miller spot welder with timer no pentration

[ng8264723]

So I have a Miller welder which will weld but it does not make a strong bond due to lack of penetration. This machine seems simple enough. Any pointers?

 

[4307]

What condition are the tips in?

 

[Rj555]

What are you welding and which Miller welder are you using?

 

[JeepsAreBuilt]

Turn up the heat ? Weld longer ? backside of metal stripped ? recondition the tips so the taper is correct and flat ?

 

[toplessHO]

and adjust the pressure too

 

[Milton Shaw]

Those spot welders are made for very light gauge steel such as duct work for HVAC work. The shape of tips, amps, time and pressure are all important to get a good weld. Cars are put together with primarily spot welding and those are done with very big industrial transformer machines. When I worked for GM in the 60"s all the spot welders were manually operated and weighed up to 650 lbs that was counter-weighted to help the operator reach the exact location needed. All cars now seem to be done with robots that replaced about 1000 men in each body shop handling those welders. Those spot welders even had coolant circulating through the tips to keep temps down. Also coated steels will affect the weld. Practice with the settings of amps, pressure etc with scraps of the same material you are using until you get those settings right. The spot should be sunk into the surface if the temp and pressure were right. Keep trying. Look around your car body to see what I am talking about on spot visual appearance and keep at it until you have that appearance and then they will hold.

 

[EdT]

There is probably info on the Miller site or someplace online. IIR a spot weld is dependent on several factors. Current, duration, pressure, tip shape, and cleanliness of the metal. I frequently use the most basic hand held Miller spot welder and each time I test my joints before I start "production". The test is simple. I weld some pieces of scrap material the same as I'm planning to use and then I tear the joint apart and see what I have. A good joint will tear a chunk (called a nugget)of metal out of one piece or the other. If it just peels apart, it's NG. Varying any of the first four factors will make a change. My welder does not have a timer, so I count. The simplest change is to change the timing and that usually does it. I do redress the tips from time to time. They should be flat (not rounded) and about 1/8" in diameter. It's also important that the tips oppose one and other and are not offset from one another. Of course, all this doesn't matter if you're trying to weld material beyond the capability of the machine. After a while, you get a feel for what will be a good joint just by observing the HAZ and the interface between the tips and the metal. I've done hundreds (maybe thousands) of spot welds on repro parts and, as far as I know, I've never had a failure.

 

[AndyA]

As others said, you can't expect the handheld miller spot welder to do much thickness. Mine claims 1/8" of total thickness, but it doesn't really perform very well that thick.

The output of a spot welder is low voltage/high current. So any additional resistance really kills the performance (not enough voltage to push through much resistance). Clean and tighten the connections where the tongs are clamped. Longer tongs also lower your weld current.

Also I've had problems with shorting out from the braided strap to the case. In this case you hear the thing humming/buzzing, but get no weld output at all. Surprisingly it doesn't pop or spark or make any other indication of a problem. Just no weldy.

 

[rsanter]

I have a miller spot welder that I have been using for auto body panels, it makes very strong welds no problem.

Clamp pressure
Tip diameter
How long you weld and are you pulsing the switch
How clean the material is

Bob

 

[ng8264723]

http://www.ebay.com/itm/Miller-Port...item35f45b77cd:g:xgYAAOSwo6lWLq-9#ht_52wt_900
Mine is like the above but probably older. the case is blue. Even with the timer cranked the weld is weak. We are only welding sheet metal. I can't get the model number b/c it is at the body shop now. It's pretty frustration though. I bought it for one job and it couldn't do that. the guy swore it worked. I didn't check it until a few weeks had gone by. Those of you guys that have one. Do you have to remove the tongs and clean them? The tips seem fine we sanded them smooth

 

[rsanter]

Resistance welding is all about having a clean contact patch between the tips and the metal and then the two pieces of metal.
Clean all the contact points, and before that remove the tongs and see if the tongs are clean where they are clamped onto the machine

I have had the 110v version and now have the larger 220v version. The 220 is a way better machine but the 110v version worked just fine for welding inner panels and qtr panels onto cars.
Having the larger spot welder has made it possible for me to file the tips for a larger contact spot so my welds look very much like factory spot welds.
Have you tried it without the timer? I don't have the timer and mine works just fine without.

One thing I have learned is that if you do not have good clean contact between the two pieces of metal you will either not get a good weld or you can even blow a hole where you wanted the spot weld.

Bob

 

[ng8264723]

The metal that we were welding was cleaned as were the tong tips. I haven't removed the tongs yet. I will try that. Of note I was told the machine worked well and then was sitting for a few years

 

[EdT]

What gauge metal are you trying to weld? Is it a 120 or 240 volt welder? As mentioned above, I weld a lot of 19 ga SM parts with a 120volt machine. It takes about 4-6 seconds to get a sound weld. So, if the timer is cutting out too soon, that could be your problem. Approximately what duration of "on" are you getting? My GUESS is that the timer is an older RC decay type timer and it is possible that the capacitors have died which would alter the timing. Electrolytic capacitors often go bad just from sitting around so they may have been OK a few years ago and be bad now. Depending on the age of the machine, it could also be a more modern 555 timer circuit or something similar. I'm not a sparky so I don't know how to test the caps reliably. You could probably bypass the timer to see what's happening.

 

[ng8264723]

It is a 120 volt machine. I thought the timer was going for a good 4 seconds or so. The metal we tried was autobody sheetmetal for a mustang

 

[EdT]

Well, that's probably a good deal thinner than what I've been dealing with. Are you plugged directly into a wall outlet that's high enough current rating to do what you want? If you're on an extension cord or something, there could be a large voltage drop which could be the problem. Power drops as a square function of the voltage to if you lose 10% of your voltage, you're down about 20% on power plus whatever losses there are in the transformer etc.. If you're plugged into a duplex wall socket you could probably get a volt meter into the other socket and see what happens to the voltage when you try to weld. It will probably drop, the question is how much?

 

[MBfreak]

I have an Italian made hand held spot welder. The transformer is integrated and it runs on 220. Weighs around 15 lb
The "TIMER" on it is pretty smart. It is a dial, but the actual duration of the weld depends on the actual welding current. Clean surfaces and good tips gives a much shorter time than if surfaces are not shiny and tips burned.

With correct surface preparation it produces perfect spotwelds every time.

Ola

 

[EdT]

So, did you ever figure it out??

 

[ng8264723]

No it's at the bodyshop. I will grab it in a week or so

 

[wazzabie]

Do you have a dedicated 20amp circuit for the miller 120v spot welder? I have found the 220v version to be much better for autobody sheet metal work.

 

[WILD-BILL]

Do you have a dedicated 20amp circuit for the miller 120v spot welder? I have found the 220v version to be much better for autobody sheet metal work.

Do you realize this post is 4 yrs old?