heliwelder 250 ac/hf question

By Lawrence (*****)

Date 12-16-2002 20:00

Jim,

Assuming your machine is a few years old, the high frequency will go between a set of points. If you have an owners manual you will be able to find out what the proper gap is and check it. If the machine is very old the points may need replacement. It will do little or no good to try to refurbish the points yourself as they are most likely made from tungsten.

That would be my first step in troubleshooting an older HF setup

Lawrence

By awill4wd (**)

Date 12-17-2002 08:13

Jim, we have an even older Esab DTA 200 and I concur with Lawrence's view to check your high frequency 1st. I find the easiest way to find "points" on a machine is to turn it on and press the trigger and listen where the HF crackle comes from on the machine that way your able to say roughly where to look. Do not pull any panels off when the machine is running (common sense).
If your Esab is anything like our earlier one it uses what appears to be a spark plug rather than a points arrangement.
Regards Andrew.

By ScottV

Date 12-17-2002 16:49

Jim,try a different torch.My brand new Inverter was acting up with one of my torchs,and I changed it to check if there was something wrong.It was the torch.Two of the same,brand new torchs sometimes one will act up.When it does it,stop and rub the tungsten on the work with the power off.Then hit the foot pedal,and see if if it starts normal.I thought I give you another place to look for problems.

By jlauto

Date 12-19-2002 02:20

Thanks to all for your input. I did locate the h/f unit on the parts diagram that came with the unit, also the original bill of sale for 1900.00 and change in 1983. Hope to pull the cover off and at least look it over, the picture looked more like the tungsten points set up previously mentioned. I have switched torch assemblys, but the no-starts occured with either set up. I am optimistic that the miss fires seem to be decreasing as the unit is being used more.

What would be proper tip prep for either .040 or 1/16" zirc. for use on very thin aluminum ? (pop cans :) Thanks Jim.

By ScottV

Date 12-19-2002 03:13

Jim,I just grind to a point,and weld with it.It will form a ball no matter what you do.On my inverter it will hold the point a little longer.I used to have a esab 252 ac/dc squarewave machine with all the options.It was a very nice welding transformer based tig machine.I am sure you will like yours also.All those machines are very bullet proof.

By jlauto

Date 12-20-2002 12:10

I have read in a previous post about striking on copper before using the new tungsten, also was mentioned in a text book (Modern Welding, c 1984) to keep a copper strip by the welding station. My concern is a wandering arc when first starting to weld, paticularly getting tack first
started. The arc circles down the side of the tungsten before settling on the tip, "pedaling " to max heat seems to hasten the process. Also the molten puddle seems to attract the arc, probably due to the higher emisivity of the hot metal ? Since my '83 vintage heliwelder is a transformer/rectifier machine, is it a balanced sine wave on the a/c ?
Thanks again, Jim

By ScottV

Date 12-20-2002 15:42

I think it was done to from the the ball on ac.Switch over electrode positive on a new ground tungsten,and it will form a ball right now when you hit the foot pedal.On mine I just don't have to mess with it.I am pretty sure its a sine wave machine.I could not prove it though.I do know one thing when its a squarewave machine they plaster stickers all over it telling you so,at least the ones I seen.Also on arc starting it helps when the tungsten is warmed up.

By welder_guy2001 (***)

Date 12-21-2002 01:24

maybe your tungsten is too thick. but then again, if it was too thick, you'd have problems keeping the arc going. or maybe you're stepping on the pedal too slowly. try to get a feel for how far down you have to press the pedal while you're welding a good bead, and the next time you start the arc, press the pedal down to that same level whenever you want to start. you don't have to wait for the arc to get established and then put more amps into it...just start the arc hard and fast and the wandering shouldn't be a problem.

your machine is most likely a sine wave machine, since they didn't come out with affordable square wave machines until recent years.

By jlauto

Date 12-22-2002 02:39

I am using 1/16 zirc with at about 40A max on remote. Preheating the tungsten did help stabilize the arc start. Going to max pedal also helped but it's a lot harder on by nerves. I'm too accustomed to oxy/act flame, adding heat with a pedal is a little different ! After I get the feel for this machine, I'm going to try a newer unit with square wave and other toys just for fun. Safe and Merry Christmas to all. Thanks, Jim

By welder_guy2001 (***)

Date 12-22-2002 23:19

another thing that might help you get accustomed to TIG welding is welding on 1/8" aluminum. it doesn't burn through as easily as a soda can and it's a lot easier to see what you're doing. you'll need a 3/32" pure or lanthanated, or zirconiated tungsten and around 160-200 amps. just don't get a thoriated tungsten...that's bad news for aluminum, but great on steel.

which makes me think of another point...you're using zirconiated tungsten...have you tried different kinds of tungsten? i've found pure tungsten to be pretty nice.