3/4" Scale J1e

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Berkman
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Re: 3/4" Scale J1e

Post by Berkman »

There are videos of C&O 2716 running with a booster engine clearly audible.

https://youtu.be/0xLUxb63VYE?t=2629

you can very clearly hear the "little chuffs" of the booster engine.
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Help My Friends
Here is the next part for the booster engine. To start with we have here some drawings. This is the lower part of the axle bearing housing. The top drawing here is a side view. This casting bolts up from below and forms a oil reservoir. It has two hinged covers at the front and some flanges for bolts. The second drawing is a sectional view. Next we have a start on the center section that houses the large gear. A 3/4" end mil was used to form the half round opening for the axle.
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Now it's time to start sticking the housing together. The sides are made from .090" brass. #00-90 screws are used. Silver solder will be used for most of this bearing housing, both the top and bottom part. Then it can be soft soldered to the main housing. Once again, as this is a master to pull a mold off of, things like soft solder and filler can be used.
More to come.
Jack
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Hello My Friends
Just a couple snappies today. In the top photo the upper aft housing is being trued up and the recesses for the bolt flanges are being cut. Before going in the mill vise it required a few light taps with the precisioner (hammer). Light cuts are being made as there isn't a really secure way to hold this little devil without some time consuming fixturing. This part will be permanently attached to the main housing. Then we have this piece on the table with the bolt flanges just set in place for a look. There are also some #1-72, and #0-80 nuts set in place. Once again just for a look. It's often good to do this as actual scale sometimes don't work out. I have made things like this to scale and then couldn't fit a nut driver in there. I hate it when that happens! I have some ultra thin wall nut drivers made from Allen head screws but sometimes even these won't fit. Now that everything looks good the flanges can have their bolt holes drilled and then they will be silver soldered in place. The other part in the photo is the lower housing. This will bolt on from below and has to be removable to get the trailing truck axle into place. There will be a Delrin AF split bearing that the axle will ride in. This booster engine is proving to be a fiddly little puzzle, and as usual is taking quite a bit longer than I thought it would. Still having fun though. Making cool little trinkets lie this from bar stock and solder is always a most satisfying endeavor. :D
Jack
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Hello My Friends
Here is some more concerning the booster engine. These four photos show the machining sequence for the shelf that the two doors at the front of the engine will hinge and rest on. There is a 1/16" half round recess for the hinge pivot. Later on there will be three hinge barrels set into this recess. The thick section of this part is where the bolts that hold the bottom casting in place will thread into.
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Last edited by JBodenmann on Thu Nov 04, 2021 8:58 pm, edited 1 time in total.
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Now you can see how this whole mess fits together. The little doors will hinge in the half round groove. The end plates with the bottom half round cut outs must still be made, and will most likely get epoxied in place. The axle housing top half gets stuck to the main body, probably with soft solder. Once all this is looking good, but not permanently stuck together, attention will be directed back to the main body. There is a cool pressed sheetmetal top cover on the main body of the prototype. I want to try pressing a lid. Probably .040" copper. Some simple sort of die will be cobbled together. I only need one as a mold will be made from it. There are also some curved bulge like shapes on the bottom which were clearance for the connecting rod big ends. Then the cylinders with their cylinder cocks and such. There are also some drain plug bosses here and there. No shortage of things to do. :D
Jack
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NP317
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Re: 3/4" Scale J1e

Post by NP317 »

Always educational to watch your fabrication methods.
'Gives the rest of us some confidence in our own methods.
Working in a vacuum can sometimes be hard on self-confidence.
Thanks for sharing.
RussN
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Hello My Friends
First off, thank you Russ. If my photos and line of baloney should happen to encourage or motivate others, that just made my day. Here are a few snappies for tonight. This particular booster engine had three pressed steel covers. One wide cover at the front, and two smaller ones towards the cylinder end. The wide cover was to access the crankshaft and connecting rod big ends. The other two were access to the crossheads. At first I thought that they were just flat steel covers with some bulges pressed in them to clear the connecting rod big ends. This would have been an easy press job involving some very simple dies. Then upon closer examination of the prints it was realized that they weren't so simple. In addition to the bulges, there was a radiused offset all around the perimeter. There are three different covers...suddenly press dies were looking too complicated. I hate it when that happens! :roll: So they were machined up from .100" free machining brass. The small radius was done with a 3/64" radius, corner rounding end mill that I just happened to have laying around. The two bottom photos show the covers plunked down with some #0-80 nuts scattered about just for a look. Next up will be the bulges and such. These will probably be brass and soft soldered in place. I jump around a lot when making a complicated little assembly like this. I am always hesitant to start permanently sticking things together lest I build myself into a corner. This happens very easily, and sometimes our enthusiasm to start sicking things together can get the best of us.
See You In The Funny Pages...
Jack
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Hello My Friends
Just a little progress on the booster. The top covers have been drilled for the #0-80 bolts that will come later. Also the bulge in the front cover for the idler gear. There is also a transverse bulkhead under where the front and rear covers meet. The front of the main enclosure can now be started. The cylinders will bolt to this. The cylinders will have a sheet metal wrapper, also mounting points for the cylinder cocks and their operating cylinders.
No shortage of things to do!
Jack
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Hello My Friends
Here is some progress on the cylinders. As this is not an operating model of a booster the cylinders are not like the prototype. A brass cylinder was made and then cut in two using a slitting saw. The third snappy shows the set up for the first silver soldering operation. Everything well cleaned, fluxed, and the three pieces set between some pieces of fire brick to hold them in place. After this operation the work piece went into the acid pot for a swim. Then it was flipped over on the fire brick and the same routine was used to solder the other rectangle in place. This is a bit dicey as just enough heat should be used to silver solder the new joint, without melting the first operation. Any remaining solder operations will be done with a variety of soft solders. Now it's time to add the cylinder head.
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Here we have the cylinder and roughed out cylinder head sitting on a piece of fire brick. After fluxing with stay bright flux, some small bits of stay bright solder will be placed here and there along the inside. Then things are heated up and the solder slurped into the joint. Then the cylinder - cylinder head assembly got zoomed on the small disc sander to clean things up. The bottom three photos show the operations to make some ears that the big steam lines will mount to. First the boring bar set to the correct radius. Then a 5/64" end mill to cut a very small radius where it meets the cylinder head. Odd little shapes like this can be a fun puzzle. Do all the shaping, filing and metal finishing you can, and then the very last thing to do is to part it off. This was done with a 1/8" four flute end mill.
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JBodenmann
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Re: 3/4" Scale J1e

Post by JBodenmann »

Here is one of the steam line brackets. It will be soft soldered in place. Then a look at the underside of the booster showing the flanges that will bolt the bottom of the cylinders to the main body. These flanges will get #1-72 nuts and bolts. Last one shows the mocked up booster with the cylinders mostly finished. You can see the brackets for the steam piping. Still to be added are the outlets for the cylinder cocks and their operating cylinders. Cylinder heads, and large plugs for the piston valve access. There will also be jacketing around the cylinders once the castings come back from the foundry. All the major parts are done. Just lots of small details remain.
See You In The Funny Pages...
Jack
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