Stuart No 4 Engine

[f350ca]

Sorry its been a while since I've posted here but drop in often and check out the incredible work being done.
I keep busy in my machine shop and cabinet shop but seams all my metal work is in scale not suited.
A couple of weeks ago I answered an ad for a metal bender on Kijiji, while picking it up I noticed a beautiful old wooden machinists chest. When I commented on it the chap said it had belonged to his father in laws dad, and he was upstairs. He and I got into a great conversation while going through the contents of the chest. He asked me if I'd be interested in a set of castings for a Stuart Engine. Seams he'd bought them years ago for his dad but he'd never got to them. So outside we go (with the bender), he goes to a large shed and comes back with a box. After looking them over I ask him how much he wanted for them. Well I'd like to see it completed and you look like someone who could do it, how does $50 sound. Any gun slinger would be proud how fast I drew my wallet.
This build may take some time as other projects will likely be pulling me away, but here goes.

The castings were incredible, never thought to ask how old they are.

The new kits come with all the bar stock, this one didn't, nor the rings, guess we'll be making them.

When it comes time to paint, Im lousy masking so I prefer painting before machining. Just so happens I'd just got into powder coating and thought this would be a good project to practise on. Sand blasted the castings and gave them a spray and bake.

Like the finish powder coating gives, though it may appear a little thick for models. I think this engine being on the larger size can pull it off.

Thanks for looking.

Greg

 

[f350ca]

Started on what I think is called the frame. Decided the best plan of attack was to hold it in the bore for the cross head and machine the top and feet as reference surfaces.
Made an expanding mandrel to mount it.

Worked quite well for the top but when I machined the feet there was a small hard spot and the interrupted cut caused the casting to shift slightly giving a slight runout on the top surface.

To true it up we gave the feet a lick on the surface grinder, then polished up the top.

With reference surfaces to go off we bored the hole for the cross head, leaving it a half thou under for lapping. The powder coat is tuff enough I could clamp on it and not leave a mark, and the edges stay remarkably sharp.

Next we needed a lap. Have tapered reamers for dowel pins (1:48) so decided that would be a good taper to work with. Set up the taper attachment and made a mandrel, then drilled and reamed an aluminum blank for the lap. With it on the mandrel I turned it to size then slotted it on the bandsaw to get it to expand. Over did the slots, now it expands too easily so had to clamp it to the arbour to get it to drive. Had valve lapping compound on hand so went at it.

Got what I think will be a good finish, was concerned too polished wouldn't hold oil. Only took minutes to get it dead on size.

Greg

 

[f350ca]

Machined the base and crank case, sorry forgot to take photos of the set ups. Pretty straight forward clamping them to the tooling plate.

Greg

 

[spacy]

just finished machining a number 4, look forward to watching your methods as i paint and assemble mine

big beast arn't they

 

[rklopp]

A Stuart No. 4 was my first engine. That was 45 years ago. I started in 8th grade and finished by 12th. I built it using a 9” South Bend lathe and a drill press. My Dad bought me a SB milling attachment halfway through. I still have the engine, but my skill and machinery upgrades have been phenomenal in the interim! The SB is long gone.

 

[f350ca]

Was surprised at the size of it spacy. A group of us built a paddle boat a few years ago, a replica of a logging boat used in this area called an alligator. It could winch itself overland between lakes or around rapids. The engine we used is almost identical to this one, only 5 inch bore and stroke.
Wish we had projects like this in high school rklopp. We got to make hammers and screw drivers. At least we had shop.

Have the crank bearings shaped and mounted. The bore is at 3/8ths right now, haven't decided how I'll open it up to final size.

Greg

 

[packrat]

I liked reading your post on the Stuart #4, love the bigger steam engines full size and models.
I am working on a Stuart #5A right now {almost done} Bought a full size engine from a friend
that needs some restoring it has a 5 inch bore.

 

[f350ca]

We think the engine for the boat was 5 inch bore, never did take the head off to measure.
Here's a link to the engine on a dry run.

Thought the crank was cast iron, wrong, was a low carbon cast steel, miserable to machine. Tried every grind in HSS I could think of and a couple of inserts, nothing gave a nice finish. In the end I rough cut it with a sharp pointed tool then file and emery close to size and lapped to final dia. In hind sight I should have cut one out of plate.

To machine the throw I made a jig that allowed one end to go inside and a grove to hold the throw with a light press fit.

Decided to open up the crank bearings on the mill with a drill and reamer. I fastened a block to scrap to the bed, drilled and reamed it to 3/8ths, then mounted the crank case with a dowel between a collet and the bored hole. This aligned the bore to machine. I then brought an angle plate up to it and clamped everything.

Have to remove a bit of the casting in the crank case, The throws don't clear at the bottom, Oops.

Had a 1 thou over reamer, and lapped the crank to 2 tenths under, so have 0.0012 clearance. It rotates but is that going to be enough clearance for oil.

Thanks for watching.
Greg

 

[Charles Lamont]

More than enough. For a running fit 0.001 per inch of diameter is ideal. Looking good.

 

[f350ca]

Paying projects have been hampering progress, but stole a little time for the engine.
Had a wee bronze bushing to use for raw material. They came out of a seismic vibrator, weigh about 50 pounds each.

Made the reversing handle from it.

And the arm it swings.

Greg

 

[f350ca]

The weather is turning cold and a couple of days of snow, good time to play in the shop.
Made the links that connect to the quadrant, then had to make the bolts. Used some 1/4 dia mystery stainless. Machined nice.
The bolts are 1/8th with 5-40 threads. Made the heads 15/64th across the flats by .11 tall. Is there a standard for model fastener heads? Seam to look about right.

Made the lock nuts at the same time.

Then tackled the quadrant. Mounted a sacrificial aluminum plate to the rotary table and pinned the part with 1/8th dowels. Got most of it cut before i had to add the clamp to stop chatter.

Made the sliding block that the valve rod attaches to at the same time. Need to file out the ends of the slot square.

Thanks for watching.

Greg

 

[f350ca]

This thing is eating up too much of my precious time, bloody thing is addictive.
The intake ports were cored in the cylinder but were too far apart at the valve end. Had to cut the openings closer to the exhaust port, but this meant that the valve wouldn't cover the end.

Cut a thin slice from a scrap of cast iron and ground it to .1 thick, then cut the ports with the correct spacing and size.

Sandwiches nicely behind the valve chest.

Made the connecting rod today. The drawings show the joint straight across the journal, decided to step the joint to locate the haves and not rely on the bolts.

Starting to look like an engine.

Know I could machine a full sized one faster. lol

Thanks for looking
Greg

 

[Cymro77]

Nice work! Enjoying your explanations, great photos. I completed a #4 some years back, someone else had started it, screwed up and quit. My biggest nightmare was making new bearing blocks from scratch. It is monster, takes way too much steam for my little boiler.

 

[Buchanan]

I see a Hardinge in the photos1. That is a beaut of a machine. Enjoying the build.

 

[f350ca]

Other projects have been stealing my time.
Can imagine this engine would take a substantial boiler to keep up with it.
They are a nice little lathe, mine is the original HLV with the narrow bed and manual speed adjust. Showing some signs of her age but can still nudge parts out of her with reasonable tolerances.
Didn't like the bulky look of the valve rod castings, so decided to make an attempt at building them from scratch. Still need to make the offset clevises for the ends.

Not sure I like the look of these either, may go back to machining the castings. lol

Greg

 

[Cymro77]

They certainly look "delicate" the machine itself is a "monster" in my book. I have to admit you do beautiful work! Way too much time on your hands!!

 

[f350ca]

Was making bushings for a small backhoe out of 660 bronze, thought it would make good piston rings. When I split them didn't they close, don't think I've ever cut a ring that it spring open. With some gentle flexing in the jaws of a small vice got them sprung the right way.

Have it together enough to try it on air. After a little fiddling with the valve timing it purrs like a kitten.

Will try and get a video posted.

Greg

 

[spacy]

just catching up, pleased its running, did you change the valve round as you have it in upside down, should look like this. The modern drawings dont show it clearly but the older ones have a cross section and show it clearly. If you would like a private copy PM me.

Just finishing mine and first air run coming up Christmas Day

 

[Charles Lamont]

Your eccentric straps and rods are very nice work. I have seen a lot of full size eccentric straps, and the shape of yours is entirely new to me. I can't see any good reason why they should not be rounded off that way, if you are happy with them being highly unconventional in appearance.

 

[f350ca]

I'll double check but thought I had it in as per the drawing. The one I got is dated from the 50's for the engine, and a little newer on the reversing gear section. Both drawings are on one sheet, the reversing gear full scale and the engine shrunk and aged to almost unreadable. Had to scan the drawing and blow it up on the computer to decipher some of the numbers. Would REALLY like a copy. Will fire of a PM, now that would be a Christmas present.
Have to agree Charles, they are a little unconventional. The castings that came with the engine looked more crank rod sized than valve train. Guess I got a little carried away with the rounding over bit and file. lol

Greg