3/4" hudson project

[Bill Shields]

Before we get accused of hijacking a thread any more than necessary, let's start anew

This is my double poppet throttle, as best I can remember from 1970's memory.....

I built the boiler to mount the 'head' to a couple of studs, protruding flange and o-ring.



The head solders to the body, the rest drops in:









Make a cover for the head, and come out the bottom or bottom /side as fits.

cam is also self-explanatory, to go though the smokebox cover with an extension.

The boiler doesn't have much of a steam dome, but it is there, Priming isn't a problem, nor is lack of 'superheater'



Yes, the camshaft assembles with a set screw - don't silver solder it together unless you are really creative at assembly time.

I used a packing gland with graphoil packing.

Here it is early outing, no paint...



The small poppet makes for very easy opening, controlled starts. By the time you get to the main valve, she's really rolling and you better hang on. I very RARELY get to that stage, unless hauling a load up hill.

[Bill Shields]

This is what the inside of the smokebox and front tubesheet look like.

Yes, I CAN put in superheaters, but have never seen the need.



Copper tubes, silver soldered in place. Heads not thick enough to roll..

Note the cylinders - not casting, welded fabriction from steel plate

[Bill Shields]

The cylinder castings were total trash - very porous, so I made a cylinder set from 3 thick pieces of plate (like the extra weight):



After cutting out with a torch, did some machining to size



Then cut in passages, and weld-prepped with a hand-held carbide burr grinder - not pretty, but who cares?







Made little 'covers' for the exhaust, which I silver soldered in place



and voila':



Sorry, I don't have pictures of everything - this was 35mm slide days. Maybe I can find some later

Anyway, you get the idea.

The main cylinders and valve chests are also silver soldered in place around the outside joints. Internal joints were just allowed to 'rust in place' and have never leaked after the first couple of immersions in water (intentional).

The flange for the smokebox is TIG welded to the cylinder assembly.

[Rob Gardner]

Bill,

Again, great to get to meet you in the meet at Waushakum last month. Thanks for the pics of the fabricated cylinders. I take it that the 3 "notches" you milled in the top of of the cylinder openings were machined on the backside of each of the two outer plates? It also looks like you ground out or milled the passageway to get the steam to and from the power piston at a bit of an angle and then the middle plate closes both of the passageways in?

Thanks,

Rob Gardner

[Bill Shields]

Yes, that's it exactly

[Sandiapaul]

Bill,

Thanks for the info...I like the cyls. I am planning of fabing cyls eventually and this looks like a good plan.

Paul

[Steve Bratina]

Nice work Bill. I always though you were quite a wise guy! It shows that the only real casting you need to build an engine is the wheels. Everything else (even the wheels I guess if you tackle it) can be laser cut, hacked out or fabricated.

[LVRR2095]

It shows that the only real casting you need to build an engine is the wheels. Everything else (even the wheels I guess if you tackle it) can be laser cut, hacked out or fabricated.

Al Milburn built a beautiful 3/4" scale Atlantic where everything was hacked from solid. The drivers were sawn out by hand with a jeweler's saw, then filed to the correct profile...then sand blasted so they would look like castings!
Keith

[JBodenmann]

Hi Bill
Thanks for the info on the throttle valve. Looks like a winner!
Jack

[Bill Shields]

WISH I had more dimensions, but this was from 'pencil and paper' days and I am not sure that after 30+ years I have the drawings.

Did it like this because I wanted a 'light' touch, since the linkage is not the most rigid in the world, and didn't want to spind the wheels if I did pull too quickly, since running propane, sudden surges can be 'lights out'.

Not sure my solution is the best, but works well for my application and has never leaked since it is 'self sealing'. Even after 30 years of neglect, doesn't leak on hydro.

I seem to remember (need to look), that out of the bottom of the valve, I put a 1/16" copper line with a P trap in it, and threw it over the side as a condensate drain.

I thought about putting a steam trap on it, but never got 'round to it'.

Loco runs good, and it it "ain't broke'....go build something new!!!

[rwmorris]

Bill,

Thanks so much for sharing more pics of this engine! Such an awesome job on the whole thing!

Cheers,

Robert M.

[Andypullen]

Interesting...So...I'm guessing the eccentric on the throttle is inside the body and as you said is setscrewed to the shaft. No way to silver solder it in place in there. The eccentric lifts the "pilot" valve and then lifts the main valve? Right?

Let me know when you're back from France....I'd like to take a peek at the throttle if I could.

Interesting cylinder assembly, too.

Andy Pullen