How to purge this?

[Shox Dr]

Block each fin off with putty or tape or both. How many have you to do?

 

[Misterg]

Block each fin off with putty or tape or both. How many have you to do?

Just the one!

Sorry if it's a daft question, but what do you mean by putty? (Actual window putty?) Do you mean pressing it against the back of the weld to shield it? Or constructing a 'cave' around the fin that can be purged with argon?

 

[Shox Dr]

There is a putty available I forget the name. I've not used it so cant comment on placement, though using it to build an enclosure to encapsulate each or a few fins at a time is how I would use it, keeping it away from the heat much as possible. Lets us know how you get on please

 

[Misterg]

Lets us know how you get on please

Thanks - Will do. (Currently waiting on a few bits to set up a purge line.)

 

[Misterg]

Mark one purge box:

I didn't have any reasonably fine mesh, so just covered the base with fine pea gravel

Seems to work after a fashion:

(It looks worse in the picture than it does in real life - there's no 'sugaring' that I can see)

Had a quick go with a test piece to try and dial in the settings (I'm very much a newbie).

Best example (Pulsed 0.8Hz@20% 110A peak / 25A background). Inside:

Outside (back of weld):

I'm not convinced that it's very effective, but it looks like it would work to keep the blades in place without messing up the back surface (I'm not too worried about getting a fully penetrated weld as long as the blades won't fall out.

I'll probably have a try using a gas lens as I've just realised that I have a suitable tap for making an adaptor (Fender guitar jack plugs and TIG torches share the same thread size - who knew! )

Thanks for the advice - I will continue to experiment.

 

[zeppelin builder]

Outside (back of weld):

View attachment 290052

I'm not convinced that it's very effective, but it looks like it would work to keep the blades in place without messing up the back surface (I'm not too worried about getting a fully penetrated weld as long as the blades won't fall out.

I'll probably have a try using a gas lens as I've just realised that I have a suitable tap for making an adaptor (Fender guitar jack plugs and TIG torches share the same thread size - who knew!

That there is the feline equivalent of Auswitch

 

[Munkul]

Well you've convinced me! It's not perfect, but it's good enough to stop sugaring, so it works

 

[Misterg]

The MK 1 version was a pain to try and position the part at a good angle to weld (and to reposition for each vane) so I had a 2nd try:

I made an adaptor to connect the purge line to a gas lens (a dummy TIG torch head) as suggested above:

I fitted a #8 cup with gas lens (the biggest I have) with a stub of tungsten in the hole and mounted the adaptor and the welder earth clamp onto a magnetic base so that I could use the earth clamp to hold and position the part. Added a bit of tinfoil:

5LPM on both backing lens and torch and it worked an absolute treat!

The test piece again: The little bit of colour on the weld came after the post-flow shut off (it's the middle weld).

The vane only had a little colour where the coverage from the gas lens wasn't as good (or maybe the stream from the torch interfered with it):

The advantage is that I just needed to turn the gas on while I was actually welding - a lot less gas usage and better protection than trying to purge the 'litter tray' version.

It's definitely a useful trick to keep in the bag - Thanks for the tip @Mullet52

I've just got to pluck up the courage to weld the real one now

 

[Mullet52]

No problem! I knew that would work. I use one of these magnetic arms. Jubilee clip the gas lens on the end. I reckon it would be perfect for what you’re doing.

 

[Hitch]

We make up quick and dirty purge pieces a lot, a bit of tube stuffed with some scotchbrite and the end shaped to suit the job, tape in a purge line into the back and you have it.

 

[stuvy]

What’s the part for? General curiousness and being nosey

 

[Misterg]

What’s the part for?

It'll hopefully end up as a static nozzle / guide vane (NGV) assembly for a model gas turbine engine. When I get a bit of time, I intend to start a build thread to document the construction of what will probably end up as an expensive door stop.

 

[stuvy]

It'll hopefully end up as a static nozzle / guide vane (NGV) assembly for a model gas turbine engine. When I get a bit of time, I intend to start a build thread to document the construction of what will probably end up as an expensive door stop.

please do it sounds really cool

 

[Bki26]

It'll hopefully end up as a static nozzle / guide vane (NGV) assembly for a model gas turbine engine. When I get a bit of time, I intend to start a build thread to document the construction of what will probably end up as an expensive door stop.

Nice, had a feeling it might have been an ngv initially. You a member with the www.gtba.co.uk lot?

I'm currently building the more redneck version using an 85mm turbo and the help of the guys at https://jetandturbineowners.proboards.com/

 

[Misterg]

Nice, had a feeling it might have been an ngv initially. You a member with the www.gtba.co.uk lot?

I'm currently building the more redneck version using an 85mm turbo and the help of the guys at https://jetandturbineowners.proboards.com/

Yes, joined the GTBA very recently - there's a lot of historical stuff there, but very, very quiet now - about 1 post a week. (Also look at JATO occasionally).