Vinnie,
Here in most states in the U.S.A. it is not legal to do body panel replacement with this type of spot welder. The reason is that it is very operator dependent. At our stamping plant we did lots of spot welding for Ford, Toyota, John Deere and others. Your controls on the factory welders allow you to give the weld pulses that in the case of zinc coated materials first burns through the zinc with a low amperage pulse then it hit it again and maybe more than once to make the weld. During the course of the day you are required to do weld tear downs to check what they call Nugget size. The two panels cannot pull apart it has to pull a chunk out of one panel and leave a hole. If you fail a weld tear down you have to quarantine the previous parts back to your last good tear down and you might have to add welds or scrap them. You get about 3 cents per spot weld as a supplier to automotive so not big money.
Now all that said I do have a Miller Spot welder 220 Volt that I have used successfully, but it is not legal to do work for others.
Obviously the factory units have water cooling to the weld tips and they are quite large over 100 lbs. so they have balancers attached that allow the tips to turn on any angle and remain perpendicular to the metals surface. Most today are attached to a robot that does that easily. There are schedules programmed in for weld tip changes or in the case of a robot you have an automated station that actually recuts the tips while on the welder. The points mash out and get too large and the current is not concentrated enough.
There are some smaller Home or Small Shop units that do have water cooling and better controls and will do a much better job. You might do some checking and see if you can rent a unit since you are not going into the Beater Shop business.
This is similar to mine.
https://www.ebay.com/itm/MILLER-PORTABLE-SPOT-WELDER-WELDING-MACHINE-LMSW52-LMSW-52-18-220V/133252727339?hash=item1f067b422b:g:YsUAAOSwEDFdxwRj
If you do go with the one you are looking at you will need lots of practice. It is up to you on how long the current is on, you pull the trigger. You will need a set of the long reach arms to get to all of the weld and you will probably not be able to get to all with spot welder. You will need lots of clamps to get everything in place and correct location.
A big CAUTION. The weld arms will get very hot I burnt a friends arm helping me once really bad and it just touched him for a second. Keep a big bucket of water handy so you can quench the arms to cool. As the arms heat up the resistance changes so your welds change.
You will need to remove any of the so called weld through primer on your panels. At the factory on seams they used and expanding weld through seam sealer. Once welded and in paint operation the heat makes it expand to fill any gaps. I doubt you can locate that for personal use. You will need to practice a lot, do weld tear downs and check that your weld tears the metal and that the spots do not pull apart. The welder will come with some instructions. You cannot weld really close together. The current will jump to the adjacent weld and you will get a bad weld if too close together.
I will get you a welder name that is a step ahead of what you are looking at but much more cost. The name escapes me right now.
The weld tips are not cheap around $30.00 US for typical pair. There are pointed, round nose, flat and combinations of each for different situations. We used some that had been cryogenic treated to lengthen life and also Tungsten tips.
How I ended up with one was my X wife crashed the 20th. Anniversary Mustang I bought new. It required a frame pull of over 4 inches to get the front rails back. It also required new radiator support, new left and right inner panels from shock tower forward.
Was on frame machine first the we got all the panels clamped in place and measured out. Then we welded them with the spot welder. Would stop and cool it and do a test weld on scrap part and check. We rebuilt and painted the car in 9 days and worked full time job while doing the repair.
As the X wife was a horrible driver she crashed it again and needed new front fenders hood again. The radiator support and inner panels were not as bad but did need a frame pull. I was there when he pulled it and figured the panels would tear apart but the spot welds held and he got the front end back to spec.
So yes you can get good welds with the portable spot welder and yes they will look original. It does take some learning and skill which we all have seen how capable you are at learning new skills.
There are rebuild shops in the U.S. that do have tested and approved spot weld equipment for doing panel replacement but they are expensive. AMD and Grave Robbers are two of the shops in Georgia that have good equipment but they still use MIG and TIG in places.
Here is a link to info on AMD. They are more into GM and Chrysler but I do see the Ford logo there also. They have done bodies for my friend that does restorations. You can see one of the spot welders there with the heavy arms that can really clamp the material together.
https://www.amdinstallation.com/
Grave Robbers is not as good a shop and neither of them do the body work just panel replacement.
https://www.graverobberssheetmetal.com/index.php/custom-frame-jigs
As you see both shops do use chassis jigs to keep everything in alignment which makes it much easier to get good panel alignment. I think both have online quoting also. You can get a price of about any type work without being there.
You can see lots of clamps in the shop at AMD and you will need also. You should figure out some way to support your car in the same way they do. Can be stands of wood or jack stands that you shim to get the chassis level on the original Datum points.
I will get you a name for the next step better welder. You might uses it then sell it unless you are going to do another?
When you are spot welding if you see big flashes and sparks going everywhere the metal is not being clamped good enough which causes an arch that splashes the molten metal out.
We use to weld the front floors for the Econoline van the whole floor for the Aerostar Ford van. The BMW X-5 floor pans. Lots of sub assemblies for Ford, and BMW. We had hundreds of welders.
I am sure you can do a great job as you always do it is all dependent on panel fit to get a good weld. I also like to braze some areas right on the edges for insurance.
