Assessing an unknown engine

[RobFrost]

Great work Rob, really enjoying this thread.

Karl

Thanks for the encouragement!

Cleaning has been the name of the game this week.

To avoid individually scrubbing every last nut, bolt and washer, I availed myself of some cheap chinese manufactured produce in the form of a tumbling cleaner. It came in the week and I loaded it initially with the parts from the dismantled throttle bodies. I read not to use crushed glass, due to the risk of silicosis. But I had some crushed glass to hand so I put that in along with some water and a squirt of washing up liquid to aid with grease removal.

I resolved to keep the glass wet and dispose of it before any dust could become airborne.

I was able to work in the garage on other things while the intolerable assault on my eardrums was going on in the background - not the tumbler, rather Radio 1 playing the latest Coldplay single.

After white noise from the tumbler had anaesthetised my coldplay-related aural injuries for a good three hours, it was time to release the pristine shiny metal parts from their vortex of infinite microabrasion.



Looking good, I thought!

Whenever I'm unfortunate enough to watch any "Aussie Gold Hunters" (and that is a lot more often than I would like to admit), I usually think to myself that you wouldn't catch me swilling around in a wet pan of sand for a few fragments of shiny metal. However that is exactly what I found myself doing for the next couple of hours. Some of the nuts and washers are so tiny that I had to spread the entire pot of sand out one grain thick, so I could see through it and be sure I was not discarding any valuable little nuggets of Porsche.

Once separated, I moved the items through a system of buckets within buckets designed to wash off the sand while simultaneously preventing any plughole-related mishaps. All in all a good result. Second batch went in today.




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[911hillclimber]

That lot does look impressive Rob.
You could have tried Radio 2 or 4 or nothing!

[RobFrost]

If I'm going to weld this engine case I'll need to get some practice in with my new tig welder. First attempt is a benchmark of where I'm starting from.



Slowly getting better but it takes time to learn what needs adjusting. I think the power's too high here.



My first impression is that tig seems to require very much more precision than gas or mig. If you touch your welding rod to your oxy acetylene torch it doesn't really matter, and if your gas torch comes away from your work it doesn't really matter, you just move it closer again. No matter how often I sharpen the electrode, this appears to be its go-to shape.



When it's like that, the ark shoots all over the place like one of those glowing plasma balls. I seem to spend 10 minutes grinding the electrode for every one minute welding.

Slowly getting better. You really have to pay attention and think why you're getting the results you are. I've reduced the current to something more suitable but the lack of straightness here is, I think, due to poor lighting and my inability to see the line I marked to weld along.



Let an expert the weld the case, you might say. But where's the fun in that?

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[Bruce M]

I’ve got a tig coming too so will be learning soon. Only been doing my research so far.

Blue electrode is general purpose but chartreuse is popular too as it’s a bit more hardy. Red is old school.

Typically 1.6mm electrode is 1-2mm material. 2.4mm for 2-3mm material.

#6 cup for aluminium, #8 general purpose, #12 stainless. Although #8 can get you by

Gas flow of pure argon, is the cup size in litre per minute (min setting). Plus 2 litre/min is the max.

Amp setting baseline is 1amp per 1/1000 inch of material thickness.

A/C for aluminium only. D/C electrode negative otherwise.

A/C frequency baseline is 120hz. Go down towards 60hz for thick material which requires a lot of heat input. Above 120hz for thin material that easily blows through.

AC duty cycle baseline is 30% electrode positive (which breaks down the anodised layer). Higher than that tends to ball the electrode but may be needed for cast material with more impurities / porosity.

Again these are theory notes not based on experience (yet)

[911hillclimber]

Interesting.
I thought tig was much like gas welding.
In the past I could gas weld like a god, but mig welding put an end to that practice!

Those cases are gold just Rob, I would be finding an expert, but all for diy!

[RobFrost]

Interesting.
I thought tig was much like gas welding.

In principle it's much the same but it seems like you need an extremely steady hand to tig weld. Come away for a moment and you lose your arc. Touch the work and you have to regrind your tip. Touch your rod to your tip and you have to regrind your tip. And you can't simply point the torch at your rod to melt your rod, like you can with gas. The rod has to be precisely introduced between the tip and the work to melt it. As a result, it's imperative your rod is finer than your work, otherwise you would end up applying too much heat to your work in order to melt your rod. All the while, visibility is worse because the torch is fatter and gets in the way, and the arc is extremely bright. You can't simply lie on your back in any position with your hands floating like you can with gas otherwise you wouldn't have steady enough hands. You need to set yourself up in a comfortable position, ideally with your hands resting on stuff. Due to the precision required you can't wear heavy welding gauntlets like you would with gas (like I'm doing at the moment). I think I'd be better with a bare left hand but I'm not confident I'll not electrocute myself yet.

[RobFrost]

I’ve got a tig coming too so will be learning soon. Only been doing my research so far.

Blue electrode is general purpose but chartreuse is popular too as it’s a bit more hardy. Red is old school.

Stay away from the red ones, the reason they're old-school is they're radioactive. It doesn't penetrate far, so the risk is low unless you breathe or ingest it, in which case it is pretty bad. So you have to be very careful to capture the grinding dust and dispose of it.

[deano]

I too found that TIG needs a very steady hand. I have never done gas welding. In my case, as an electronics engineer, I think its a lot like soldering. In fact, my soldering and TIG technique are near identical I think - apply the heat and apply the stick to the heated surface. You know when the settings are right when it melts quickly and creates bugger all heat marks (and distortion) around the weld line.

Here is a video I did a few years ago on prep for TIG, try not to fall asleep I thought there was one of my actual TIG welding I did but I don't seem to have uploaded that one to Youtube.

https://youtu.be/l8j5kvXdIKQ

[911hillclimber]

Are the Machine Mart TIG units worth the money?

[Bruce M]

Machine mart are fairly good about warranty so that worth something. RTech seems to get good feedback for something up to commercial use.

I’m getting a Chinese AC/DC machine which is good enough for my hobby use. Will need to check it carefully for assembly mistakes. Gas tight hoses etc. but for £330 a little home QC is expected.

[RobFrost]

Machine mart are fairly good about warranty so that worth something. RTech seems to get good feedback for something up to commercial use.

I’m getting a Chinese AC/DC machine which is good enough for my hobby use. Will need to check it carefully for assembly mistakes. Gas tight hoses etc. but for £330 a little home QC is expected.

If you Google some of the Chinese brands you find a lot of people asking how to repair blown boards and components. If you're going to bother, personally I'd bite the bullet and get something a bit better like an R-Tech, Parweld, Miller or Lincoln. I was lucky in that a Lorch came up lightly used nearby with accessories for reasonable money.

[neilbardsley]

Rob if you get stuck there is Bob near Hinckley that runs the Machine Shop. Which you can turn up and use the machine and welders. For a very small fee Bob I'll weld it for you or teach you how to do. He is pretty good with a Tig welder. Ex Triumph and TT mechanic.

https://the-machine-shop.co.uk/

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[911hillclimber]

^^ That's got to be the ticket!

[RobFrost]

Rob if you get stuck there is Bob near Hinckley that runs the Machine Shop. Which you can turn up and use the machine and welders. For a very small fee Bob I'll weld it for you or teach you how to do. He is pretty good with a Tig welder. Ex Triumph and TT mechanic.

https://the-machine-shop.co.uk/

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Thanks Neil, that's a great tip. As it stands I've ordered a magnesium ingot on which to practice. Which way I go will depend how confident I get in my abilities but obviously an expert is a useful fall-back position.

[impmad2000]

Great contact Neil, I’ll make a note