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H/F Spotwelder w/ AK-Builder Lower Tong??

1701 Views 24 Replies 13 Participants Last post by  2ndAmendican
Hey folks. To those of you who have this model/type spotwelder, have you had issues with the lower tong tip heating up to the point of failure (melting) until you have no tip left?? I have only welded the rails into 3 receivers, and the lower tip is gone!!! I tried to clean it up and re-adjust my handle, and press on, just so I could finish the task, and now it's toast. (I did finish though) When it first started to fail, it almost blew a hole straight through the receiver. It happened so fast, that I was lucky to catch it in time. All the other spot welds I did were based on the appearance of the glowing red spot, and came out great. Probably about 10-12 seconds. The one when it failed was about 5 seconds in, and then it started sputtering and shooting slag out. I released the switch, and immediately pulled the receiver out of the tongs. Hole went about 3/4 the way through. Will have to have my buddy TIG it up for me now. Any rate, about half of the length of the lower tip was just melted away, with bits of slag from it all over the place.

Where do I find replacement tips for the lower tong??? I thought someone had said National Welder's Supply, but I couldn't find anything on their website. Any and all help/advice is much appreciated.

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Those tips are the uppers. They won't work on the lower tong. His site says that if needed, the lower tong tips are a screw in replaceable type, but I didn't see any info as to where to get them, or a part number etc... If Curtis was open today, I'd call him. I was hoping to find out so I could pick some up this afternoon on the way home from work, but that idea is a bust I do beleive. Thanks anyway Sjohnson.
Hello 2ndAmendican,
Sounds like you were really cookin' with your spot welder !!! If your lower welder tip is a screw-in item... remove it and take it to a good hardware store (not lawn & gardern type) and look for a small copper bolt that can be customised for your application.

I made my HF spot welder lower tong to use a large copper rivet (no threads). If you have a lathe you could make a bunch of tips from solid copper rod. An electric drill and some files may also work.

Cooking the spot weld for 10+ seconds is a bit much. Little wonder that your tips melted into a blob. The trick is to get a short burst of electricity to quickly form the weld nugget. Cut the power. Leaving the tongs clamped for a few seconds after that. They then will pull some heat back before releasing the part. That insures the weld has cooled enough to knit strongly together. Industrial spot welders often use water cooling through hollow tongs to allow production and heavy duty spots.

Viper Dude is spot on. You could also take the lower tong to the store and try various TIG tips until you found the one that fit.
Geeze....I use the 110 volt model & 3 to four seconds is tops. Probably not even that.I count 1,2,3,4 pretty quick & release it.
Wow 10 seconds is way to long.. My tips have over 50 build on them! and just now starting to where. 3/4 seconds max leave clamped let cool move to the next. If you do not let your tips cool they will get deformed!
The spot weld area on the receiver doesn't even start to glow until after approximately 8-9 seconds. The spot welds that look picture perfect were right at about 10 seconds. This was with the spot welder plugged into a regular multi-plug strip, which I did to give me GFCI capabilities to keep from overloading the room circuit. I didn't know about leaving the tongs on while the spot cools. I always released it from the spot immediately. Is there a you tube video of a "proper" spot weld procedure?? I really need to see one being formed. Thanks for the input guys.
Third video Build Videos
I didn't notice any others on YouTube but I'm sure they're there.

About the "keeping it clamped" part. Think of it this way, your melting the two pieces of steel and keeping the tongs locked a little after the weld is done, the clamping force is squeezing the melted steel into a tight single piece, if you release the pressure to quick it allows the two pieces to separate a little (most likely a few thousands of an inch but that could be enough to weaken the weld a little)

The multi plug strip is most likely acting like a voltage/amp reducer, that might be why it's taking longer.
Thanks Coils. I found that one, but it sure doesnt look like what I experience. That whole procedure takes ALOT longer with my H/F unit. When I used it direct plug style, it burned through in about 3 seconds, so I used an extension cord to try to control it better. That one came out OK, but the spot welds were UGLY and pitted. The last 2 came out much better with the plug strip, but the tip was burning up. I have an old scrapped flat, so I guess once I get some more tips, I can play around spot welding until I find the sweet spot. Thanks for the input. Any and all is MUCH appreciated!!
I have the HF version also and it should be 3/4 seconds. Best not to use the extension and focus more on short welds that it was designed for. once you practice a few times you will get the hang of it.
Your welcome and I wish I could help more. I can only say what Pat did for right now, I know it's usually takes only a few seconds on this thin steel. I'm not sure why your having problems with the tips though?
Are you getting the right clamping pressure?
It sounds like you are just touching the metal, are you holding down on the handle while welding?
When I used it direct plug style, it burned through in about 3 seconds, so I used an extension cord to try to control it better.
Did the welder come with an operating manual? If so, you might want to take a look at it, with special attention to the manufacturer's recommendations about the electrical hook up.
AKarl, I'm not sure how much pressure there should be when clamping down on the handle, but I have the tongs adjusted for what I would consider a "medium" amount of pressure.

ACMcom, I do have the manual, which is just basic info. Most of the info I have used over the last year (with regards to the spot welder) has been from other people's experience here on Gunco. Several people said that to "help" control burn through, that they tried varying lengths of extension cords, to help decrease the power somewhat. When testing on some scraps, I had burn through in about 3 seconds, so I hooked up an extension cord. It definitely helped, and I was able to spot weld the rails this way. I didn't really have any problems until this last receiver. Even on this one the first 4 welds looked darn near factory.

How long should you let the tips cool down after each spot weld???
I leave the work clamped together for at least 3 to 4 seconds after the metal stops glowing. More time spent with the spot welder off also helps to cool down the welder as well as the work. Most welders have an on/off duty cycle rating any way. Keeping the tips clean will make for a better weld, and will also require less time and current to weld. I hope this helps.
buy both parts upper and lower. I did and they are perfect. G.W.
GWSmith, what do you mean "buy both parts upper and lower. I did and they are perfect."???
I have had my tip fail on my welder but it is home-built. Sounds like the issue you are having is what I've suffered before since you are needing them to be there for more than 3 seconds.

It is probably a combination of several things:

1. Bad connectivity between pieces. Most likely the case.

If you're welding rails, you need to make sure they are CLEAN and free of oils. Also make sure the area to be welded is free of coatings and "bare" metal. Use some sandpaper, scrape the parts clean and degrease with carb cleaner or something similar.

The tongs should *only* be touching at the tips. If you have them situated in such a way they are touching several places then you'll get current running and the parts will heat up, but no welding. The tip gets red-hot and destroys itself.

I have found that if I prop up the welder on boards it will make work a little easier since you aren't fighting all the pieces. I wear gloves, and hold the receiver in place with one hand and the welder handle with the other. They should clamp together firmly but not "vise grip tight". I do use C-Clamps and/or vise grips to hold the rails in place until the first weld. If your tongs are touching the clamping tools, the heat will transfer and you'll get them red hot but no welding! Grind on the tong arms if you need more clearance.

2. Bad connectivity at the tip.

If your tip is heating up, LET IT COOL DOWN again before welding. The best welds I have gotten is on cold metal, giving it 10 minutes between welds. Yeah, go watch TV or something and come back every 10 minutes. Also cover the metal so it doesn't cool down so quickly to minimize warpage. Makes a world of difference on how much warpage you get.

1-2-3- if you're using the 110v model, you need only to get the metal to that orange-red color and it takes perhaps 3 seconds on the timer. I count One Mississippi, Two Mississippi, Three! In a normal conversation pace and then that will do it for me.

Also, as I said I hold the receiver. If I get bad connectivity, I'll wiggle the receiver gently until it "makes contact". It is very obvious when it does as you hear that electric hum and the metal glows orange. THAT is a good connection. If it isn't a good contact it will spark and stutter some and just get hot. If that happens I stop and re-clamp the tongs. And wiggle some more.

You should assume all the parts are going to be bowed just a little and behave accordingly. Again, those clamping solutions I use help tremendously. It is a PITA to clamp everything down, to be sure, but it helps until that first critical weld can be made. YOu may need to adjust the tongs to have more pressure against them. When you push down the handle, it should be hard enough to hold the receiver in place without help. If you think about how hard it is to push a stapler handle (the big ones) that is close the the right pressure. Maybe a bit harder than that.

3. Scale buildup on the welder tip.

File it down gently in-between after it cools down so the copper is shiny! Also, the BOTTOM of the tips can scale up too!!!!! Be aware of that. Mine is loosening up in the arm so I think it is arcing in the threads. I take my tip out, clean the threads with a wire brush and put them back in the tong. A *GOOD* threading should not arc, but if the tip is getting that hot, it can deform and get loose. At that point it is probably time to buy a new tip.

Mine is right now loose enough that it will fall out if I tip it over. It will still work but it is really a pain. I clean up both ends and lay it down in place and I can manage. But it does get that hot and I really need a new one. As has been said, just get a copper bolt from a good hardware store, tap the thong, cut the bolt to shape and install!

I don't know what to say about extension cords. I have a 20-amp socket and I plug it in directly. I think some people need them for the 220 models, and I understand those are a "one Missi" count.
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Also, as an added note...

If you have bead blasted (glass or aluminum grit) the receiver/rails, you will have trouble getting a good weld. I bead blast, then where the rails are spot welded on, I use wet/dry sand paper to smooth the areas on both.

Then I spot weld the rails. Once this is done, I then re-bead blast to provide a uniform finish prior to phosphating.

Trying to spot weld without doing this will cause arcing between the two surfaces and it will not weld.
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