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Ricoch3T
06-09-2007, 11:03 AM
How many of yall finish your welds when doing floor pans or splicing panels together?
If you do what is the proper technique for doing this without getting the weld or metal too thin? I've seen some people finish butt welds and such that look like they didn't put a patch in at all and I've tried myself on some scrap metal but it seems to be too thin when I welded it when i'm done.

hotrdblder
06-09-2007, 11:40 AM
tig, weld is way softer and way easier to work

Ricoch3T
06-09-2007, 02:46 PM
Thats what i hear, and I've been to another metal working forum before where some of them even recommend gas welding. But even with the mig I should be able to make a seamless weld and finish it without pinholes or problems where the metal is thin and weak along the seam correct?

hotrdblder
06-09-2007, 03:16 PM
yes you should but with mig it is hard to do, everything has to be perfect, gap, prep,torch height, etc, then grinding needs to be done carefully, i am not sure why your so worried about it i would grind it down then skim it with filler and have a day

rocketrod
06-09-2007, 05:01 PM
Thats what i hear, and I've been to another metal working forum before where some of them even recommend gas welding. But even with the mig I should be able to make a seamless weld and finish it without pinholes or problems where the metal is thin and weak along the seam correct?
I wouldn't sweat it, whether you are using mig or tig, just take your time and either will be fine.

Mathius
06-18-2007, 01:14 PM
yes you should but with mig it is hard to do, everything has to be perfect, gap, prep,torch height, etc, then grinding needs to be done carefully, i am not sure why your so worried about it i would grind it down then skim it with filler and have a day

I concur. I will probably not be grinding down my welds on my floor pan. They are ugly, and the wire I used leaves a very hard weld, but the inside will be covered by carpet, and the underside can be rhino lined or something.

I didn't have a plasma cutter, or any other great cutting tools, nor did I have exactly factory floor pan replacements, and several other factors that led me to have to lay down some pretty sorry looking welds. There were places where I had to span a 1/4" gap with 0.23 wire. Talk about a pain. You want the weld to come out looking pretty too?

I think about the only chance of grinding all your welds, is if you are very patient, have a lot of skill with an electric grinder, and finish it off with an air angle grinder and a roloc disc.

I care more about my floor being solid for the first time in 3 years, than I do about what it looks like. When I do some welding on a body panel, then I'll take the time for finishing details like that.

Mathius

Ricoch3T
06-20-2007, 12:08 PM
That was my main concern strength. I had your same situation on the floor pan, but I'll be knocking the weld down a little (leaving a decent size bead). I didn't know if there were any metal workers on here that could shed light on finishing it and having the strength to boot. When I usually finish one I take time to only hit the weld and not the surrounding metal, then finish with a polish pad. It leaves a nice surface but sometimes the weld area is thin.


I concur. I will probably not be grinding down my welds on my floor pan. They are ugly, and the wire I used leaves a very hard weld, but the inside will be covered by carpet, and the underside can be rhino lined or something.

I didn't have a plasma cutter, or any other great cutting tools, nor did I have exactly factory floor pan replacements, and several other factors that led me to have to lay down some pretty sorry looking welds. There were places where I had to span a 1/4" gap with 0.23 wire. Talk about a pain. You want the weld to come out looking pretty too?

I think about the only chance of grinding all your welds, is if you are very patient, have a lot of skill with an electric grinder, and finish it off with an air angle grinder and a roloc disc.

I care more about my floor being solid for the first time in 3 years, than I do about what it looks like. When I do some welding on a body panel, then I'll take the time for finishing details like that.

Mathius

BRIAN
06-22-2007, 07:07 PM
I disagree, you can finish a mig weld to a where it will almost disappear. Tig and gas welds put in heat but the weld is not brittle and can be worked. A mig weld needs to have perfect prep and it can come close especially on a floor.


Penetration and preperation are the key. Buy a set of the orig Panel Clamps as they will give you the perfect gap which is roughly the thickness of the panel or a little more. You have to skip around but you also have to have the weld penetrate rather than what you see all over the web. You see tons of big names that grind the crap out of these lumps they call welds. That type of weld will crack when ground down. Also do not use a grinder or 36 grit disc to prep the panel or you will thin out the edges. Pulse your welds letting the weld just start to turn from red and hit your next. You will be surprised with better prep how clean your butt welds will be.

Sheetmetal welds take lots of prep to get them right. Don't just cut a piece and pull the trigger.

I have pics but they say they are too large. If you want I will email a pic and you tell me what I used.

Mathius
06-26-2007, 01:28 PM
I disagree, you can finish a mig weld to a where it will almost disappear. Tig and gas welds put in heat but the weld is not brittle and can be worked. A mig weld needs to have perfect prep and it can come close especially on a floor.


Penetration and preperation are the key. Buy a set of the orig Panel Clamps as they will give you the perfect gap which is roughly the thickness of the panel or a little more.

Not accurate. If you don't have the panels cut to the proper size and shape, panel clamps aren't going to help you. If you don't have good cutting tools, cutting the panel to the right size and shape can be a PITA.

Mathius

BRIAN
06-28-2007, 08:06 PM
Not sure what that means about not cutting correctly?? If you do not have tools to cut sheetmetal you are about 5 steps behind and do not need the welder or clamps??


Simple shears or $2.00 cut off wheel on your grinder are about all you need.

Mathius
06-29-2007, 02:27 PM
Not sure what that means about not cutting correctly?? If you do not have tools to cut sheetmetal you are about 5 steps behind and do not need the welder or clamps??


Simple shears or $2.00 cut off wheel on your grinder are about all you need.

That's because you're obviously basing everything on your own setup. 0.23 wire is going to need a VERY precise gap as opposed to a bigger wire, because your tacks are going to be smaller. You may even choose to run a bead over a short distance with 0.23 wire.

Grinder is not that expensive, but a compressor is. Not everyone has access to one that is going to run a die grinder. They take LOTS of air.

You can go electric, but I personally have never seen an electric die grinder. I know they must make them, but it isn't something you're going to find in a local store.

You can use a sawzaw to cut the old material out of the car, but you can't use it to trim your patch panel. You'll vibrate the hell out of the panel and cut nothing and probably hurt yourself.

Big angle grinders aren't going to give you precision cuts.

Etc. etc. etc.

You're right on one thing, preparation is 100% more important than the weld itself, if you intend to grind it down. But once you've cut a panel too short, you either have to keep cutting and make another patch panel, or try to span the gap with whatever wire you're running, which is a lot harder to grind down.

Mathius

Karch
06-29-2007, 10:06 PM
Makita and Milwaukee make electric die grinders. In fact, at a very reputable advanced porting shop, when they hand grind, they only use the Milwaukees...and these things are heavy and something like 11 amps.

RobM
07-01-2007, 02:25 PM
Use a die grinder with a wheel, grind perpendicular to the weld. I use this kind of wheel... http://www.autobodytoolmart.com/images/PRODUCT/medium/4290_91.gif
with this kind of grinder....http://buy1.snapon.com/catalog/objects_lg/48400/48363.JPG

get the weld down flush with the surrounding metal then finish the weld with what’s called a "roloc" disk (I like a 50 or 80 grit wheel) on a 90 degree die grinder,

for this i use this kind of disk....http://www.autobodytoolmart.com/images/PRODUCT/large/11323.gif

with this kind of grinder....http://buy1.snapon.com/catalog/objects_lg/43600/43542.JPG

when doing this grind parallel with the weld. This should take very little metal away all your doing here is getting rid of your grinding marks and leveling. if you really want it nice DA over every thing with 80 grit sand paper. Then finish with body filler or seam sealer.

this is pretty much the standard technique in most automotive fabrication in my opinion

Ricoch3T
07-01-2007, 06:03 PM
Thanks for the info. I have been doing something similar to this (after I'd been doing some reading and slowly figuring it out on my own) but I noticed sometimes I still get some pinholes in areas where either I didn't penetrate the metal enough or didn't have enough heat. Most of the floor pans and stuff I can weld on both sides tho if it doesn't look like it penetrated enough.

Also it seems like with the mig welded it is capable to fill in bigger gaps. I'm one of the unfortunate people that can't follow a line with the body saw i'm using. Cut off wheels work better for me I've been finding out but didn't know that until recently. Also the body saw is quicker. But anyhow the mig WILL fill in a gap, it just takes time and the ones I've looked at knocking down you need to make sure you didn't build up on only one side (the side you grind down). So say I fill in a gap from inside the car, naturally most of your weld will be inside the car with you, if you look at the underside you will notice that its welded and strong, BUT there will not be enough material left after you grind it. The underside will also have to be welded to achieve a solid surface for grinding.
Of course this takes more time than if you did it correctly with a small bead and tight gap.
Thats my opinion on the subject anyway. I might be wrong though. I'm still learning with the sheetmetal myself


Use a die grinder with a wheel, grind perpendicular to the weld. I use this kind of wheel... http://www.autobodytoolmart.com/images/PRODUCT/medium/4290_91.gif
with this kind of grinder....http://buy1.snapon.com/catalog/objects_lg/48400/48363.JPG

get the weld down flush with the surrounding metal then finish the weld with what’s called a "roloc" disk (I like a 50 or 80 grit wheel) on a 90 degree die grinder,

for this i use this kind of disk....http://www.autobodytoolmart.com/images/PRODUCT/large/11323.gif

with this kind of grinder....http://buy1.snapon.com/catalog/objects_lg/43600/43542.JPG

when doing this grind parallel with the weld. This should take very little metal away all your doing here is getting rid of your grinding marks and leveling. if you really want it nice DA over every thing with 80 grit sand paper. Then finish with body filler or seam sealer.

this is pretty much the standard technique in most automotive fabrication in my opinion

RobM
07-02-2007, 02:40 PM
A lot of people have their own little tricks of the trade…. Its all about trial and error and practice.

One thing to remember is a nicely finished weld is a lot like Nice body work its all about the prep!

You need a nice tight (yet relaxed) gap.
When I say a relaxed gap I mean the gap has to be tight but not too tight. The panels being welded can’t be pushed together to hard. You don’t want an interference fit here. The reason for this is because if the panels are bitted together too hard they will warp badly when you put a lot of heat into them. A badly warped weld is hard to finish out with out turning the surrounding metal into tin foil. So again a tight yet relaxed seam is where its at.

I suggest first tacking the panel in before the seam gets fully welded. First put tack on the corners to keep it in place then alternate tacking all the sides of the panel until you have a tack about every 1.5-2 inches of the seam.

I have better luck stitch welding the panel as opposed to just doing one long bead. This entails doing a series of tacks one after the other to create a bead this allows the use of much more heat and results in better penetration. Make sure to make one tack after another before the previous one cools enough to not be cherry red any more. Also push into the weld with the gun don’t pull…..if your welding from right to left angle the gun to the right this will also help penetration.

Use this technique to fill in between those tacks that are 1.5-2 inches apart. Keep the welds only 1.5-2 inches long will keep warping under control. Skip around the panel try to prevent putting a lot of heat into one area. After a weld is completed cool it down with compressed air if possible.

before you weld make sure what your welding is clean. This will help all aspects of the weld. I can elaborate on this if you want

80proZ
07-02-2007, 04:17 PM
I'll agree with most of what RobM said except the gap.You need a slight gap(about .023 mig wire) around the entire patch.
What will happen when you start to tack is the weld will cool and shrink,drawing the patch closer to one side of the hole and leaving a larger gap on the otherside.If you make the patch to tight,it will make the seams rise above the surrounding area,making it much harder to make dissappear.
TIG welding floor pans would be a waste of time IMHO.The seams and surrounding area would have to be spotless to make a good weld.Welding with a MIG is much more leinent and forgiving than the TIG.And grinding it down takes very little time.Personally i use a 4 1/2" grinder and cutoff wheel to do all my cutting and a 120 grit flapper wheel to grind down the welds.
I just finished some patches on my floors today,except for grinding, i'll post some before and after pics tomorrow.

Mathius
07-02-2007, 05:55 PM
Use a die grinder with a wheel, grind perpendicular to the weld. I use this kind of wheel... http://www.autobodytoolmart.com/images/PRODUCT/medium/4290_91.gif
with this kind of grinder....http://buy1.snapon.com/catalog/objects_lg/48400/48363.JPG

get the weld down flush with the surrounding metal then finish the weld with what’s called a "roloc" disk (I like a 50 or 80 grit wheel) on a 90 degree die grinder,

for this i use this kind of disk....http://www.autobodytoolmart.com/images/PRODUCT/large/11323.gif

with this kind of grinder....http://buy1.snapon.com/catalog/objects_lg/43600/43542.JPG

when doing this grind parallel with the weld. This should take very little metal away all your doing here is getting rid of your grinding marks and leveling. if you really want it nice DA over every thing with 80 grit sand paper. Then finish with body filler or seam sealer.

this is pretty much the standard technique in most automotive fabrication in my opinion

Man, I don't know if I'm using the wrong wire, or if I'm just buying crappy grinding and cutting discs, but I ground away with a 4.5" angle grinder today on one of my welds and couldn't level it. Didn't want to go too hard, because it'll just destroy the surrounding sheetmetal in the process. Took it down as far as I could, roloc 36 grit sander, and still couldn't clean it up.

I have a flap disc I could try.

Mathius

80proZ
07-03-2007, 04:12 PM
Here's some patches i finished up to day
This one is right where your right foot would sit if not on the pedal
https://static1.pt-content.com/images/noimg.gif
finished and ready for some primer
https://static1.pt-content.com/images/noimg.gif
the following is a series of pics from start to finish of another patch i did just below where the dimmer switch is located on an 80 camaro,which is what im restoring/modding.
https://static1.pt-content.com/images/noimg.gif
https://static1.pt-content.com/images/noimg.gif
https://static1.pt-content.com/images/noimg.gif
https://static1.pt-content.com/images/noimg.gif
https://static1.pt-content.com/images/noimg.gif
both these patches took me a total time of about 3 hours from start to finish.including the time to fab up the patch.The first one took the longest to fab as it has a nice compound curve to it.
Hope these help alittle

Mathius
07-03-2007, 04:45 PM
Here's some patches i finished up to day
both these patches took me a total time of about 3 hours from start to finish.including the time to fab up the patch.The first one took the longest to fab as it has a nice compound curve to it.
Hope these help alittle

Those pictures look like you're using something like .030 or .035 wire?

I wonder if maybe the 0.023 wire is too small and makes grinding harder. It seems like I end up having to run a weld on both sides of the panel, rather than just one tack that holds both sides, because of the wire being so small. I wonder if that is the problem. Maybe there's more metal concentrated at the weld, than a simple large tack that would spread out.

I'm working on an inner fender right now that the battery tray area has rusted away on my '76 Malibu.

I'm contimplating throwing a few tacks on it to hold the patch in place, and then taking it over to my buddy's house and welding the rest of it up on his bigger machine and seeing how those welds grind down.

Mathius

80proZ
07-03-2007, 05:21 PM
i'm using .023 wire.ER70s alloy
What about your heat and wire speed?What kinda welder?What alloy wire?

Mathius
07-03-2007, 07:07 PM
i'm using .023 wire.ER70s alloy
What about your heat and wire speed?What kinda welder?What alloy wire?

Lincoln 135 something or other. Don't know the alloy offhand. It's either lincoln or hobart wire too, not cheapy stuff. 0.23.

This thing doesn't give a voltage setting, just a,b,c or d heat settings. and 1-10 wire speed. wire is on 5 I think... heat is on b or c. can't recall offhand. Not that that will really help you anyways.

Biggest 110 unit I could find.

Mathius

RobM
07-04-2007, 12:51 PM
I dont know why your having trouble grinding the welds.... what kind of disk are you using? You should be able to grind the head off a 3/4 ' grade 8 bolt with one of these wheels with no trouble i cant imagin your welds are that hard.

By the way 80proZ.. looking back I agree with the .023 gap on a patch panel. thas kind of what i was thinking when i was talking about the relaxed seam concept.

Mathius
07-04-2007, 05:39 PM
I dont know why your having trouble grinding the welds.... what kind of disk are you using? You should be able to grind the head off a 3/4 ' grade 8 bolt with one of these wheels with no trouble i cant imagin your welds are that hard.

I have ground bolts off with my 4.5" angle grinder, multiple times. I've ground rivets off the frame of my old Ford Ranger I used to own. But for some reason I can't get my welds down flat without major pressure, and it starts to damage the surrounding material. A roloc disc doesn't seem to do crap to finish it off (36 grit).

I have yet to try the three flap discs I bought.

I'll try to remember to look up what alloy wire I'm using tomorrow. I'm trying to decide if I'm going to weld the fender here, or take it to my buddy's.

EDIT: If I weld it here at home, I'll try your suggestion of 0.023 gap. If I take it to my buddies, I'm gonna do it how I always do, (eyeball it) just for consistencies sake to see if its my setup or not.

Also, when I get done with the project I'll have pictures. It's just that I don't have a digitcal camera, so I'm using a disposable, and I have to use up all the pictures before I develop them, so I have to finish the project first.

Mathius

Mathius
07-05-2007, 12:47 PM
What alloy wire?

ER70s-6

I started thinking.. could shielding gas effect weld hardness? I don't use the typical 75/20 mix that's recommended for this wire. In school, we ran 100% argon on half the stuff in the class, because they could switch it over to aluminum easily. I started doing the same at home for the same reason.

I wonder if I'd get better results with 75/20 mix?

Mathius

Ricoch3T
07-08-2007, 09:31 PM
I use the 75/20 mix and the weld still seems pretty hard to me. I've never gone straight argon tho so I can't really compare. I can knock a normal size bead down pretty quick with the 4" grinder. The ones that take longer are the bigger gaps I've had to fill in some what.

Also to get off topic a little, are you pushing aluminum wire with your lincoln? I read somewhere the push type of welders don't work very well with aluminum


ER70s-6

I started thinking.. could shielding gas effect weld hardness? I don't use the typical 75/20 mix that's recommended for this wire. In school, we ran 100% argon on half the stuff in the class, because they could switch it over to aluminum easily. I started doing the same at home for the same reason.

I wonder if I'd get better results with 75/20 mix?

Mathius

Mathius
07-09-2007, 12:22 PM
I use the 75/20 mix and the weld still seems pretty hard to me. I've never gone straight argon tho so I can't really compare. I can knock a normal size bead down pretty quick with the 4" grinder. The ones that take longer are the bigger gaps I've had to fill in some what.

Also to get off topic a little, are you pushing aluminum wire with your lincoln? I read somewhere the push type of welders don't work very well with aluminum

No, they advertise you can use aluminum with this welder, but I can't imagine it would work on anything thick enough for me to care about. The machine advertises it will do up to 1/4" steel with regular wire, and 5/16" steel with flux core.

I'm pretty sceptible about those numbers, being that this is just a 110 unit.

But when I need to run aluminum, I pack up the argon bottle and run over to my buddies and use his big miller 220v with the spool gun.

Once this heat breaks, probably over the weekend, I'll be out there finishing up my inner fender, and I'll try to post some pictures of what I'm dealing with.

It's supposed to hit 93 degrees today, and 90 tommorrow, then rain Wed. and back to the mid 80s.

Mathius

B Schein
07-09-2007, 06:03 PM
It takes a long time to learn how to but weld patches with little to no distortion as well as have the appearance that it was never fixed. I can do it if I take my time but it has taken me ten years of working on my own cars as well as worked at a professional hot rod shop. The trick is to tig weld them. When you tig weld the weld is much softer then a mig weld which allows you to hammer the weld. That is the real trick when you are able to hammer the weld any distortion that accurse do the heat and any miss alignment can be worked out. Al so when you tig weld it the weld is much less to grind off. If you have some thing that you are welding and can be planish you can get an almost perfectly seamless weld. You also need to pay attention when you are grinding not to stay on one spot to long or dig the wheel you need to keep the wheel as flat as possible to the panel to avoid grinding one spot to long. You also need to be patient it takes along time to do this don’t expect to weld the whole thing in five minutes and get that type of finish.

MonzaRacer
07-09-2007, 07:51 PM
As for welding take about $50 to $75 bucks to local welding shop and some scrape and your welder to a local welding shop and ask for the best MIG welder in the shop to give you an hours tips and practice.
Anyway I have a welder similar just like the mentioned Lincoln.
Mine is an Astro Pneumatic with 2 flip switches,min, max, 1, 2, and variable wire speed.
Best advice I can give is start with slow wire speed and mid heat (as you will find high heat will blow holes easy.
But the way i have is a max ,1, setting and I set my speed on waht would be around 4 on the lincoln if I had to guess, it should sound like a steady buzzing/arc with out pushing the gun or the wire burning up to the tip.
As for straight Argon your getting alot of extra heat in the weld as Argon wont cool aas well as CO2/Argon.
also if you dont ask the company that makes the wire whats best it can weld worse.
As for .023 not welding good or being hard to dress down, your weld should not be very tall if you do it rightabout the same height as the thickness of the metal your welding.
As for using a Roloc to dress down the weld it will do it but takes time AND they have to be on a grinder goint at least 20,000 ropm, they are not low speed gringind discs, a good 4 or 4.5 in angle grinder from Makita, Milwahkee, or even your generic tool supplier will grind down welds then use a Roloc sanding disc to dress it up better.
I also use a straight die grinder with a cutoff wheel attachment tool to grind down welds, its not as pretty .
Now as for air compressors being expensive if your doing this kind of work a $350 4 hp(110v) or 5hp(220v) 15 to 30 gallon compressor will do this work you just have to give it time to catch up if you use samll tank model and this extends dressing time.
Be forwarned if you look at compressors do not believe that a 110 compressor is a 5hp, 110v cannot make a 5hp compressor it a 4 hp, if you look at it the motor will be rated for 110/220 and most likely wired for 110 when you get it.
220v compressors are worth every dollar and they will keep up with even a cutoff wheel (mine is a DeVilbis made Craftsman 5 hp 30 gallon oil lubed) and be very wary of the oil less lager compressors, as they cant run as continuos as an oil lubed one.
also most oil lubed ones will run 20W20 oil(recommended) but I will use 15W40 Shell Rotella T in the winter and straight 30 weight in summer,,, if in the exposed to the current outside temps.
And lots of air flow help them cool so building a small shed for them isnt ok unless it has a big fan to move air through it.
But back to the welding. I used 035 flux core on my floor repair the other day, lots of slag, beads, and such and it liked to burn through the thin areas.
Before I had 023 and 75/25 and welded just about anything I wanted.
If you all had to work where I am now you would quit.
Right now I am in rock driveway , and 2 extension cords and my oldradio, a fan and my welder trying to build a car,,,,in the hot sun, no garage or car port(I may try get one assoonas my ESOP cash comes in).
As for the difference of hardness between mig and tig it depends on the filler, the heat used, the cooling used. I tiged theother day and used simple coat hanger rods,,very sweet and cheap. they last forever.
The fact of the matter I am a novice with tig and the heat control is awesome and you can nearly make a smooth weld.
for mig with any wire I would try to keep my pannel fitment with a single edge razor blade gap all the way around. Klecos and a backup tab to lay your patsh against while tacking is a neat way and you only 1/8 in hole to fill a mig will do it very well if you are a ovie welder put a pop rivet in the hole then weld it up.
If you have air a simple panel flanger will make life easier too as you can flange the area and then lay it in. you dont have to have a flange all the way around just 2 or three tab on floor pans and trunks just hit it with your finish prep. i f its a little warped a little filler goes a long way.
As for me i could care lesswhat the floor panels look like as long as they hold and can be made water tight.
also if your trying to mate thin metal to heavy metal its a dance of welding on the heavy metal and letting the weld grab the thin metal.
As for gas welding I replaced a whole quarter on my 70 Monte Carlo after caving it in with a replacement from another car with a gas torch and bailing wire( yes actual wire they used to bail hay with)AND I welded along the body contour/edge at top of the quarter panel and had it perfect till I thought I needed to pry it out and weld it.
Had a body shop offer me a job hanging parts for them!
My next roll of flux core wire is going to be 030 till I can afford to buy my tank.
Also you can use the "tack and smack" method to align a panel. If the contour is hard get it close, then tack in few places and beat it into submission (alignment) and weld.
Lucky me only has a few small holes to fix and a little mini tubbing to do other than fabbing the rear suspension from scratch.
als ounless your a master welder or have lots of experience miging a cage wont pass most tech inspection from sanctioning bodies. Been ther done that, had to go back overthe welds with TIG to smooth then.
Can it be done? Yes my old boss Paul Mann assembled a Zeeker Crome -Moly tube frame for his Turboed 91 Pontiac Trans Am,,,,and it passed so it can be done, it now runs a 427 sbc w/twin truboes and runs low 4s in 1/8th.
Good luck.