Stuart 5a stationay build

[Bob Sorenson]

Looking good! That key came out well.



What I do when I broach a keyway with a bottle jack press is use the press and release method. Start broaching the keyway, release the pressure on the broach and then press again. Do that a few times until the broach is well seated in the bushing and you shouldn't have any problems.

Ok, understand. I'll ty that next time. However, using my mentor's press was a good reason to go over for a visit.

 

[packrat]

I have a 5A, they are a beautiful steam engine, I have been working on mine for some time now...
Have enjoyed your post.

 

[Bob Sorenson]

Thanks packrat, this build is going well.

Time to get started on the engine standard. The rough casting is absolutely fabulous. It machines very well and has a smooth nice finish. It is very symmetrical all around which makes setup easy. A couple of small holes here and there, nothing to worry about. The first step is machining the bottom of the feet. Plug the bottom of the cored hole with an aluminum rod. This end of the cored hole was very smooth, and the plug gently tapped in.

Next, plug the top of the core and center the standard as truly as possible on the faceplate. This end of the core was rather rough, so I used two-part epoxy to install the plug. Center drill the plug and support with the tailstock. Turn the top face of the standard and the rim to final dimensions. Face the top as close to the plug as possible without digging into it.

Boring out the crosshead guide part of the standard requires the use of a steady rest. The standard sticks out too far to turn without the extra support. The steady rest that came with this lathe does not have the capacity for the standard. I fabricated this one from some 6” steel pipe and bar stock. The rubbing surfaces are hard bronze. Install the steady rest without disturbing the faceplate setup.

Drill and bore out the plug.

Rough out the crosshead guide bore. Get to within about 0.010” for the final inside diameter.

The rough boring operation went very well. The homemade steady rest is rock solid. The boring bar was overhanging a bit, so I decided to remove the steady rest for the last couple of passes. A very sharp broad nosed tool left an exceptionally clean finish.

Next time we’ll drill the bolt patterns.

Take care, Bob.

 

[GreenTwin]

Beautiful work on that base.

1st rate setup for sure.

.

 

[Steamchick]

I like the care taken using the fixed steady, and the fitting of plugs to use the tailstock centre support.
I had not thought of all that. I would have simply set-up in my Milling machine, inverted on the top part of the casting, using a temporary insert in the rough bore for alignment with the Quill. Then milled the underside of the feet and drilled the bolt holes. The feet would then be mounted on the milling travelling base and I would have bored from above. Or with the lathe I should have mounted the feet on an angle plate on the cross-slide, and bored from the headstock.
But it's simply how I was taught to rotate the tool and transit the workpiece for circular parallel bores.
Each to his own, and my idea is probably the wrong one?
So well done with a clearly explained machining process. It's good to learn..
K2

 

[Bob Sorenson]

I flipped a lot of mental nickels on doing the standard. Thought of doing it on the mill, setting up on the lather cross slide. Also thought of mounting the casting on a squared-up plate and use the plate as a "tumble jig" on the mill. Then I remembered Andrew Smith's book on making the #10V. Decided to go with his method but added the plugs and steady rest to reduce chatter. Fortunately, it all worked out. It's better to be lucky than good.

Next step on the standard is drill and counterbore bolt patterns. This is done in one setup on the mill. Use a parallel of length or bar stock to align the standard feet to the X axis.

Use the top surface of the standard to center and zero out the scales. The standard is rather tall. Taller than any drill bits I have. So, make some extensions as needed.

¼” x 28 is the clearance on the standard feet. Either make an extension for the drill bit, or get one of those long bits.

The plans do not specify counterbores on anything. However, bolts and washers will definitely foul on the casting fillets. This is a simple, single flute counterbore made from ½” diameter O-1 stock.

Now it’s a simple matter of running around the top flange and drilling for the bottom cover.

The Machinists Handbook has formulas to figure out the bolt circle. Or model it on a CAD program.

Next time we’ll finish the standard and maybe get started on the big end brass.

Take care, Bob

 

[Steamchick]

Excellent work Bob, as usual. Keep it up!
A pleasure to read your posts and see how it should be done, properly.
Thanks,
K2

 

[Bob Sorenson]

Thanks. These Stuart kits are great to work.

A small erratum to the last post. The photo “Standard 11” shows drilling the top of the standard flange for the bottom cover and cylinder. Drill these holes to exactly 3/16” for now, as opposed to the 13/64” shown on the plans. The reason will appear shortly.

The underneath surface of the top flange has a very steep drafting angle. The holes in the flange will need counter boring for the assembly nuts to sit squarely. The feet of the standard interfere with straight access to the bottom of the flange. So simply using a regular counterbore will not work. A special tight spot reverse counterbore head is required. McMaster Carr has these reverse counterbores. So, spend some of your kids’ inheritance and get one. Reverse counterbores are a 2-piece tool, a shaft, and a cutter head.

The cutter head locks to the shaft.

Insert the shaft thru the hole and attach the cutter. Run the mill at a very slow speed, 60 to 70 rpm. Gently raise the quill to take the cut.

This tool cuts very well. I thought it would chatter, but not at all. It was well worth the investment. I can’t think of another way to cut these counterbores. The last step here is enlarge the 3/16” holes to 13/64”

There are some cast in bosses on one side of the standard. The plans do not show these. They are for some kind of union for lubrication of the crosshead. I could not think of any good way to set up the casting, so a pin and eyeball in the center of the standard bore did the job.

This is 10 x 32 tap. Not sure right now if I’ll use an oil cup or some kind of pump for oil.

That’s it for the standard. Next time is the big end brass for the connecting rod.



Take care, Bob.

 

[GreenTwin]

Very clever solution to leveling the underside surface that casting.

 

[krypto]

That's something I haven't seen before. Thanks for showing!

 

[Charles Lamont]

To save money, but not time, a reverse, or better, double sided, spotfacing cutter is not difficult to make from silver steel (drill rod).

 

[Bob Sorenson]

I wasn't sure how those reverse spotface cutters attached to the shaft. Now that I know, it would easier to make.

Today is the big end brass, the bearing portion of the connecting rod. The 5a kit comes with castings for the big end brass.

As with the main bearing castings, I’m not going to use them. Don’t want to find out these “gunmetal” castings are as soft as butter and will wear out as they did on the #4 project. Instead fabricate the big end from bronze bar stock.

Rough out some bar stock to the correct width and diameter. Drill clearance for the studs. There is a small detent to accept the bottom end of the connecting rod. Saw in half.

Machine and profile to final dimensions.

Clamp the halves together and accurately center drill the center. Set up in the 4 jaw chuck and bore to diameter for the crank shaft.

To turn the final profile, use a little stub mandrel. Turn both sides and that’s it. Easy job.

Next time is the connecting rod.

Take care, Bob

 

[GreenTwin]

You have some great lighting in those photos.

What is your light source ?

I always seem to get dark areas and harsh shadows.

.

 

[Bob Sorenson]

These are LED strip lights they put in. 4 foot long, like fluorescent fixtures. Very bright. I use a cell phone camera and get dark areas and shadows too. Found that zooming in close and standing farther away cuts that down.

 

[user 52078]

Next up is the sole plate. Mill to clean up the bottom edge of the casting. Then, 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.

View attachment 148045

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.

View attachment 148046

Mill the outer cheeks of the bearing pockets to final outside width.

View attachment 148047

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. Anyway, mill them flat and they will be there if needed.

View attachment 148048

Deck off the sole plate and mill slots for the bearing caps.

View attachment 148049

The DRO makes this easy and very accurate. A 1-1/8” parallel dropped in perfectly.

View attachment 148050

All the tapped holes in the sole plate are ¼ x 28.

View attachment 148051

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”.

View attachment 148052

That’s enough for today, we’ll pick back up with more on the sole plate next time.

Those little nibs on the side would give you something to clamp on. Then you could work on the whole top face without having to work round or move clamps. TBH not enough casting suppliers think things through and put such "clamping lugs" on castings. Machine them off as a last op.
Martin

 

[sawyer massey]

That is going to be a great looking machine

 

[Steamchick]

I should use such clamping lugs to bolt the engine to a wooden display base, if not powering a boat or other proper job.
K2

 

[Richard Hed]

Ladies and Scholars:, I am curious as to the power out put of the Stuart 5. Can any scholar enlighten me? A couple years ago I bought a 10 H and a 10V for my son to learn some machining on. He turned his nosse up at them so I proceeded to work on them. At that time, the cost plus shipping was quite reasonable. Now, however, I understand that the shipping has gone thru the roof and out into space, else I might be interested in buying a 5H, more for the horsepower than the fun of making it. Also the price of the castings have nearly doubled in a few short years.

I lookt on ebay and the prices there are absolutely unbelievable. Truth is, I can hardly believe a company can remain in business with such high prices--people are buying them, or else they WOULD goi out of business.

The formula I use for power output is PLAN/33000. That is, P=expected pressure, L= length of stroke, A=area of the piston surface, and N= number of strokes per minute. This gives very different expected horsepower than what Stuarts claims. Frankly, I doubt if many peeps actually test for horsepower.

 

[GreenTwin]

Stuart lists the 5A at 1.5 bhp at 100 psi, 800 rpm, with a 2.25" bore, 2" stroke.

That is a pretty high speed for a steam engine, ie: high speed for the old school steam engines that generally ran between 75-100 rpm.

Porter's new "high speed steam engine" ran at 300 rpm.

And then there is continuous power ratings, and non-continous ratings.
An automobile engine won't last long if run at its rated horsepower, whereas a Detroit diesel will run thousands of hours at its rated hp.

I would guess a more reasonable maximum rpm for that type of steam engine would be 300 rpm, which puts you at 0.56 hp if I did the math right.

Steam engines do produce a lot of torque, and the plot of the torque curve can be as important or more important than horsepower.

A continuously run engine needs to produce a reasonable amount of torque and horsepower at a reasonable and maintainable rpm.

.

 

[Richard Hed]

Stuart lists the 5A at 1.5 bhp at 100 psi, 800 rpm, with a 2.25" bore.

That is a pretty high speed for a steam engine, ie: high speed for the old school steam engines that generally ran between 75-100 rpm.

Porter's new "high speed steam engine" ran at 300 rpm.

And then there is continuous power ratings, and non-continous ratings.
An automobile engine won't last long if run at its rated horsepower, whereas a Detroit diesel will run thousands of hours at its rated hp.

I would guess a more reasonable maximum rpm for that type of steam engine would be 300 rpm, which puts you at 0.56 hp if I did the math right.

Steam engines do produce a lot of torque, and the plot of the torque curve can be as important or more important than horsepower.

A continuously run engine needs to produce a reasonable amount of torque and horsepower at a reasonable and maintainable rpm.

.

Yes, I saw that and I considered it to be an absurd RPM. My calculation using the "PLAN" formula gave 19HP at that rate (not, apparently bhp). 19 HP would blast that engine to smitherenes. 800RPM would rattle it to pieces. Maybe I made a miscalculation, still, 800rpm is absurd. I thimpfks Stuarts made a mistake. Using PLAN does not give the same HP values as Stuarts bhp values. The two should give similar but not identical values. Bhp gives smaller values (me thimpfks) than HP as HP is a direct power reading but bhp takes into consideration such factors as friction, heat and other losses. Correct me where I am wrong.