Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Amazing progress, appreciate the tight fit of valve seats in small bore.


Len.

Getting close to finishing this thing now, got the water hopper finished and painted.



And wasted a pound of silver steel rod learning how to make long thin valve stems, still ended up with the stem finish of an old nail but at least the ridges are smooth and the stem parallel and a good fit.



The valves run direct in the aluminium head so i guess they will wear loose quickly, but i can always go back and add proper valve guides later.



The fuel tank is quite heavy and the carb design had it all hanging on a 4mm threaded piece of brass rod with a hole up the middle, seemed a bit weak to me, plus the plan had the jet (and tank) soldered into one half of the carb and a separate piece for the adjusting needle assy soldered opposite.  After making the carb to the original design i decided to start over and redesign with a larger one piece jet assy. holding the tank with an M6 thread instead.



Finished carb



With tank ready to fit



Well after the pushrod guides were done, so fiddley, i was itching to see if it would run.  Put some petrol oil mix in the tank and gave it a spin, it fired but the valves were seating poorly and did not have enough compression to keep running.  This was not the worst though, the crank quickly started to run out of true and upon inspection i found the soft soldered joint to one side of the crankpin had loosened 

If anyone has any advice they can give me on how to make a stronger crankshaft it would be gratefully recieved.  In the meantime i have ordered a milling slide for the lathe (i don't have the money for a proper mill) and will be scratching my head trying to think of ways to make a more rigid crank, preferably without the soft solder.

Best wishes

Ade

Ade,
 Your progress is excellent! Your current issues seem familiar to me and I am sure you will overcome. To build 3 engines I built 7 or so cranks and more than six valve/valve guide assemblies.
My machining skills are rudimentary, but do you have a four jaw chuck?

Len.

Ade,
 I was told all it takes to build an engine is the willingness to fill a 55 gallon drum with botched parts. I have seen silver solder used with success with steel, but a quick search on google had puddle in the results. Have you considered Loctite? Have seen it hold fine in a pinch if fits are tight, but maybe a kludge too far with your nice work so far.


Len.

This is just my opinion and at the end of the day what would i know .
You have done well with your engine and are to be congratulated.

The crank shaft ?
I would throw the brass webs away. And also the roll pins .
Steel webs and taper pins and the silver solder  ( in that order )  ( not soft solder and the roll pin )
And no loctite . loctite is a glue and you do not glue metal together
Crank webs are to be a tight fit on the shaft and heating webs and cooling shaft will make it a bit easier to press into place .
Ok i will no resume my sideline seat

Cheers
Dennis

This is just my opinion and at the end of the day what would i know .
You have done well with your engine and are to be congratulated.

The crank shaft ?
I would throw the brass webs away. And also the roll pins .
Steel webs and taper pins and the silver solder  ( in that order )  ( not soft solder and the roll pin )
And no loctite . loctite is a glue and you do not glue metal together
Crank webs are to be a tight fit on the shaft and heating webs and cooling shaft will make it a bit easier to press into place .
Ok i will no resume my sideline seat

Cheers
Dennis

Hi Dennis,

Thank you for the advice, much appreciated.  I have some 10mm 304 stainless flat bar which is wide enough to make some new crankwebs out of, this would allow me to do away with the 5mm brass webs and soldered in support collars, might be the way to go?  Have ordered some taper pins and reamer   

Many thanks
Ade

Hi Dennis,

Thank you for the advice, much appreciated.  I have some 10mm 304 stainless flat bar which is wide enough to make some new crankwebs out of, this would allow me to do away with the 5mm brass webs and soldered in support collars, might be the way to go?  Have ordered some taper pins and reamer   

Many thanks
Ade

Sounds like a plan but stainless can be a pig to work with and i am not sure if it can be silver soldered

Cheers
Dennis

Bonjour Ade,
Your video is private, we may not see it