Author Topic: 3 inch boiler build  (Read 7441 times)

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #75 on: August 08, 2018, 06:35:16 AM »
Aha - yes, thanks Dan. That works.

It seems immediately obvious now that you have explained it!

gary

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #76 on: August 14, 2018, 11:03:52 PM »
Hi -

I've been trying out Stag Wellseal this evening on a few fittings:

https://www.heritagesteamsupplies.co.uk/gasket-sheet-jointing/jointing-compounds/wellseal.html

It's transparent, dark brown, runny and very sticky and looks for all the world like something chocolatey which you might squeeze on to an ice cream from a plastic bottle. You clean any grease from the mating threads (I used acetone), then anoint them with the Wellseal. You then leave them apart for about 5 minutes while the Wellseal thickens up, after which you either add a bit more Wellseal (if required) or just screw them together. Apparently it never really sets, so it's easy to remove the fittings if required and clean it off with a solvent.

I must admit that the stuff inspires confidence - it's so damn sticky!  It gets right into the threads and it's hard to imagine it not making an effective seal. However, the proof of the pudding will be in the testing. If it doesn't work I'll try one of the various Loctites, but for now I remain hopeful.

gary

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #77 on: September 02, 2018, 12:21:22 AM »
Progress has been slow due to hot weather (barbie season) followed by a major renovation of our living room which is currently ongoing. However, I took today off and spent some time in the workshop.

Stan Bray (on whose design this boiler is based) has little to say about he configuration of the cap, smoke stack and steam stop and safety valves*, so I found myself having to figure it out myself. It was necessary to make extensions for the bushes on the top of the boiler so that the valves will sit above the cap. The first picture below shows the internal thread on one of them being tapped in round bronze bar in the lathe using a piloted spindle (which is a godsend - no more squint threads!):



I figured it would be easier to gauge the required heights for the extensions if I made the cap first. The photo below shows that the underside of the brass cap has a circular locating groove into which the top edge of the boiler fits. This was milled on my Dore Westbury Mk I using a rotary table. This is not the tidiest piece of milling in the world - a result of several issues which currently beset the mill (a situation which will be addressed in the near future...). It's not critical though as it won't be seen. You will also notice that the groove is a bit on the wide side - it's the size of the smallest endmill I currently have. Below you will see the cap (in which the hole for the smoke stack has not yet been made), the bush extensions, the cap retaining nuts (made from brass hex bar tapped M12), and the two valves:



The last photo shows a trial fit of the unfinished cap assembly. Unfortunately the two valves are out of perpendicularity with the top of the boiler. This happened either at the end plate forming stage or while silver soldering. They look squint but there is nothing I can do about it now other than put the fiery flame on it again and that isn't going to happen. It's not perfect but it shouldn't affect the functionality and will be good enough given it's my first effort. It does however mean that there is a small gap between one side of each nut and the cap. To prevent combustion gases from escaping via that route I would like to close this using some kind of soft washer or gasket which would have to be heat-resistant. Any suggestions from you good people regarding what I should use for this would be welcome. In the photo you will also see that most of the fittings are now in situ. They are sealed (hopefully) with Wellseal. Not so far away now from the second hydro test at 1.5 wp...!  The picture shows the boiler in its current state sitting on the belt sanding attachment of my beloved Coronet Major woodturning lathe/all bells and whistles wood machining workstation:



gary

* Edit 4/9/18: actually this isn't true. He does discuss it in his book, but there are aspects that I don't find very clear.

Offline Gas_mantle

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Re: 3 inch boiler build
« Reply #78 on: September 02, 2018, 12:42:22 PM »
Taking shape nicely Gary, it ought to be steaming away shortly  :)

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #79 on: September 02, 2018, 01:01:25 PM »
Cheers Peter!

 :ThumbsUp:

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #80 on: September 02, 2018, 10:14:31 PM »


Taz says: 'How come the smoke stack is squint, Garyboy?'.

I say: 'Sorry Taz - It's because it's just rough cut and not soldered in yet. Just offered up for show'.

Taz says: 'Hmm. How come the valves on top of the boiler are squint then?'.

I say: 'Apologies, Lord Taz - the bushes in the boiler top plate somehow got misaligned and they are hard soldered in so I'm afraid it's a done deal, even if it looks a bit naff. They will still do the job though'.

Bad Boy Taz says: 'Ha. Aren't those top cap retaining nuts a bit big and out of scale for a model boiler?'.

I say: 'With respect, Your Highness, no. It's not a model boiler. It's a real boiler, albeit a tiny one, and I have this functionalist and you could say industrial aesthetic going on here. I'd even have preferred more utilitarian looking handwheels  or levers on the valves if I had the nous to make them myself'.

Taz looks disdainfully at me and says: 'Pretentious git. So how are you going to make decent seals in that groove under the cap and under those squint retaining nuts so that air doesn't get sucked in and combustion gases don't escape?

I say: 'I'm hoping the guys on the forum can recommend an appropriate heatproof gasket material, O Mighty One'.

Taz says: 'Right you are then. Meanwhile, feed me....'....

Online Kim

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Re: 3 inch boiler build
« Reply #81 on: September 02, 2018, 10:52:07 PM »
Sorry I can't help you answer Taz's important question, but I will say I enjoyed reading your conversation with Lord Taz!  :ROFL:
Kim

Offline zeeprogrammer

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Re: 3 inch boiler build
« Reply #82 on: September 02, 2018, 11:09:31 PM »
My first suggestion might have something to do with removing a certain critic. He's tough!

In my book that's a fine looking boiler.  :ThumbsUp:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline b.lindsey

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Re: 3 inch boiler build
« Reply #83 on: September 03, 2018, 12:42:29 AM »
It's coming together nicely Gary. Taz will come around and agree soon enough.

Bill

Online mikehinz

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Re: 3 inch boiler build
« Reply #84 on: September 03, 2018, 01:09:22 AM »
Lol!  We have a Siamese and I never let her into the garage when I'm working out there.  She's way too critical!  The Lab retriever on the other hand loves everything I do.  Go figure! 

From my perspective, excellent work! 

Mike
MIke
Wichita, KS, USA

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #85 on: September 03, 2018, 12:44:38 PM »
My first suggestion might have something to do with removing a certain critic. He's tough!

Carl - that would be my Inner Taz that you are referring to. You are right - he must go. As for the real world, fur and claws Taz depicted above, he is far too useful for keeping our old house free of mice   :)

Thanks to all of you for your comments - I feel encouraged!

Offline Gas_mantle

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Re: 3 inch boiler build
« Reply #86 on: September 03, 2018, 01:02:47 PM »
Looks good Gary, next time you update your thread could you show a pic of the underside showing the tube arrangement etc.

Thanks  :)

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #87 on: September 03, 2018, 09:26:12 PM »
Will do so Peter.

Cheers,

gary

Offline Gas_mantle

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Re: 3 inch boiler build
« Reply #88 on: September 03, 2018, 09:48:22 PM »
Thanks, any thoughts on what engine you will build first? You can't have a boiler with nothing for it to do  ;)

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #89 on: September 03, 2018, 10:35:20 PM »
True!

I plan to start with a simple single-acting oscillator of about 1" bore. My thought is to make this out of bar stock and keep it as rectilinear as possible just to get started. I'm thinking perhaps of going with plans by Andrew Smith or Steve's Workshop but upping the size a bit.

After that I might be looking at another similar engine (or a double-acting equivalent if I feel confident) but made from my own castings in aluminium and/or brass from my home-built furnace. At this point I might think about getting funky with the shapes to make them look interesting:


After that - assuming I haven't thrown down my tools in despair by then - I could perhaps move on to a mill-type engine such as Andrew Smith's Vulcan or a version thereof. This could be made from a combination of bar stock and my own castings and again I might aim for a 'different' look. Making the valve, eccentric and so on will of course be a major step up and challenge.

Then - if I live long enough - I'll turn to the PM Research #6 kit of castings which is sitting on my shelf even now. I'm assuming that by that point I'll be competent enough not to destroy the castings. It will also require a bigger boiler than the one I'm building now... I might have to either bite the financial bullet and buy a Castle Steam V6 or build something equivalent  ;)

That's my path mapped out from my present vantage point, Peter. It could of course all change. I plan to build an astronomical telescope too (6 inch F15 refractor), but steam engines have jumped the queue and I'm absolutely determined to keep going with them until I see at least one flywheel (and hopefully more than one) spinning on live steam!

That's my best-laid plan. We shall see...

gary