I have been playing around with my Miller DC Thunderbolt for scratch start tig. It is a late 90's model with the crank handle on the top, and different plug taps to select AC or DC.
I wanted to check the accuracy of the amp indicator. I dialed the Thunderbolt to 50 amps and put my cheap Craftsman amp clamp on one of the leads. When I struck the arc, my amp clamp was reading about 90-92 amps for the entire 10 second weld.
I am wondering which reading is more accurate. I was welding 16ga steel square tubing. It took about 3 seconds for a puddle to start forming and I never blew a hole in the metal. Do you think I would have blown a hole if I was really pushing 90 amps through the welder on 16ga steel? I don't have any other experience with tig to compare, I just started playing with this setup a week ago.
To get an idea wether or not your amp-clamp is 'out' or not, get a thick piece/block of scrap steel and clamp the torch in such a way that it can be held at a fixed distance. Now manually strike the arc. eg. use a fille rod to 'contact' it or do a scratch-start and clamp it in place. Put some shielding around it so you can do the rest without your mask on.
The big steel scrap block will take the heat
Now put your amp meter on one of the leads and crank the machine up to it's (rated) max. amps and see what it shows on the amp meter. That should match pretty closely. Some amp-clams are sensitive to direction, so make sure you flip the direction of the clamp on the lead too to see if you get a correct/plausible reading. Do make sure you keep the other lead away from the clamp.
If you don't get a good reading then the meter may be b0rken..
If you do get a good/plausible reading for the max amps of the machine then you can start dropping down the amps on the machine and check with your amp meter to see if it corresponds to the markings and perhaps mark them where it differs.
I did a similar thing when I adapted my machine to take a foot pedal (it's a base model that lacked some of the circuitry) and had to calibrate the pedal range so it got the whole range correct from '0' to 'max' and didn't end up either topping out too soon or starting out at something like 20A
Bye, Arno.
The big steel scrap block will take the heat
Now put your amp meter on one of the leads and crank the machine up to it's (rated) max. amps and see what it shows on the amp meter. That should match pretty closely. Some amp-clams are sensitive to direction, so make sure you flip the direction of the clamp on the lead too to see if you get a correct/plausible reading. Do make sure you keep the other lead away from the clamp.
If you don't get a good reading then the meter may be b0rken..
If you do get a good/plausible reading for the max amps of the machine then you can start dropping down the amps on the machine and check with your amp meter to see if it corresponds to the markings and perhaps mark them where it differs.
I did a similar thing when I adapted my machine to take a foot pedal (it's a base model that lacked some of the circuitry) and had to calibrate the pedal range so it got the whole range correct from '0' to 'max' and didn't end up either topping out too soon or starting out at something like 20A
Bye, Arno.
I decided to check the amp draw when burning a stick at the 50 amp setting. When burning a stick, my amperage averaged out to about 50 amps. I did vary quite a bit as compared to tig, but it averaged 50.
Anyone know why it draws about 90 with tig, but 50 with stick when it is set at the 50 amp setting?
I was going to do a few more checks at different settings, and a full scale check as Arno suggested, but I was having problems with my phone. (I use my phone to record the ammeter so I can keep my eyes on the weld)
Anyone know why it draws about 90 with tig, but 50 with stick when it is set at the 50 amp setting?
I was going to do a few more checks at different settings, and a full scale check as Arno suggested, but I was having problems with my phone. (I use my phone to record the ammeter so I can keep my eyes on the weld)