spot welder power settings

[rhubarbray]

Hi everyone,newbie here. I had no idea the welders forum could have so many members! Perhaps I`ve come to the right place.
I`ve got a spot welder I`m trying to use for thin stainless sheet. (.020") Problem is, it`s way too powerful and there`s no adjustment. I`ve been looking at some way of toning down the power and was wondering if I can use a variable speed control device for controlling the input voltage. The welder is a 110v AC. Would this work?
The owners manual that came with it stated that for that gauge of steel the switch should have to be depressed for 2-4 seconds. I can`t hold the switch for more than 1/4 sec without blowing holes through both pieces!
Any help appreciated.

[DesertRider33]

I don't know much about spot welders. From what you said about blowing holes through it in 1/4 sec when it should take 2-4 sec to make the weld, I'm wondering if you have the polarity backwards?

[RancherBill]

I looked at a Miller spot welder and the length of the tongs seems to cut down on the power

http://www.millerwelds.com/pdf/spec_sheets/SW1-0.pdf

[rhubarbray]

There`s no polarity to adjust. Plug it into the wall, push switch. I did see the comment about longer tongs limiting the current,.......what about making longer tongs with thinner rods? Instead of 1/2" copper what about 3/8" brass? I think 1/4" or 3/8 copper would bend too easy for a sufficient grip.

[mrandrei]

You can actually use a buck transformer to minimize the voltage to the spot welder. Or a variac.

[Billy]

Assuming we are talking about a resistance spot welder ?

Measure the surface area of the electrode tips and reduce the face surface area to about 3mm, as when you reduce the surface area the "grunt"will reduce.
You may need to trial and error a bit.
It is best done in a lathe but can be hand ground.

Make sure that the contact surfaces of the electrodes are meeting flush and square, adjust if necessary.

DO not use brass, use only copper.

[pulser]

The main variables in resistance welding are the current, the time, the clamping force, and the electrode design.
Obviously, higher current and/or time puts more heat into the weld.
Clamping force affects the resistance in the joint. Low force is higher resistance and more heating. Increasing force makes better contact, less resistance, and less heating.
The effect of electrode design/dimensions I'll leave to someone else.

[rhubarbray]

I re-read the owners manual and found I had misread one part. Th length of time for the weld to take place wasn`t 4 seconds it was 4 CYCLES as in Hz! How the heck is anyone supposed to accurately depress and release,...many times,... for 1/15th of a second?! Is there a timer of some sort?

[Matthew_ScaredyCut]

Originally Posted by rhubarbray

I re-read the owners manual and found I had misread one part. Th length of time for the weld to take place wasn`t 4 seconds it was 4 CYCLES as in Hz! How the heck is anyone supposed to accurately depress and release,...many times,... for 1/15th of a second?! Is there a timer of some sort?

I haven't understood for the longest time why spot welder timers aren't readily available. Apparently it's not too tough to make one but I'm not living on Gilligans Island and I'd like to buy one at a reasonable price. Here is a thread I found that includes talk of a home made timer:
http://www.theringlord.org/forum/ind...showtopic=4534

I am going to try using a dimmer on my spot welder and I'll let you know how well it works.