Thread: Dorman spot welder help needed.

Hi, I have just acquired a used 30KVA Dorman spot welder & am having trouble getting it to work. It originally came from the ACT TAFE, fitting & machining section. The model no is 1/PS/201/C with serial No 1330.

It appears to have done little work & since I don't really know much about them I am hoping I have missed a step when trying to use it.

This is what I have done so far:

Connected airline - top electrode lifted away from bottom

Plug into power - 32amp 3 phase

Switch on main switch

Got two pieces of 1.6mm in place & pressed foot pedal...nothing happened.

Then I thought maybe I should hook the water up as there may be a pressure switch to prevent overheating...did this, still nothing.

Now, this machine has all sorts of adjustments including "cycles squeeze time", 'cycles weld time", "cycles hold time"' "cycles off time", "heat control" & "weld time range". It also has two toggle switches which are "weld - no weld" & "Non repeat platen delay - repeat"

I haven't adjusted these accept the "weld - no weld" toggle, which didn't make any difference.

At the rear of the machine, on the transformer is a large rotary switch going from 1 to 6, I have tried this in a couple of positions...again no luck.

Apparently these machines were fairly common, so I am hoping someone here knows a bit more about them & can help me out...perhaps the machines is plain stuffed??

Anyway, any help or suggestions would be great. Thanks WC57

Longish shot. Give the squeeze time pot a spin.
Is there a red power on light on the front of the control box?

Good luck

Stuart

Thanks for the reply Stuart. I played around with it a bit more today including adjusting the squeeze time knob down to zero...still no good. There is a red light that comes on inside the control box near the three big fuses when the main switch is turned on.

I have checked all the fuses that I can find, including the 3 glass ones in the control box, behind all the adjusting knobs & switches.

I also checked the operation of the foot pedal with my multimeter & it is fine.

This machine look like new inside & out, very clean & no signs of damage, it would be a shame to see it go to scrap.

An operating manual would be great if anyone has one. I have searched the net without luck...it feels like I may be missing something or some step in switching these things on.

Thanks again.

Got a picture of the front panel?

The old controllers are pretty basic just four timers in series.(unlike the new ones is seems).
You could try turning the squeeze time pot while your foot is on the pedal. I was hopping the pot was just a little dirty, the rest aren't going to do anything until its done its job.

You could be right it might be something simple

I dont understand "heat control" & "weld time range" as a pot. As a switch they would make sense.

If it ends up that the controllers toast, its not the end of the world to replace or even do without depending on what sort of use you have in mind for it.

Stuart

Found this on Google, they bought out Dorman on 1983. Email address is [email protected]


INDUCTOTHERM GROUP AUSTRALIA PTY LTD

62 Bardia Ave Seaford. Victoria 3198, Australia Ph. +61 3 97866000
Kryn

Sure, I will try to attach a pic of the control panel here.

I did email Inductotherm on Tuesday but have not received a reply, I will ring them today.

Hi, I just spoke with Inductotherm & they appear genuinely interested in trying to help me out. Unfortunately one service guy is on his way back from overseas & the other is off sick today, but the lady said she would look around for any info she could & email it to me

One pic below shows some wires running from terminals marked Emergency stop up to somewhere in the main transformer. I will follow it up & see where it goes.

The other shows the four big fuses I have checked. The two on the left are only 2amp & the ones on the right are 6amp. I would have thought there would be a main, bigger fuse somewhere?

Did you find an emergency stop anywhere???? It might be that it is in the OFF mode!!!!! Or someone has cut the switch off??? As it came from a TAFE, there would be micro switches on the door panels, guarding etc, if they are not in place, it won't work either.
We have a machine where I help out that someone keeps bumping off, via this switch, bloody nuisance.
Kryn

I reckon Kryn is onto it - being in a TAFE, its quite possible the E-stop switch was wall or floor mounted, and was probably just cut off when the machine was removed. If you take the two wires off the terminal strip there (obviously with the power off) and test between them for continuity, you'll probably find they're open circuit, as stop switches should be 'normally closed'. Meaning that in theory, if that is what you find, and you can't locate any E-stop buttons on the machine, you should be able to bridge those two terminals together and it should operate just fine (minus an E-stop, of course). Personally I'd go looking for a contactor that it operates somewhere on the machine, and verify with a multimeter that the wires on the other side of the terminal strip do in fact go to operate a contactor or similar first though.

Thanks Jekyll & Hyde, I traced the E Stop wires back as far as I can go...they disappear into the main transformer somewhere. I have admitted defeat & have a sparky coming tomorrow morning to check it out. Fingers crossed it is something simple, will let you guys know how I get on. Thanks again

As you're the only one going to use it ATM, .I'd put a bridge across the 2 terminals, just to see if it works, then put an emergency switch in, once we know that is what the problem was.
Kryn

I worked for a while in a place that did spot welding, so I may be able to help with what the controls do -

To get a decent spot weld, the metal has to be clamped firmly together and then a current passed through the electrodes, high enough that the resistance between the two pieces of material heats the joint locally and melts the materials. The pressure then forces the pieces together and holds it until the molten 'nugget' solidifies and makes a weld.
Typically the timing for these is measured in cycles (cycles per second = hertz), so in your photo, a hold time of 25 cycles is 0.5 seconds.

Squeeze time = hold time before the weld is made
Weld time = time the current is applied for. This would be used in conjunction with the 1 to 6 transformer tapping elsewhere on the machine to get the right heat in
Weld time range = adding 10's to the weld time (guess, but probably good)
Heat control = a chopper arrangement like a light dimmer that limits current
Hold time = time that the joint is held after welding
Off time = time before making the next weld
Weld/ No Weld = setting to turn off the current - sometimes you want to check set up or electrode pressure
Non repeat/ repeat - some times you may want a row of welds. I'm guessing that allows you hold your foot on the pedal and lets the welder repeat the cycle.

While spot welding looks simple, there is a lot of science behind it if you want to get into that. Electrode tip size is important, as is tip cooling.
The standard reference that we used was the Resistance Welding Manual by RWMA (Resistance Welding Manufacturer's Association). My 4th edition has an ISBN of 0-9624382-0-0. It has a lot of the background metallurgy about the process but also suggested settings for various thicknesses and materials. You might be lucky and find one second hand on line somewhere.

Sometimes there is a contactor that controls the application of welding current. I'd be checking whether that is working - if it has been sitting around for a while it may be stuck in the off position and need freeing up.

Michael

Thanks Michael, very helpful information. I think you might be onto something with you comment regarding a contactor controlling welding current. Hopefully I will know more by the end of today. Regards Bruce

Originally Posted by Michael G

Sometimes there is a contactor that controls the application of welding current. I'd be checking whether that is working - if it has been sitting around for a while it may be stuck in the off position and need freeing up.

But that would only come into effect after hold time. I assumed by "nothing happened" that the OP meant the electrodes didn't close.
Now it could be the air solenoid, but I'm pretty sure you would still hear other things happening if it was trying to weld with the electrodes open. Maybe they are both stuck

p.s. Bruce if you have an analog watch(even a quartz one) take it off before you start welding unless you like time travel

p.p.s

Originally Posted by Michael G

Heat control = a chopper arrangement like a light dimmer that limits current

I'd like to know more about this as I didnt think transformers responded well to clipping.(but what else could it be?

I was looking for something else but here is a copy of a procedure I wrote on spot welding as well as a spreadsheet for basic setting up and QC of the process.
SPOTWELD.DOC
SETTINGS.XLS

The heat control stuff is out of my reference book. Without seeing the machine it is hard to know what it is and how it is set up/ constructed - I could be wrong. However, materials like stainless steel don't conduct heat well and although they spot weld very well, a standard steel setting does not work as well. With my little hand held unit I normally have to hit SS twice - once to heat it and then to weld otherwise fusion is not as good.
Attached are the pages on heat control.

Stuart's stuff.pdf

Michael