Benson inverted steam engine

[gbritnell]

Gentlemen, I've had this engine on the back burner for some time so I thought it was about time to get back to work on it. This is the Benson vertical steam engine. (some videos on Youtube) Not one to leave things alone I took the drawings and scaled them to .75 of the original. The flywheel is a little over 5.00 inches in diameter so with the cost of brass out of this world I decided to fabricate it. I started by cutting rectangular segments then cut the ends at 45 degrees. I made a fixture to hold all the pieces true and silver soldered them together. After cleaning up I turned the O.D., I.D. and faces leaving a little for later truing after assembly. I drilled for the spokes and made a hub with pin holes to locate the inner ends of the spokes. The spokes were turned with a taper leaving enough of a true diameter on the outside to allow them to slide out then back into the hub. This required a more elaborate setup for assembly. All the parts were cleaned and fluxed then soldered with Stay-Bright alloy solder. After assembly a bar was turned with a diameter that would fit the hub hole. This was threaded and the flywheel was mounted and trued up. The cylinder has a conical band replicating the original ornate casting so I turned that shape then made and fitted the steam chest to the cylinder. This was also soldered together. The base has a lot of steps and radii so the rotary table was used extensively. The top of the column has a rectangular shaped bracket that hold the crankshaft and this also was a fabrication. I will post more as the engine progresses.

[RReid]

Great looking parts. I especially like the look of the cylinder/steam chest assembly. I'll keep that approach to flywheel fabrication in mind for the future! Looking forward to what comes next.

[crueby]

Another George build, excellent!! 




I've thought about making a flywheel like that but didn't think I'd get the joints good enough. Do you think it would be worth doing half lap joints and screwing the overlaps together for soldering rather than making a holding jig? Or would that be even harder to get good fitting joints?




I remember watching the wheelwrights at Williamsburg building wagon wheels the way you did, fascinating to see them go together.




 

[Craig DeShong]

I was wondering what George has been ‘up too’.  Now we all know.  Great start George, I’ll be following along.

[Don1966]

Awwww George my friend you exceeded my expectations ……..did I say……..I……………likeeeeee……

Ps    Are we going to polish it….?.

 
Don

[Kim]

Excellent!  I'll be following along too, George.

Interesting way to make a flywheel.  I've seen ship steering wheel's made that way, but never thought about a fly wheel!

Kim

[AVTUR]

George

Is this the Anthony Mount engine? I only ask since I am coming towards the end of making my Hick Crank Over engine and may get another set of castings to carve.

AVTUR

[Chipmaster]

Superb, wish I could achieve finishes like that.
Andy

[kvom]

3/4 size is quite challenging.  I did the 1x size and it was a good challenge.  Made me wish I'd followed Jason and done 2x.

Timing the engine was/is a challenge as the view into the steam chest is blocked by the cylinder.

Waiting to see how George does the gears for the governor.

[Jasonb]

Well I don't expect George will be buying in his gears

Mine was actually 1.5 times the original A.Mount drawings but 2 x would be impressive.

Though I was a bit disappointed when I saw the model as I was expecting to see a model of something else made by Bensons with an INVERTED arrangement not the true vertical that it is.

[bent]

Yup, I like the flywheel too, need to try a built-up one of these days.   

[gbritnell]

Time for a Benson update. I have finished the parts for the throttle valve, cylinder cover, piston and rod, crankshaft and crank arm. The steel parts are all 303 stainless steel. When I get to the gears for the governor I'm going to see if I can increase the size of the crank gear to speed up the governor at least by 50%. This should make the throttle work better. All the videos I see of the full sized model show that at slow speeds the governor weights hardly move.

[gbritnell]

On this engine there is a support arm that attaches to the column and terminates with a bushing that supports the piston rod. Kind of like a crosshead of sorts. In the original drawings they have you fabricate it by silver soldering the plate and arm together. Rather than try to fiddle with soldering and alignment I opted to cut it from the solid. The concession being that I would make a bushing for the piston rod and soft solder it to the arm with everything in place. I made a step-off  chart from the CAD drawing and created the profile of the arm. It was then cut free with the slitting saw. 

[gbritnell]

I completed the eccentrics and straps along with the rods and clevis ends for the valve and water pump. I assembled all the parts to this point to get a peek on how it will look.

[Roger B]

Looking good (as ever)