Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines
The Regular Stuff: Chat, Buy, Sell, Off Topic, etc. => General Discussion - Scale Model Gas Engines - Hit & Miss - Throttle Governed - Non-Compression – etc => Topic started by: Jim on August 07, 2023, 02:32:03 am
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Its a split cone hub that when the bolts tighten on the outer hub clamp down on the split hub by pulling it in. Don't know if its a new invention or they've just copied it, but now its being applied (thankfully) on some Chinese engines and I hope it filters down to all of them.
Yep, that is exactly what I was envisioning!
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Its a split cone hub that when the bolts tighten on the outer hub clamp down on the split hub by pulling it in. Don't know if its a new invention or they've just copied it, but now its being applied (thankfully) on some Chinese engines and I hope it filters down to all of them.
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Nope, certainly did not miss that comment, but it does seem like we are talking past each other somehow.
So, what is the functional basis of their method of securing to a shaft? Did my "guesstimated" description even come close to how it works?
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Daniel I think you missed the comment I made above in a post -
"And that new system the Chinese are using to fix the flywheels on is just a brilliant solution I hope it filters down to all engines petrol and steam
coming out of China"
I'm not sure if you've ever had the frustrating and utter displeasure of trying to take a stripped grub screw out of one of these Chinese Hit & Miss engine flywheels,
so yep.....I hope this new method of fitting flywheels filters down to all the Chinese fabricators.
And these earlier H&M engines are greatly known for 'free spinning' flywheels.
[attachimg=1]
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Daniel if you ever get an engine with this new (or copied) wheel hub system you will be an instant convert.
I've read countless stories of people who stripped the soft as butter allen screws by trying to over torque them to stop spinning flywheels and they are a major PITA
to drill out and remove and a lot of folks aren't set up to do it.
Even just thumb pressure on the hub locks it in place, in testing the gov and taking the wheel off and on many times I've just for sake of time put one bolt in and
it holds it firmly in place.
So Jim, what is that system comprised of? A cone tapered, split inner hub that acts like a collet to grip the shaft as it is drawn into a tapered bore in the flywheel by the cinch bolts?
If you build yourself an engine, pulley or new flywheel for something in the future, are you going to be machining and using this system yourself, taking many hours of close and careful work, or are you just going to drill and tap for a set screw with a flat on the shaft that will do the job fine with 15 minutes work? Granted, if not done correctly a setscrew clamping system on a fully round shaft can and will cause trouble for someone who doesn't do it properly but works fine if well done.
I built a collet chuck for my lathe once and can tell you that mating tapers and sizing them to properly perform their function is not quick nor easy and is fraught with great potential for failure and scrap!!!
In truth even a keyway is an easier endeavor, though it does want specialized tooling (a broach and a way to properly use it) to accomplish that method of securing a flywheel as well.
When properly done, CNC machining can make a setup like this with reasonable ease, not so a home machinist using traditional tooling and methods.
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Daniel if you ever get an engine with this new (or copied) wheel hub system you will be an instant convert.
I've read countless stories of people who stripped the soft as butter allen screws by trying to over torque them to stop spinning flywheels and they are a major PITA
to drill out and remove and a lot of folks aren't set up to do it.
Even just thumb pressure on the hub locks it in place, in testing the gov and taking the wheel off and on many times I've just for sake of time put one bolt in and
it holds it firmly in place.
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Seems like that clamping system is the Bee's Knees alright, but I suspect that a bit of slackness in tolerancing could render it inoperable. Grubscrews, set-screws and like forms of clamping are not all that bad except when attempting to use such methods on a hardened shaft that has no flat, recess nor spot-hole for the screw to set against to prevent slippage and rotation. Super simple to mark the preferred location to land the setscrew on the shaft, then simply drill, file or mill a small detent flat or hole into that spot on the shaft and lightly cinch your screw down onto it!
Also, angling the alignment of the axis of the setscrew so that your tool, be it Allen wrench or screwdriver, is clear of the flywheel rim is usually a good idea, while having a slight angle of impingement of the screw on the shaft it is to grip, can be a good idea as well, if properly done.
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The PM Research 'tap' has been fantastic to be able to stop fuel just running everywhere.
And that new system the Chinese are using to fix the flywheels on is just a brilliant solution I hope it filters down to all engines petrol and steam
coming out of China. Its so simple, just one bolt will hold the flywheel on tightly and there's no danged allen/grub screw at the back that was almost
impossible to get to and so easy to strip trying to get it tight enough to firmly hold the flywheel on.
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Thanks Daniel and Gil, this is the nicest looking Chinese H&M engine that I have bought.
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Jim, your mini Olds hit and miss engine looks great presented on your custom made skids. The brass and the flywheel paint really sets off.
Outstanding!
Gil
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Must wonder if perhaps the position of the adjustment that makes the point contact isn't the key to finding the best Hit & Miss functionality profile?!?!
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Also these 'points' are a lot different to the Hall Sensor on the other Chinese H&M engines that I have.
[attachimg=1]
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Thanks Rog and Daniel much appreciated.
I still need to do a little fine tuning on the hitting and missing but REALLY happy so far......they are a lot different than steam engines to work on!
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Well Jim .... You've certainly "tarted" that engine up to the level of a stunning display model, and now you even have it running great!
No surprise that you are well "chuffed" with that little beauty!!!
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Jim, I really enjoyed your explanations, mods and the finished product...dang that runs sweetly!
Rog
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Enjomor 6cc Hit & Miss Engine Modifications and running and hit and missing.
Many many thanks for all the help & suggestions I've received.
Just a REALLY great looking Hit & Miss Engine, any other hints if you think it could run better, much appreciated as always.
https://www.youtube.com/watch?v=lS3QxpWQzbo&t=345s