Project TIG

[Parm]

Ive been self learning to weld for the last few years now, having started with a hand me down buzz box and now graduating to a clarke hobby mig which is serving me well for my needs.

like most blokes on the forum I have a real fetish for tools and often want things that I have no need for, well a TIG welder is one such thing.

Having acquired the High Frequency unit from a member here the mission is now underway to build myself a AC DC TIG machine. I will qualify at the get go that I'm not a proffesionionl welder, Infact im not even a good welder but I can stick metal together.

The fun thing for me with all this is to come up with what I need, find ways of making things happen while looking for solutions to over come the challenges I have. To give you an insight into how my head works, I spend a lot of time in the car when visiting clients, I use this as my thinking time to design projects and come up with solutions with the stuff I have to hand.

Well on with the HFU

First I must start with a massive thank you to all the members who have helped, given advice, sent me things and planning to send me things. Massive thank you to you all. None of this would have been possible without your help. I don't want to single people out but you know who you are

So onto the project

I've sussed out where all the cables go, got to now order some cable and make leads with dinse plugs

Need a DC source for welding steel and SS, so been very busy reading about this, had a consultation with an electronics engineer mate, not on this forum and ordered the bits to make a full wave rectifier p

Water cooled TIG torch has been promised, so will need a water cooler

Been reading about a TIG cooler, several options available to me and I have all the bits n bobs for one option but not sure which way I'm gonna go yet

I will use this thread to update on progress as I go

 

[skotl]

That sounds very ambitious, Parm! Look forward to seeing how it turns out

 

[Parm]

Ok, I've come up with a design and circuit diagram for the full wave rectifier, ive had it approved by my electronics guru, it's all approved now so parts have been ordered. I have an enclosure that it will all fit into so happy days.

Also been checking out water coolers, I now have some good options and planning to use some parts that can't be used (allegedly) and some other quite novel parts to make it a little more interesting

More to come soon

 

[Parm]

That sounds very ambitious, Parm! Look forward to seeing how it turns out

Have faith in me my man, this will be the most technological (not to mention most dangerous) project I'm about to embark on

 

[Parm]

Let's see the rectifier design then

Here it is, do you have any knowledge of such things ?

 

[Parm]

Have you included the varistor to offer protection to the hfu? Not sure it's required if so, but it shouldn't do any harm to have it there...

Might be worth whacking in a decent sized cap to go with the inductor (already got a suitable inductor?)

I'm not too sure about the varistor and big caps are not recommended from what I've read. As for the inductor I'm planning to make one.

I'm not realy au fait with such matters so have passed it on to an electronics wizard mate who's checking it all out. The design comes from an American chap who was on the forum and no longer active. He's made quite a few of these with great success. I've just taken his diagram to copy and make one of my own with some help

 

[skotl]

Have faith in me my man, this will be the most technological (not to mention most dangerous) project I'm about to embark on

Every faith, my friend

 

[Parm]

Unless you have one already (or have already ordered one) I wouldn't bother with the varistor myself - it won't 'hurt' but I don't see a reason for it to be there really.

As for smoothing caps, they're pretty much optional depending on what you want - there's advantages and disadvantages both ways really.

If you were wanting to have a slope in/out they'd mess with that, but seeing as you don't have that functionality available to you they could help give a smoother arc (possibly with a slightly more 'enthusiastic' start). The HFU is expecting a full time input so it's not going to bother that.

Cleary you have some understanding of such matters, so what would you suggest for a choke ?

 

[HughF]

Length of cable, bit of iron

I'll get that torch off to you tomorrow mate, been hectic and ill, apologies

 

[Parm]

Length of cable, bit of iron

I'll get that torch off to you tomorrow mate, been hectic and ill, apologies

I've seen a very good one made with 25mm square tube knocked up into a frame but there's all sorts of conjecture on the web as to the pros and cons. As usual there's those that have to follow a written instruction and can't deviate from the norm and then there's chancers like me !!!

I'm reading, consulting and understanding to build up my confidence to do this cause with the sensible hat on there are some big risks playing with high current stuff that I don't fully understand.

But having said that my mate has checked out the circuit diagram, seen the HFU and ordered me some components. I've had a good rummage round and found some hefty new heat sinks, 12v and 240v cooling fans, a couple of cases and a good few other usefull components, plan is slowly comming together

And thanks Fella

 

[HughF]

I've got a ferrite cored choke I'll include in the package for you... Beefy yet compact, from a scrap inverter welder I gutted...

 

[Parm]

I've got a ferrite cored choke I'll include in the package for you... Beefy yet compact, from a scrap inverter welder I gutted...

Top man, what a star

 

[Parm]

How 'accurate' do you want the choke to be?

Given that this is all experimentation, either nick one from a scrap welder or do what Hugh said.

A bit of square tube would 'work' but an iron core will be better than effectively an air core - you might saturate it but if you're 'just' using bits of cobbled together stuff it's not an issue.

Possibly mount the choke in a separate box for the time being to make changes easier?

Play around, the worst that can happen is you'll overheat the choke (unlikely, but hey).

Another one ive seen is a 2" diamter steel bar about 8" long, wrapped with heavy gauge welding wire

 

[Parm]

Even a length of wire wrapped into a coil and taped together will form a choke - I'm not telling how many turns though, it's a secret

Lol, spoil sport, Now that's not in the spirit of this forum

From what I've read even the major manufactures don't have a proper formula, it's all trial and error

 

[Parm]

Ok, fine, I'll let you in on it...

Wrap the cable around your hand until you run out of cable or get bored, then tape it up.

Gotta say, the choke has been the most elusive part of the whole thing, converting AC buzz boxes to DC is a big thing in the States and there's lots of information but no consensus on what's right, wrong or acceptable. I've seen solid cores, ferrite cores,mc rushed ferrite cores in card board tubes, old mains transformers, microwave transformers and everything in between. The only thing for sure is that lots of people have had a go and they mostly seem to work

 

[Parm]

When I 'converted' my buzzbox to DC, I used a modified rectifier from a car battery charger/jump starter and a couple of fans.

I didn't bother with a choke or caps and the difference is obvious 'twixt AC and DC operation.

Ok ive seen that one too but didn't fully understand it, I looked inside my quite decent battery charger and couldn't convince my self that the weedy looking transformer and electronics would be man enough for the job.

Always doing things on the large side, My mate has ordered some hefty 500 amp shotocky diodes to build the rectifier. Probably over kill but it's being planned so that if ever I get the chance with a proper power supply I can use the full 350amps with the HFU

 

[Parm]

These are the types of diode that have been ordered and the proposed heat sink and mounting arrangements

And this is the coil design that I was looking at

 

[Parm]

I don't know about that, only just seen the dodgy wiring now that you've pointed it out.

Pic below is the plan so far for diode arrangement, mounting and insulation with perspex and copper lightening bar buss bars. I have all parts except the diodes.

How would you mount the diodes to the heat sink without heat sink becoming live. There are isolating heat sink tabs made of mica but are they any good ?

 

[skotl]

These are the types of diode that have been ordered and the proposed heat sink and mounting arrangements

View attachment 87526

And this is the coil design that I was looking at

View attachment 87527

These look nice and meaty

That aside, I agree 100% with pdg that perspex is an odd choice of material to mount heatsinks on.

 

[Parm]

These look nice and meaty

That aside, I agree 100% with pdg that perspex is an odd choice of material to mount heatsinks on.

I agree, probably like most of us this has been cobbled together with what ever was to hand. Ive got some quite large heatsinks and my eye on an old instrument case that I think will be perfect for the job. But before anything gets assembled my electronics guru mate will be advising on the final design and construction details