[massajamesb]

I will take your work for it, I am not real sure of the cause, but I am real sure of the effect!
I know I am not the only one who has done this, someone else please chime in and let me know I am not the only tig welder who has been electorcuted.

:withstupi

[handlewanker]

Hi Tad, just reading your post again about the current control with the moving core.
I have a 200amp stick welder, about 10 years old, which I'm going to convert to tig, with the current control adjusted by moving a piece of the core in and out on a leadscrew and winding handle.
Is this the same as you describe?
Could I arrange to move the piece of the core in and out as the welder is working?
I'm not sure if there is some magnetic force present, while the transformer is working, making the need to secure the moving core bit from being pushed or pulled into the core, which is held by the leadscrew.
In other words can the movable bit in the core be moved while the welding process is being carried out, so varying the current as the welding progresses?
Would a variac work on the primary of the welding transformer to vary the output current of the welder progressively?
As I understand it the variac, or auto transformer, is a variable voltage transformer
If it is possible to use a variac, then it is a simple process to move the rotor as it only has to travel about 360deg from full off to full on.
Any info would be welcome.
Ian.

[handlewanker]

Hi corvus, 200 amps and weighs 50 lb, now that I can relate to.
How much did you pay for it, or what is the current price in USA?
The non continuous HF, is that a characteristic of inverter types?
Looking at the specs as you quoted makes for a neat set-up.
It might be the way to go if the price is right, it would save a lot of experimenting and a lighter unit.
Ian.

[thkoutsidthebox]

Massajamesb, I spoke to a mate of mine today, who is a welder, and he reckons it was the HF that you got a zap from not the 400amp welding current as the voltage on the welding current is too low to zap you due to your body resistance being too high.

Yes it is the HF. This causes the arc to jump, and its actually caused by not starting the arc before placing the welding rod near the pool. i.e: Move rod into area, then start arc, using HF start, arc accidentially jumps onto rod instead of onto workpiece, and travels into Mr.Welder as a result. Nice! Simple prevention, always start the arc and get a nice pool before putting your rod in there. Once there is a pool and current flowing, the resistance will almost always be less through the workpiece and metal table or ground rod than through the welders body, so at that point its not a worry.

My welding instructor was telling me last Monday night (Because I was asking him about this due to this thread ) that a student was standing beside him before, holding the tig torch. He was pressing the button absentmindedly, and when the torch came within about 1" of said instructors leg he got a nice surprise as the HF caused an arc to jump across! He didn't tell me what happened to the student!

[millman52]

A good bit of interesting reading on this string. Since I originally asked about what I needed to convert something I already have, I have been guided & decided against it. I do have some follow up questions. What kind of performance difference in ease of use, quality of weld & things of this nature could I expect between a machine like this, http://cgi.ebay.com/ws/eBayISAPI.dll...DME:B:EF:US:11 or a similar machine made by Lincoln, or Hobart as compaired to: http://item.express.ebay.com/__Welde...mdZExpressItem.

Other than the obvious of amperage difference & I'm sure the older Miller & like iron is most likely 100% duty cycle & of course much heavier & bulky.

Is there a big difference in the weld characteristics?????

[CNC Pro]

Yesterday I was on the phone with a Miller application engineer. He also recommended the Miller Dynasty 200 DX as a very good choice for a all ‘round machine.
One thing I did question was using a HF welder while running my CNC machines and what I may expect as far as interference with the CNC motor signals.
He mentioned the Miller Dynasty 200 DX’s non-continuous HF would greatly reduce these issues.

[tadream]

Other than the obvious of amperage difference & I'm sure the older Miller & like iron is most likely 100% duty cycle & of course much heavier & bulky.

Is there a big difference in the weld characteristics?????

Long answer, short: The old Miller IS one of the sturdiest, most dependable machines ever built. It is also cheaper to repair, as it has no circuit boards whatsoever. The Lincoln, and almost all modern TIG machines are "square wave" machines, and while that is actually a bit of a misnomer, provide generally better arc characteristics. They also allow unbalanced AC output, meaning that you can set them for more or less cleaning depending on the material you are welding. Those old machines weld fine, and can usually be had pretty cheap, but be aware that the HF points and cap might need to be replaced, which is around $160 worth of parts alone, so factor that possibility into your calculations. There is a difference in weld characteristics, but not a HUGE difference. You can do the same quality of work with either, but it might take a bit more skill on the older style machines.

[tadream]

Is this the same as you describe?
Could I arrange to move the piece of the core in and out as the welder is working?
I'm not sure if there is some magnetic force present, while the transformer is working, making the need to secure the moving core bit from being pushed or pulled into the core, which is held by the leadscrew.
In other words can the movable bit in the core be moved while the welding process is being carried out, so varying the current as the welding progresses?

Possible, yes, practical, no. Not sure what model you have. Probably a Miller Thunderbolt or similar? The core is indeed very difficult to move while current is being drawn, so you'd have to remove as much friction/mechanical resistance as possible, and it would still be difficult and slow. Current changes wouldn't occur as quickly as you would like.

Would a variac work on the primary of the welding transformer to vary the output current of the welder progressively?
As I understand it the variac, or auto transformer, is a variable voltage transformer
If it is possible to use a variac, then it is a simple process to move the rotor as it only has to travel about 360deg from full off to full on.
Any info would be welcome.
Ian.

Yes, it would work in a sense, but it would have to be a very heavy duty variac to handle the primary current. It would also be lowering your input voltage and therefore your arc voltage as well, so as you lower your current, you would lose arc stability. I hate to keep shooting down your ideas, because you've got a really good grasp of the way it all works. The only problem is that you are trying to add a lot of features to a machine that has none to start with. You can make a TIG out of a stick welder, but you really need something that was built with remote control in mind to make it easier on yourself. The best way to add it would be through the use of SCRs and a control circuit to fire them. You also need a switch to change from AC to DC, because using them to control an AC output requires that the current path be routed differently. This is how the Syncrowave and all of the modern square wave TIG machines work (hint, hint). Want some schematics to see what you're up against?

[handlewanker]

Hi Tad, I don't mind being "shot down" every time a wild idea occurs, it's the only way you can confirm whether or not you're on the right track.
So at the end of the day,as the wise man said, I heard about the Miller Dynasty 200 DX and went on the 'net to see what it was and who's offering what for how much.
I got a price of about US$2200 or thereabouts, so as it's Sunday I'll have a look at the local market on Monday, in down town Dandenong, which is in ORSTRAYLEAH, for the uninformed, where Wombats and Possums prowl the back gardens and pinch the apples off ya trees.
I reckon if I was to sell the 200A stick welder for a couple o' bob and have a go at the Miller, I'd be better off all round.
Strewth mates, have you read the specs for the Miller Dyanasty? And all this in a 50lb (25KG) package.
I have to say that I'm retired and don't do any serious welding work, but it gives me a buzz to be able to do all those jobs you'd pass on to the experts.
Maybe I'll get some of those $5 jobs from my ex employer that take him 2 hours to do.
Apart from that I like having a bit of High tech stuff to mess around with.
If I do go down the "break the bank" path and splash out I'll blame it on Corvus.
All I need to do now is turn out the "treasure" stacked in the garage and put it up on Ebay.
Gonna make a fortune.
Ian.

[Normsthename]

Be prepared to electrocute yourself

I thought that was part of the apprenticeship!
It certainly wakes you up when it happens!

Andy

[handlewanker]

Hi all, just got a price for the Miller Dynasty 200 DX, (what a little beuty), at A$5600, that's Aussie dollars.
I think I'll stay with the rework of the stick welder I've got for the moment, 'till something else turns up.
Anyway, I've already bought a set of 300 amp diodes, a tig torch, flowmeter/regulator and one of those auto darkening helmets, so I'm halfway there.
Ian.

[D_ego]

Hello I made a table to weld (GTAW) to drive a high frequency equipment. the equipment works well but when the arch is created the engines don't work, i want to know why. I am working with a kit xylotex of 3 axes.

forgive my english

[millman52]

Hello I made a table to weld (GTAW) to drive a high frequency equipment. the equipment works well but when the arch is created the engines don't work, i want to know why. I am working with a kit xylotex of 3 axes.

forgive my english

I'm no expert here but my best guess is the high frequency noise (electronic interferance) from the tig arc start is interfering with your computer controls.

you might be able to work it out by using a seperate ground rod for your tig machine & table. Your computer & controls need to be on a seperate circut & the ground for them needs to go back to your power box ground.

There is several posts on the boards here with similar problems using plasma cutting equipment. Search them out & see what others have to say about the subject.

[massajamesb]

I thought that was part of the apprenticeship!
It certainly wakes you up when it happens!

Andy

(nuts) doh!
you bet it does.
I had to learn tig welding the hard way, and that was by trial and error. No prior experience, and no one there to teach me.
Thank God I didn't decide to learn how to be an electrician the same way, huh?
Thankfully, I don't do GTAW or electrical work for a living.

[Normsthename]

you bet it does.
I had to learn tig welding the hard way, and that was by trial and error. No prior experience, and no one there to teach me.
Thank God I didn't decide to learn how to be an electrician the same way, huh?
Thankfully, I don't do GTAW or electrical work for a living.

I got a beauty of a shock the other week:rainfro:
I was welding some bits on the bench (metal bench.....) and the part was not secure and it lifted up while I was welding losing its earth, so it went thru' the shortest path......me!
My knee was touching the bench leg, and the current shot up my arm and down out thru' my knee
If I had any hair, it would have stood on end!

Andy

[Farmers Machine]

I have been welding for more than 35 years and just purchased a Lincoln Precision Tig 375. I used to have a Miller Syncrowave 350 but it would not burn Lincoln 5P and the AC Tig always had a hard time starting. The new lincoln welds with any stick as good as my 1964 SA 200 engine drive and the tig goes down to 2 amps on the low end 420 on the high end. the pulsed Tig is very useful joining thin sections to heavy sections. The machine is offered as a ready weld pack and comes with a foot control but I also purchased a hand amptrol for work on a ladder piping oilfied equipment. A tremendous amount of whistles and bells that will some day cause grief but with 3 year warranty this machine will be paid for many times over before it ever cost any thing to fix it. I would vote this machine as the finest Tig/Stick machine I have ever used and would reccomend it to any one. The Farmer

[zcases]

Millman I used to have the Miller 330 A/BP Goldstar just like in the auction you found. I did a variety of welding with that machine from stick on large pipe jobs to aluminum tig (heavy and light) and stainless tig (light .020" wall stuff). That machine would last another few decades trouble free in my opinion. I just updated to a Syncrowave.........Actually one of the biggest improvements I like is the fan is on a thermostat and doesn't run all the time. But the Goldstar is a totally capable reliable machine.

[XEC747]

Practice make perfect(nuts)

[thkoutsidthebox]

Nice. ....what is it?

[XEC747]

An inlet manifold trumpet for a v8 supercar(aussie 5ltrs that produce about 650hp on pump fuel) :cheers: