New member........Heatsink ideas

[Bertieboy]

Hi guys, Ive been reading your posts for a few weeks now and have decided to join...I like the idea of getting some work done during the day and loggin on at night to surf the net for info and participate in constructive talk..........been weldin for a while now nearly had to give it up due to having an operation on my heart and the risk being, I would wake up with damage to its electrical system...however all was well and no pacemaker needed!!! Bloody lucky actually as I have a 1966 holden Im restoring and own an old IHC truck that needs work and a safe that Im fixin up and a trailer Im building and................you get my drift!! Ive vowed to not take on any other projects until Ive finished what I have......then again that go cart post got me fired up and thinking..........the kids too. Actually that gantry looked good too as I dont like borrowing my mates engine crane......Anyway the skys the limit and I have plenty of wire for my little mig....just scored an oxy set last week and I will be asking some questions, due to my lack of oxy knowledge.....also I do have input to offer as well, as I have a background in the automotive trade and have had to build many things due to lack of funds,but having time as Iam a single parent.[ mr mom]....anyway enough of me and my question is that Im replacing the outer half skin on some doors off my 66 holden and need to take it real EASY as I cant afford to have any warpage......the weld is basicaly made up of many spaced tack welds and what I need to know is someone said years ago there was some STUFF that was like grease that was in a tin and was slopped onto the area near a weld and that acted as a heat sink and when done, simply scoop up and put back in tin...now Im in Australia and havent seen anything around like this. Is there anything that could act as a heat sink? what about a piece of billet alumimium/copper to be placed on the skin near the weld...any ideas guys? and thanks for listening.....Ill try not to yak on too much, in future...haha....cheers, Pete........oz

[yammahoppy]

i remember watching a classic car restoration tv show and the guy used that stuff. it was blue and looked like playdough. he made a little circle around the place he was welding and it seemed to work pretty well. dont know the name of it but ill look on the web to see what i can find.

JASON

[yammahoppy]

COOL BLUE

check out this stuff. might be what you are looking for.
Cool Blue .

hope this helps

JASON

[metal tech]

www.mcmaster.com #76685A65, Heat Containment Putty I believe the Eastwood Co. also has silmiliar stuff in their catalog. I have also used .062 copper (chilled in cold water) for backing to prevent nasty burnthru. I think if your mig is set right you won't have much problem with burnthru, practice on same thickness material until you feel good. Hope this helps.

Al

[Roger]

Anti Heat heat guard compound is listed in my miller 2002 welding components and parts guide. Don't know price but local welding dealer can get it for you.
Part # AHTB 12 oz tube
Part # AHQT Quart can

More of a car body shop item so I expect dealer supplying that trade would have it in stock locally.

I think it's made of the super absorbent granules that soak up water in disposable diapers and used as soil additive to hold water like jello. In that case garden or agriculture supply would be cheap.

[DaveD]

I got some 3 foot long 1/4" x 1-1/4" copper bars off ebay a while back for the same purpose. Figured I could cut all kinds of lengths and bend them to fit curves. Haven't tried them yet because of priority changes. I'd like to hear how the heat putty stuff really works though since that seems a lot easier than trying to back something up with copper bars.

[Hobart Expert Rock]

BERTIEBOY.......WELCOME ABOARD.........I'VE USED A PASTE AVAILABLE THRU MC MASTER CARR BEFORE. BUT DON'T RECALL THE NAME.........IT WORKED WELL AS I'M SURE MOST OF THE ONES OTHERS ARE TELLING YOU ABOUT WILL WORK AS WELL.........I'M GLAD YOU SIGNED UP AND JOINED......... WE WILL BE ABLE TO HELP IN MOST INSTANCES.... ABOUT THOSE DOOR SKINS ON YOUR VEHICLE.......... HOW THICK ARE THEY..........?..........WHAT WIRE (SIZE) AND GAS ARE YOU GOING TO USE.............?..........TRAILER LOOKS NICE......... POST SOME PICTURES OF YOUR VEHICLE AND WE WILL SEE WHAT OTHER KINDA OF ADVICE IS GENERATED............. THERE ARE A LOT OF MOTOR HEADS ON HERE. ENJOY THE SITE AND ASK AWAY WITH THE QUESTIONS.... THERE ARE MANY EXPERTS ON HERE........... SOME YOU DON'T EVEN SEE..................BE SAFE.......................ROCK...........
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[Bertieboy]

Thanks guys for the input!!!. something that is putty based sounds better, rather than a paste, style which is what I heard about years ago....that cool blue stuff looks good,"webmisteress" hey!!..........the wire Im using is .6mm and the body panels I havent measured but their a pretty heavy gauge, much like the old holden Im restoring, similar say, too an old 60s chev........not like some off the newer stuff. the gas is a 75/25 mix argon and ?...I forget now....my welder is australian made and I made a small rolling cart from 2 ramps a mate was throwing out....I can turn my machine down and the wire feed, and practice on scrap to make sure Im getting penetration.........my main problem was the heat issue..... slight bowing of the door, when finished....I lined up all the doors lying flat and layed small 10mm welds, alternating from door to door......coffee.....doorto door...etc..made an afternoon of it and ended up with these doors bowed in about 4-5mm in the centre......could not straighten and I now know how hard mig welds can be!!. This time Im trying again.......but I want it right.....I have new half skins and Im ready to go,I was even going to weld in a small lenght of 25/25mm tube behind where the seam would be, BEFORE I started...will that help? or will it hinder the situation futher as a dolly etc cant be put behind the seam due to the tubing? anyway I will hunt around again and hopefully the heatsink stuff isnt too expensive. I stopped on the project a few months back when I stuffed up the doors.........ive now calmed down and need this car finished as Im paying rego and my regular car has a cracked head!!I dont want to rush though as I do have an old ute to get around in for now...Ill try and dig out some pics of my car....heres my welder

[Hobart Expert Rock]

BERTIEBOY..........JUST CURIOUS WHAT IS THE NAME OF YOUR WELDER................?.......110V/230VOLT..............?...ROCK..
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[Gramps]

Rolled up wet towels work pretty good as a heatsink for working on automotive sheet metal. They are cheap and don't leave a mess to clean up either. T

[Bertieboy]

wet towels, sounds good to me Ill give it a try.......as for my welder rock, its a CIGWELD 240v twin 130amp....its been goin now for 2 years and gets the job done......the only issue I have with it, is it has 4 heat settings that are switchable and sometimes I need a setting inbetween....the wire feed is dial controlled so thats OK.....other than that, its great.........still only a toy though compared to some shop setups.................

[Roger]

Heat sink will not fully solve problem as when steel is heated by welds it will always shrink. Make short welds. Then while cooling, hammer and dolly to stretch. Then another short weld is only way. Grinding welds can also heat steel enough to shrink it.

The other way but not practical for your situation. Weld joint will shrink so you must plan for it or fixture so it can't happen as they do for aircraft welds or welding bicycles.

[Gramps]

No matter what you do you are going to end up with some crowning from the welding so you will need to do some metal shrinking. If you hammer the welds while they are still hot and quench them with the wet towels you can minimize the streching but be careful because the quick cooling can shrink the weld too much. It would be best to get some scrap metal the same thickness as the door panel and experiment on it. I use gas and hammer weld auto panels but it takes practice to be able to do it right. When you get good at it your panels will not need a lot of work to get them ready to paint.

[Bertieboy]

thanks guys....so OK, I know for sure Im not gifted with a hammer and dolly and practice makes perfect{eventually}..........I felt that I HAD taken it easy with the last doors and your right, there still will be slight shrinkage enough to make a nice straight door unusable.........I understand about slight restretching after each weld, but I dont trust my hammer and dolly skills as yet ,so can I cheat?what about a fixture like youve mentioned, Rodger? you mean a jig or some sort of brace? removable? or as I previously mentioned{box tube}?......thanks again guys...I understand there are no shortcuts to a good job and I will try my best.....I now know the skill needed to replace skins etc and will give it a go once again and I now have a huge amount of respect for guys that can work metal !!!, well.....cheers, Pete......

[Roger]

Should be using MIG wire not flux core as less heat easier to turn down for minimum weld.

Here is best site I've seen dealing with panel beating but mainly is about aluminum.

http://www.tinmantech.com/html/articles.html

The first 2 tack welds or 3 are most important as they will pull parts out of alignment doing more damage than warping sheet matal. So it needs to be well clamped before tacking then checked to make sure it's still ok after tacking. You can also position parts so shrinkage pulls parts into alignement. I have wedged flat screw driver blade in gap to hold alignment while tacking.

Back when they gas welded fender halfs they used large copper ficture exact shape of final fender to confine heat and prevent warping.
Roky D. posted aircraft fixture for TIG welding that prevented warping and confined shielding gas to weld area.
But, not practical for sheet metal repair work.
Welding shrinks & hammering stretches is only way. Short welds, back stepping, confining heat with heat sinks, wet towels, ect. helps minimise problems. Get it good enough then hide your limitations with body filler just like the pros.

Could also rivit in backing bar to hold alignmet while tacking. If it was copper backing bar then steel weld wouldn't stick.

Butt welds are hardest to make.