Accucraft 3-cylinder Shay safety valve fail......................

tac foley said:
We are hoping that some of the penetrant will seep through the threads of the safety valve
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Tac, I hope not, or your safety will be leaking. Or maybe that's part of the problem.

Did you try the stuff for removing scale in an iron? Pour it in the top and leave for an hour or so.

Here's another wrench option. They are used for taking the cap off a boat strainer - the 2 prongs fit in the holes on the top and then you twist it off.
I appreciate this is too big for your dome, but you do have a couple of holes in the top that are not on center. Maybe a long piece of metal with holes where the dummy valves were, with M2 (M1.5?) bolts through into the top of the dome?
4493367_1500.06072018020046.jpg
 
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musket the dog said:
My other thought is how is the dome's saddle attached to the boiler cladding? Just thinking out loud, but if it's soldered, it might be easier to remove it entirely with the dome still attached,
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My C-19 had the dome bolted from inside the boiler cladding. I had to remove the boiler intact in order to swap the domes. Quite a performance.

Neil Robinson said:
I suggest you attempt to purchase a replacement dome cover and valve.
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Accucraft don't tend to supply spares like that, but the support guy (David?) often has a scrap loco in his pile and can send the piece you are looking for.
Tac - I usually use Skype to phone overseas (often to the UK!) I would phone support and ask if they have a dome, so that you can wreck the old one and replace it.
 
tac foley said:
Tomorrow will see the serious bit of drilling an access hole clear through the dome, above the level of the safety valve, to put a silver steel rod though it to get some better purchase.
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There's a prototype for everything. Check the G1MRA NL&J about the Nord 4-4-0. It had the regulator valve behind the chimney/stack, and a rod through the sand and steam domes back to the front of the cab! You could drill your hole and then make it part of the loco with a rod to the cab.
 
Fred2179G said:
There's a prototype for everything. Check the G1MRA NL&J about the Nord 4-4-0. It had the regulator valve behind the chimney/stack, and a rod through the sand and steam domes back to the front of the cab! You could drill your hole and then make it part of the loco with a rod to the cab.
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Good idea!! How long ago was this, I wonder. If it all goes well, I have a selection of cast brass handwheels on pipework that could fill in the holes!!
 
Hi Tac, Can't remember if you tired this or something similar yet. Put a clay dam around the dome and fill it with penetrating oil? I realize there appear to be flat faces where the dome meets the skirt that's soldered on the boiler but the oil may be able to penetrate to the threads. Maybe another thing to try before resorting to major surgery is to fill the cavity on the dome with penetrating oil again but then try pressurizing it with air. If all the holes are threaded can you put plugs in all but the one used for an air connection? This may force the oil into the threads.
 
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The cavity on the dome has been filled from Day 1. It is now a week since I inverted to and filled the boiler the Penetrant. As I mentioned above, it all else continues to fail I'll be resorting to hole-drilling and using a soft hammer on a length of silver steel passing through the holes. I'm not giving up on this - it is just too expensive not to try everything I can think of. I have no source of compressed air, BTW.

My grateful thanks for all your continued support in this unwanted adventure.
 
Phil, with the construction of the dome, filling the dome does nothing... a fact that 80% of the commentors fail to "grok" even after repeated attempts.

Tac has filled the boiler and inverted it, the only way to get to the threads, other than building a "dam" around the dome and filling the "moat" between the dam and the dome.

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Okay, Gentlemen, I finally gave up.

I KNOW that some of you will cut me out of your will, but I cut the top off the dome with a fine hacksaw - it took me an hour.

1647275224106.png

The removed part I intend to level off in my little Unimat lathe, and carefully file the 3/4" high stub flat to match. I'll then make an internal flange so that the top will just drop onto the bottom remaining section.

Now I have to figure out how to remove the safety valve...Perhaps drilling a couple of holes in the top of the body to enable me to get some very fine-nosed pliers in there might do the trick - anybody have a better idea?

1647275430656.png

I'm all ears...
 
Greg Elmassian said:
Just a question, it appears that the construction matches the picture we have been using (and I just re-posted).

Just verifying that information is correct.

I would get a spanner with the 2 pins, and drill 2 holes in the thick part and try to unscrew it still.

4493367_1500.06072018020046.jpg
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Might be easier to drill the 2 holes as you say, then put a couple of rods in each and try putting a long rod between them , and twisting 20220314_172107.jpg
You'll have to excuse the carp drawing
 
Devil's advocate - if the dome was so solidly seized what's to say the safety valve is not similarly seized in its threaded receptical. I'm still surprised you have had to resort to physically cut the top of the dome off. I still hope you have a positive outcome. Max
 
tac foley said:
The removed part I intend to level off in my little Unimat lathe, and carefully file the 3/4" high stub flat to match. I'll then make an internal flange so that the top will just drop onto the bottom remaining section.

Now I have to figure out how to remove the safety valve...
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Tac, I suspect your safety valve looks like this, which is the common older-style. (I googled "Accucraft safety valve".)

AP-21101-Safety-Valve.jpg


Here's a pic of the one on my C-19 inside the dome - the loco is the same era as yours.

IMG_3117-valve.jpg

You can see the serrations on the outside of the valve body. If you poke a thin screwdriver or pointy object in the dome, you will be able to feel the bumps around the circumference.

You may be able to grasp it with fine point pliers or tweezers.
 
Well, now you have butchered the dome, you can make notches/slots or drill holes at either side which will be hidden by the dome top.

Untitled-1.jpg

Paul's suggestion of putting a steel rod in each side hole and then twisting it off with a longer rod seems doable?

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tac foley said:
Okay, Gentlemen, I finally gave up.

I KNOW that some of you will cut me out of your will, but I cut the top off the dome with a fine hacksaw - it took me an hour.

View attachment 296187

The removed part I intend to level off in my little Unimat lathe, and carefully file the 3/4" high stub flat to match. I'll then make an internal flange so that the top will just drop onto the bottom remaining section.

Now I have to figure out how to remove the safety valve...Perhaps drilling a couple of holes in the top of the body to enable me to get some very fine-nosed pliers in there might do the trick - anybody have a better idea?

View attachment 296188

I'm all ears...
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What about a stud extractor?
 
Fred2179G said:
Well, now you have butchered the dome, you can make notches/slots or drill holes at either side which will be hidden by the dome top.

View attachment 296192

Paul's suggestion of putting a steel rod in each side hole and then twisting it off with a longer rod seems doable?

View attachment 296193
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The strain of even using a strap wrench was twisting the frame, so although I was thinking along your lines, as was old pal Garrett on the FB pages, that's a no-no. Thanks all the same - all comments are appreciated - none are hoo-poo'd.
 
Fred2179G said:
Tac, I suspect your safety valve looks like this, which is the common older-style. (I googled "Accucraft safety valve".)

AP-21101-Safety-Valve.jpg


Here's a pic of the one on my C-19 inside the dome - the loco is the same era as yours.

View attachment 296191

You can see the serrations on the outside of the valve body. If you poke a thin screwdriver or pointy object in the dome, you will be able to feel the bumps around the circumference.

You may be able to grasp it with fine point pliers or tweezers.
Click to expand...

Wow!!! That's GREAT news!!! I might actually be able to DO that. It will have to await daylight, though...
 
maxi-model said:
Devil's advocate - if the dome was so solidly seized what's to say the safety valve is not similarly seized in its threaded receptical. I'm still surprised you have had to resort to physically cut the top of the dome off. I still hope you have a positive outcome. Max
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It was not an easy decision, and that's a fact, but one of necessity, without doing that I would never have even seen what the safety valve looked like, although, given the age of the model, it is no surprise that it was the old serrated body style. Needless to say, that is NOT what I will be using to replace it. I have a couple of Aster units that are hexagonal and therefore much easier to remove using a choob wrench.
 
tac foley said:
I might actually be able to DO that.
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As long as the valve isn't as tight as the dome threads . .

Another thought. Now you have the dome open, can you open up the hole by cutting away the thick sides? I have no idea what kind of tool would do that! Taper drill? Sanding drum in a Dremel?
Give yourself more room to grab the valve body.

Final thought (I'm full of bright ideas when it's someone else's loco that needs fixing,) you can make a tubular box wrench that will fit tightly on the serrated exterior of the valve. A brass tube just a little too thin can be bashed down over the valve body.
Or if that's too scary, take a tube that is a snug fit on the valve and add some serrations inside it, with wire or similar. Solder them to the inside of the tube.

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