Amps don't reach preset while welding, is this right???

[Blaster]

So I've been doing a lot of 1/4" 6061 Alum lately with my PP256. Sometimes it seems like, at a joint I've been doing repetitively, I'm just not getting the heat I need. The same heat I had before (it seems like that maybe, but I'm not sure). I slow down, work both sides, do a better job of preheating before I start but, I get by....

Today a buddy of mine stopped by and I said to him [i]"Tell me what happens to the Amp Display as I weld". I was surprised to hear him say 154, 177, 191, and the like with the pedal floored. The Amp knob is all the way up, the display says 256 (sometimes 255/254), and during the post purge 24.

I'm using the pedal, a CK 250A WC torch, and the ground clamp is directly on the assembled piece, and the machine connections to both the Ground/Torch are tight.

As I said, I only notice it now and then, I'm not sure what the display was reading at those other times. I think it doesn't happen when I first start welding for the day (at least I know I've finished for the day and thought "Didn't feel like it had the balls it should have on those last few welds, I hope nothings wrong,,," and then the next time I start welding I'm reassured because it does just fine).

Shouldn't the display be reading 250A if the pedals all the way down as I weld????

[performance]

Running with the pulse, it will move around, and definitely not show max amps. Depending on the balance and the frequency settings, the readings will change because of the way the meter is calibrated. Also if the foot pedal gear has slipped on the belt, it could read less.

[everlastsupport]

Yea, make sure the pulse is off. That will cause the display toggle between the amp levels.

Also you can ohm the pedal and make sure it is going all the way. 3-4 and 4-5 are the pins to check ( low to 50K and 50K to low on the two). Do you get all the power you need with the trigger?

So glad I am not typing from my samsung tablet

[Blaster]

Come On guys,,,, If I was in Pulse, I would have mentioned it

120Hz - 30% - 1/8" electrode all the regular settings for doing new 1/4" Alum...

BUT, my pedal IS giving me some surprising readings from 3-4-5

I get 3-4 2Low and 35-40High (Off to Full)
I get 4-5 55High and 20Low "

In 3-4 I Go Full and get different readings each time, usually 35-38 Ohms but never higher than 40. Does this mean I have a problem with my pedal? I'm gonna open it up and take those reading from the Pot itself to eliminate a problem with the wire (which I have repaired from having dropped a 300Ltr cylinder on it from 8" off the cart, but maybe another conductor got damaged I didn't notice )

But, to be clear, you're saying the digital display should read 250A while welding, Full Pedal, no-pulsing, if it's set to that?

[Paul Moir]

Yeah, or near to it.

Sounds like either the sprocket on the pot is loose, or the pot is going south. It should be at least consistant. (ps "20Low" is in Kohms not ohms right? It's not autoranging right? And "55high" is in K ohms too right? You know, only a factor of 1000x here! )

[Blaster]

OK, so I opened the pedal and was surprised to find things looking so Out-of-Wack

First, the Belt isn't fully running on the cogged Gear, it's 1/2 derailed because it isn't lined-up with the relief in the roller that the belt stays centered in. I can only assume it was assembled this way and not that way it's designed to be.

Second, the Belt and Gear appear to have differing TPI (or per mm I'm sure) because the teeth engage fully in only 3-4 places then ride-up, on top of each other, on the way to the attachment point (not the spring). Whole thing looks kinda Mickey Mouse to me.....

Just getting it open is an experience in poor design. Really,,,,, #1 Phillips (or ISO I guess) pointing down to the floor. These tiny screws are the "feet" I slide the pedal around on? THEY won't be going back! I picked the crud out of them but still had to resort to pliers to get 'em out...

So here's what I had at the pot (I knew I could repair a wire properly ) Grey=5 / Brown=3 / Green/Yellow=4 / I assume 3 is the wiper.

With the pedal "Floored";

.............55
........... /...\
........../.......\
....Grey...Brn..Gr/Ye
......\......../\......./
.......\...../...\...../
.........35.......22


After realigning the gear and resetting it's position;

.............55
........... /...\
........../.......\
....Grey...Brn..Gr/Ye
......\......../\......./
.......\...../...\...../
.........54.......55

The only thing is, the "at rest" readings for 3-5 I can get to 1 BUT the 3-4 is about 5 (if I adjust it lower it doesn't hold, drifts into the 100's so I assume it off the mark inside) Also I made sure the Phillips Screw "Stop" was hitting...

Is this going to be OK, as long as I have 5-3 at 55 pedal OFF and 3-4 at 55 FLOORED?

What's with the Belt Tooth / Gear Tooth mismatch? Is this going to continue to give me trouble?


.

[everlastsupport]

Sounds like the rack and pinion (belt and gear) in the pedal skipped like Mark said. We had to mention pulse to cover other things people do miss. Did you test full power without the pedal?

[Blaster]

Didn't try, just opened the pedal. I haven't yet welded with it. I assume this will make a difference!