Stuart D10 ( yet another thread ) - RC Groups
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Dec 27, 2012, 06:38 AM
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Build Log

Stuart D10 ( yet another thread )

A reasonable human being will occasionally sit down and do nothing... just.. you know... relax... I always found that too boring, why relax when you can tinker ?? Make things !!! One of many things that caught my attention over the years are miniature steam engines.
Tesla coils, thermite, Wimshurst generators being other things that caught my attention...
Anyway, a few weeks ago i finally decided to "have a go" at building a miniature steam engine. Stuart Turner seemed like a good choice so $300 later I ended up with a set of castings and raw material.
Whole lot of fiddly small pieces that need to be machined... with... mills and drills and lathes and other machinery !!!! I hope they come with manuals and "how to" instructions.... I have seen people using them, I mean, how hard can it be ??
I thought that it would be a good idea to take some photos and share them with other members of this forum, seems like there is a lot of people here that know a thing or two about machining.
I'm hoping that I will be able to get some advice... Is 1200 RPM too fast for a reamer ??
So, two days ago I started, your comments would be appreciated
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Dec 28, 2012, 02:13 AM
Taking care of the pond.
Nice metal work.
Dec 28, 2012, 07:37 AM
Registered User
-kno3-'s Avatar
Very interesting, I'll watch this. However it's not the first time I read complaints about Stuart castings. Are they really that bad?
Dec 29, 2012, 03:29 AM
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Over all, they are quite good, but this piece was worse than usual. Fortunately I have access to tools with carbide inserts, HSS tool would not be able to machine this part.
Dec 30, 2012, 05:39 AM
dunc2504's Avatar
Nice machine tools you have available .
I have duilt several Stuart engines now , and have found the castings to be quite good , certainly for the money , I have never found a lump of slag inside one , unlike one of my expensive bronze cylinder castings for my loco (on the last cylinder hone)
All the plans and drawings I have seen in the UK for steam stuff is in imperial , but Hey ! we did invent it (or at least develop it ) .the only ones that I have seen that are not are German or Japanese .
Hope You have all the Ba and Me taps and dies you are going to need to finish the engine .
Dec 30, 2012, 06:09 AM
Registered User
Hi Dunc,

Machines are courtesy of my employer, they were kind enough to let me use the equipment on the weekends and during holidays. Just wait till you see the WaterJet cutter !
As far as castings are concerned, I have seen worse, a LOT worse ( not from Stuart ) ! Hard spots, inclusions, porousness, and yes you are right, you always discover them on finishing cut !
Imperial is ok, been working with it for a long time, in Australia we use a mix of both, metric and imperial. But still, when I encounter 21/64 or something like that, I have to reach for the calculator.
I will have to buy some taps and dies, mostly BA's, the rest should be available at my factory.
Dec 30, 2012, 07:06 AM
dunc2504's Avatar
I have a set of laminated conversion tables (printed from the internet) stuck on the wall in the workshop , as the metric system was in when I was at school (just) . and all my gear is in metric . I have now got Ba and Me tap/die sets and imperial reamers , drills, number and letter drills , collected as I needed them .
Building from castings is by far the cheapest way of owning a Stuart engine , and I think , far more fun .
Look forward to the next post .
Dec 30, 2012, 10:09 PM
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Last day of 2012, no better way of spending it than making bits and pieces in the workshop. So, today I did some work on cylinders....

Off to Sydney Harbour now, it will be crowded, noisy, messy, you name it but it is whole lot of fun !! Did I mention the fireworks ? Nobody does it better !!

Happy New Year everybody !!!
Jan 02, 2013, 02:31 AM
Registered User
Today's exercise was making cylinder covers. There are only steam chest covers and the flywheel left as far as Cast Iron parts are concerned.
Soon I will have to start working on the crankshaft, I think that I will take Loctite and pins approach. I don't like the idea of soldering because of possibility of distortion.
Can someone please tell me about the pins, are they small dowels ? Where can I get them from ?
Also I am considering making counterweights on crankshaft webs, did anyone try doing this ? I think that it will add to the dynamics/appearance of the engine, maybe even make it a bit smoother.
Jan 02, 2013, 03:05 AM
dunc2504's Avatar
You could cut the crank webs from round stock (some have done this to give counter weights) and in my opinion , pinning (just steel dowels) and soldering is the way to go . With the crank shafts pushed through and cutting out the mains after soldering I had no problems and a true running strong crank.
The method was shown in an old book I had , and may be shown on the plan (well my old copy anyway ).
Jan 02, 2013, 04:08 AM
Registered User
Thanks Dunc,

Making counterweights of any shape is not going to be a problem, I have access to a Water Jet cutter ( I operated it for 5 years ). So your recommendation is to use dowels and soldering ? Standard procedure, drill, ream then tap in the dowels ? 2 mm dowels will be sufficient ?
Jan 02, 2013, 07:28 AM
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ooyah's Avatar
Originally Posted by ZED_C
Thanks Dunc,

Making counterweights of any shape is not going to be a problem, I have access to a Water Jet cutter ( I operated it for 5 years ). So your recommendation is to use dowels and soldering ? Standard procedure, drill, ream then tap in the dowels ? 2 mm dowels will be sufficient ?
Zed ,
You are a very fortunate guy having access to so much machinery, the majority of us have to do with a modelers lathe and if fortunate enough to have a mill consider ourselves lucky.

We all have our preferred method of making crank shafts for the Stuart engines, Having made several D10's and on the first one I silver soldered the webs to the shaft and boy what a mess, it seamed to take for ever to clean it.
I now make the webs from round bar, shape to balanced type, glue them to the shaft with Loctite 603, leave overnight to cure, drill and ream for 5/64" Taper pins, cut out the part on the main shaft not required and now no mess to clean.
Apart from the aesthetic appearance of balanced webs it makes no difference to the running of the engine.
Here are some pics of a Launch engine crank shaft.

Best wishes with your build.

Jan 03, 2013, 05:11 AM
Registered User
Thank you George,

Yes I am very lucky being able to use all the equipment. However, I would like to have hobby mill and a lathe in my own garage workshop. Cheap Chinese machines are now available, mills and lathes for about $1000. I have to admit that second hand Myford 7 would probably be better option than brand new Taig. Some of the machines will stay out of reach of hobbyists and probably most businesses forever.

I like the way you made counterweights out of round bar, Dunc mentioned that method earlier. I think that they help make whole thing look much better, all that movement on low speed...

I need some clarification regarding "Silver Soldering", seems like there is confusion out there when people use this term.
To my best knowledge and understanding soldering is classified as follows:

1. Soft Soldering, Tin/Lead alloy, flux usually incorporated into the wire (Core Flux) usually used in electronics and for bonding of parts not exposed to high stress or high temperature, SILVER in color. Because of its color people sometimes wrongly call it Silver Soldering.

2. Silver Soldering, alloy actually contains Silver (available in different percentages), flux is powder kept in separate container, mixed with water etc. etc.

3. Brazing, Brass rod is melted and used to join parts

Now, which one of these is used to fabricate D10 crankshaft ? No. 2 sounds like most logical choice.

Today I managed to make steam chest covers, and some experimental balanced webs.
Jan 03, 2013, 02:05 PM
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ooyah's Avatar

No 2 is the preferred method with about 42% silver, most model engineers use Silver Solder rather than Lead based soft solder for brass and copper joints.

My preferred method for crankshafts is to taper pin and glue, saves a big clean up.

Please check your drawing for the crank shaft webs, Stuart used to supply 5/32" flat bright bar for them and the drawing showed a dimension of 25/32" between webs for the inside bearing.
In their wisdom as they could no longer get 5/32 " bar they supplied 3/16" thk bar but didn't notify or modify their drawing which should be 23/32" if the 3/16" bar is used.

I challenged them on this and they said that there was nothing that they could do as they just had 5,000 new prints made, that was the old company not the new owners.

Don't forget to drill the 3/16" dia x 7/16" long hole in the shaft as this is for an extension if you wish to make an engine driven boiler feed pump at a later date.

When machining the bearings , cut them a bit oversize to length, take a piece of 1/32" thk strip and bend it to the curve of the bearing bottom which allows you to set it up in the 3- jaw to drill and ream, face to size.

I hope this is of help to you.

P.S. do you have a name ,or do you prefer ZED

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