TIG on a budget

[small.planes]

Evening All,
Whilst ive been using OA for about 10 years, and MIG for a few Ive yet to venture into the wonderful world of TIG. I have a few questions, and Im sure that the experts here can help :)
Id like to get a TIG, Ive discounted Aluminium welding from the list (my Mig does ok with that for what I need), but it looks like Ill have stainless and other high nickel (inconel) alloy items to weld. Id also like to put my OA 'out to pasture' apart from cutting. Firstly is DC ok for what I want to do (stainless, steel, inconel, other metals)?
Then how do you size a TIG? I think Ill need to weld upto about 2mm thick, but down to *really* thin (basically foil, certainly ~0.3mm stainless). I have no idea what amp range this would be. What size torch / electrode am I likely to need?
Do I need a foot pedal? Inverters or transformers? I wont be lugging it about, I intend to setup a weld bench for this to learn at and then the parts Im aiming at require reasonable precision.
Can you braze with a TIG?
Any recommendations on units would be nice, Im in the UK, so that might limit what I can get. I have a budget of about £300 - £500(hence no AC), less would be nice, but if I need to stretch it a bit then I can.

cheers

Dave

[Jim Caudill]

I'm going to let others from your own country give you more specific advice, but I'll make a few observations. In general you will be welding with DC electrode negative (DCEN) and using 3/32" electrode. You will want to be able to go down to 1/16" or up to 1/8" electrodes as well as having some 3, 4, &5 cup sizes. I would opt for a "pedal control", but that is what I'm used to. I didn't bother to convert your metric sizes to fractional or decimal, but to weld really small takes a really good (expensive) welder. You can weld 16ga or so with most welders, but to go smaller will require a welder that can set low amps and have a stable arc; hence the "more expensive" comment. I would look for an "inverter based" welder as opposed to a transformer model. A new Miller inverter for the hobbyist would run around $1,500us, so you should be able to come across a used outfit for between 1/2 and 2/3 of that amount. There are various options that cost more money, such as high-frequency starting, solenoid gas control, etc. So, get a handle on what you want and start looking for the next "great deal" so that you can post your "tool gloat" here on the forum. Miller's new Diversion model is pretty neat ($1,275us from cyberweld), but you won't find any used ones.

[macona]

Miller 150STL would be perfect for what you want to do.

[small.planes]

OK Ill look into the specs on that. Im not sure if Miller is easily available in the UK, but the specs on the web should give me a better idea of what to look for.

I assume a pedal allows you to 'tune' the amperage on the fly, a bit like moving an OA torch further/nearer? Is the other option just fixed amps, set on the machine? if so a pedal sounds much better for thin stuff.

0.3mm ~12 thou, which is pretty thin, so I guess Ill need a very low min amps, How do you figure out what amps are needed?

cheers

Dave

[Smokedaddy]

Dave,

Just for kicks, go here ...

http://bbs.homeshopmachinist.net/showthread.php?t=30211&highlight=smokedaddy

scroll down about 6 or 7 messages and look for my posting. It will have a couple of links there like this one ...

http://www.pbase.com/smokedaddy/image/101061361

I am not sure what you are doing but this would be your least expensive method, if it works for you. Oh, I have the little Miller Maxstar 150STH with a foot pedal, nice little machine. It's not like the high end machine with super fine arc control but I like it. I picked up a nice used one, complete, including bottle, locally for $800.00. Thermal arc is a nice machine too but they are both based in the US.

-SD:

[Ries]

Miller does sell 150 STH units in the UK-

Here is one-
http://www.westcoweld.co.uk/dc-tig-welding-equipment/miller-maxstar-150-sth-2.htm

but I am guessing they are expensive, compared to euro machines.

No prices on this website, but they have a few small inverter welders from EWM that are probably cheaper, like this one-
http://www.westcoweld.co.uk/dc-tig-welding-equipment/emw-tetrix-180-activarc.htm

I have used a Maxstar 150 quite a bit, and for things like you describe, its a great machine, but it costs more than you budget.

[small.planes]

The main use immediately (after figuring out how to use it...) is for parts for a very small Gas Turbine, hence the need to be able to weld stainless and heat resisting metals, such as Inconel. The thinness comes about because some bits are thin, and also I need to save as much weight as possible in other bits.
In the future I would like the convenience of an electric welder, over the OA set, and only 1 bottle to rent (almost impossible to buy your own bottles over here) instead of 2. Ill then be welding a variety of other metals, but alloy is one area Im not heading into yet with this. My MIG runs alloy wire ok, and produces a nice weld for the odd occasions I need to.

From the miller data sheet I guess Im looking for as low an ampage as I can get (5A or less!) upto 150A, with a remote amps control.
Any other goodies to look for? HF start, pulse modes or other things?

This electrickery stuff is all a bit confusing, to many options :confused: OA is simple, big flame, little flame ;)

Dave

[small.planes]

Ok, after much poking around I found the 150 STH here (http://www.weldmet.co.uk/product_info.php/cPath/108_109/products_id/1739)
Looks like a good machine, but yeap, more than I was intending to spend. :(
However buy a good machine once, or regret living with a bad one?
I have yet to find a machine that looks of similar spec for under £500, maybe I should just bite the bullet. At least with the economic slow down I might be able to negotiate a little.

It does come in a nice case, which is useful for swinging thing with SWMBO ;)
guess I'd best check the Bank account....

Dave

[macona]

The STL is cheaper and is lift start only. The STH is high freq start and quite a bit more. I would order one from the US and have it shipped.

-Jerry

[small.planes]

Just a few months ago when the $ was really weak I would have just done that, now Im not sure I'd save anything over the more expensive (but in this country already) STH after currency conversion, import duty and VAT are added on...

What is the advantage of HF start over lift? I assume it means the start is done by 'hovering' over the metal, not touching it and lifting off.

more reading required I guess.

Dave

[Dawai]

HF start is like " lightning" strikes to light the tungsten arc without contaminating the tip..

I used to like to use the hf box with 7018 rods.. they build up that glass on the end.. you have to BUMP them hard to light them.. with a hf box, they light before you touch off..

This new miller 200 synchrowave (new to me, old design) is as good of a stick welder as any I have ever tried.. I can weld by sound if I can't see..

[macona]

Lift arc does not contaminate the tungsten either. I actually prefer it over HF for low current work. It works by a low current low voltage at the tip. When you touch and pull off it applied weld current and the arc starts. Works great!

[torker]

Lift arc does not contaminate the tungsten either. I actually prefer it over HF for low current work. It works by a low current low voltage at the tip. When you touch and pull off it applied weld current and the arc starts. Works great!
That is pure bull$hit. You obviously havent been x-ray tested over and over.
The only way to pass consistant testing is IF you use and know the same machine all the time or if you use hi-frequ.
Try walking into a jobsite with strange equipment and say that.

[torker]

If I remember right...an average pulpmill shut down would have about 20 tig weldors.
Somewhere around 2% of the welds would be failures.
#1 ranked failure... tungsten inclusions from scratch start machines.
#2 failure... sawtooth formations.
Oh...and don't let the failure rate bother you until you've been there. This isn't welding on a bench with a foot pedal....
It's real world dirty smelly black liquor pipe welding. Laying on your back...or almost standing on your head to get into some gawdawfull hole where no pipe should have ever been placed.

[macona]

Scratch start and lift arc are two totally different creatures.

From millers site:

"The Lift-Arc feature provides code-quality arc starts (no tungsten inclusion) without the use of high frequency."

If they lied about this they would get sued or a heck of a lot of returns when people bring back the machines from constant tungsten inclusions.

[torker]

Macona...the machines we used there were all Miller 304 inverters. Awhile back also. Maybe better now..they were a pain then.

[wmgeorge]

Scratch start and lift arc are two totally different creatures.

From millers site:

"The Lift-Arc feature provides code-quality arc starts (no tungsten inclusion) without the use of high frequency."

If they lied about this they would get sued or a heck of a lot of returns when people bring back the machines from constant tungsten inclusions.

You are correct. The lift part seems to be some sort of electronic "on" signal back to the control board. I've used both HF start and the Miller lift arc... for the money I'd take the lift. HF is fine, costs more, but I'd have second thoughts about using in a damp location. A lot of these pipe fitter/ welders (my son is one) don't always get a nice sunny dry day or a shop to weld in, on a shut down or construction job.

[EVguru]

Id like to get a TIG, Ive discounted Aluminium welding from the list (my Mig does ok with that for what I need), but it looks like Ill have stainless and other high nickel (inconel) alloy items to weld. (snip)

Do I need a foot pedal? Inverters or transformers? (snip)

Can you braze with a TIG? (snip)

Any recommendations on units would be nice, Im in the UK, so that might limit what I can get. I have a budget of about £300 - £500(hence no AC), less would be nice, but if I need to stretch it a bit then I can.

I bought myself a TIG fairly recently. It's a 200amp AC/DC with HF start and pulse facility. I've used it to weld cracked stainless motorcycle mudguards (at about 5 amp), put a new section into the alloy oil tank of a Triumph Daytona, weld new exhaust thread inserts into Morini cylinder heads, make up a set of process tubing in 316L for work, etc, etc. It's a machine I'm really pleased with. I've had no problems that weren't caused by being a TIG novice. I even took it to a friend of mine who's welds professionally, I had trouble getting him to give it back (he was used to a Murex 375)!

What is it? It's a Chinese made Jasic WSE200P, which cost me about £500 (they're a bit more now). It's not a heavy use industrial machine, but I've heard of people using them that way. I'm an electronics design engineer and I've had a look inside. Other than a couple of mechanical contruction issues (don't use it as a work bench!) it's nicely put together with conformal coated boards and even ROHS compliance marks. I'd done quite a lot of reading to find the right 'brand'. Many are re-badges and some machines are truly awful (they were asked to supply the cheapest machines, so they did). Many people just order a container load, flog them off and disappear, avoiding any comeback. That doesn't mean there aren't machines well worth the money.

I bought mine off ebay, from a trader going by the name shop-river. He seems to care about customers and has even sourced replacement boards (using emailed pictures) for owners of machines who've been let down by their suppliers.

I'd say you need to get a pedal, it's much easier. You can Bronze weld with TIG, but I probably wouldn't try brazing becuase of the Zinc (metal fume fever).

[shawnspeed]

If you are producing turbine impellers for a small gas turbine , I would suggest looking for an oven brazing operation in your area.....you will have less balance problems and greater reliability...And yes you can brase with tig , you just can't use regular brazing rod tho....have to get some silicon - bronze tig rod , they also produce it for mig machines also....Good luck, Shawn

[small.planes]

EV, cheers for the tip, Ill look into those. Do you also post over on mig-welding?

shawn, I wont be (certainly in the near future) building up impellers.
The turbine design Im aiming at is ~200K rpm, but there are other parts that need fabricating, and I have a sideline in RC helicopter parts.
The brazing question was just a wondering really, as if I can get rid of the OA set totally, with a TIG and a plasma then the dangerous gas storage and cylinder rental are both reduced. I still have a big propane torch for 'general heating'

Dave

[shawnspeed]

one other thing ...if you are doing Stainless Titanium and inconell you might want to look into building a chamber simmilar to sand blast cabinet that you put your part in a flood with argon....it beats tring to figure out how to back -gas odd /small parts...Shawn

[small.planes]

Yes Ill do that. My welding table (yet to be actually constructed into a table) is an old 2' square CI surface plate that some muppet had allowed to get surface rust, and then 'cleaned up' with a flap disk! I planned to weld/braze 6" or so deep sides and back onto it, and have a clip on front, so it wasnt in the way normally. Argons heavier that air (it is isnt it?) so I figured that would 'submerge' the parts pretty well.

Dave

[Dawai]

I've wondered...
OKAY.. I am a electrician.. not a welder.. but...

IF, hooking a exhaust pipe on a car to a box to evacuate the contaminating gas would work?

If hooking a exhaust pipe on a car works to stop explosions while you are welding a harley gas tank.. why not??

If that would work? why would a burner that runs till it runs out of oxygen work also in the same box? oxygen is the contaminator?? I mean.. preheating in the same box would be cool too.. Run a propane flame till it will not burn anymore?? then shut it off and weld like you purged with $20 worth of argon?

[Cheeseking]

The STL is cheaper and is lift start only. The STH is high freq start and quite a bit more. I would order one from the US and have it shipped.

-Jerry

I've got the Maxstar 150 STL in my home shop and I've been generally pleased with it although it's hard to not compare it to the $2900 200DX's at work and wish I saved my coins for that one instead. In my opinion, the HF start is a really, REALLY nice thing to have. I have yet to get the hang of the lift arc start and it always seems to jazz up my electrode/sticking etc. Also, I don't have a foot pedal at home which allows you to keep the torch perfectly positioned as the arc starts. With HF and foot pedal amperage control, welding is a dream. At work, I feel as if I'm a semi-accomplished welder. Soon as I get home in the basement I'm a hack.
If you can hold out and save up to afford the extra cost of the STH you will not be sorry.

Now I must excuse myself and get back down there. I'm finishing off a custom fireplace screen I started months ago and it needs to get done before company comes for Xmas!! :D

[macona]

I've wondered...
OKAY.. I am a electrician.. not a welder.. but...

IF, hooking a exhaust pipe on a car to a box to evacuate the contaminating gas would work?

If hooking a exhaust pipe on a car works to stop explosions while you are welding a harley gas tank.. why not??

If that would work? why would a burner that runs till it runs out of oxygen work also in the same box? oxygen is the contaminator?? I mean.. preheating in the same box would be cool too.. Run a propane flame till it will not burn anymore?? then shut it off and weld like you purged with $20 worth of argon?

OOhh.. Bad idea...

Stopping explosions and providing an inert atmosphere for welding are two different thing. Exhaust is primarily composed of three things. Water Vapor, Carbon Dioxide and Carbon Monoxide. CO2 and CO are rather reactive gasses and would cause problems in the weld.

If there were cheaper gasses to purge with people would use them.

One welder I was working on was connected to a chamber about 8' cubed! Can you imagine how much it cost to fill it? It was made from a rubberized canvas material and dropped over the part and clamped to the base plate. Took about 45 minutes to fill. The sides of the tent bulged from the weight of the argon.