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

Since completion of my vertical Domestic engine, I had not been able to get it to run properly and consistently.  The problem was due to two things, both having to do with the fuel flow. 

It's a poor design, at best, with fuel flowing into the mixer by gravity, and even the difference between a full tank of fuel and a near empty tank causes a difference in the fuel flow to the mixer.  The real problem, though, was in the fact that there was no fine adjustment for the fuel mixture, with the mixing screw needle made according to the blueprint. 

The first picture shows the mixing screw made to spec.  This simply made it nearly impossible to have any real adjustment of fuel flow, as this large tapered needle seated in a number 60 drilled hole.  I have tried turning thinner needles with a finer taper on the lathe, but they never come out right, or they bend before I'm finished. 

I finally got the idea  from one of my old wind-up phonographs, to cut the end off the mixing screw and solder an old phonograph needle into the end of it.  It has the perfect fine-tapered end that I needed, and the engine has now been able to be fine-tuned to run perfectly. 

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Clever.

brilliant deduction Watson, er'...Doug your prowess with those hit miss engines is admirable. Once we finally figure out its a design flaw & start looking "outside the box" many opportunities present themselves.

That is pretty clever Doug, will certainly keep that one in mind !

...I have tried turning thinner needles with a finer taper on the lathe, but they never come out right, or they bend before I'm finished....

I have a friend who is very much into old RC engines, and faced the same challenge a couple of years back. He found that it with tiny tips like this, is much easier to "grind" them instead of cutting.
He uses his Dremel in the lathe, with one of these adapters:
https://www.ebay.com/itm/The-ORIGINAL-Dremel-tool-holder-frame-1-2-in-X-1-2-in-Shank-for-your-lathe/113612709777


Might not be of use, or even interest to you, now that you have found this solution to your immediate problem.
Just thought iŽd share, in case someone should face a similar problem, with something needing a slightly different angle than that of a phonograph needle.

That is pretty clever Doug, will certainly keep that one in mind !



I have a friend who is very much into old RC engines, and faced the same challenge a couple of years back. He found that it with tiny tips like this, is much easier to "grind" them instead of cutting.
He uses his Dremel in the lathe, with one of these adapters:
https://www.ebay.com/itm/The-ORIGINAL-Dremel-tool-holder-frame-1-2-in-X-1-2-in-Shank-for-your-lathe/113612709777


Might not be of use, or even interest to you, now that you have found this solution to your immediate problem.
Just thought iŽd share, in case someone should face a similar problem, with something needing a slightly different angle than that of a phonograph needle.

That is interesting. I could see other possibilities for it as well!
crazydoug