Stuart Turner 5a Build

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xo18thfa
Posts: 181
Joined: Tue May 17, 2005 11:59 pm
Location: Harrisburg, South Dakota

Stuart Turner 5a Build

Post by xo18thfa »

This project is the Stuart Turner #5a steam engine from a casting kit. Unlike other Stuart kits, the 5a kit is castings only. There are no other materials, fasteners, or supplies. The threaded parts are all British standard, mostly 1/4” BSF and 2 British Association (BA). Since we must provide all the fasteners, switch over to the Unified Thread Standard equivalent, which is ¼ x 28 and #10 x 32. The casting kit comes with a set of plans. The plans are a (probably 1/3) reduced photocopy of the old school vellum blueprints. They are mostly legible.

Get started with the base casting. Start off by trimming up the bottom to clean metal. Don’t take too much off, there is not a lot of height “meat” on this part. Be sure the 7.5” flywheel has room to turn. There was some “chill” on this bottom edge, however, a carbide cutter went thru it.
Base 1.jpg
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Use a 1” diameter pin to probe the corners and the mounting lugs. Tap the casting around until centered.
Base 2.jpg
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The base casting is not shown in the plans. Match the hold down bolt pattern from the sole plate. Tap with ¼ x 28.
Base 3.jpg
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The mounting lugs turned out to be 7-7/8” apart. At first, I drilled for ¼” hold down bolts. Later expanded to 5/16”. Mill off the mounting lugs to about ½” thickness and deck off the base to clean metal.
Base 4.jpg
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Next up is the sole plate. Mill to clean up the bottom edge of the casting. Using a 5/8” or ½” pin, probe all the corners and hold down bolt pads. Center up the casting as best as possible. Once centered, zero out the DRO or dials on the mill.
Sole Plate 2.jpg
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Run around the inside of the sole plate opening to clean it up. Mill the inner cheeks of the bearing pockets to the final inside width.
Sole Plate 3.jpg
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Looks like we are done for today. The system let me upload only six photos for now. We'll pick back up next time.

Take care, Bob.
Bob Sorenson, Harrisburg, South Dakota
Odyknuck
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Re: Stuart Turner 5a Build

Post by Odyknuck »

So what exactly is this engine, stationary?
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Dick_Morris
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Re: Stuart Turner 5a Build

Post by Dick_Morris »

Joe Pie on Youtube is building a Stuart D10. It's a two cylinder baby brother to yours. If you haven't already completed yours he has some good ideas on set ups and machining.

Your post prompted me to pull a half-done Stuart #4 from the shelf. I wonder what I did with the drawings?

Odyknck - Yes, a vertical stationary engine but I think some have been used in small steam boats. At 2-1/4" bore (corrected). I think the #5 is the biggest of the Stuart-Turner line of engines.
Last edited by Dick_Morris on Wed Jun 07, 2023 6:55 pm, edited 1 time in total.
Odyknuck
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Re: Stuart Turner 5a Build

Post by Odyknuck »

Ok, Thanks for the info Dick.
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xo18thfa
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Re: Stuart Turner 5a Build

Post by xo18thfa »

Yes, it's stationary. The largest single cylinder in the Stuart line. 2.25" bore, 2" stroke.
stacks-image-71af091.jpg
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I plan to do the reversing gear and add a mechanical lubricator. Might make a go-kart out of it.

Been following Joe Pie closely. His setups for the D10 and the miniature shop machines are very helpful on this build.

For Dick_Morris, I built the #4 recently. If you can't find your plans, let me know.

Take care, Bob
Bob Sorenson, Harrisburg, South Dakota
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Dick_Morris
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Re: Stuart Turner 5a Build

Post by Dick_Morris »

Bob - Please check for a private message.
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xo18thfa
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Re: Stuart Turner 5a Build

Post by xo18thfa »

Back on the sole plate today. Mill the outer cheeks of the bearing pockets to final outside width.
Sole Plate 4.jpg
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I’m not sure what these little tabs on the ends of the sole plate are for. They are on both ends. They might be a bracket to hang an accessory item. Mill them flat and they will be there if needed.
Sole Plate 5.jpg
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Deck off the sole plate and mill slots for the bearing caps.
Sole Plate 6.jpg
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The DRO makes this easy and very accurate. A 1-1/8" parallel dropped in perfectly.
Sole Plate 7.jpg
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All the tapped holes in the sole plate are ¼ x 28.
Sole Plate 8.jpg
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Next, rough out the bearing seats using a ¼” ball end mill. Using some shop math, calculate a table of X and Z axis values for the cutter. The final bearing diameter is 15/16”. Rough out to 7/8”.
Sole Plate 9.jpg
Sole Plate 9.jpg (301.34 KiB) Viewed 54799 times

That’s enough for today, we’ll pick back up with more on the sole plate next time.
Bob Sorenson, Harrisburg, South Dakota
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xo18thfa
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Re: Stuart Turner 5a Build

Post by xo18thfa »

Back on the sole plate today. The plans call for a small pin at the bottom, center of the bearing pockets. This isa to prevent the main bearings from accidentally spinning in the sole plate. The plans don’t call for a specific size, so 1/8” diameter seems about right. Drill 5/16” deep.
Sole Plate 10.jpg
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There was very bad sand inclusion on two of the bolt down pads. Too much to simply ignore.
Sole Plate 11.jpg
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The best way to fix this is on the rotary table with a 1/8” diameter ball end mill.
Sole Plate 12.jpg
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Go in with a pointed stone on a Dremel to clean up the milling marks.
Sole Plate 13.jpg
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The Sole plate is nearly done. Next step is to bore out for the main bearings. But, to do that we need to make the bearing caps. Start those next time.

At the time of this writing, the lower rotating assembly is actually done and turning. Here is where it’s at:

https://www.youtube.com/shorts/XqysDNgXtMM

Take care, Bob
Bob Sorenson, Harrisburg, South Dakota
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Dick_Morris
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Re: Stuart Turner 5a Build

Post by Dick_Morris »

Doubleboost on Youtube has a video today about returning a Stuart 5A to life. I think he did another recent video on the 5A. I found that using closed captions does a better job of understanding the accent than I do!
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xo18thfa
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Re: Stuart Turner 5a Build

Post by xo18thfa »

Hi Dick: Who had those #5a videos? There is a British guy named Kieth Appleton who has done a lot of #5a restorations.

Thanks, Bob
Bob Sorenson, Harrisburg, South Dakota
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xo18thfa
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Joined: Tue May 17, 2005 11:59 pm
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Re: Stuart Turner 5a Build

Post by xo18thfa »

Today starts the bearing caps for the crankshaft. The bearing caps are very rough castings.
Bearing Caps 1.jpg
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After cleaning up with the belt sander, clamp in the mill vise with some plywood jaws and mill off one side.
Bearing Caps 2.jpg
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Clamp the bearing cap directly to the milling table to mill the other side to final thickness.
Bearing Caps 3.jpg
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Center and level the bearing caps in the mill vise as true as possible. Mill the bearing cap retention notches and rough out the bearing slot as done on the sole plate. Drill for the cap bolts as well.
Bearing Caps 5.jpg
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Flip the bearing caps over and spot face for the cap bolts. The #5a plans do not specify any method for bearing lubrication, other than just drill an oil hole. Initially I tapped these with #10 x 32, but later widened them out to ¼ x 28. Eventually there will either be an oil cup or a fitting for an oil line.
Bearing Caps 4.jpg
Bearing Caps 4.jpg (233.28 KiB) Viewed 54462 times
The fit is very good. Probably, at this point, stamp numbers on the parts for each side. As assembly progresses, keep all the parts in the same keyed location.
Bearing Caps 6.jpg
Bearing Caps 6.jpg (220.42 KiB) Viewed 54462 times
Next time we’ll line bore for the main bearings.

Take care, Bob
Bob Sorenson, Harrisburg, South Dakota
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Dick_Morris
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Re: Stuart Turner 5a Build

Post by Dick_Morris »

Who had those #5a videos?
Youtube name Doubleboost.
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