Stuart “Minor” Beam Engine Build, 12 years and counting

[Djangodog]

I am posting this thread to document the build and to point out any issues with the castings or drawings or machining operations.  I understand that the Stuart Beam build has been done in the past.  I hope that my build log won’t be completely redundent. 

I think that I bought this casting set in 2010 or 2011.  A previous owner had begun to machine the cylinder and flywheel.  Fortunately, they had some material left on most dimensions, and I will adjust the mating parts to correspond with the surfaces that had to be taken down below the dimensions on the drawing.

A word of caution regarding old castings and new drawings.  Stuart made some changes over the years and if you are working to the newer drawings and have old castings you will find out that the castings for the crankshaft bearing, (old), are not wide enough to work with the tapped holes in the base, (the old bearings are 1 3/8” and the new base drawing has them at 1 1/2”.  I will make the bearings from solid stock to match the holes that I put into the base.

I am glad that I still had my surface grinder when I began this build.  As I generally do, (I have only built a few engines, so generally is a stretch), I began with the base, (skimmed the top and bottom flat and parallel and then surface ground the surfaces, centered up the casting and put the holes in, (straight forward except for the bearing spacing issue).

I am also glad that I still had my south Bend Heavy 10 back when I did the flywheel.  The back gear was needed to avoid chatter.  I don’t remember exactly how I went about machining the flywheel.  My best guess is that I roughed it out using a four jaw chuck and finished it on a mandrel.  There are still some casting defects, but I can live with that.  It runs true and looks decent, so all is good.

Because of the previous work, I had to take some parts of the cylinder undersize.  The overall length and bore are to print, but I will have to reduce the outside dimensions and hole patterns of the steam chest and cover to compensate.  I do have a spare cylinder, but it’s not a great casting.  I have not decided yet if I want to use it.

That was where I left the engine twelve or so years ago.

Today’s job was to machine the column.  The casting was a bit rough and being that the column is a central part of the engine, I decided to machine everything.  As typical, I centered the two ends and mounted the part between centers.  I cleaned up the back face of the top portion and them faced the end to the .500” dimension.  I turned the columns around and repeated the operation and brought the overall length to 6”.

The center portion did not run very close to the outside surfaces of the flanges, so I held the top of the column in a four jaw chuck, squared the face and got the column running as true as a casting can and using a small boring bar, I carefully bored the center on the other end so that it ran reasonably true to the cast column.  Supported by the tailstock center, I was able to clean the column, (I had to remove approximately 1/16” for it to clean.

The mill work was fairly straight forward and there were no surprises.  I may leave the column bare.  I have plenty of time to make decisions regarding finish.

That’s all for today.  All comments and advice, good bad or indifferent are welcome.

Thanks

[Kim]

I'll look forward to following along with your build! 
Kim

[Jo]

The standard sized Stuart Beam engine is a very forgiving casting set/model and for that reason ideal for a beginner so you will be amazed what you can get away with and yet it still runs well.

Jo

[Jasonb]

Long time since I made mine

Regarding the bearing pedestals what heights are shown on the new drawings? They only seem to list one casting now and if that is the 1.5" spacing one it is 7/8" tall at the split rather than 5/8" so may also affect con rod length. I've seen people having the tall casting for the Victoria and you end up with the crankshaft ctr line above that of the cylinder.

[wagnmkr]

One of my favorite engines. I will be watching this one.

[vtsteam]

 Watching along.

[Michael S.]

I built my Beam machine in 2005. The blueprint and the castings matched.
What I can still remember were the glass-hard spots on the underside of the machine base.

Michael

[Djangodog]

I built my Beam machine in 2005. The blueprint and the castings matched.
What I can still remember were the glass-hard spots on the underside of the machine base.

Michael

My castings are fairly old and they came with a drawing that I assume was original.  I wrongly assumed that the latest drawing would simply be more accurate and because of its size and the separation of parts, be easier to use.  The attachment shows where I went wrong regarding the base and the bearing castings.  I know better than to not compare the two drawings.  I also see another discrepancy regarding the distance from the  base of the cylinder and the location of the bearings for the valve actuation mechanism. 

I got lucky today.  I found that I had a piece of C544 Bearing Bronze that I can make the lower half of the bearings from.  I am now going to review the entire drawing more carefully and convert all sizes to decimal inches.  I will also notate any changes required to account for the slightly altered cylinder.

 

[Jasonb]

It is possible to make the pedestals and caps from something like steel or aluminium and just fit separate bronze bearings, have a look at my post just over half way down this page which will save expensive bronze. Bit late now but the 2BA or 10-32 which you may be using is also a bit on the large side.

https://www.model-engineer.co.uk/forums/postings.asp?th=168849&p=32

[Djangodog]

It is possible to make the pedestals and caps from something like steel or aluminium and just fit separate bronze bearings, have a look at my post just over half way down this page which will save expensive bronze. Bit late now but the 2BA or 10-32 which you may be using is also a bit on the large side.

https://www.model-engineer.co.uk/forums/postings.asp?th=168849&p=32

Thanks.  I had considered making the base of the bearing from steel.  I also considered plugging the holes and relocating them to the 1 3/8” spacing.  I already have the Bronze and it will match the rest of the engine, so I will probably go that way.

I agree that the 2BA holes look a bit large, but that was the specified thread.

[ettingtonliam]

I notice that you said that you surface ground the base casting. Back in the day, up to 1974, anyway, Stuarts stated in their catalogue, that they surface ground the base casting, because it only took them about 70 seconds on their surface grinder, so it seemed a reasonable thing to do. By 1995, there was no mention of this anymore, so presumably they'd stopped doing it.

[Djangodog]

I notice that you said that you surface ground the base casting. Back in the day, up to 1974, anyway, Stuarts stated in their catalogue, that they surface ground the base casting, because it only took them about 70 seconds on their surface grinder, so it seemed a reasonable thing to do. By 1995, there was no mention of this anymore, so presumably they'd stopped doing it.

The cast base that came with the casting set was ground, but the casting was so poor that I sent to Stuart for a new one.  The replacement was not ground.

I have only built a 10H and D10 with reversing, so I don’t have much experience with model castings.  The 10H and D10 castings were quite good, but these castings have been disappointing.  The 5A that I finished for my father only had a few Stuart castings and since my father had already machined them, I can’t say anything about the quality.  I do know that they were not machined below the nominal dimensions and had no imperfections remaining. 

The beam was extremely rough and the 3/8” width was already .360” in some areas.  It mostly cleaned up at .352 and I can alter the other parts to compensate.  The distance from the center boss to the next was off, so I milled around the smaller boss with a ball end mill.  The worst of it was a blow hole in the casting where the crank pin passes through.  I was leaving a little stock to bore, but the drill walked far enough off that it left me with an elongated hole.  I bored the hole to .219”, (7/32”), and will adjust the crank pin to compensate.  There is still a void in the hole, but it should be fine, (most of the hole is full and the larger pin should more than make up for the void).     

I kept one of the Moore boring head sets and my R8 adaptor.  I miss that jig bore, but the Bridgeport bores quite well, especially when using a good quality boring head.

The first image shows the blow hole before I bored it oversized. 

The other engines are shown for comparison of casting quality.  No filler was needed.

[vtsteam]

Djangodog, sorry to hear about the poor quality castings. As a person who casts iron for my own projects, that's very disappointing to hear. Seems like the beam had three strikes against it. The blowhole is unacceptable, as is the undersize casting thickness. The latter is a fault of the pattern itself, and the boss distance problem might be also, unless it was caused by the pattern shifting.

At any rate, the molder is not doing even rudimentary checking of the finished casting, if it's under-thickness. While people expect castings to need machining for precision, there must be enough material to do that, and a check of overall dimensions for something this size is easily done. Castings are expensive these days, and basic QC ought to be applied. If a pattern is undersized, every casting will be, so it's in a foundry's own interest to check at least the first casting.

An internal blowhole is the only problem that would have been missed if there had been any QC, the main cause is too much moisture or poor permeability of the sand. That's an actual molder's problem, rather than a pattern maker's.

At any rate, good of you to save the part, and lucky you could work around the problems. Sorry you had to. 

[Djangodog]

It’s beginning to resemble a beam engine.  I machined the entire cylinder cover so that I can leave it natural.  I still have some hand work to do on the beam.

The cylinder will get made over tomorrow and I hope to machine the steam chest as well.  After that it will be onto the glands, bearings and crank shaft. 

 

[Djangodog]

I decided to go with a new cylinder so that the steam chest and cover will be close to the dimensions on the drawing, (.025” under in width and height and not quite clean).  All holes are in, including the four 8BA for the straps over the lagging. 

The blemish near the exhaust port is a casting defect. 

The steam chest, cover and glands are next.

[Djangodog]

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

[Charles Lamont]

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

[Jasonb]

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.

[simplyloco]

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.

[ettingtonliam]

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.

[GWRdriver]

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

[Jo]

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 

[Djangodog]

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.

[Djangodog]

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. 

[Michael S.]

The parts look very good! And next is the crank?

Michael

[Djangodog]

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. 

[Djangodog]

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. 

[Djangodog]

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.

[Kim]

Them's a lot-o links there!  Very nice! 

Kim

[Djangodog]

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).

[RReid]

That's coming along very nicely!

[Admiral_dk]

It's really starting to look like an Engine 

Per

[Djangodog]

I was going to make the connecting rod today, but I found that I no longer had the material that I wanted to use, so I moved on to the entablatures.  The Major Beam has a much nicer looking entablature, bit it seemed that that style would extend a bit far past the cylinder.  Jay Leno has a nice little beam engine and the entablature on his is attractive, so I went with one based on that style.  It may still get support columns, but for now it seems quite rigid and uncluttered. 

Tomorrow the shop gets a good flush.  The little engine still has a way to go.

[Dave Otto]

That looks very nice!

Dave

[Chipswitheverything]

The redesign of the entablature looks very nice indeed, makes a great improvement.  I imagine that there was a pretty considerable amount of careful machining involved to produce that component.   Dave

[wagnmkr]

Yes, I like the alteration to the entablature a lot. It makes that part look "finished".

[Djangodog]

The redesign of the entablature looks very nice indeed, makes a great improvement.  I imagine that there was a pretty considerable amount of careful machining involved to produce that component.   Dave

Thank you all for the positive comments. 

The entablature was made from a piece of .500” thick low carbon steel.  It was machined complete including the holes before machining the thickness down to size.  The tool path left an island in the center and a groove along the inner edges which I finished to .500 wide.  I inserted some .500 by .250 thick parallels into the grooves so that I could machine the part to .375” thick.  It sprung open a bit when complete, but I was able to straighten it.  The recesses were cut using a keyway cutter.   

[Djangodog]

A little more progress.  I drew up my version of the connecting rod yesterday.  The material should be here later this week.  The eccentric and pulley went well.  Having a Hardinge HLV is great until you need to slow things down, (flywheel, pulley grooves…).  I ended up grooving the pulley with a ball end mill and rotary table.  At times like this. I miss my old South Bend Heavy Ten.

Lagging the cylinder is next. 

[Michael S.]

Now I notice that you designed the upper cross bar completely differently. That looks really good! 👍
Is that your idea? Really well done.

Michael

[Djangodog]

thanks.  It’s loosely based it on Jay Leon’s full size beam engine. 

[Djangodog]

My bar stock came in, so I moved on to the connecting rod.  It’s loosely styled after the Major Beam connecting rod.  I still need to add the bushing to one end, but it is otherwise done.  Tomorrow will be an off day, (except for cleaning the little shop again).

[Dave Otto]

Nice sequence and beautiful result!

Dave

[Djangodog]

Nice sequence and beautiful result!

Dave

Thanks. 

I made up the hardware for the connecting rod this morning. 

I’m running low on parts now and it’s time to figure out what I want to mount the base and pedestal to.  I was considering putting threaded inserts into a piece of granite of using some Aluminum jig plate.  Any suggestions would be appreciated. 

Selecting of the color scheme is still open.  Suggestions?

Thanks

 

[Djangodog]

The recessed features of the cylinder got a coat of flat black.  Once dry, a 1/16” thick layer of cork was glued to the recessed surface and fit up with some 1 x 5 mm Mahogany, (lightly sanded and pre treated with Danish Oil).  Once fit, the lagging was lightly glued to the cork and another coat of Danish Oil was applied.  The straps are .018” thick Brass shim stock.  The features for the drain cocks are cast in a bad place for lagging straps, so I made straps that surround the drain cocks.  The first set of straps was .1875” tall and looked wrong.  The second set is .125” and looks more appropriate.

[crueby]

The lagging and straps look great, nice proportions!   

[Chipswitheverything]

Very nice work done on the good looking con rod, and the lagged cylinder looks very smart too.  This build with attention to extra detail is really getting the best from the smaller sized Stuart beam engine.  Dave

[Roger B]

Looking good  I like the connecting rod and cylinder lagging 

[wagnmkr]

This build is looking very nice. I love the mods you have done.

 

[Kim]

Well done!  The dark lagging and the bright brass look good together! 
 
Kim

[Djangodog]

Thank you all for the kind comments. 

Spent the day making the piston, piston rod, spacers and shafts for the parallel motion.  It works as it should.  Stuart did not allow for clearance in their dimensions, so if you make everything at the mean, you will have some interference.  Removing a little material from the excess lengths of thread takes care of any issues.  The slide valve and linkage are next. I still need a base, some paint and I want to reduce the size of the heads on the 2BA screws and of course make some gaskets.

 

[Charles Lamont]

It's all looking very nice. I think the lagging looks spot on.

[Djangodog]

The slide valve and valve related parts are machined and in place.  The last part, (three parts), will be the rod that actuates the valve mechanism.  The engine should be ready for a test run on Tuesday, then it will be dismantled and finishing touches made. 

[wagnmkr]

You are cracking right along with this!  It is looking very good. You have reminded me I need to give the beam engine diorama a dusting. Of course, I get to play a bit as well.

[Djangodog]

It lives!  I mounted the engine to a nice piece of Cherry and tested it.  The steam chest gaskets are in place, but it was run with no rings, no cylinder gaskets and no gland packing.  Despite that, it ran fairly well on 15 psi, and less and it sounds much better in person  I did not run anything in.

It’s time to tear it down and make some finishing touches and add some paint, gaskets and gland packing.

<a href="https://www.youtube.com/watch?v=Y04ryZvgBJ4" target="_blank">http://www.youtube.com/watch?v=Y04ryZvgBJ4</a>

[Dave Otto]

Congrats on a runner. She sounds and looks great!

Dave

[crueby]

Runs great even without the  gaskets and such,  going to be even better with them! Great work!

[Kim]

Very nice!  So fun to see it run, isn't it! 

Kim

[Admiral_dk]

Gongrats - a very fine runner - even without the packing 


Per   

[ShopShoe]

Congratulations.

That turned out very well. I will be watchig for the final version.

Thank You for posting.

ShopShoe

[Djangodog]

Congratulations.

That turned out very well. I will be watchig for the final version.

Thank You for posting.

ShopShoe

I appreciate all the comments and encouragement.  A governor may be added later, but it won’t be a Stuart governor, (it will be smaller and probably use bevel gears). 

The weather forecast sounds like Sunday will be a good day for painting.  That gives me some time to get things ready.  It was nice to see it running. 

[Don1966]

Awesome another runner

Don

[Djangodog]

Here she is, (not complete, but the governor and better plumbing can wait).  I told my wife that this one would not be Stuart green and black, but that is not the case.  The base casting looked nice in its natural state, so at least for not, it will remain bare. 

[crueby]

Fantastic!   

[Kim]

Beautiful!  The colors look great 

Kim

[Michael S.]

I really like the red stripe on the flywheel.
You have built a very well done model.

Michael

[Roger B]

Splendid     

[wagnmkr]

A good looker and a good runner.

[Djangodog]

Here is an image of my governor prior to setting up the bell cranks and linkage. Unfortunately, small governors aren’t effective at low speeds, so I ran the engine a bit fast to show the function.
Stuart beam engines have 1/32” side to side clearance between the connecting rod bushing and crank pin which makes an annoying clacking sound.  I will be making a new bushing with minimal side play and eventually running a flat belt to bevel gears for the governor.
The governor is based on the Stuart Watts Governor.  The balls and manifold are scaled down by 20%, the arm length increased by .125”, the spring replaced by a weight and the hardware is my own.
I’m fairly happy with it, but it remains a work in progress.

The second picture has it in its home.  It is kept in an antique barrister bookcase to keep it clean.  The environment in a wooden case is nice and stable so oxidation should be minimal through the years.

[Djangodog]

I made a new connecting rod bushing with minimal side to side clearance and it quieted the engine down.  I also ran it at approximately 4 psi.  I still want to add a regulator and dedicated air line.

I’ve enjoyed the project and adding some personal touches and I am grateful for the encouragement and comments along the way.

[crueby]

Very nicely done!   

[wagnmkr]

Another lovely beam engine completed. It is a very good looking machine

Tom

[Admiral_dk]

Love the finished look 

Per

[Zephyrin]

beautiful engine, runs well too, congratulations !
does this nice bucket is made for collecting exhaust condensates and oil ?

[Djangodog]

beautiful engine, runs well too, congratulations !
does this nice bucket is made for collecting exhaust condensates and oil ?

Thank you all for the comments.

The bucket is there to collect exhaust oil and to add a little to the engine visually.  I had some leftover thick walled bearing bronze tubing and some Mahogany hanging around, so I made it up.  There is a stepped Brass plug at the bottom and it has a .375” long by .500” diameter protrusion to locate it into the wooden base, (it lifts out for cleaning).  I will ran lines from the drain cocks to the bucket in case I ever decide to run it on steam.

<a href="https://www.youtube.com/watch?v=GrBypFjFlJE" target="_blank">http://www.youtube.com/watch?v=GrBypFjFlJE</a>