3/4" Scale J1e

[JBodenmann]

Hello My Friends
Now that the booster piping is mostly finished I thought it would be fun to start on the stoker engine. Here is a photo of one with the top cover off. It has two cylinders with an enclosed crank case. It was reversible by reversing the porting. There was an external reversing valve with a rod that went through the cab floor. The fireman could pull this rod up or push it down to reverse the engine to clear the auger if it jammed. He had a throttle valve in the cab to control the speed. I will be making a dummy, not a functioning stoker. The second photo shows a piece of .100" brass. This will form the bottom, and crank shaft end of the main body. It has been sized, annealed, and then formed around a piece of 13/16" round brass. It was clamped in the mill vise with the 13/16" round, and formed with a hammer and a block of wood. This bottom piece will now be used to mark up the sides.
More to come.
Jack

[JBodenmann]

Hello My Friends
Just a few more tonight. The sides were marked, cut out, and fastened to the bottom with #00-90 round head screws. Now everything cab be silver soldered together.
Jack

[JBodenmann]

Hello My Friends
Now that the main box has been fitted together it's time for silver solder. The usual routine, dis assemble, clean with alcohol to remove the cutting oil from drilling and tapping the holes. Brass sheet, as opposed to bar stock is usually very hard, having been work hardened during rolling. I have had drill bits stick to this stuff and snap off, especially with small drills as used here. #60 for the tap drill, and #56 for the clear drill. So oil is always used. Everything will now be assembled with flux, making sure to coat all mating surfaces and the screws. The screws are done up tight and then backed off a quarter turn. The top photo shows our work piece well fluxed with snipped off pieces of solder here and there. Then it's placed on piece of fire brick on a lazy Susan so it can be rotated and evenly heated. I use the oxy acetylene torch for this. For something this size, probably a number three tip and a soft carburizing flame. The solder should flow nicely into all the joints and under the screw heads. Always place the solder before heating when possible. The second photo shows the part after soldering, and the third after a swim in the acid pot. I use Sparex solution in a cheap crock pot. The bottom photo shows our little stoker engine main body after a zoom with the disc sander and a #220 disc. It also was trimmed a bit using the milling machine. Now parts can be added with soft solder, the feet, the bearing housing for the crank shaft, and various small parts like the drain plug and filler tube bosses. Also the cylinder mounts. The top cover is just a piece of sheetmetal as opposed to three separate castings like the booster. This little fellow is much simpler than the trailing truck booster and should be finished up pretty quick.
See Ya' Later Alligator
Jack

[JBodenmann]

Hello My Friends
The stoker engines have four small feet, two on each side. Here is how you might go about making them. First some scribbles were made and then a short length of 1/4" square brass long enough to make two parts was sized to .240" wide by .200" hi. Then a slot was milled down the center. The slot was .175" wide as that's just wide enough for a nut driver for a #1-72 model bolt. It's always good to think ahead and plan for such things as it can make life easier down the road.

[JBodenmann]

Now to cut out most of the center, leaving 1/16" as in our first photo. Then they are drilled for a #1-72 bolt. The tops are angled, so this was marked out with our old friend the ultra fine point Sharpie. Then over to the disc sander. You could spend some time and make a little jig to hold then in the mill vise, but the Sharpie disc sander is faster. Get R' Done. Now we can set the main body on the feet to have a look. Starting to look like something

[JBodenmann]

Hello My Friends
Here is some more progress on the stoker engine. In the top two snappies a diagonal offset is being machined. A 5/16" round nose end mill was used for this. Then the crank shaft bearing housings. Notice the little round piece on the left in the fourth photo down. When it was parted off the little dag in the middle was left in place. This will drop into the hole on the large part behind when soft soldered in place. Just a little short cut to speed things up bit. And lastly, the booster body with this assembly just super glued in place temporarily for a look. It can be knocked off later if need be. The mountings for the cylinders have been started, but are not ready for photos quite yet. Having fun here
Jack

[NP317]

Like I said: Sculpture.
RussN

[Asteamhead]

Hello Jack,
Remembers me of building the HT-Stoker engine for my A 1239!
Body made of brass, silver soldered. Easy access and ball bearings throughout to reduce maintainance
Carry on, we will watch!
All the best by Asteamhead

[JBodenmann]

Hello My Friends
Thank you Russ and Asteamhead. That stoker engine is really cool! That's a lot of parts to squeeze in that little box. What we have here today is a bit more like sculpture. The last pieces have been added, the outer mounts for the long arms. These were made of 1/16" PVC from McMaster. This is nice material to work with. Just a bit more smoothing and filling and the booster steam lines will be mostly done. Only the air throttle, and elbow where the steam line connects to the left hand cylinder remain to be made.
See You In The Funny Pages...
Jack

[JBodenmann]

Hello My Friends
I managed to get some time in on the stoker engine. One cylinder and cylinder head were made. I only need one of each as molds will be made to make more. The cylinder mount was also made. This spaces the cylinders out from the enclosed crank case to allow access to the packings for the piston and valve rods. It also allows a free space for any steam leakage to escape without entering the crank case. More to come.
Jack

[Dick_Morris]

I don't think anyone has linked this video of a stoker engine running with all the covers off. Note the live steam locomotives in the background.

https://www.youtube.com/watch?v=Rhv9prC ... el=PRR5406

[JBodenmann]

Hello My Friends
Thanks for the link Dick. That's very cool. That is a very different stoker engine than what I am familiar with. The access covers in the side are something I haven't seen before. A very nice restoration, especially considering the rusty mess he started with. I have been following the group restoring this Maine Central Pacific. I saw her years ago when she was rusting away in the park. A very cool engine. But it was just heartbreaking to see the condition she was in. They are doing a fine job. This is a very interesting engine as for a pacific she had some modern appliances. Coffin feed water system just like my #5344 will have. They sent me a bunch of photos of the centrifugal pump. Coffin still makes centrifugal pumps for ships and nuclear power plants and such. They sent their centrifugal pump to them and they re built it! How cool is that!
Jack