Gallery, Projects and General > Project Logs
Small "Mill Engine Plant" (Display)
DeereGuy:
Peter after seeing the detail on you boat I can hardly wait to see the rest of this. You always pay so much attention to detail when your building something. Here you have building a total all in one spot stream system with it's own reservoir. Good job and please continue on...
sbwhart:
Coming along nicely Peter, :thumbup: you'll have a cracking display when you've finished, well explained to.
Have fun
Stew
klank:
Thank you all for the encouragement and kindness.
Not been able to do much these last weeks - got personal problems with me old Dad.
Anyway - done a bit over the last two days - working on a steam control valve and lubricator.
I appreciate this is not, by any means, big stuff, but making little fittings in brass I find very relaxing and satisfying - a change from having-at big lumps of steel in complicated ways.
My first plan was to make a separate steam control valve and displacement lubricator - the latter being adjustable, based on the type used in the Boarderer/Marcher marine engines. However, whilst idly flicking through the pages (yet again) of TC's book on model steam engines (Vol 1), I saw a photo of a combined steam control valve and lubricator - all in one. It is part of his design for "Hercules" - a steam powered crane. It is a nice, elegant looking, compact unit, doesn't seem difficult to make and of course is backed by TC's step by step instruction - useful for those of us with minimal confidence/experience.
I decided to have a shot at this - materials were (just) available from my little stocks.
Here are the main component parts - I did not take pics. of the machining - its all very straightforward.
The valve spindle itself is stainless steel, all else is brass hex and a bit of brass bar.
The main body should be of brass square stock - but I don't have any, so used hex and turned off the corners a bit at each end to make it look less "linear".
The spindle, gland nut, threaded insert and inlet fitting (facing the camera at the left hand end) need no further word.
The outlet, at the bottom I modified from the design a little, to fit my engine - a simple brass round fitting, silver soldered and let into the body and a short length of copper pipe (with nipple and nut fitted first) soldered into the fitting.
The oiler itself is incredibly simple in operation - in fact it is hard to understand how it works at all!
According to TC, it is originally a design by a really old time engineer who went under the name of "LBSC" - a.k.a. Curly - who published a huge amount of model engineering material from the 1930's up to the 1960's (approx - not sure).
Going off topic - for those who don't know - LBSC stands for the (late) London, Brighton and South Coast Railway (absorbed into the Southern in 1924). He had a love of that grand old company and published plans for model engineers to build one of its locos in the 1930's. One of the first perhaps.
Back on topic :-
Anyway - TC said that this lubricator design has worked for him for over 25 years!
All it is is an oil reservoir, fitted with a close fitting screwed cap (no air hole in the top), and the waisted bottom drilled with a number 70 drill - a tiny pin hole - situate exactly opposite the steam outlet hole from the body. And thats it!
Its not an obvious displacemnt lubricator. The only way I can visualise it working is through the "venturi" effect (like a carburettor bleed hole) of the steam rushing past the hole and drawing a mist of oil out as it goes by.
There is no means of blocking the hole, and thus I don't know if the oil will ooze out when not in use.
I appreciate that steam oil is extremely thick and viscous (is it Rape-Oil?), so maybe it won't drip through such a tiny hole?
Drilling that hole gave cause for thought. It has to penetrate approx 5mm of brass. After much thought and seeking advice, speed of rotation seemed to be the crux of the matter. In the past I have had conspicuous failures and flops when trying to drill holes 1/16" or less and ended up with useless items with broken drill bits embedded in them.
I had made some time ago a small drill adaptor to fit my tailstock, lever operated (sliding chuck) with a good quality pin chuck on the end. Girding up my loins, I put my (only) number 70 drill in this lever/tailstock chuck adaptor with only 2 mm projecting, and cranked up the lathe to its max. - over 2000 rpm on mine (never done that before!) - this speed, noise and some vibration does concentrate the mind!
I just touched the end of the drill bit against the brass bar end (all carefully surface finished and just kissed with my smallest centre drill bit first) and a tiny sliver of brass curled off. Great - I carried on very slowly, wood-peckering the drill in and out/cleaning the swarf off with a little paintbrush and slowly extending the length until it broke through. Very satisfying.
I then silver-soldered everything together - using silver solder paste (as used by hobbyist jewellers). I found using this material in these operations to be a revelation. No bits of silver solder wire to get and keep into position, and no fluxing. Just make sure the joints are clean, and annoint them with the (brownish looking) goo. Add heat from the torch with my smallest nozzle, play the flame gently near the joints and wait for the silver colour to show and run into the joints - easy peasy.
No doubt I may find a dud joint when I steam it, but the silver collars around the joints look o.k.
And here it is mounted (temporarily) on the engine.
I deliberately made the valve spindle/handle "over long" to allow for my hamfisted fingers and to bring the control to an easy point to reach, because the steam inlet - pipe position fixes the whole affair a bit back from the edge of the display board.
I shall run the steam line from the dome off-take, via a globe valve and then back into the boiler cabinet for a turn, down by the hottest part, so as to act as a "steam dryer". In these circumstances, I fancy cylinder lubrication becomes more essential.
As I have said before - this is all "basic work" for experienced engineers, but I do hope it may help a few to have a go at "steaming" something.
My garage/workshop shall now be known as the "Dampf-Haus".
More to follow when I get time to myself.
Stilldrillin:
Lots of very good info/ experiences there Peter! :thumbup:
I`m going to have a look for some of the jeweller`s silver solder......
David D
klank:
Hi David
I sourced my paste from CupAlloys :- http://www.cupalloys.co.uk/ (usual disclaimer).
I had checked around for the "best" value deal for silver solder paste, and found their prices very good - I bought a 10cc syringe of the stuff - delivery was very quick too, and the bloke at the end of the 'phone was extremely helpful - giving advice on soldering technique when using this stuff in model engineering applications.
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