Yet Another Webster Begins

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Maybe some one with CAD skills can provide a quick drawing of how to make these work, they really are the cats meow.

On my hit and miss engines I use a female clutch in the drill and engage the end of the crank shaft or a crank extension if too short. The clutches are supposed to run on a hardened shaft but you can get away with a non hardened shaft for a while, then sleeve it with a a hardened collar.
 
Maybe some one with CAD skills can provide a quick drawing of how to make these work, they really are the cats meow.

Yeah, some idea of how they work and how to use one is what I'm looking for. Boca Bearings is where all my bearings came from, so I'll look there.

I gather the inside diameter has to match the shaft (1/4") and then the outside is what you spin.
 
Correct. 1/4" is a little small but will probably work. Make an aluminum pot to press the clutch into and on the other end insert a steel shaft to hold in the drill. Be careful to get rotation correct before pressing in the bearing.
 
Bob---I posted a thread and drawings for a starter spud like the one I use in my variable speed drill to start my engines. It was in a post tiled "Gentlemen, start your engines" a few years ago. Now I can't find it. If anybody can find the link, please put it up for Bob.---Brian
 
This is what I use. to get the curved holes I drill the main hole (6mm) 6mm in from the end which will leave 3mm of metal between it and the end, then with a 6mm round file, file down from half a hole to the side of the first one and when it breaks in to the first one it will naturally take the path of least resistance and work its way in to the first hole.

IMG_2236.JPG
 
Bob---I posted a thread and drawings for a starter spud like the one I use in my variable speed drill to start my engines. It was in a post tiled "Gentlemen, start your engines" a few years ago. Now I can't find it. If anybody can find the link, please put it up for Bob.---Brian

I have your drawings and started to make one this afternoon.
 
What Coulsea does looks nice, but it isn't really necessary with these little engines. A straight slot works fine. All of the old cars that came with a crank for use when the battery went dead were like Coulsea's. That was so that if the car started when you were cranking it, it wouldn't wrap you up in the crank---it would self-eject. When I was in high school I had a model A Ford with one spot on the flywheel ring gear where the teeth were ripped off. If the engine stopped with that particular spot lined up with the starter, you would have to either push start it or use the crank.
 
It took me a minute to figure out why your piston looked so odd ... :)

Then I realized it wasn't a piston, but rather a starting spud - right? Looks good, with one comment - make sure the pin is not too snug in the slot; you want it to be able to disengage easily, even when your drill may be at a bit of an angle.
 
It took me a minute to figure out why your piston looked so odd ... :)

Then I realized it wasn't a piston, but rather a starting spud - right? Looks good, with one comment - make sure the pin is not too snug in the slot; you want it to be able to disengage easily, even when your drill may be at a bit of an angle.

Yes, it's a spud. The slot is loose, that tool just falls out of it, I just have no experience with how loose it needs to be.
 
You will find that if your slot is shaped as a one way clutch the drill will disengage smoothly when the engine starts. Image would have the angle on the back side left as hidden line.
 

Attachments

  • image_2021-02-16_102204.png
    image_2021-02-16_102204.png
    2.6 KB · Views: 163
Last edited:
Back
Top