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

[Greg Elmassian]

Best of luck Tac!

I believe credit for leather pieces idea is from someone on MLS, but if it works I'll take credit ha ha! Just kidding, hope for the best for you.

Greg

 

[DafyddElvy]

I found out today a member of our local group has or had the same loco, I have emailed him to see if he can offer advice.

Sorry he couldn't offer any advice other what has already been said. On the engine he has the false dome definitely unscrews anti clockwise.

He did have one idea though, could a jar lid remover thingy be used to help grip the dome, just a thought.

 

[tac foley]

Ye, it's called a strap wrench. It didn't work.

Not did firing up and cooling the dome down with cold water.

Guess we are down to the wire now, and it's the angle-grinder putting a couple of flats on it to get a proper wrench on it.

It's way too late the think about it now, but it's a great pity that a £2000 loco back in 2007 can be left as a shelf-queen because some klutz got over-eager tightening it up in the first place.

I'm not a happy bear today, in spite of it being the annual remembrance of my natal event.

 

[DafyddElvy]

One last idea, I know you are trying to remove the dome to change the safety valve, but how about steaming the loco the heat things up, just a thought.

 

[Greg Elmassian]

The issue is that this is internal threads, the center if there is steam will heat first.

Thus the dome will get a bit hotter that what it is threaded into. Since it is an internal thread, all you are doing is making it tighter.

Tac, I meant a couple of thin strips of leather with the strap wrench.... to prevent slipping.... I asked if when you used the strap wrench if it slipped.

Greg

 

[maxi-model]

Allow me to test my understanding.........Tac, are you unable to rotate the dome at all ? Unless there is something unique about your example then the instructions given to remove should hold. Unless it has seized for some reason (build up of lime scale or some other contaminant ?), then a drop or two of good old penetrating oil and a bit of time for it to get to work should free it up. Or possibly some lime scale removing solution ? Max

 

[Greg Elmassian]

No offense Max, but seriously did you read the thread? All has been tried in this FOUR page topic.

Everything you have suggested has been tried, all the questions you have asked are answered.

1. cannot rotate (otherwise it would be off already)
2. yes, siezed, or locked in place with corrosion or scale or both or alien glue
3. yes penetrating oil
4. yes, lime scale solution

And even more...

 

[PhilP]

Something I have seen work, but the loco would have to be really well supported:

You need;
Battery drill/driver - must have a clutch.
Adapters to be able to use a socket.
A socket (very slightly) smaller than the dome. - needs to fit over / on the top..
A piece of soft leather.

Support the loco well. - You will be bearing down on it. It must not be able to 'bounce' or rotate.
Set the drill to unscrew, and a medium-to-high torque..
Place leather over dome. Press down really firmly, and operate the drill..

You do not want the socket to rotate. You want the ratcheting clutch to percussion the dome.


Supporting the loco, so you can bear down with your weight, and the vibration, might be a step to far?
But I have seen this work on a vintage vehicle, with a very rounded nut.

PhilP

 

[JimmyB]

Something I have seen work, but the loco would have to be really well supported:

You need;
Battery drill/driver - must have a clutch.
Adapters to be able to use a socket.
A socket (very slightly) smaller than the dome. - needs to fit over / on the top..
A piece of soft leather.

Support the loco well. - You will be bearing down on it. It must not be able to 'bounce' or rotate.
Set the drill to unscrew, and a medium-to-high torque..
Place leather over dome. Press down really firmly, and operate the drill..

You do not want the socket to rotate. You want the ratcheting clutch to percussion the dome.


Supporting the loco, so you can bear down with your weight, and the vibration, might be a step to far?
But I have seen this work on a vintage vehicle, with a very rounded nut.

PhilP

So you are really talking about a hammer drill, where it will be shocked off.

 

[Paul M]

Ye, it's called a strap wrench. It didn't work.

Not did firing up and cooling the dome down with cold water.

Guess we are down to the wire now, and it's the angle-grinder putting a couple of flats on it to get a proper wrench on it.

It's way too late the think about it now, but it's a great pity that a £2000 loco back in 2007 can be left as a shelf-queen because some klutz got over-eager tightening it up in the first place.

I'm not a happy bear today, in spite of it being the annual remembrance of my natal event.

Happy birthday tac.
I know you have tried all the suggestions, but before you start attacking the poor thing with angle grinders and things, how about soaking it in oil and leaving it for a few days. It probably won't work, but it will give you a chance to have another think

 

[Greg Elmassian]

There may be a point here... if the dome is as shown, then putting fluid inside will NOT hit the threads, it will funnel down the center and drop inside the boiler.

Make sense?

Does it make sense to put in the boiler and leave the boiler upside down?

Then the penetrant could collect in the saddle, which should be surrounding the threads...

Just thinking that putting any liquids in the dome would just never touch the threads at all...

Greg

 

[maxi-model]

Happy birthday tac.
I know you have tried all the suggestions, but before you start attacking the poor thing with angle grinders and things, how about soaking it in oil and leaving it for a few days. It probably won't work, but it will give you a chance to have another think

Precisely my point Paul. Unless there is a design difference then something has seized ad caused that seizure. As the dome/saddle threads are so coarse and the dome is shown so neatly seated on its saddle cross threading is unlikely. Yes you may need some form of "strap wrench" to budge it initially but give the milder alternatives a chance first. That or have a word with Mike Darby in Warwick, an Accucraft service agent with some experience of these locos (including my own).

Greg, I believe that so far I am the only respondent so far who is actually in possession of one of these locos. And, who has taken the trouble of disassembling the the recalcitrant part, that is on Tac's example, to try to offer a practical solution. Max

 

[Greg Elmassian]

I was just surprised you asked about several things that were already tried.

But it's very valuable that you have the picture, extremely.

As in my last post, I think having it upside down and putting in the boiler will be the only way to engage the threads, based on the "anatomy" of the threads and dome.

It should collect in the saddle and get to the threads, that is my theory why nothing else has helped, because no other way to direct the liquids tried.

Greg

 

[LVT]

I was just surprised you asked about several things that were already tried.

But it's very valuable that you have the picture, extremely.

As in my last post, I think having it upside down and putting in the boiler will be the only way to engage the threads, based on the "anatomy" of the threads and dome.

It should collect in the saddle and get to the threads, that is my theory why nothing else has helped, because no other way to direct the liquids tried.

Greg

As there seems to be a consensus that no penetrant is reaching the threads, perhaps a tiny hole, or two, drilled into the saddle, intercepting the thread area, could allow injection of penetrating oil or descaler. Seems a little less obtrusive than grinding flats on the dome. A frustrating, fascinating challenge, particularly considering the intricacy of the rest of the model.

 

[PhilP]

So you are really talking about a hammer drill, where it will be shocked off.

Not quite..
A drill driver clutch will provide a shock, but only when the 'bit' (socket, in this case) stalls..
The percussion is what you are after, but you don't want the socket spinning on a ceased dome!

PhilP

 

[tac foley]

Happy birthday tac.
I know you have tried all the suggestions, but before you start attacking the poor thing with angle grinders and things, how about soaking it in oil and leaving it for a few days. It probably won't work, but it will give you a chance to have another think

Thanks, Paul. It has now had penetrating oil in it for five days and nights....................

 

[tac foley]

As there seems to be a consensus that no penetrant is reaching the threads, perhaps a tiny hole, or two, drilled into the saddle, intercepting the thread area, could allow injection of penetrating oil or descaler. Seems a little less obtrusive than grinding flats on the dome. A frustrating, fascinating challenge, particularly considering the intricacy of the rest of the model.

Good idea, I'll probably give it a try tomorrow............................the GL knows I've tried everything else short of the percussion/hammer drill idea, although that too, sounds good.

 

[Greg Elmassian]

It has had penetrating oil, but was it introduced to the dome or the boiler?

I think the inside threads have thrown a curve ball..

Greg

 

[Rhinochugger]

My twopennyworth - so we need to get penetrating oil on the threads - but do we? the crud has likely formed a seal above the threads if we look at Max's photo.

So, what if the loco is laid on its side, and oil dripped onto the joint? Not going to get in there very quickly, but a little and often. Or how about a poultice arrangement where the oil can wick into the crud that's forming the seal?

 

[Gtarling]

Tac - you have mentioned 'penetrating oil' several times, but what actual product are you using? Only asking, as so many seem to think that WD40 is penetrating oil - it's not.

G.