# Another Stuart Twin Launch build started.



## David Shealey (Feb 27, 2020)

My dad got a Stuart Twin Launch kit as a retirement gift when he retired in 1980.  He put together a small shop over a couple years, and barely started the work on this, but he passed away in 1984.  I got the kit about 4 years ago planning to finish it one day.




  Well, I have now started on it.  My dad had only completed the base plate and main bearing caps, so not much was done.  His long time work on all types of old engines led him to add Babbitt main bearings to the build.  Somehow, he got the babbit off center, so the bearings are not constant babbitt thickness.  I was thinking of getting some Babbitt and re-machining the castings, but upon removing the caps and looking at it, the bearing surfaces are really good, so will use as is.  The 5/16 shaft turns easily and smoothly! Will have to do a lot of clean up and finishing of the base casting.
 This will not be a build log, but will post mods and unique methods of fabrication. His kit did not include the reversing gear, so I will be making all that from scratch.


----------



## David Shealey (Feb 27, 2020)

I have started the reversing gear, first done is the Eccentrics.  I looked at every build post I could find on the Stuart Launches to get other's build procedures.  One thing I did like was one that made the eccentrics with outside flanges instead of the little centralized bosses.  Makes it a lot easier to get  the bearing surfaces the right diameter and smooth.  I came up with a method of machining these I have not seen before. I made a fixture that locates them on the hub, with a dowel pin in the eccentric that locates in two holes to get the angle spacing.  Made them from 303 Stainless Steel, and ground the bearing surfaces with a home made tool post grinder.


----------



## Rudy (Mar 12, 2020)

David, you have already done a great job here! Like the way you make the eccentrics. I actually remade mine on my 10V to something similar. Makes a better bearing surface.

I will do a Twin Launch my selves (I have a thread on a "Modified Expansion Engine). I think this is a very good representation of a classic steam engine used in so many smaller boats those days. All moving parts are so visible and it is a pretty little thing. However, it has a challenge (this style of engine), at least to me. The cross head guides are hanging more or less in the free. The cylinders and crank case is separated by columns that gives little reference between the two halves. Compared to other engines with a solid "A" shape standard with guide for the cross head, that can be made in the lathe or mill with exceptional precision beyond the accuracy of your chuck or tools in general. Simply by doing clever setups.
So the Twin Launch intrigues me because I don't see any obvious way to make the cross head travle in line with the cylinder bore, other than go by the numbers in the drawing. This means I can't exploit the intrinsic accuracy I can achieve by machining a part from start to finish while left in the machine all the time. My approach is always a smooth running engine with no binding or slack, right from the start. No need for running in to make it turn freely, just like an engine from a car manufacturer. However, this is me and I fully accept the method of making it tight from the start and run it in to smooth everything out. In this case this might be the best approach.
I will follow you project with interest. Good luck!
Rudy


----------



## David Shealey (Mar 12, 2020)

Thanks Rudy!  I am quite particular about the way I do things too.  10 years as a tool and die maker and machine builder, followed by 40+ years as a machine design engineer.  Professional CAD user  since mid '80s.  I am currently working on the eccentric con rods from bronze bar stock, spending more time on the tooling and fixturing than will likely be spent on the parts themselves.  I will post about that as I get into machining them.  I had an old Palmgren dual X/Y table I used on a drill press for small parts before getting a Bridgeport.  I am currently adding iGaging absolute DROs to it.  I had done some pretty complicated parts on in the past, but counting and reading the little dials on it was not fun. I have a rotary table for the Bridgeport and will mount the X/Y table to that, so will have a "Manual CnC" (Crank n Crank) setup.  I know I could do a lot of the parts by hand with sawing and sanding/grinding, but decades of designing and building machines with all machined parts and  little to no hand work, just cannot do this differently.  8>)


----------



## Rudy (Mar 13, 2020)

David, I suspected you where a bit above an average hobby machinist .
I'm particularly interested in how to achieve accuracy, so I'm looking forward to see how you will solve the cross head task.
I have an idea my selves, but that includes some modifications to the design. I will still keep the original style though.
Haven't decided if I will buy the kit or just the plans and maybe the cylinder casting. Not to save the $, but I like to make things my selves. Making parts from castings is actually more difficult than making from scratch i think, but making from scratch, looking like castings is pretty difficult.
Rudy


----------



## David Shealey (Mar 13, 2020)

The plans are pretty dismal, basic is not even a good description.  Glad I spent decades doing mechanical design work, I can only imagine the difficulty of making sense of the plans by a hobbiest that has not had a lot of experience.  I am doing this project mostly as a sentimental thing, since my Dad wanted one for years, got it as a retirement gift, but passed away before he got to do much with it.  I am doing all the reversing gear from scratch, as none of that was in his kit.  The cylinder casting is about the only thing that would be difficult to do from raw stock and have it look like an old engine.  Would be pretty easy though if one wanted a more modern look.


----------



## David Shealey (Mar 13, 2020)

My lathe and mill.


----------



## Rudy (Mar 13, 2020)

Nice shop David. You got some seriously good machinery for a hobby shop.
Agree about the DRO. I Can't even imagine doing anything without. Got it installed both on my mill and lathe.
Stuart has a good reputation, but I don't quite agree. Have just one kit under my belt, but i had to get two of the castings replaced due to poor quality. I found the plans ok, but I had to figure out the important stuff my selves. I invented my own therms and put abbreviations on the plans to help me keep track on what to pay attention to. Like: "R" meaning Related to another part and remember to fit it to this. And "CR", Critical Relation to another part, meaning something like sliding tight fit. And "CRA", Critical Related Assembly, meaning several parts has to be thoroughly fitted together and figure out the sequence to make them. "NC", Non critical, go by the measurements in the plans.
This helped me to do things in right sequence and plan ahead for the best possible setups.
The result was an engine running at 0,44 PSI with no clunking or tight spots, and no need for running in, so I'm pleased with that.

Here is a peak at my shop and my Stuart 10V.
Rudy


----------



## David Shealey (Mar 13, 2020)

Nice shop!  Wish I could keep mine that clean.  I put 3 axis DRO on my mill as soon as I got it.  Had the lathe for a few years before adding the DRO, what a difference!  I "grew up" running machines years before DRO's were even a thing.  Quite a few years "dial counting, then Trav-A-Dials came out, that was an improvement, then the first DRO's a year or two before I moved into engineering and design.
After decades of design work, first look at the Stuart drawings was shocking.  I have done CAD models and drawings of the parts I am making from scratch.   The Stuart drawings are basically "Make it kinda like this." 8>)  I thought of 3d modeling  the whole engine, but that would take quite a bit of time, not sure it would be worth the effort, but would make design upgrading easier.


----------



## accelo (Mar 13, 2020)

Rudy;
I love your nomenclature;
Like: "R" meaning Related to another part and remember to fit it to this. And "CR", Critical Relation to another part, meaning something like sliding tight fit. And "CRA", Critical Related Assembly
The mistakes I made on my Snow engine are all in the "related to" category.
Like machining pillow blocks individually instead of mounting them and then completing the align boring.
Nothing in the plans about the procedure either.  
I know everyone figures this out,on their first model.  But I would certainly wish they had spend more time on the instructions!
The assumption is always the machinist is an experienced builder.  Which isn't always true.
My other beef is the lack of overall dimensions.  Typically the CAD program will chastise you for over-defining.
Gee, make it easy to at least pick up the correct blank without adding up 5 dimensions and two radius. 
Rick


----------



## Jules (Mar 17, 2020)

accelo said:


> Rudy;
> I love your nomenclature;
> Like: "R" meaning Related to another part and remember to fit it to this. And "CR", Critical Relation to another part, meaning something like sliding tight fit. And "CRA", Critical Related Assembly
> The mistakes I made on my Snow engine are all in the "related to" category.
> ...


I believe one the aims of the Stuart engines is to teach you about building assemblies. Checking drawings and working out the best methods of producing the model. 
They have not changed a lot in decades. 
If they were easy then you wouldn’t learn as much. 
I made a few mistakes making mine but I doubt (hope) I don’t make the same mistakes again.


----------



## David Shealey (Mar 27, 2020)

I was not sure how the valve timing worked, with the 40 deg difference in the eccentric, so I spent the last couple days modeling the reversing assembly and one piston in Solidworks.  After running motion study, I see that it works very well.  I posted a short video of the simulation on Youtube. The valve openings are sketch lines to see how the valve timing is with the piston movement both directions. Video is here:


----------



## David Shealey (Jan 22, 2021)

Putting the engine together over the past couple weeks, got one cylinder timed fairly well, but see that it will never be the same between forward and reverse, will have to settle for best combination.  Now started the other cylinder, but it was WAY off!  I have read every posting I could find on these engines (Twin Launch), but have never seen anything stating that the eccentrics have to be opposite hand! The Stewart drawings show only one, but if assembled with the hubs facing outward on each end, one will have to be opposite, with the angle offset opposite from the other facing the hub end.  8>(    Grrrrr.  I was pretty upset thinking I would have to make one over from scratch, but think I can save it by boring it out and inserting a new hub with the extension on the opposite side.
EDIT:  My mistake, all I had to do was reverse the valve actuation connecting rods on that side!  Relieved!


----------



## xpylonracer (Jan 23, 2021)

Smart video David, better than a thousand words.


----------



## David Shealey (Jan 23, 2021)

xpylonracer said:


> Smart video David, better than a thousand words.


Thanks!


----------



## David Shealey (Jan 23, 2021)

Here are pictures of my CAD design of the fixturing for most of the reversing gear parts.  Sometimes fixture design and build takes longer than making the part!


----------



## David Shealey (Jan 23, 2021)

I did the machining of the parts shown on the fixture using an XY stage with iGuaging digital readouts, mounted on a rotary table, on my Bridgeport with digital readout.  My own manual CnC (Crank n Crank). I did drawings of the parts in Solidworks, with all the angles and locations to follow.


----------



## David Shealey (Jan 23, 2021)

I did the Crankshaft much as I did the eccentrics, mounted in a fixture that located on the crank centerline with the correct offset for the crankpins, and the crank web located in a slot in the fixture.  That made machining the crank easy, and precision.  Much better than most of the ways I have seen these done.


----------



## David Shealey (Jan 23, 2021)

I originally made the valve eccentrics with set screws, but hated the idea from the start. My many decades as a machinist/tool and die maker/machine design engineer made me hate set screws on shafts with a blinding purple passion!  I decided that was not going to happen, so modified them by turning the hub down, slitting it, and making a clamp to clamp it on the shaft.  That makes timing much better, and will not mar the shaft in any way!


----------



## David Shealey (Jan 23, 2021)

I modified the design of the reversing lever stops to make the stops adjustable, also mounted to one of the steam shaft studs on a little bronze bushing so that timing can be done with the steam chest cover plate removed.


----------



## David Shealey (Feb 10, 2021)

Due to my absolute hatred of set screws on shafts, I also did the flywheel with my version of a taper lock bushing.


----------



## David Shealey (Feb 10, 2021)

I had wondered how I was going to control the air into the engine, thought of several options, decided to design my own input manifold with valve incorporated. I used o-rings to seal the copper line between cylinders.


----------



## David Shealey (Feb 10, 2021)

I posted a short video of the engine running!  It ran great right out of the gate!


----------



## Steamchick (Feb 11, 2021)

Hi David, It certainly manages the quick changes of gear! Do you plan a boiler and boat? - or is life easy enough (!) just making engines??
A great job. well finished and sounds sweet - with no clattering! Proof of the care you have taken.
Well done!
K2


----------



## David Shealey (Feb 11, 2021)

Steamchick said:


> Hi David, It certainly manages the quick changes of gear! Do you plan a boiler and boat? - or is life easy enough (!) just making engines??
> A great job. well finished and sounds sweet - with no clattering! Proof of the care you have taken.
> Well done!
> K2


THANKS! 
I did this in memory of my dad, who got the kit from his coworkers at retirement. Unfortunately he only got the base plate done before he passed in 1984. After my mom passed, we cleaned everything out to sell the house, and I got the kit, and a few years later decided to finish it. I have no plans to build a boiler. One of my hobbies is machining, since I did that for a few years before going back to school and becoming a machine design engineer, which I did for over 40 years. I built up a pretty nice shop in my basement, and have really enjoyed getting back to the early days, except better now with the nice DRO's which were not around in my tool and die maker days. It has been fun figuring out how to do pretty complex shapes without CNC!
All the reversing mechanism parts are aluminum bronze and 303 stainless steel
I did the valve timing as close as I could by eye during assembly, surprised how nicely that worked! In the CAD layout I did, saw how the timing looked, and increased the size of the valve slider from the drawing size of 0,562 to 0.600, thinking I could narrow it as needed. Looks like no changes needed! Actually A little larger would have worked even better. At VERY low speed it will lock up in one direction, but not the other. I think the clanging some get is the valve opening too soon before TDC/BDC, which my increased valve size overcame. I read that with steam early opening is better, but since this one will never see steam glad I did the oversized valve. 
All those years of machining and designing lead me to build this with close tolerances. All the bearings are 0.001-0.0015 clearance, so no bearing noise. Before putting the rings and gland packings in I could spin the engine with two fingers on the shaft!


----------



## Steamchick (Feb 11, 2021)

You have done something to make your Dad proud! Run it often and think of him and what you did together. This engine is one of those. 
My mate is an ex-toolmaker and abhors my "lack" of precision. So I appreciate what you have done - beyond my skill.
Well done!
K2


----------



## David Shealey (Feb 26, 2021)

Steamchick said:


> You have done something to make your Dad proud! Run it often and think of him and what you did together. This engine is one of those.
> My mate is an ex-toolmaker and abhors my "lack" of precision. So I appreciate what you have done - beyond my skill.
> Well done!
> K2


Thank you!


----------



## grahamgollar (Feb 28, 2021)

David Shealey said:


> Due to my absolute hatred of set screws on shafts, I also did the flywheel with my version of a taper lock bushing.View attachment 122947
> View attachment 122948


I was interested in your personalised taper lock bush. I was recently machining a 3 throw crankshaft from 1.75" solid instead of the 'Lego' kit construction suggested by the drawings. I left an oversize flange at the flywheel end but needed a similar flange on the free end for locating the centres of the crankpins during the offset machining (I know - I should have left a flange on that end as well, too late!)
Anyway, I discovered a supply of miniature taper lock bushes which are available down to 1/4" dia and fit into a parallel bore. They only cost peanuts so it wasn't worth the bother of making my own design. They go by the name of Translock, grip really securely and are available in Imperial and Metric ranges. I guess you older hands know of these but, despite using very large Taperlocks in years gone by, I had never realised that there were miniatures available.


----------



## David Shealey (Feb 28, 2021)

I have used Fenner Drive bushings, along with Misumi, Ringfeder, and others in my decades of machine design. I had looked at the Trantorque Micro from Fenner, but the OD and length was too large to fit easily into this small flywheel, so I made my own. The Trantorque micro was about $20, my home made one was fab time only.  8>)



grahamgollar said:


> I was interested in your personalised taper lock bush. I was recently machining a 3 throw crankshaft from 1.75" solid instead of the 'Lego' kit construction suggested by the drawings. I left an oversize flange at the flywheel end but needed a similar flange on the free end for locating the centres of the crankpins during the offset machining (I know - I should have left a flange on that end as well, too late!)
> Anyway, I discovered a supply of miniature taper lock bushes which are available down to 1/4" dia and fit into a parallel bore. They only cost peanuts so it wasn't worth the bother of making my own design. They go by the name of Translock, grip really securely and are available in Imperial and Metric ranges. I guess you older hands know of these but, despite using very large Taperlocks in years gone by, I had never realised that there were miniatures available.


----------



## lathe nut (Mar 2, 2021)

David, thanks for sharing with us, that is one good looking engine, great workmanship and runs great, you have to be proud of that one, thanks again, Joe


----------



## David Shealey (Mar 2, 2021)

lathe nut said:


> David, thanks for sharing with us, that is one good looking engine, great workmanship and runs great, you have to be proud of that one, thanks again, Joe


Thank you Joe!  It was a really good exercise in design modification, fixturing, and machining.  Kept me off the street for a LOT of hours. 8>)


----------



## Richard Hed (Apr 4, 2021)

David Shealey said:


> My dad got a Stuart Twin Launch kit as a retirement gift when he retired in 1980.  He put together a small shop over a couple years, and barely started the work on this, but he passed away in 1984.  I got the kit about 4 years ago planning to finish it one day.View attachment 114030
> 
> Well, I have now started on it.  My dad had only completed the base plate and main bearing caps, so not much was done.  His long time work on all types of old engines led him to add Babbitt main bearings to the build.  Somehow, he got the babbit off center, so the bearings are not constant babbitt thickness.  I was thinking of getting some Babbitt and re-machining the castings, but upon removing the caps and looking at it, the bearing surfaces are really good, so will use as is.  The 5/16 shaft turns easily and smoothly! Will have to do a lot of clean up and finishing of the base casting.
> This will not be a build log, but will post mods and unique methods of fabrication. His kit did not include the reversing gear, so I will be making all that from scratch.
> ...


When I was a very small kid (last week), my Dad poured and scraped some babbits.  I asked what he was doing and he told me.  But in all my life, that is the only time I ever saw anyone doing it.  I have since wondered what the exact composition of babbit is.  Does anyone know?


----------



## Richard Hed (Apr 4, 2021)

David Shealey said:


> Nice shop!  Wish I could keep mine that clean.  I put 3 axis DRO on my mill as soon as I got it.  Had the lathe for a few years before adding the DRO, what a difference!  I "grew up" running machines years before DRO's were even a thing.  Quite a few years "dial counting, then Trav-A-Dials came out, that was an improvement, then the first DRO's a year or two before I moved into engineering and design.
> After decades of design work, first look at the Stuart drawings was shocking.  I have done CAD models and drawings of the parts I am making from scratch.   The Stuart drawings are basically "Make it kinda like this." 8>)  I thought of 3d modeling  the whole engine, but that would take quite a bit of time, not sure it would be worth the effort, but would make design upgrading easier.


you got that right about "shocking" Stuart drawings.  I have to admit, I wasn't "schocked", I was PISST!  Frankly I thot these drawings were unbelievable.  It would take so little effort to correct them yet it is not done.


----------



## Steamchick (Apr 4, 2021)

On Babbits... my Stuart Sun engine had a bit of wear on the big-ends. So I tinned them with a "lead-wipe" of electrical solder... perfect! A couple of thou of solder took up the slack and left a tin-lead surface.
K2


----------



## David Shealey (Apr 4, 2021)

Richard Hed said:


> When I was a very small kid (last week), my Dad poured and scraped some babbits.  I asked what he was doing and he told me.  But in all my life, that is the only time I ever saw anyone doing it.  I have since wondered what the exact composition of babbit is.  Does anyone know?


There are several grades of Babbit.  Most common ones consist of Tin, Lead, Copper, and Antimony.








						Babbitt (alloy) - Wikipedia
					






					en.wikipedia.org


----------



## Steamchick (Apr 5, 2021)

When I worked for a local Car manufacturer, on crank bearings, we took Glacier metals which were an Aluminium - Tin Alloy for a "lower performance" Cast Iron crankshaft engine. The Glacier specialist and my Company's Doctor of Tribology were discussing how much silicon was in the alloy, which they claimed "polished" the cast-iron crank by a burnishing process. The alloy was cast onto the steel backing - just like Babbit - rolled and pressed, clipped to size, set in pairs and broached to size. (I remember setting bolted-up half bearings in the 4-jaw in the lathe as an apprentice, and boring the Babbit to a thou tolerance. I can't remember the detail...). As the process was not as capable as the engine design required, they were all measured (automatically) and graded, then we built the appropriate grades of bearing against the Housing and journal dimensions. This was the way to ensure the correct clearance to within a few micron tolerance. A factor of 10 or more times better than we can achieve in our home workshops!
Of course, higher performance engines, with forged crankshafts, used phosphor bronze shells which had expensive anti-corrosion metal plating (A couple of microns of Indium? Niobium? - I can't remember...). Who has seen corrosion on their model Phos-bronze bearings? Probably no-one, as we mostly don't run pressurised oil in model engine bearings... so we see wear marks. But full-sized engines for thousands of hours use need these levels of technology.
K2


----------



## David Shealey (Apr 5, 2021)

Richard Hed said:


> you got that right about "shocking" Stuart drawings.  I have to admit, I wasn't "schocked", I was PISST!  Frankly I thot these drawings were unbelievable.  It would take so little effort to correct them yet it is not done.


Not only are the parts poorly dimensioned, some wrong, some missing dimensions, and NO tolerances given, but there is no assembly drawing.  For some reason the parts have numbers in the corner, as if they are going to be referred to, but the assembly drawing has no references, and is missing detail. Glad I spent years on a drawing board, and many years on CAD designing machinery, was able to figure it out relatively easily.  I imagine someone without a lot of experience having a very hard time making anything precise.


----------



## Steamchick (Apr 6, 2021)

My experience with the 1963 drawings of the Sun engine were much the same. But I could easily rectify the errors. I understand your frustration about them being wrong. Bad business from Stuart I reckon. How about castings? Mine were all good.
K2


----------



## James Barker (Apr 6, 2021)

David, I REALLY like the design changes you made to the eccentric as well as the reversing lever. I am wondering how much vibration that clamping arrangement will make with the engine running. Of course steps could be taken to balance that out. Well done. 

BC1
Jim


----------



## Steamchick (Apr 7, 2021)

On Taper-locking parts to shafts: On small shafts I use simple Olives (double taper sleeves) with a nut over the whole that screws onto the boss of the flywheel. Sometimes proprietary plumbing fittings, sometimes my own made parts. On a recent build of a double Sturmey-Archer generator, the central holder to hold the the outer magnets is clamped to the shaft that way. Most wheel bosses (e.g. on a toothed-belt drive I have in a boat) have a suitable boss to thread for the nut, and a small countersink acts as the taper on the part. If you need the olive to easily come off, I suggest using an O-ring, as the friction is adequate for most model applications where I have done this. It does not look "authentic original", but is a very simple way to secure flywheels and pulleys to shafts on many models.
K2


----------



## David Shealey (Apr 7, 2021)

Steamchick said:


> My experience with the 1963 drawings of the Sun engine were much the same. But I could easily rectify the errors. I understand your frustration about them being wrong. Bad business from Stuart I reckon. How about castings? Mine were all good.
> K2


My castings were good, but some were not used since the kit was non reversing, and I made all the reversing gear from scratch, so some of the original castings were not used at all. Actually, the only castings used from the original kit were: Cylinder, Connecting rods and caps, Base and main bearing caps, steam chests and covers, and bottom cylinder covers.  I machined the pistons and top cylinder covers from Cast bar stock, higher quality than the CI in the kit. Everything else was from bar stock.


----------



## Steamchick (Apr 7, 2021)

Sounds good!
K2


----------

