the group has yet to decide what will be covered in the different sections, or the order they will be presented. What you see is a working document with some notes about what I think should be covered. I am sure the form will change many times as we work towards the finished article.

As to the text on the buttons, there appears to be a Java problem and I am not a programmer - plus it has been years since I worked on any website. The buttons do have text that shows up sometimes. I am working on it. The only thing more stupid than a computer program is an amateure trying to write one.

I live in Madera County, just north of Fresno.

Randy, thanks for the input. I will add the changes you suggest about preparation, the UV protection, joint strength and location. Please check back this evening and see if I got them right.

One question I do have, can the glued joint be worked if needed? What about collision damage down the road? Or just a few alignment corrections as you assemble your truck?

 

WillyB -

Generally speaking, no, the glued joint is not workable after cure. Most adhesives are too brittle to take that. Urethanes are probably a little more accomodating that way than epoxies, because urethanes are tougher (meaning they "give" a little). Adhesives are usually a blending of toughness and strength. The stronger ones tend to be more brittle. The tougher ones have less ultimate strength. But once you start working the joint, it wants to delaminate. Minor movement of the joint might be accomodated. We would have to try a test on that or ask o professional bodyman for input.

 

Great article ***** B,

One other thing you may want to consider discussing is the price of the special applicator gun required to dispense and mix the adhesive

I use the 3M panel adhesive, they wanted £150 for the applicator

I found one from another manufacturer that was easily modified for a tenth of that price, I don't know if the situation is the same in the USA

Stephen

 

***** B, great article. Also go over to HAMB and search the archives, panel adhesives have been discussed several times and you might pick up a few extra talking points.

Ive been using the 3M products with good results with patch panels for some 80's era vans. Went 3M only because the body shop supplies & paint store is on a road I use daily AND I got a Senile Citizen discount. The applicator was around $44 before the discount.

 

I have incorporated Randy's suggestions, not sure which version you other guys read. I hope we improved it.

Silly me, I never thought about applicators - guess I thought you squeezed the glue out of a tube, mixed it with a toothpick, and smeared it around the joint with your thumb. I guess there is another update to do!

HAMB sounds like a good idea, except I have no idea what that is - please edify me.

One other serious question, how deep do we want to go in an article geared for beginners? Or maybe we should leave this portion simple, and get into more details when we do the Tips and Suggestions portion? I already plan on doing Randy's suggested tables there.

 

"gluing" would certainly solve some of the problems some welders have....i never really thought of doing to it BIG panels like that though....interesting....i welded a bunch of things shut on my floor today....make it all smooth, and then i wont need to buy the fancy molded carpet.....haha...gluing probably would have made those jobs easier too....

 

WillyB -

You are the master! That was a truly nice job of updating. You said it better than I did.

 

I know I first learned of using adhesives one day when I was talking to my families auto body guy (we live in prime car/deer collision territory so we're on a first name basis). At the time we had a little ford ranger with a toasted roof (the PO parked it upside down in a ditch). He said we could get a factory skin for pretty cheap and glue it on, said it was faster and easier and just as strong as welding.

After that I did a bit more research into the whole idea and learned of its benefits... thats what lead me to use it on my F-3 project. As you can see in the article, I used it for the back wall, but I also have plans to use it to glue in my floor panels (16 gauge steel) over the welded 1x1 14 gauge steel tube frame. I do plan on placing a few tack welds to add even more strength. I may even use it for a few interior "skinning" projects to finish out the extended portion of my cab.

 

*****,

You asked what HAMB is....

It's a website for hot rodders similar in set up/ function to this one.

Two major differences;

1. It's not a one make dedicated site.

2. They eat you alive if you ask a question that anyone thinks is stupid or has been asked before.

A goggle using HAMB should get you there. Just keep your mouth closed.

 

Don't know if this has already been mentioned but a word of caution when using the panel adhesives..........DO NOT LEAVE ANY ON THE METAL SURFACE THAT WILL BE IN DIRECT CONTACT WITH THE PAINT. It will cause the paint to swell. I left some in a seam after wiping smooth and the finish paint lifted showing the seam perfectly. Had to take it back to bear metal and remove all product showing in the seam and repaint. This was even after it had cured for a few days before paint.

 

Strange comment. Ive been on HAMB since almost the beginning BTW. It has matured over the years and has IMO the absolute best tech stuff on the internet. There are still a few jerks and posers but they just bother each other.

Interests over there range from rods to customs to trucks and pre muscle car 60's stuff. Several magazine authors, editors and tech staff are regulars.
If you are going to post for the 1st time then common courtesy is to do an introduction. The archive is BIG.
Go here http://www.jalopyjournal.com/forum/