Imagine a 1" dia. shaft driving a #40 chain, 32 tooth, 3.5" dia.
sprocket.The shaft drives a cam that takes 50 ft/lbs torque. The shaft
rides in two pillow blocks and a bearing in a block, all mounted on a 1/2"
plate 12" long. The cam drives a guillotine wire cutter. When I want a
longer cut, I slide the plate and all, up to 1" of movement in slots.

I've used split tapered bushings to mount the sprocket to the shaft and it
works great, but I have to move the sprocket with a size change and
re-timing the cam is a bitch. If I put the sprocket on a key with a set
screw, I think it will booger-up the key and such quickly. Do you think if
I use multiple keys or splines I can let the sprocket float without a
fastener? Timing is +/- maybe 2 degrees. Makes sense to me and that scares
me. If so, how many / how big keys?

P.S. I desided to shelf the AR-15 build, I just don't need it. Thanks for
all the tips though, I learned a lot! I'll post pix of the new machine (8
month build) this month...it's RADICAL, nothing like it in the world!

On Fri, 05 May 2006 02:55:02 GMT, "Tom Gardner"
wrote:

Imagine a 1" dia. shaft driving a #40 chain, 32 tooth, 3.5" dia.
sprocket.The shaft drives a cam that takes 50 ft/lbs torque. The shaft
rides in two pillow blocks and a bearing in a block, all mounted on a 1/2"
plate 12" long. The cam drives a guillotine wire cutter. When I want a
longer cut, I slide the plate and all, up to 1" of movement in slots.

I've used split tapered bushings to mount the sprocket to the shaft and it
works great, but I have to move the sprocket with a size change and
re-timing the cam is a bitch. If I put the sprocket on a key with a set
screw, I think it will booger-up the key and such quickly. Do you think if
I use multiple keys or splines I can let the sprocket float without a
fastener? Timing is +/- maybe 2 degrees. Makes sense to me and that scares
me. If so, how many / how big keys?

P.S. I desided to shelf the AR-15 build, I just don't need it. Thanks for
all the tips though, I learned a lot! I'll post pix of the new machine (8
month build) this month...it's RADICAL, nothing like it in the world!

I'm no machine designer, but I would think that impact would not be
good on any small sliding fit like a spline or multiple keys. How
about separating the functions: : use a split tapered bushing for
locking the sprocket (proven to work), and a keyed co-axial
"locating" hub affixed to the sprocket that maintains rotational
position when adjusting axially but leaves actual lockdown to the
split tapered bushing once it's axially located correctly?

On Fri, 05 May 2006 02:55:02 GMT, "Tom Gardner"
wrote:


I've used split tapered bushings to mount the sprocket to the shaft and it
works great, but I have to move the sprocket with a size change and
re-timing the cam is a bitch. If I put the sprocket on a key with a set
screw, I think it will booger-up the key and such quickly. Do you think if
I use multiple keys or splines I can let the sprocket float without a
fastener? Timing is +/- maybe 2 degrees. Makes sense to me and that scares
me. If so, how many / how big keys?



If it's of any value to you,I have on on a piece of
equipment splined sprockets #60. with set screws.
Carries a significant load at high speed. It's
been in service 40 years.

Don't run without set screws, use at least two.
Splined shafting, hubs ect should be standard off the shelf items.

ED

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On Fri, 05 May 2006 02:55:02 GMT, "Tom Gardner"
wrote:

Imagine a 1" dia. shaft driving a #40 chain, 32 tooth, 3.5" dia.
sprocket.The shaft drives a cam that takes 50 ft/lbs torque. The shaft
rides in two pillow blocks and a bearing in a block, all mounted on a 1/2"
plate 12" long. The cam drives a guillotine wire cutter. When I want a
longer cut, I slide the plate and all, up to 1" of movement in slots.

I've used split tapered bushings to mount the sprocket to the shaft and it
works great, but I have to move the sprocket with a size change and
re-timing the cam is a bitch. If I put the sprocket on a key with a set
screw, I think it will booger-up the key and such quickly. Do you think if
I use multiple keys or splines I can let the sprocket float without a
fastener? Timing is +/- maybe 2 degrees. Makes sense to me and that scares
me. If so, how many / how big keys?

P.S. I desided to shelf the AR-15 build, I just don't need it. Thanks for
all the tips though, I learned a lot! I'll post pix of the new machine (8
month build) this month...it's RADICAL, nothing like it in the world!

I used to make clutch adapters for power takeoff from big Cat engines.
These involved taper lock hubs. The hubs were keyed to the shaft AND
to the the clutch adapter. The clutch adapter was basically a 14 to 18
inch dia (HP dependent) flywheel with a tapered bore that matched a
taperlock hub. I bored the flyhweel with the taper, broached a 3/8
keyway using a tapered broach guide (hadda make that too), then
installed the taperlock hub into the flywheel. This assembly was then
locked to a shaft in the lathe and the flywheel faced one last time to
insure no runout. It looks like this solution might work for you. You
can bore the sprocket for the taper by using the taperlock as a gauge.
You can broach it in the lathe if you are only doing one. If you have
the sprocket located by a spline or keys and don't harden both the
spline and sprocket it will beat itself to death very fast. Any slop
which allows the sprocket to work with and against the rotation will
wallow out the softer parts. Not only that, but as it gets worse it
will transmit potentially damaging shocks to other parts of the
system.
ERS

"Don Foreman" wrote in message
...
I'm no machine designer, but I would think that impact would not be
good on any small sliding fit like a spline or multiple keys. How
about separating the functions: : use a split tapered bushing for
locking the sprocket (proven to work), and a keyed co-axial
"locating" hub affixed to the sprocket that maintains rotational
position when adjusting axially but leaves actual lockdown to the
split tapered bushing once it's axially located correctly?


I see it! Simple, robust and accurate...you ARE a machine designer!

In article , "Tom
Gardner" says...
Imagine a 1" dia. shaft driving a #40 chain, 32 tooth, 3.5" dia.
sprocket.The shaft drives a cam that takes 50 ft/lbs torque. The shaft
rides in two pillow blocks and a bearing in a block, all mounted on a 1/2"
plate 12" long. The cam drives a guillotine wire cutter. When I want a
longer cut, I slide the plate and all, up to 1" of movement in slots.

I've used split tapered bushings to mount the sprocket to the shaft and it
works great, but I have to move the sprocket with a size change and
re-timing the cam is a bitch. If I put the sprocket on a key with a set
screw, I think it will booger-up the key and such quickly. Do you think if
I use multiple keys or splines I can let the sprocket float without a
fastener? Timing is +/- maybe 2 degrees. Makes sense to me and that scares
me. If so, how many / how big keys?


I'm afraid I don't have a complete mental image of your mechanism - is
there some reason you can't use a taper-lock or QD hub on a keyed shaft?
The key maintains timing when you slack off the taper-lock to adjust
position.

If you do decide to use a keyed shaft with a sliding fit, besides the
other warnings about wallowing out the keyway, keep in mind that another
potential failure mechanism is the key rocking in the shaft keyseat. The
key should be an interference fit in the keyseat and care should be
taken to make sure the keyseat walls are parallel. A deeper that normal
keyseat (i.e., rectangular key) will also help, but has the downside of
weakening the shaft.

If you go the spline route...
http://catalogs.hubcityinc.com/farmr...roducts.html#2

A sexier alternative splines...
http://www.generalpolygon.com/apps.htm

Ned Simmons

Tom Gardner wrote:

Imagine a 1" dia. shaft driving a #40 chain, 32 tooth, 3.5" dia.
sprocket.The shaft drives a cam that takes 50 ft/lbs torque. The shaft
rides in two pillow blocks and a bearing in a block, all mounted on a 1/2"
plate 12" long. The cam drives a guillotine wire cutter. When I want a
longer cut, I slide the plate and all, up to 1" of movement in slots.

I've used split tapered bushings to mount the sprocket to the shaft and it
works great, but I have to move the sprocket with a size change and
re-timing the cam is a bitch. If I put the sprocket on a key with a set
screw, I think it will booger-up the key and such quickly. Do you think if
I use multiple keys or splines I can let the sprocket float without a
fastener? Timing is +/- maybe 2 degrees. Makes sense to me and that scares
me. If so, how many / how big keys?

P.S. I desided to shelf the AR-15 build, I just don't need it. Thanks for
all the tips though, I learned a lot! I'll post pix of the new machine (8
month build) this month...it's RADICAL, nothing like it in the world!




Just throwing a little fuel on the fire... I have a very old traversing
head shaper where the head mechanism slides via the sliding key in the
shaft method. It's worked for over 100 years with some fairly high
pressures on a 1" shaft and 1/4" gib key. Yes, there is a bit of slop
due to the sliding fit of the key but neither the key nor the shaft
keyway have any specific bend or mushrooming or shearing from the
thrust. It works, although not if you want high precision.

Koz

Just throwing a little fuel on the fire... I have a very old traversing
head shaper where the head mechanism slides via the sliding key in the
shaft method. It's worked for over 100 years with some fairly high
pressures on a 1" shaft and 1/4" gib key. Yes, there is a bit of slop due
to the sliding fit of the key but neither the key nor the shaft keyway
have any specific bend or mushrooming or shearing from the thrust. It
works, although not if you want high precision.

Koz

As good precision as you get on a chain drive, it stretches anyway. I'll
bet all those shaper parts are hard, aren't they?

"Eric R Snow" wrote in message
...
On Fri, 05 May 2006 02:55:02 GMT, "Tom Gardner"
I used to make clutch adapters for power takeoff from big Cat engines.
These involved taper lock hubs. The hubs were keyed to the shaft AND
to the the clutch adapter. The clutch adapter was basically a 14 to 18
inch dia (HP dependent) flywheel with a tapered bore that matched a
taperlock hub. I bored the flyhweel with the taper, broached a 3/8
keyway using a tapered broach guide (hadda make that too), then
installed the taperlock hub into the flywheel. This assembly was then
locked to a shaft in the lathe and the flywheel faced one last time to
insure no runout. It looks like this solution might work for you. You
can bore the sprocket for the taper by using the taperlock as a gauge.
You can broach it in the lathe if you are only doing one. If you have
the sprocket located by a spline or keys and don't harden both the
spline and sprocket it will beat itself to death very fast. Any slop
which allows the sprocket to work with and against the rotation will
wallow out the softer parts. Not only that, but as it gets worse it
will transmit potentially damaging shocks to other parts of the
system.
ERS

I see how to do it, thanks! It's these minor set-up problems that kills
production for way too long. I have to make sure it's so simple an
opperator can do the set-up.

"Ned Simmons" wrote in message
...
In article , "Tom
Gardner" says...
Imagine a 1" dia. shaft driving a #40 chain, 32 tooth, 3.5" dia.
sprocket.The shaft drives a cam that takes 50 ft/lbs torque. The shaft
rides in two pillow blocks and a bearing in a block, all mounted on a
1/2"
plate 12" long. The cam drives a guillotine wire cutter. When I want a
longer cut, I slide the plate and all, up to 1" of movement in slots.

I've used split tapered bushings to mount the sprocket to the shaft and
it
works great, but I have to move the sprocket with a size change and
re-timing the cam is a bitch. If I put the sprocket on a key with a set
screw, I think it will booger-up the key and such quickly. Do you think
if
I use multiple keys or splines I can let the sprocket float without a
fastener? Timing is +/- maybe 2 degrees. Makes sense to me and that
scares
me. If so, how many / how big keys?


I'm afraid I don't have a complete mental image of your mechanism - is
there some reason you can't use a taper-lock or QD hub on a keyed shaft?
The key maintains timing when you slack off the taper-lock to adjust
position.

If you do decide to use a keyed shaft with a sliding fit, besides the
other warnings about wallowing out the keyway, keep in mind that another
potential failure mechanism is the key rocking in the shaft keyseat. The
key should be an interference fit in the keyseat and care should be
taken to make sure the keyseat walls are parallel. A deeper that normal
keyseat (i.e., rectangular key) will also help, but has the downside of
weakening the shaft.

If you go the spline route...
http://catalogs.hubcityinc.com/farmr...roducts.html#2

A sexier alternative splines...
http://www.generalpolygon.com/apps.htm

Ned Simmons

The tapered bushings don't have a keyway...but they WILL!