How to Simulate Factory Spot Welds with a MIG Welder
Here's how you can simulate factory spot welds with a MIG welder and a few other simple tools. Plug welds or rosette welds made with a MIG welder are standard repair practice, but they don't necessarily look factory authentic. You will see how I fake the appearance of these welds to look more like resistance spot welds.
Carbide burr used - amzn.to/2CsHUSm
00:00 Simulate spot weld appearance tutorial
00:34 Resistance spot welder doesn't use filler
00:57 Entry level spot welders don't have long enough tongs to access all areas on a car
01:10 Plug weld or rossette weld made with MIG welder
01:44 Punch 3/16" - 5/16" hole in upper sheet metal
02:09 Clamp two pieces of sheetmetal tight together
02:35 MIG weld starting at center of hole and move to outside of hole in a circular path
03:23 Set MIG welder hotter than you would for a butt weld
03:42 Spray a light coat of primer
04:00 Use 60 grit Roloc disc to grind down proud area of weld
04:25 Use carbide burr on die grinder to put divot in center of smoothed MIG weld
05:40 Spray another coat of primer on
05:55 Use eraser end of a pencil to push primer up the sides of crater
06:39 Test simulated spot weld strength with impact hammer
This video series filmed in my home workshop highlights the technical details of my classic car restoration (An aircooled Porsche 911). I’m starting with a stripped out shell from 1974 and backdating it to the earlier longhood look. (Backdated Porsche means to make it look older than it is). It’s not easy to build a car in a small garage but I hope to inspire other gearhead minded people like me to build something cool with DIY style.
In the first few episodes I will focus on the autobody metalwork to transform this junker into something fun to drive. Extensive metal fabrication is needed to give the body the wide and low stance that I'm looking for. Metal fab can be time consuming but its the detail that set each car project build apart from the rest. My classic Porsche strives to be unique with custom hotrod touches throughout. There will be some rust repair in the front trunk area including the infamous suspension pan...home fab style.
I plan to update weekly videos detailing the customization of my classic sports car. This is a low budget build so I plan to make many of the custom parts myself wherever possible. I hope you enjoy my car vlog that will hopefully become an autocross racer or track car someday.
Engine plans are 3.0L+ with individual throttle bodies ITB
Custom brakes and suspensions mods are also planned.
Please stay tuned for all updates on this project series.
Product and tools info at www.ahhgaragetime.com
My Classic Car Restoration Future Plans
I plan to modify the suspension and brakes with improved aftermarket parts from Elephant Racing and Tarett Engineering as money and time allows. Larger brakes from a late model Boxster will be used since this car didn’t come with any brakes and they seem to be the best bang for the buck. The engine will be from a later Porsche 911 to with at least 3.0 liters and I hope to use a custom individual throttle bodies with a modern injection system and software.
In other words, this build will be a mashup of all Porsche’s best years. The classic look of the early lightweight body with a more modern air-cooled drivetrain. Call it a restomod or hotrod if you like, but I’m going to make it my own with custom touches along the way. Please join me in this detailed restoration journey.
Porsche...there is no substitute
Visit my website at www.ahhgaragetime.com or
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Here’s a recommended book.
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Thanks for watching! I will have a regular Saturday video this week also!
I’m detail oriented as well and I’ve done what you do with grinding a depression in the center but I really like your primer and pencil trick!
Cool, glad you liked it.
Great vid! I like the shorter “tips and tricks” format, it complements your longer, in-depth vids. If I could ever get my plug welds to look as nice as yours, I don’t think I’d ever want to hit them w the die grinder :)
Thanks man, I'll try to do more if I can.
I probably will use this method when installing my quarters. I look forward to following your build.
Awesome man! Thanks for joining this channel. I'm going to check your out now
Loved the video. Thanx for sharing 2 reasons to pronounce your spot welds. 1. To look as close to factory as possible. 2. In case the panel is ever replaced again , you can find the welds to grind out so as not to butch your panel.
Thanks, both good points. Hopefully I never have to replace again!
I think I will give it a try with my 46 Wiilys.
I just use a flat ended punch, and punch a dimple next to the plug weld look perfect with some paint on it...
That's a good way to go too! Thanks.
That makes sense as well.
this would only deform the surrounding area , i MiG weld is far too hard for a punch to dent in this manor
@@davidlaw7321 Not on the welds, but in between them...
To answer your question is it over restoration: yep. To answer your question is it something i would do: definitely!!
Awesome man!!!! I'm not alone....
genius
Speaking of details, it does matter which direction, if it has slag, you drag (flux core).
Flux core? Why use that on thin sheet metal? Yuk
@@GarageTimeAutoResto because it’s cheap and does the same shit.
Super useful. I am working on a project that the community historically has used spot welds for a particular application. I don't want a spot welder in my shop because the shop is small and I didn't want to buy a single use tool for a single job. I am an aviation mechanic who is familiar with rosette welds as a way to repair structural tube steel and engine mounts. I am going to cross this technique over to my new community for my future builds. Thanks!
Same situation here about not having space for another welder. Takes time, but only needed on viable areas!
thankyou for the good advice i will try it this week
Best of luck!
What?? A weekday video?? Awesome, as usual! I do the same thing, depending where it’s at.
I know right. I felt guilty that last weeks video was so long. Now I need to get back in the garage to film Saturdays video! I only have one day in the Garage this week.
That's a cool technique. I'm going to give that a try with my everlast welder
Cool, let me know how it works out.
Thanks as always
No problem! I hope it's useful.
That is awesome
If I had a very small area but not for an entire floor pan, I'd be happy with your original weld myself
Sure, thats fair. I only do this on highly visible areas.
this is some next-level ish. are you an engineer? or a mechanic? or just a weekend warrior? thoroughly enjoying every one of these vids. your patience and your attention to detail are astounding. and i’m so glad it’s a Porsche you’re building. keep up the good work.
Thanks, and yes I'm all three! To me the advantage of doing your own work is you can do this detail stuff. No one cares as much as you!
Shoot man I’m a beginning welder. I’m just happy when my welds stick lol however I can definitely see why you want to mimic the factory spot weld. It just flat out looks better. That’s something I would take my time and do once I get better at welding.
Just keep practicing. That's the only difference between a pro and beginner!
I just did this on some 1mm ss but with a stick welder, with mig if u want a nice structural weld u wanna start from the outside not from center
I think it's looks good pretty good tip thanks
Thanks Donald! It does look great once painted!
Just drilled out over 150 spot welds on a TR4a not looking forward to doing this to each and ever one ...that said its a good tip....Thanks😎🇬🇧🇺🇸👍🙏
It's hard work drilling them out isn't it. And you counted! I only simulate the spot welds in a few visible areas.
If it’s a special project (to me) id go the extra mile and make it as perfect as could be
Agree 100%. That's the advantage of owner builds....extra care the shops can't afford to throw in for free.
A tip to you since you gave me a lesson. You used the right primer. Self etch goes over bare metal when filler is not used. If using filler you spray epoxy first. Most Urethane primers aren't direct to metal. So, self etch primer first on all new metal, sand with 220 and then seal with epoxy for maximum corrosion resistance.
Thanks Harley! I really like the epoxy primer I'm using. It really sticks well to stuff and I don't mind sanding first since this isn't a production type job. In other words a labor of love
@@GarageTimeAutoResto I hear you on that, epoxy is always for the win. I'm going through the labor of love on a 69 mustang, and hopefully even more cars after this one. My love is bringing the car back to life, and the project itself. Good luck with your project :) looking forward to more videos
Great video. I'm about to do this on a 60 Ford pickup. I'm trying to figure out how to take it a step further. How can I simulate the spot weld entirely in metal? After doing the divit grind (after the MIG weld) I was thinking heating the weld and trying to dimple it with molten metal but I would imagine that would crinkle and warp the metal.
That would get everything too hot, in my opinion. But try it on a scrap first?
Neat trick
Thanks! It's time consuming but does the job
Pretty neat stuff, since you are doing a resto-mod I think it would be cool to seam/stitch weld your 911 as detailed in the factory 964 workshop manual (volume 5 section 51) to replicate the 964 Carrera RS body in white and its added rigidity.
Thanks Iggy! I was not familiar with that section in the 964 manual. I will definitely check that out. My only concern is rust protection on the backside of the welds. I'm also going to add some chassis stiffening parts.
Here is a link to the workshop manuals. The fifth volume near the end details the procedure (I just copied the link from rennlist) but yeah from what I’ve seen it is a tedious process getting the sealer out of the seams. www.dropbox.com/sh/vdyoerit6qoyja9/AACIDrY1oTL8sUS7wReYMEwPa?dl=0
If it prevents someone panicking about your restoration work then good. You haven't cut corners at all- it's not disguising a half arsed job. Like builders bog over scrunched newspaper in a divers door.
awesome!
Thanks, you must have watched it in 2X speed!
I can speed watch:D
If i were going to go to the extra work of making the welds look like anything other than what they are, I would just grind them roughly flat and fill any dimples. I don't think anybody but you would care, as long as the welds don't look awful. Thanks for the video.
Yep, most people don't care. It's really a technique for the concourse judges crowd or those who are trying for authenticity. Some cars warrant this detail and others do not. My car probably doesn't deserve this type of detail, but I did it anyway, ha ha. Porsche people are weird!
I never thought about until I watched this video. I drilled out about 50 on the rocker and haven’t welded it up yet. Something to think about
Some cars I think it's worthwhile.
Sorry but after year's of working in a body shop I can't say I have ever seen a spot weld that looks like that ! Plus grinding it like that is going to weaken the actual weld ! In fact when you come across a panel that has been plug welded in place, that's how you would separate the two panel's by grinding out the middle of the Plug weld to weaken it as you would drill out the middle of a spot weld.
Love it, the primer / pencil eraser trick is genius!
👍
Enjoy your video! Do you use a weld through primer? Saw some tests and they will rust inside around the spot weld burned primer Looks like the duplicolor weld through primer works good
I flood the seam with reduced epoxy primer after welding. I use a brush or syringe. Another great product is cavity wax. It wicks uphill..
@@GarageTimeAutoResto That is a very good idea, thanks for sharing 👍🏻
I use the spot weld drill bit after all the welds are flushed out I then use a very very light skim if fillers.. Not even a skim.. I just rub it through the little indentation the spot weld bit makes, then 2k prime it and a light sand gives a realistic enough finish!
Cool, so you drill between the welds?
Self taught and have come up with this technique except pencil paint idea 👍
We cheat whenever we can!
If I'm replacing a full floor pan, now can I remove the old pan at the factory welds, to install new pan? Or would it be best to leave factory welds, an just weld the floor in? Hope all of this makes sense!
Most guys remove the floor at the factory spot welds and plug weld the new ones back in. This is much easier than butt welding an entire floor. The trick I showed is only needed for a few areas that are visible.
@@GarageTimeAutoResto Okay thank you, wasn't sure if I had to butt weld or not. Thanks for the advice 👍🏿
Nice and like, tks T
Of course, thanks for watching!
Mate you are really digging into some nerdy ocd topics now. Which is Awesome!!!! Looking forward to a show on your power train plans and gear boxes.
I promise the engine/transaxle will be nerdy😀😀😀. It may take a while to get there at this rate.
I kinda thought about that process except for the eraser at the end. I would certainly take those extra steps on quarter fender lips, bottoms of inner and outers that are visible. I don't think that it adds that much extra effort. The details like this is what separates a good job from an excellent job. Do it on every job? Maybe not. Depends on the job, the goal and the customer.
I agree 100%. Some customers or cars warrant this level of restoration and some do not. Different strokes for different folks.
Its a little ‘to much’ i think but then again i think its a good idear because if you some day need to replace a part again, the spotwelds are easy to find. With the regular mig welds its almost impossible to find them :)
Great point! I sure hope I'm not replacing the same thing again!
that's a fun idea to make it look factory! i am detail orientated but that is still more than i would go for a complete restoration if i was only replacing a few parts than this might be reasonable but for a complete floor it is a bit overkill, i just grind the rosette weld flat (don't like seeing a large bulge). the motor mount looks nice, what is your tig welder setup? looks like you are running a cooler! :) -912r69
That spot weld trick is only for highly visible and painted surfaces. For instance I did this on the battery and gas tank supports. My TIG torch is an air-cooled one, just like my 911 and 356, ha ha. It's a miller diversion 180 with a CK torch.
Can you tell me the thickness of your welding wire please?
Sure, .030"
I'd probably just grind it flat although you wouldn't know where your spot welds were when you paint it so I'd probably use a punch to put a little dot in the center
👍
thanks for trying and sharing, but it's not even close.. maybe with some modification upon your base inspiration it will be perfect again, thank you so much salam
Close to what?
What do you set your welder at?
I have a Miller 135 and I set the heat to 5 and the wire feed to about 45
Easier to do this with a tig welder
I make it proud then grind it flat and when I primer I use a pencil eraser and put the dot in. And yes I do it for 2 coats so it doesn’t look like a nuclear blast like yours just saying
Thanka
I dont see a lot of people using TIG welders in car restorations. Mostly MIGS. AM I off on rhis or is rhere a reason people prefer MIG over TIG? I own a MIG, but plan to buy a TIG at some point. I also have a plasma cutter. Dont see a lot of people using those on cars either. I much prefer it to a grinder.
Yep, times are a changin'. All the high end resto shops use TIG now and many guys like me do too because the cost has come way down. I made a video on why I prefer TIG over MIG. Link below. kzhead.info/sun/iJeBpshubqB7omg/bejne.html
TIG uses A/C so not great with all the electrics etc in modern vehicles, even when isolated. so in general within the industry MIG/MAG is used, Obviously TIG is fine on cars that are stripped to a shell though
How do you spot weld when you don't have place to clamped other side
The table is metal and the ground clamp is attached to the table.
@@GarageTimeAutoResto Yes, but I mean one tooth goes on top and the other goes in the bottom to provide the bitting force to weld two metal sheets but what if there's no surface for the bottom part of the tooth to bite on?
VW must have used a different spot welding technique on 914s. None of my spotwelds had any indentations and in removing the inner firewall I had almost finished before learning the technique that prevented the cutter from spinning all around the area. Do you have an IGBT welder? I ask because both my stick/TIG and MIG welders are. My welding school instructor practiced with my Everlast 200 ST and found that on stick it required only 58% of the power that the school’s Lincolns and Millers used. I’m wondering if I should use the 58% as a starting point for MIG settings
That's weird you can't see the spot weld indentations. Did you strip the paint? It is hard to drill spot welds without wandering. My TIG is an IGBT welder, but my MIG is not. I tend to run my MIG welder on a hot setting because I'm usually using it for plug welds or heavier metal stuff. If you are using to butt weld then you need to use trial and error. It's hard for me to explain here, but I use technique to prevent blow through as opposed to the welder settings. Sorry if that makes no sense, but I whip the torch around quite a bit.
@@GarageTimeAutoResto I found that the successful method of cutting out plug worlds involved a lot of kissing. You hold up the drill to the weld and let the cutter just “kiss” the metal until a shallow groove is formed. Once that is there, increased force can be used to actually grind away the metal. Unfortunately for me I was almost finished with the firewall.
That's what I do too. Sometimes if my cutter is dull, I will center punch it and then start a hole with a 1/8" drill bit. No matter what you do it's hard work.
Try using a gas welder to fuse the panel with little or no filler rod.
My experience is that starting with hole is the best way to guarantee penetration to the lower layer. I suppose you could gas weld through a hole, but I've never tried that.
@@GarageTimeAutoResto Eastwood use to sell a spotweld gun rhat used an arc welding electrode. Only place Ive been able to find it is on Amazon UK. www.amazon.co.uk/Spot-Welding-Gun-Carbon-Electrodes/dp/B00UTSCDNU Eastwood now sells a mig cup and plier set for spotwelding. They also do a tig version. You seem to have a handle on it, Im just sharing my own. knowledge.
I like it. I just worry about blowing holes through the material. I been getting a lot of practice in spot welding making a duel wheel well for an RC trailer. I need to start using my gas instead of flux wire when I do that. Just found myself in some spots having to chose my battles. The front view where my 1/4" steel meets 22mm sheet metal. Took me a long time but when I finished I made it look like 1 piece.
Welding different thickness material is tough! Good job
@@GarageTimeAutoResto thank you kind sir! I just need to keep practicing. When I complete my trailer project I will post it up. I still want to make a longer tongue and redoing the ramps where they come up and lock in place. Right now they slide under the trailer from the sides.
What would happen if you used TIG? I’m not sure how strength of resistance spot welds compares to TIG fusion spot welds or TIG plug / rosette welds. m.kzhead.info/sun/ZpGFg9l-qqOlips/bejne.html
The TIG in video works well for perfectly fit panels where you can clamp with pliers. There are many areas on the suspension pan for instance where you can't get a good clamp. That is where MIG is more reliable because there is a hole in the top layer. As always, many way to skin the cat.
I think the original Mig weld looks better than the "Doctored" one.. Why do you need to simulate factory welding.
Because I prefer that the repairs are non detectable to the average eye.
I prefer my spot welder.
I thing its better when the welds are not showing , looks better
Agree, but sometimes factory appearance is worth more $$$
@@GarageTimeAutoResto may be, but if the car is restored the value is in the restoration, restored cars normally are better than the original, that makes them worth more too .
The correct way to plug weld thin sheet is to use your welders timer relay and crank up the wire feed to max. That way you never need to drill the top shetr, the plug weld fuses both sheets through and through
That makes absolutely no sense at all
think you may have too much time on your hands :], would have focused on sealing the two pieces of bare sheet metal you stuck together, in about a year or so it won't matter what the spot welds look like, because all the attention will be on the developing rust... JMO but thanks for the video
True, I recommend weld thru primer, then flood the seams with epoxy primer, then cavity wax on internal panels. Then seam seal and paint.
I can attest to the usefulness of this tool. www.harborfreight.com/air-punch-flange-tool-1110.html Beats drilling and deburring holes for spotwelds.
Yes, I agree. I use the hand style punch.
You could be weakening the welds.
Maybe, I tried to separate them with an air chisel and could NOT.
Thats a whole lot of work to fake it. And it does weaken the weld. Just buy a spot welder
The trouble with spot welders is that they don't reach into finished cars without very custom tongs. In which case they can't pinch hard enough for a safe weld. Rosette welds are much stronger for repairs even if a little is taken out of the center. I even tried to break this apart with an air hammer.
@@GarageTimeAutoResto There is spot welders that don't only use the tomgs
Sorry, those don't work well.
@@GarageTimeAutoResto You'll come up with any response to make your point of view make sense. Maybe you don't know how to use them. When removing factory welds you have to replace with the same amount and more. But you can do all that extra work.
It's not just me saying it, rosette welds are the industry standard for repair work. Check ASE and ICAR
Best way to replace factory spot welds is with a squeeze type resistance spot welder, like the ones made by ProSpot and Elektron Bremen. Both these brands are approved by the major manufacturers to repair their cars to factory acceptable specs . These machines have all the factory settings preloaded and automated, so all one does is adjust the settings for the appropriate gage of metal and type of metal , then pull the trigger. Any quality repair shop should have one these welders or another reputable brand. The cheap spot welders don't cut it. And spot welders used in non-automotive industry are also not designed for this type of repair so won't have the appropriate squeeze pressure , amps and hold time set in the machine. If you are spot welding Boron Steel, which is what certain structural parts in some cars are made of, you need a spot welder, as a MIG welder will input too much heat, consequently compromising the integrity of the engineered part. Plug welds using a mig welder is the go-to option if you can not access both sides of a panel or component, which is obviously required by a spot welder.
I agree, I've seen a ProSpot in action and they are incredible! But way too expensive for DIY'ers like me. Even the PRO shops around me that specialize in vintage Porsches don't have them.
@@GarageTimeAutoResto Yeah they are expensive. I am in a 1 year Tech school program learning AutoBody & chassis repair , alignment and painting. At school we have a ProSpot I4 , which cost the school around $24-$26K. We get lots of hands-on time with it. Apart from cost, ProSpot welders are ideally suited for 3 phase electrical supply, which many small shops don't have. The ProSpot owner's manual does mention the use of single phase but I am not sure if that means ProSpot makes single phase machines also. The body shop that fixed my truck didn't have 3 phase. They used a Millermatic to make plug welds on the truck cab.
Yep, a shop needs lots of insurance business or a lot of business in general to justify that equipment expense. I agree with you that the hand held units aren't up to the task with repeatable results. Gotta spend the big bucks to do it right. That's why us hobby guys do the plug weld thing. They are strong and cheap, plus I can reproduce the appearance of factory. It just takes more time. Of course a better tool can do it faster, but I can only dream. Thanks for sharing your experience and best of luck on your new career. Are you going into classics or general collision repair?
@@GarageTimeAutoResto Thank You While the program is intended to educate people entering the collision repair industry, I plan on building rat-rods , restomods and restoring my sister's Defender 110. This program does teach a lot of stuff that classic car restorers and custom car builders will find useful, such as sheet-metal shrinking, stretching, hammer+dolly work , oxyfuel welding & brazing , pre-paint prep and painting . School gives a lot of importance on repairing per manufacturer specifications. On following I-CAR guidelines , and I-CAR certification is advised. While a ProSpot is costly, it is actually cheaper when you consider the risk of liability from a repaired vehicle that is involved in an accident. The ProSpot logs the number and type of welds done on a vehicle, which can be used to provide evidence to insurance companies and in civil suits / criminal suits.
I'd be shocked if they had specific settings and locations for a 1974 Porsche.
What a waste of time. Plus it looks bad