Attaching a sprocket to a round shaft

[Pooh_Bear]

Well, I got lots to think about now.

How long will the poly drum last? I expect at least as long as the mixers
sold in stores that have poly drums. Mine is a LOT thicker material too.
If it does wear out then it is easy to get all of them I want.
I have several more out back of the house stored under the deck.

I calculated that it has a max capacity of just over 4cf of concrete.
But I will probably only mix about 3cf per batch.

The sprocket is just about in the center of the shaft. Not near either end.

I feel very confident about my ability to grind a keyway
with an angle grinder and a cut off wheel.

I could check into having a machine shop cut a keyway for me.

I was also thinking about tapered bushing sprockets.
The tighter you tighten the tapered bushing into the sprocket
the tighter it grips the shaft it is on. But I don't know if it would slip or not.

I guess I could weld the sprocket in place and if there is a problem
with the inboard bearing I could just cut the shaft and make a new one.
To make this one I took a square piece of plate steel and drilled a
3/4 hole in the center and welded a 3/4 shaft into it.
So it wouldn't be too hard to duplicate if I ever needed too.

Wish I could use bicycle chain. Easy to get and cheap.
The chain is gonna cost a lot more than the sprockets.

Pooh Bear

 

[ovrszd]

Yep, I vote for welding the sprocket to the shaft. At 23 RPMs on a cement mixer, the odds of the inner bearing failing on this shaft are slim to none. Properly lubricated, the pillow bearing will easily outlast all the rest of the components of the mixer. Go for the weld and never have to jack with it coming loose all the time.

 

[SPYDERLK]

Taper bushing sprockets are great!, but expensive. The Loctite alternative would work cheap, be removeable and not mar the shaft like welding and not stress the shaft like keyways and pins, and yould have some left over to use for other stuff - - it keeps forever almost. Bicycle chain is too light duty. Tractor supply chain cost is not bad.
Larry

 

[scott_vt]

Scotty if i understood you right, you said that a go-kart application was more demanding than a concrete mixer, because a concrete mixer runs at the same speed where the go-kart engine varies its rpm all the time.

I did not doubt the solution you carried in

Another solution would be to drill a hole axially, so that it would have a half circle in teh sprocket and the other half of the circle in the shaft, then tap a pin into it, as like a normal square key. Problem is that this only works when the sprocket is on the end of the shaft.

Mornin Renze,
Thats kind of interesting, do you know what they call that arrangement ? Yep, you got it, a DUTCHMAN DUTCHMAN= HOLLAND, sorry just a little humor this morning !

 

[sandman2234]

I used a QD brand of taperlock bushing when I build the poorboy's trencher and stump grinder. The stumpgrinder has sheared a 2 gallon bucket of shear pins and the QD has never slipped, and I do mean never.
They might be a little on the steep side to buy (I had mine so no $), but they are reusable, so figure on buying one to last a lifetime, vs having to mess with broken pins and sheared keys while the concrete is hardening.
David from jax

As far as taking five or ten dollars into a shop and having a keyway cut, good luck. I wouldn't do it for that, and I don't make my living at it, more of a hobby. I would do it for free before I did it for that price.
Last time I paid someone to cut a keyway was in the early 80's and he wanted more than that then...
David

 

[Pooh_Bear]

Today I ordered two #50 sprockets from Surplus Supply.
One was about 3 inches in diameter, the other was about 4.5 inches.
These were just plain bored sprockets with keyway.

I've got an X-Y mill table on my drill press.
I may drill a series of holes along the shaft where I need the keyway,
then grind the rest of the material out with the angle grinder.
If that don't work, I'll just weld the sprocket in place.

Almost $25 for 2 sprockets and shipping.
And the chain will be about the same when I order it.
Ouch.

Pooh Bear

 

[Soundguy]

I wouldn't even worry about drilling the series of holes.. unless I had a end mill and mobile table. Id just brace my grinder and stock up in a jig and run that for the key way.

Soundguy

 

[chickenman]

i had the same problem, my solution was to weld a split collar to the pullys and clamp to the shaft

depending on the load it should work maybe you could weld half of the split collar to the sproket on both sides for more grip

 

[bamatoolmaker]

I am only about 2 hrs away from you If you are willing to bring it to my shop which is about 2 miles off of I59 I will fix it the best way FREE.

 

[Pooh_Bear]

I appreciate the offer. But I'm just gonna try grinding a slot
and if that doesn't work I'll weld the sprocket in place.
And fill the slot I ground while I'm at it.

I wouldn't even worry about drilling the series of holes.. unless I had a end mill and mobile table. Id just brace my grinder and stock up in a jig and run that for the key way.

If I could use an end mill in my drill press I could mill a slot in the shaft.
Or I could use an end mill to drill flat bottom holes that overlap.
Then I could mill a slot without too much lateral loading on the chuck.
I have done this in wood before using a router bit.
A 3/16 end mill with a 3/8 shank mite just work for this.
Naw, I'll just try grinding it.

Pooh Bear