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Whats purpose of the Spark Gap

Posted: Fri Jan 26, 2018 6:31 pm
by Richr
does anyone have a clue what the spark gap does.... Just adjusted it on my Everlast power TIG 200..
it was .038 and adjusted it to .030.. Made the arc steady on the min setting of 20 amps.. At the original setting the arc was cutting out, sounded like I was losing the ground clamp connection.

Re: Whats purpose of the Spark Gap

Posted: Fri Jan 26, 2018 9:57 pm
by Lightning
It's used (with other components) to make the high-frequency pilot arc used to start welding, and to keep the arc lit when using AC. On my older transformer machine (Miller 330A/BP), you can make arc starting more reliable by increasing the spark gap.

Re: Whats purpose of the Spark Gap

Posted: Sun Jan 28, 2018 9:16 pm
by Richr
vary confusing, the tech folks at Everlast just had me decrease the sparkgap to make my arc more reliable

Re: Whats purpose of the Spark Gap

Posted: Sun Jan 28, 2018 9:57 pm
by Lightning
Richr wrote:vary confusing, the tech folks at Everlast just had me decrease the sparkgap to make my arc more reliable
Well, the optimal spark gap depends on the electronics, and you can make it too large, too. A three-foot spark gap would probably not be reliable. My 330A/BP calls for a spark gap of .010" and the manual notes that it can be increased to .013" with the caveat that doing so "increases high-frequency radiation which increases interference with communications equipment."

Re: Whats purpose of the Spark Gap

Posted: Sun Jan 28, 2018 11:22 pm
by aland
Richr wrote:does anyone have a clue what the spark gap does.... Just adjusted it on my Everlast power TIG 200..
it was .038 and adjusted it to .030.. Made the arc steady on the min setting of 20 amps.. At the original setting the arc was cutting out, sounded like I was losing the ground clamp connection.
I have a Power i-Tig 201, very similar as your unit. I haven't opened it yet, but it's on my list of things to do...I want to check the gap. I think it's good to be able to adjust it, as it could help with specific welding tasks possibly, but in general it seems people set it to hold a tight arc.

My 201 goes down to 5 amps, that was one things they changed.

So far I have used it mostly for stick, but have tig welded with it a couple times. I am starting a welding cart build that will be tig'd together. Thanks for mentioning this, I'm going to check mine.

You might ask Mark over on the Everlast forum about the gap also, I've seen different gaps recommended depending on the model.

Alan

Re: Whats purpose of the Spark Gap

Posted: Mon Jan 29, 2018 9:50 am
by Lightning
If and when HF arc starting quits on your machine, the spark gap is probably one of the first things you will want to check. They can get mucked up with dust, condensation, corrosion, etc., and sometimes they need to be dressed (some recommend nothing more than paper for this, sometimes I use 1000 grit sandpaper, and a Miler tech told me not to use anything coarser than about 600 grit IIRC) before re-gapping.

Or at least this is the case with my older transformer-based machines...

Re: Whats purpose of the Spark Gap

Posted: Mon Jan 29, 2018 2:51 pm
by aland
Lightning wrote:If and when HF arc starting quits on your machine, the spark gap is probably one of the first things you will want to check. They can get mucked up with dust, condensation, corrosion, etc., and sometimes they need to be dressed (some recommend nothing more than paper for this, sometimes I use 1000 grit sandpaper, and a Miler tech told me not to use anything coarser than about 600 grit IIRC) before re-gapping.

Or at least this is the case with my older transformer-based machines...
Lightning,

Let me ask you this, cause it's something I haven't seen discussed too much.

I have an Everlast i-Tig 201. The machine discussed in this thread is an i-Tig 200, the predecessor to the i-Tig 201, but to make it more confusing Everlast came out with an i-Tig 200t which is fully digital. The i-Tig 201 is digital but has an analog interface on top of it, so it has knobs to turn rather than digital settings that require stepping through menus to set. The i-Tig 200t does have a bit better capability in regard to cellulose electrodes, specifically 6010/6011, where the i-Tig 201 will only do 6011.

What I'm wondering is if there is any advantage in being able to set the point gap, where you could adjust it narrower or wider depending on specific material one is welding? In general is there any advantage or disadvantage to having a settable point gap opposed to being handled entirely by digital ?

Thanks for any insight.

Alan

Re: Whats purpose of the Spark Gap

Posted: Mon Jan 29, 2018 4:02 pm
by Lightning
Sorry, Aland, I have no clue about that. Are you saying that some of these machines set the spark cap digitally, rather than manually (IOW with screwdrivers wrenches and feeler gages)?

Re: Whats purpose of the Spark Gap

Posted: Mon Jan 29, 2018 4:12 pm
by aland
Lightning wrote:Sorry, Aland, I have no clue about that. Are you saying that some of these machines set the spark cap digitally, rather than manually (IOW with screwdrivers wrenches and feeler gages)?
Yeah, that's my understanding, that the newer digital machines don't have a point gap that can be set and they handle that digitally...but if I'm wrong, someone will hopefully correct me.

Alan

Re: Whats purpose of the Spark Gap

Posted: Mon Jan 29, 2018 6:57 pm
by Richr
My understanding is that the digital machines have a solid-state sparkgap that needs no maintenance

My machine a Everlast Power TIG 200 has points, easy to adjust with a screwdriver, seven screws the back comes off, 10 screws the cover comes off leave the front cover alone.

Welding on DC no problem. Can get a steady arc at 5 amps..
On AC is a different story.. Adjusted the gap from .038 to .030 fixed the problem on AC...

Need a Circuit description to find out what's really going on with the spark gap or do, I care its working

Re: Whats purpose of the Spark Gap

Posted: Mon Feb 05, 2018 3:07 am
by aland
Richr wrote:does anyone have a clue what the spark gap does.... Just adjusted it on my Everlast power TIG 200..
it was .038 and adjusted it to .030.. Made the arc steady on the min setting of 20 amps.. At the original setting the arc was cutting out, sounded like I was losing the ground clamp connection.
Rich,

I have a couple Qs. I opened my i-Tig 201 which the manual says there is a daughter board and shows a pic of the points. My machine has no daughter board, and I can see the points, but they don't look like the ones pictures in my manual.

I looked in the manual for the machine you have (i-Tig 200 ????) and I don't see the points shown there.

Is it the i-Tig 200 you have?

I don't see any locking nut and I do see a very small screw on one side of the two posts, but I think I would need to remove the mother board to adjust and set up.

Does your unit have the locking nut for the point gap adjustment ?

I think I may need to call Everlast.

Alan

Re: Whats purpose of the Spark Gap

Posted: Tue Feb 13, 2018 6:45 pm
by Richr
Allan

I have a power TIG 200 DV. The only problem I had was erratic arc on AC..

It was easy to adjust the sparkgap two locking nuts and two screws... it was at .038, adjusted it to 30..
it seemed to fix the problem... still not great at low amps.. but better

Re: Whats purpose of the Spark Gap

Posted: Tue Feb 13, 2018 6:54 pm
by aland
Richr wrote:Allan

I have a power TIG 200 DV. The only problem I had was erratic arc on AC..

It was easy to adjust the sparkgap two locking nuts and two screws... it was at .038, adjusted it to 30..
it seemed to fix the problem... still not great at low amps.. but better
Rich,

Mine looks different than they show in the manual, and I don't have the locking nut. There looks to be a very tiny copper phillips head screw (my wife would call a "plus screwdriver" ;) ), but it seems I would need to take the entire motherboard out of the machine to adjust it. I posted a message on the Everlast forum, will follow up there and see what they say, but it seems they must have changed the i-Tig 201 which I have, sometime after the manual was printed.

Alan

Re: Whats purpose of the Spark Gap

Posted: Tue Feb 13, 2018 8:22 pm
by Bill Beauregard
I don't fully understand spark gap. I have pieced together a few facts:
Sine wave TIG power in AC when viewed on an oscilloscope, is a curvy line. Each half cycle, current tapers down to zero, then gradually builds in the other direction.

When we weld aluminum, most older transformer welders are balanced flow current, or 50/50 balance. As argon is not relatively conductive, it must be ionized to easily conduct. Imagine a bolt of lightning. If we could see faster than we can, we would perceive steps in a bolt of lightning. A space in ionized air conducts, electrons stop at the edge of ionized air, billions of electrons rush to this point, but are unable to move until sufficient power of electrons ionize another volume of air. Then these electrons surge forward, and the process repeats. In a bolt of lightning, each step happens so fast that our eyes can't see each step. We see it as a crooked bolt of lightning.

Welding in AC, many transformer based welders are fixed at sixty HZ. direction of electron flow reverses 120 times per second.

Electrons flowing from the pointed tungsten ionize easily. Electrons flowing from the workpiece find it more difficult to ionize shielding gas. There is more surface they are spread over, and if welding aluminum, oxide layer is less conductive than clean aluminum.

If we didn't have HF, an overrunning high voltage, low energy high frequency power source, ionization of shielding gas would have to be recreated 120 times per second.

A 1960 car used collapsing magnetic field to induce high voltage, low energy electrical charge, igniting gasoline/air mixture. Something similar happens in the HF circuits in transformer welders. The spark gap fires, dissipating a build up of electrons, then pressure falls, interrupting flow. The magnetic field in a transformer coil collapses. This collapse, brings the magnetic field across transformer coils, inducing high voltage.

varying gap changes the intensity of this process. greater HF increases radio interference. There are things you can do to reduce a problem.

Spark electrodes should be polished. sandpaper makes thousands of scratches, interfering with ionization.