70036 Boadicea

[springcrocus]

Doesn't she look just beautiful in ex-works condition? All you need to do now is make a model of her...

Fabulous work.

Regards, Steve

[Jim]

Thanks Steve and may I say it's great to see you back on the site too.

Jim

[fordfocus54]

Hi Jim,
"Boadicea" looks fabulous and a great deal better than I remember her at Immingham shed when I was a teenager! Your thread has provided a great read and a great help during the rebuild of 70022 "Tornado" which also looks a much better than the full size version did in 1967!!
I look forward to seeing more photos of her in steam in the near future.

Regards
Frank.

[Jim]

Hi Frank,

Thanks for the kind words, I must say I've enjoyed the slow journey towards getting 70036 from a few rusty castings to her present state.
 
The task isn't finished yet as I've now completed a new straight length of track so I can run the loco easily out of the workshop for its next steam up later this week. I want to be sure I've fixed all the weeps and loose bits discovered in the first steam up and most importantly I want to check that I've found out why one of the injectors wasn't picking up. I'm fairly sure it was air getting into the water delivery pipe from the tender via a loose union. I hope I'm right.

As I mentioned in an earlier post my other bit of fun is blowing 70036s's whistle, childish I know but what the heck and it gives the neighbours a chance to blow their car horns in reply. It can be a noisy neighbourhood at times

Hope you had a happy Easter

Jim.

[Jim]

Mar 31, 2018 7:44:12 GMT springcrocus said:

Doesn't she look just beautiful in ex-works condition? All you need to do now is make a model of her...

Fabulous work.

Regards, Steve

  I thought to myself, "Now that's a good idea of Steve's, build a model of Boadicea."

Then 'poof' Mr Hornby delivered before I could even find the drawings.



Jim

[Jim]

Following 70036's second steam up I've been busy sorting a couple of issues including the failure of the injectors to pick up. The problem was steam and condensate leaking past the clacks making the injectors hot. When I realised what was happening I squirted cold water onto the LP injector where upon water started flowing from the overflow and picked up as soon as the steam valve was opened. The HP was a bit more stubborn so I've since re checked the valve face to remove any traces of dirt and to lightly polish it to ensure a true surface. Hopefully all will be ok when I next steam up.

For a number of years access to my MR O gauge Nailsworth Branch has been almost impossible. So with 70036 completed I decided to construct a display shelf using a commercial rack system that turned out to be ideal, quick to assemble and very economical. As a result I now have good access to the layout, storage for my taps and dies and the BR Mk1s ready for interior detailing.



The Burrell has now been moved out from under the bench work to a spot where it's visible and accessible. There's now no excuse for not steaming it up either.

This photo is of the engine run around at Nailsworth with the track in the lower goods yard just visible. If I live long enough I might finish the layout one day.



Jim

[Jim]

Since the second steam up I've been busy sorting out some minor adjustments to 70036 that the first two steam ups revealed. These included modifying the mini blower by adding a side skirt so the draft is in one direction rather than out to the sides and all over the place.



This mod apart from keeping the smoke out of my eyes will keep the locomotive cleaner in not spreading ash everywhere..

I hope to do another steam up tomorrow to bring the pressure up to 100psi to check the safety valves are set correctly. I also want to check the HP injector to see that it is working since I modified the valve seat to improve the seal.

Jim

[steamer5]

Hi Jim,
Now that looks better! All you need to do now is were the outlet is close it in & put a vertical chimney on it! If you want a picture PM me with your email & i'll send one thru.......I really should get sorted on a photo hosting site,......

Cheers Kerrin

[Jim]

Thanks for the offer Kerrin. I must admit to being lazy in not finishing the discharge opening by closing the top and bottom off. That's a job for another day.

Jim

[Jim]

I've now done three steam ups to let the new boiler etc settle as the pressure is built up to 100 psi to check the safety valve settings. At the same time I've been able to check the minor mods made following the first steam up along with how the rosebud grate is working.
For the third steam up I built the fuel load up in the firebox and it quickly became apparent that while there was a nice bright fire in the centre of the fire box fuel round the sides was not burning well if at all due to poor air flow. I must say this didn't come as a surprise as others with Rosebud grates have had similar issues and have had to make adjustments to increase air flow in areas where it is poor.

With the grate out I set about opening the holes round the perimeter to 1/4" for two rows then stepping the holes down to leave a central rectangle of 11/64" holes where the fire was burning brightly.

This is the grate as it is now with the increased airflow round the perimeter of the grate. The next steam up will be a test of how well this works. It's easy to increase hole diameters where needed. The big hole and a couple of out of line holes were in the original plate when I 'souvenired' it to make the grate.



This is the well used grate from a NSWGR C38 that was the motivation for me going down the Rosebud path. You can see the bigger holes clearly along the sides of the grate.



The other attraction of this style of grate is that it just slides out to the side from under the fire box.



If the next steam up goes as hoped I should be ready to head to the club for a steam test. Time will tell and in the meantime a soothing ale is definitely needed

Jim

[steamer5]

Hi Jim,
So that big hole was carefully positioned to aid the removal of the grate then!

Looking good, it’s going to be interesting to here your thoughts on these grates, there’s been a bit in the AME about them, I nick Dad’s copies for a read!

Won’t be long now for an outing

Cheers Kerrin

[Jim]

Hi Kerrin,
The AME article was excellent and the C38's grate is either Martin's or Les' I can't remember which. Martin and Les built a pair of 38s  and are frequent attendees at the OSME's NSW Scale days.
My take on the grates is that you start with a uniform set of small holes, in my case 11/64ths which looked pretty close the the smallest holes in the 38's grate and that gives a starting point of 10% air flow. From there you enlarge the holes as needed to improve the air flow in the places where required, that's what Martin and Les did. When I last spoke to them 3 or 4 years back they were burning char and drew my attention to the fact that at the end of the day everything had burned a way and only fine ash was left.
I was rather surprised to find that Rosebud grates were standard on New South Wales locos, I'd always assumed they were bar grates.

Jim

[Roger]

Hi Jim,
From what you and others have found, it seems to me that a starting point might just as well be one with larger holes around the outside? I've seen a lot of pictures of these now, and that seems to be how they all end up.

[Jim]

That's true Roger they do follow that pattern though if you look at the other grate from the C38, Les has a wide band of bigger holes down each side of his grate with a band of smaller holes up the centre. I think the other factor that comes into play is the design of the ash chute and pan and the effect it has on the air flow. All this sounds like a lot of fiddling compared with a straight forward bar grate but it's not hard to open out the holes or in some rare situation close some down.
It will be interesting to see how my mods go the next time I fire up which won't be for a while yet as I'm remaking the valve seats in the top feeds as I'm not happy with the PTFE ones supplied.

Jim

[Roger]

May 4, 2018 21:41:25 GMT Jim said:

That's true Roger they do follow that pattern though if you look at the other grate from the C38, Les has a wide band of bigger holes down each side of his grate with a band of smaller holes up the centre. I think the other factor that comes into play is the design of the ash chute and pan and the effect it has on the air flow. All this sounds like a lot of fiddling compared with a straight forward bar grate but it's not hard to open out the holes or in some rare situation close some down.
It will be interesting to see how my mods go the next time I fire up which won't be for a while yet as I'm remaking the valve seats in the top feeds as I'm not happy with the PTFE ones supplied.

Jim

Hi Jim,
It does seem logical that the edge of the fire won't burn as brightly if only because the coal at the edge has something that's cold instead of more glowing coal. I'll be very interested to see what you find when you try it again. I'm definitely sold on the idea though, this is a very simple thing to make and I imagine it will last a lot longer than a bar grate too.

Have you opted to try Silicon Nitride Ceramic balls for the top feed?

[springcrocus]

After talking to others at the club who also have rosebud grates, I'm particularly interested as I may try this myself. I normally just follow the drawing but am starting to get a bit more adventurous now so am following your journey with great interest.

Regards, Steve

[Jim]

May 4, 2018 21:54:37 GMT Roger said:

May 4, 2018 21:41:25 GMT Jim said:

Hi Jim,
It does seem logical that the edge of the fire won't burn as brightly if only because the coal at the edge has something that's cold instead of more glowing coal. I'll be very interested to see what you find when you try it again. I'm definitely sold on the idea though, this is a very simple thing to make and I imagine it will last a lot longer than a bar grate too.

Have you opted to try Silicon Nitride Ceramic balls for the top feed?

Hi Roger, Yes I will give them a trial and am waiting on the postman to bring me the two packets I've ordered. Why two? well old fumble fingers tends to drop things then can't find them until he's bought a replacement so I thought I'd get ahead of the game.

I follow Everett Clem's data sheet on ball/hole dimensions when making clack valves. I've always used stainless steel balls and have never had a problem however this case seems different due I suspect to the valve seat material plus the fact that the valve seat is a separate component secured with a screw down ring and resting on a ledge in the valve body so raising the possibility of steam leaking past the actual seat.

Jim

[joanlluch]

May 4, 2018 23:00:57 GMT Jim said:

I'm remaking the valve seats in the top feeds as I'm not happy with the PTFE ones supplied.

...

I follow Everett Clem's data sheet on ball/hole dimensions when making clack valves. I've always used stainless steel balls and have never had a problem however this case seems different due I suspect to the valve seat material plus the fact that the valve seat is a separate component secured with a screw down ring and resting on a ledge in the valve body so raising the possibility of steam leaking past the actual seat.

Jim

Hi Jim,

It's good to have the valve seats as a separate component as you have, but of course they must be properly statically sealed. I'm sure you are aware of what I used for the water valve seats in my pump. This is the link to the photo in Flickr flic.kr/p/HtYNEQ and this is a quick 3D rendering of the design flic.kr/p/26LSZk5. There's an upper o-ring sealing radially against the body of the valve, and a lower o-ring sealing axially against the bottom part. Of course in reality the o-rings shown in the drawing get compressed rather than interfering the rigid part, but you get the idea. Maybe you can adapt something of it to prevent leaks around your seat component.

Using PTFE as the seats material does not seem a good idea because it's too soft. PTFE is an excellent material for both static and dynamic seals, but it must be understood. Despite it is relatively rigid and we may be tempted to use it as such, we must think of it as a deformable material which ultimately keeps rubber like properties for the last bit of its deformation. In practice, all properly designed applications with PTFE sealing components must set a physical mechanical limit to the PTFE deformation in order to take advantage of that last bit of elasticity that remains after the bulk of the permanent deformation has taken place. From a mere design point of view it's not that different than using rubber o-rings except that the range of elastic deformation in rubber is much extended and allows for more permissive designs. The case of PTFE being used as a seat of a ball check valve does not meet that criteria and thus I'm not surprised that it is causing problems.

Just as a matter of general information, check valves using rubber o-rings as the sealing material for the seats are standard in the industry and are the ones that offer the best performance. Again, they are designed to have a mechanical limit to the (elastic) deformation of the o-ring. This is an example of what I mean that I just found on the internet Check Valve Drawing . The o-ring can not be unlimitedly pressed by the back pressure, but just up to a certain extent set by the geometry of the valve. This is another example I found using a ball in this case Ball Check Valve . Again, the o-ring on the seat can only be pressed up to some extent until the ball reaches a stronger mechanical constraint.  

I hope this is informative.

Joan

[Jim]

Thanks for that very informative reply Joan. 

Your second design of a valve seat fitted with an upper and lower 'O' rings is the concept I'm looking for. As always  when modifying an already completed valve compromises have to be made. As with your design I'm sure the new bronze valve seat sealed against the lower retaining lip will solve the problem.

Jim

[Jim]

Today I spent some time making a new bronze valve seat to replace the PTFE one that was not sealing properly and so effecting the HP injector's ability to pick up. I also remade the screw-in retaining ring to replace the original one that was damaged during removal.
The new seat is bedded into a sealing material and once I'd reassembled the valve I tested it and all seems good. The real test will come when I next steam up.



I should have added that I also made a new bronze valve seat for the LP injector in case it too decides to start leaking.

Slowly things are coming together and once I'm happy that all is working as it should I shall make the trip to the club to have a proper formal steam test and hopefully a run on the new track.

Jim