New sprocket mount design

[Rick S.]

Here is a new sprocket and mount design that I came up with for another member here.
I really think this could be usefull for alot of different applications.
It mounts the sprocket on a square shaft. I think he's using this on the jackshaft from a Yamaha sled motor. I can fit a 12T minimum on the 7/8 square shaft. A spacer is required on the 12T for chain plate clearance to the mount. The mount is a v block clamp with 2 tapped holes for mounting the sprockets. With 1.03 square I can do a 13T minimum. 1.03 square is a common size on agricultural bearings units.




 

[Yoshi]

my concerns are vibration and strength.  I've personally twisted a square shaft off right at the base for a center carrier I  installed on my first 600cc buggy, and being square, it may have some serious vibration issues which may or may not be felt, or damage the motor. Just food for thought.......

[Rick S.]

Runs smooth as silk on the lathe. balanced very well. No vibration whatsoever. Not sure why you think a rotating perfect square is somehow different than a round.
On my small lathe you know right away if anything's out of balance. You do need to take care as you tighten the clamp to the shaft. The two halves need to be flush for mounting the sprocket. While squeezing the halves tight to the shaft you lightly tighten the clamp screws. Then draw the sprocket tight to the halves. Then torque the clamp screws down tight. This makes perfect sense to me.
Now if the shaft he mounts it on is not true then there could be a problem. But since it was part of the snowmobile drive I'll bet it's true and hardened as well.
This is not a Busa. it's a 540? in a pilot.
We'll find out soon since the buggy is going up to Silver lake for the opener.

[Yoshi]

Not sure why you think a rotating perfect square is somehow different than a round.

I know some people have tried to do it with a drive shaft and had some bad vibration issues, not sure if it was the material, setup, or design, no first hand experience with it myself, just what i've heard, so it would be a concern for me, not a deterrent until I knew it was defiantly an issue.........

[Admin]

Im thinking it should work great, Hyabusa maybe not, 540 yamaha 2 smoke, should work well, cant wait to hear the results...

[fabr]

This is my 2 CENTS on this .HP is always a consideration when determining suitability of any design. IMO this should work fine -probably.  However a square split hub is not cery strong.The square shaft has a lot of leverage in the hub and will try to spread it .Think square shaft in a vice and put a pipe wrench on it.You will notice the jaws are easily moved laterally in opposite directions.Same thing will happen with a square split hub.The sprocket itself being of a matching square bore will not allow that of course and the split hub will stabilize the sprocket.IMO that's a good design----FOR THE APPLICATION.

[Rick S.]

Of course it would never work if the sprocket were not square bore as well.
The split hub is just a nice way to hold the sprockets axial position on the shaft.
And perfectly acceptable as long as its balanced. In this application there are no forces trying to spread the halves. Balance was considered in the design. This is why if you look at the drawing each half is identical. Most split collars have 2 taps in one half and 2 c'bores in the other. This was not done that way. (intentionally)
I could have just waterjeted two square bore spacers with set screws. One on each side of the sprocket. But I hate set screws on shafts. I think they're junk. 

[fabr]

I noticed all that. Well thought out design IMO.

[Rick S.]

Thanks,
I know I sometimes come off as getting a bit ruffled up. I think this comes from years of dealing with engineers, and many times having to do it their way against my own better judgement. where I work we're considered the experts in our field, and this is why we're hired to design and build tools. But you wouldn't believe how many engineers we deal with that think they know better. Once in a while you get one that says you guys are the experts just get it done. With most it's a constant battle to get it done right.   

[fabr]

Hehehehehe I know what you're saying.I deal with carpenters that don't know how to square a door frame to save their life but  come in telling me the doors defective since it drags on one corner. I tend to get a bit testy after hearing that crap out of the same carpenter on every job he does.

[Rick S.]

I'm actually to the point where I'm afraid to hire any job out. When I had my drive poured, and barn built I was shocked at the lack of quality from some of the contractors. I actually had to have them tear up the last 20ft of my drive and redo the approach. The guy wasn't happy even though I paid him 1700 extra to redo it. I had actually marked out exactly how I wanted everything except for the approach, which I assumed they probably had plenty of experience with. Wrong!

[fabr]

I'm in the middle of helping our college to get a buildings trades program going here right now.1 year course with an A.A.S. that transfers all credits to any 4 year college with a program.After a  year they should be capable of at least knowing the RIGHT way to do things.