Author Topic: Stuart “Minor” Beam Engine Build, 12 years and counting  (Read 6853 times)

Offline Djangodog

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #15 on: March 14, 2023, 09:21:18 PM »
This will be the first time that I have lagged a cylinder with wood.  My thought is to use a 1/16” layer of cork and 1mm thick wood or 3/32” thick wood with no insulation..  I don’t plan to use steam, but it would be nice if the lagging could hold up to steaming. 

Does anyone have a preferred wood and treatment?  Is the cork a bad idea?  The straps will be Brass.

Thanks in advance

Offline Charles Lamont

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #16 on: March 15, 2023, 09:18:02 AM »
My opinion: With 1mm thick wood, I think it might be hard to get all the slats to line up tight together. The slats should not be too wide, and can have a fine chamfer or rounding of the edges, so that there is no risk of a sharp edge snagging on a cleaning rag. The ideal wood in full size is teak, being reasonably fine grained, tough, naturally oily, and dark enough not to shout about stains. For a model, anything with a coarse grain looks out of scale. A high gloss but lumpy varnish looks amateurish. Better to use something that penetrates the wood and leaves a slight sheen, such as Danish oil or wax oil. Here is a fine example: http://www.claymills.org.uk/tour/cd2.html
« Last Edit: March 15, 2023, 09:27:15 AM by Charles Lamont »

Offline Jasonb

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #17 on: March 15, 2023, 10:01:01 AM »
I would not go for anything over 1mm and about 4mm wide on a cylinder of that size. You can just about get away without having to shape the edges at that width and they will form a reasonable ciircle. If you make the top cylinder cover larger than the cylinder flanges by twice the wood thickness all will sit flush. 1/8" wide brass strip is about right and I would have gone for 10 or 12BA fixings. You could just fill the void around the cylinder with some cork or other lightweight material, even a couple of layers of balsa wood would wrap around.

If you have not planked before, tape a piece of polythene bag to a flat board. Take some linen either an old sheet or hankie and brush that with waterproof wood glue. Lay the overlength planks onto the wet glue butting them tightly together but try not to get glue on the edges. Once dry you can cut the sheet to size and when peeled off the board it will wrap around the cylinder. This is a lot easier than trying to fit individual planks

Go for a plain straight gran, stain to get the colour and then oil.
« Last Edit: March 15, 2023, 10:06:04 AM by Jasonb »

Offline simplyloco

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #18 on: March 15, 2023, 10:57:09 AM »
I clad cylinders first using some flexi balsa to provide a base, calculating the number of strips required  - and hence the angle between them -  and cutting the maple or teak strips at the required angle on the FET saw. Glued on to the balsa with epoxy, sanded and oiled.
Strong minds discuss ideas, average minds discuss events, weak minds discuss people.” ― Socrates

Offline ettingtonliam

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #19 on: March 15, 2023, 08:19:35 PM »
On my frst engine, a Stuart No.9, about 1965, before fitting the lovely blued lagging sheet that Stuarts provided in those days, I lagged the cylnder with asbestos paste!. I'd attacked a piece of asbestos cement sheet with a coarse file, gathered up the cuttings and made a stiff paste with water before applyng it to the cylinder and letting it dry.

We didn't know any better in those days.

Offline GWRdriver

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #20 on: March 15, 2023, 09:41:45 PM »
Does anyone have a preferred wood and treatment?  Is the cork a bad idea?  The straps will be Brass.  Thanks in advance
For many years in the US a sheet product called "scribed wood siding", or sheathing has been available.  This was most often used for vintage car (wagon) sides, but was also made in textures, such as lap siding, for buildings and structures,  It was typically milled basswood, 1/32" and 1/16" thick, in planks of varying width and length, scribed on one side to replicate T&G paneling.  I believe at one time one Mfg offered it in cherry, and perhaps also teak or walnut, to for marine modelers.

I've used it on a number of small engines, including a S-T Beam I built some years ago.  One problem is that if it's not oiled and well-sealed, and the model is steamed, the sheathing will expand.  If it isn't steamed there's not a problem.  Look here for example . . . . https://www.northeasternscalelumber.com/products/scribe-sheathing-24-long.html
Cheers,
Harry

Offline Jo

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #21 on: March 15, 2023, 10:20:49 PM »
Wooden coffee stirrers make nice cladding, they are hard wood, stain nicely and they are free   :)

Using standard wood glue they can be glued on to a piece of smooth cotton fabric and once dry the planked sheet will bend nicely round the cylinder.

Jo

P.S. The texture of linen (flax) can be lumpy so can be a pain to get the planks to lay flat when gluing them on, a cotton fabric is what you want  ;)
Enjoyment is more important than achievement.

Offline Djangodog

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #22 on: March 15, 2023, 11:28:07 PM »
Thanks to everyone for the advice.  I have some time to make decisions.  I still haven’t decided on a color scheme yet either.  Finishing is probably still a couple weeks out.

Offline Djangodog

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #23 on: March 18, 2023, 07:01:32 PM »
A little more progress.  The bearing castings were pretty rough, so rather than doing a lot of hand work to the tops, I made a little fixture and turned a cone, (this left a hyperbolic curve along the flat surfaces).  The compound was set at 25 degrees and the clearance holes were tapped 5BA, (later cleared).  They came out pretty good, but the 3/8” width is now .332” with a few witness marks remaining.  I think that I will bring the hex size of those 2BA screws down to .281 and shorten the heads a bit. 


Offline Michael S.

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #24 on: March 18, 2023, 09:19:29 PM »
The parts look very good! And next is the crank?

Michael

Offline Djangodog

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #25 on: March 18, 2023, 10:49:18 PM »
The parts look very good! And next is the crank?

Michael

Thanks.  It’s getting there.
 
I’m going to stay on the Bronze parts because the chips fly everywhere.  I will do the crank and pivot pin for the beam after that.

I don’t know if it is typical for the beam engine’s castings, but these were not great.  I’m still enjoying the project. 
« Last Edit: March 18, 2023, 11:03:51 PM by Djangodog »

Offline Djangodog

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #26 on: March 20, 2023, 10:03:43 PM »
Running out of castings, (the pulley, piston and slide valve remain).  Lots of bar stock and finish work.  The 2BA heads will get reduced to 9/32”and shortened a bit.  All screw heads will be re-faced and re-chamfered.  The crankshaft and pivot for the beam beam are next. 
« Last Edit: March 20, 2023, 10:54:12 PM by Djangodog »

Offline Djangodog

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #27 on: March 23, 2023, 09:24:03 PM »
A change of plan.  I decided to get the Watts links parts and the valve actuating links over with.  It seems that everyone has their own way of producing the links, from fabricating, to using filing buttons to making them flat as the newer drawing shows.  I went with one piece fully machined links.  I will show my method below in case anyone is looking for a method.  The radius was machined using a 2 axis Proto Trak, but a rotary table could be used.

The links were machined from 12L14 free machining, low carbon steel.  The order of operations was:

Face the .375” diameter stock to length, plus .406” on each end.
Center both ends.
Mill stock  to .315 square being careful to keep the centers central.
Mill steps to .156” thick.
Indicate the part central, drill and ream the .1875 diameter holes.
Turn the .156” diameter.
Turn 3 degree included tapers to .125” diameter, (tool set at approximately 60 degrees from Z axis, .03125 tool nose radius.
Blend tapers to create “fish belly”.
Part off centers.
Produce simple fixture and special shoulder screw, (the .1870 diameter of the shoulder screw protrudes into a bore in the fixture).
Mill radius with small end mill.
Using same shoulder screw to hold the part, lightly chamfer faces, (not shown).

The method was also used for the longer valve actuating links.


« Last Edit: March 24, 2023, 11:00:41 AM by Djangodog »

Online Kim

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #28 on: March 24, 2023, 01:22:26 AM »
Them's a lot-o links there!  Very nice!  :popcorn:

Kim

Offline Djangodog

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Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #29 on: March 24, 2023, 08:26:03 PM »
The crank shaft, crank web and beam’s pivot pin are finished.  Tomorrow is the connecting rod.  it will be functionally correct, but cosmetically more like the one on a Major Beam, (that’s the plan anyway).
« Last Edit: April 09, 2023, 11:10:46 PM by Djangodog »

 

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