TIG welder for hobby use

vyv_cox said:
Not at home now so cannot answer precisely. The machine is the 200 version. It is very easy to strike an arc on starting the weld but I do not recall the precise description. It is a vast improvement over the previous one I owned that did not have it.
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Thanks, Vyv, sounds like it's the Rohr HP-200PP which is selling for £199. The specs say HF start which the previous posts and Welding Tips and Tricks both say is the one to go for. I think I'll be getting one when I've saved up my pennies. Union Mart is a UK supplier based not far from me, and while it may not have the service backup of R-Tech, if it does go wrong at least it's not a matter of chasing a fly-by-night eBay seller or sending it back to China.

R-Tech would be nice but it's well over my budget, I can't really justify the extra cost when it's just for occasional use.
 
Elbows said:
Thanks, Vyv, sounds like it's the Rohr HP-200PP which is selling for £199. The specs say HF start which the previous posts and Welding Tips and Tricks both say is the one to go for. I think I'll be getting one when I've saved up my pennies. Union Mart is a UK supplier based not far from me, and while it may not have the service backup of R-Tech, if it does go wrong at least it's not a matter of chasing a fly-by-night eBay seller or sending it back to China.

R-Tech would be nice but it's well over my budget, I can't really justify the extra cost when it's just for occasional use.
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Be aware that the Rohr HP-200PP is only DC. You will not be able to weld aluminium if this is among your plans.

Daniel
 
danielefua said:
Be aware that the Rohr HP-200PP is only DC. You will not be able to weld aluminium if this is among your plans.
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Yes I realise that but thanks for the heads up. I've got no real need for aluminium welding, I mainly want it for stainless fittings for the boat. I can also use it as a stick welder for steel fabrication which is handy. Going for AC means a big price jump.
 
I have a Migatronic 210 amp AC/DC set with all the bells and whistles, full size bottles etc, I think I paid £100 in an auction ... it's not light though. Always handy to have one around, I welded up a custom anchor retaining pin and fixed the broken fender baskets with mine this weekend.

https://www.dropbox.com/s/qf4xmj1tye4pj2r/20190505_231336.jpg?dl=0

It is however a lot lighter than the Miller Synchrowave 500A set I picked up for £50 ... well, when I say "500A" it was not really 500A, that was the continuous rating, you could get 750A out of it for 30% duty cycle :) The only downside (apart from the vast size and weight) was its need for a 200A 3 phase supply ... but it was a gorgeous welder, and produced perfect welds in thick ally.
 
What do all you home welders do about pickling/passivating stainless after welding? I really don't want to be messing with nitric and hydrofluoric acid which is what seems to be used commercially.

I've found some mention of citric acid but I'm not sure whether that removes the chrome-deficient surface layer which can form after heating. From my researches it appears that layer can be removed mechanically but it's not always possible to get into awkward nooks and crannies.
 
I doubt citric acid will work on it's own .. it usually needs an electric current to augment it.

I use one of these:

https://engweld.co.uk/product/magiccleaner-fronius-magic-cleaner

it uses citric acid and AC current, but at ~£2,500 it might not be to everyones taste.

edit: I think the fluid is actually a citric/phosphoric mix

Before that, I used paste. A "soft wheel" can be used to polish it up too, there are other options. If you have not seen/used a 3M soft wheel, I suggest you try one, they look like a grey grinding wheel, but are made from some grit/fibre composite.

I should add that the paste is very good, just keep a tube of Calgonate Gel handy, wear gloves and goggles. Wash down outside with a hose.
 
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Yes, the Magic Cleaner is a little outside my price range :)

I've already got some of those 3M soft wheels. I'll also look into using electrolysis and citric acid, should be fairly easy to set up a small rig.
 
I use a gel, but it does have some hydroflouric acid in it.
Over on the mig-welding forum, some guys were using transformers and carbon brushes off ebay, along with phosphoric acid off the bay. Cheap and worked.

rszemeti's magic-cleaner does look good, apart from the ££££.
 
The MagicClean is basically a small sponge head, (looks very similar to "Vileda" cloth) soaked in the citric/phosphoric mix ... with a small pump to squirt the goop out from time to time ... I'm sure dipping it in a saucer of the stuff from time to time would be as good as a pump for occasional use.

The voltage is AC, so just a regular transformer of around 25V secondary should do it. 10 to 20A max.
 
DownWest said:
Over on the mig-welding forum, some guys were using transformers and carbon brushes off ebay, along with phosphoric acid off the bay. Cheap and worked.
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By "carbon brush" do you mean an electric motor brush, or a brush made of carbon?
 
I found the MIG Welding Forum thread

Just had complete success with:

Carbon fibre brush from eBay, 11 quid
Battery charger/booster set to boost mode
25% concentration (ish) phosphoric solution
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Sounds like the one for me.
 
rszemeti said:
I am pretty certain the Fronius uses AC for cleaning, and DC for its "printing" function ...
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Hmmm, maybe just bypass the rectifier in the battery charger (assuming it's an old transformer type). Mind you, the guy says it works with DC
 
Graham376 said:
Stainless also stick welds OK and no need for gas.
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I have welded stainless with Oxy Acetylene in the past too.

I was not so hot with thin aluminium sheet, but 3/16th duraluminium plate was fine. Tempreture pre weld was judged by having a piece of matchstick burn on the surface to be welded. Many pistons for racing mororbikes had their compressin ratio's increased by aluminium welding with Oxy Acetylene.

I have also welded cast iron cylinder heads and built up cast iron side valve valve seats so the antique engines could have a new lease of life. The built up seats had to be ground, not cut, as chatter of the tool would not allow the job to be completed.
 
I "cut my teeth" on oxy-acetylene. With practice, there is not much that cannot be tackled with an oxy-fuel torch. Aluminium is particularly pleasing to weld, once you get it right. TIG is easier for the beginner, but there are a lot of "thin sheet" guys who swear by oxy for aluminium. Aircraft fuel tanks are one such thing ... many are .020" (0.5mm) or less .. and seam welded on the edge of the flange.
 
rszemeti said:
I "cut my teeth" on oxy-acetylene. With practice, there is not much that cannot be tackled with an oxy-fuel torch. Aluminium is particularly pleasing to weld, once you get it right. TIG is easier for the beginner, but there are a lot of "thin sheet" guys who swear by oxy for aluminium. Aircraft fuel tanks are one such thing ... many are .020" (0.5mm) or less .. and seam welded on the edge of the flange.
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I tried that-could not cook it. But my mate Jim who made ALL the works Lola chassis, including Surtees one with the Honda engine that won him the World Title, could do it with his eyes shut. He was a master of the blue flame.

I was shown by another " traditional " mechanic/expert how to fix broken fins on cast iron cylinders. He started when a Model 'T' Ford was a new car. He was the best motorcycle mechanic I have ever known. He attended 1000 home meetings at Swindon Speedway. He was their first contracted rider, after an illustrious career on the handlebars he became the Team Manager. He then went to official Team Mechanic and then to Machine Examiner. After attending a thousand meetings without missing one he did not worry too much if it was his lovely wife Audrey's birthday and she fancied a curry!

He showed me how to fix broken fins on iron heads and cylinders using low tempreture nickel bronze.

I once repaired a Veteran-pre 1914- Precision Vee Twin engine that had had ALL its fins chiselled off the integral barrel/head units.

All 148 of them......................................

It took three months to make the new fins-from antique bedstead frames-and attatch them.

AFAIK it is the only working Veteran Precision Vee Twin engine in working order. The fins had been chiselled off to allow galvanised buckets to be brazed to the cylinder bases for simple water cooling when the engine was converted to power a saw bench. As the water evaporated away, it was just topped up in the open bucket end.

The method for afixing the remade fins to the integral head/cylinder units was to 'Tin'-rather like soldering-the fin with a coating of low tempreture nickel bronze.
Then the tricky bit came in. The head/cylinder unit was preheated on my industrial 4KW hotplate-until a gob of spit danced and would not settle. Very important that bit.

Then, on the hot plate, held with blacksmiths long pliers, the area where the fins were to be fixed was also timmed with the nickel bronze. The hotplate was gradually turned down, and then off, to avoid heat distortion/cracking.

When all fins were tinned and all the matching areas of cylinder were tinned the hotplate was turned up with the cylinder/head standing upright. When a gob of spit would dance it was hot enough. The fin, held in two mini Vicegrips was held in place while a soft flame was played over the join of the fin/cylinder joint. We started at the bottom, and worked upwards. As the nickel bronze reached melting point, my assistant-we shall call him Tony, for that was indeed his name-pushed and wiggled gently to place the newly made bed iron fin against the cylinder/head unit. Once he said 'it feels OK'-I put the torch down and blew the airline over the joint. All 148 of them...................

We usually did two each day, immediatly after the lunch break.

What I charged barely covered the cost of Tony's wages and heating the hotplate-but as far as job satisfaction goes, you could not beat it!
 
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