My home made sawmill uses L095 Lovejoy couplers to connect the engine
to the transmission, and their set screws loosen unless I pull very
hard on a long hex wrench. The cause may be the large inertia of the
bandsaw wheels, which are from a motorcycle. When the
vee-belt-tightening drive clutch is loose the belt slips freely over
the pulleys, but when stopping the belt still grabs enough to spin the
engine after it's shut off. Thus the couplers see torque in both
directions.

This suggests that adding a second set screw to lock the first does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?

"Jim Wilkins" wrote in message My home made sawmill
uses L095 Lovejoy couplers to connect the engine
to the transmission, and their set screws loosen unless I
pull very hard on a long hex wrench. The cause may be the
large inertia of the bandsaw wheels, which are from a
motorcycle. When the vee-belt-tightening drive clutch is
loose the belt slips freely over the pulleys, but when
stopping the belt still grabs enough to spin the engine
after it's shut off. Thus the couplers see torque in both
directions.

This suggests that adding a second set screw to lock the
first does help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?



When one set screw is used it is in contact with one
side of the thread groove and any motion will loosen
it. When a second screw is used the inner one will
be pushed to the other side of the v-groove and now
both screws are always in contact with the groove
but on opposite sides of it eliminating motion to
loosen them. Should work... phil

On 12/06/2019 02:49, Jim Wilkins wrote:
My home made sawmill uses L095 Lovejoy couplers to connect the engine
to the transmission, and their set screws loosen unless I pull very
hard on a long hex wrench. The cause may be the large inertia of the
bandsaw wheels, which are from a motorcycle. When the
vee-belt-tightening drive clutch is loose the belt slips freely over
the pulleys, but when stopping the belt still grabs enough to spin the
engine after it's shut off. Thus the couplers see torque in both
directions.

This suggests that adding a second set screw to lock the first does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?


Not uncommon in my experience, the last time I ran into it was on my J
head Bridgeport on the motor pulley.

On 6/11/2019 6:49 PM, Jim Wilkins wrote:
My home made sawmill uses L095 Lovejoy couplers to connect the engine
to the transmission, and their set screws loosen unless I pull very
hard on a long hex wrench. The cause may be the large inertia of the
bandsaw wheels, which are from a motorcycle. When the
vee-belt-tightening drive clutch is loose the belt slips freely over
the pulleys, but when stopping the belt still grabs enough to spin the
engine after it's shut off. Thus the couplers see torque in both
directions.

This suggests that adding a second set screw to lock the first does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?




I remember something like that being done for an air metering screw on a
PCP air rifle. First set screw obstructs the passage, and the second
one backs it up and locks it in place.

"Bob La Londe" wrote in message On 6/11/2019 6:49 PM,
Jim Wilkins wrote:
My home made sawmill uses L095 Lovejoy couplers to
connect the engine
to the transmission, and their set screws loosen unless I
pull very
hard on a long hex wrench. The cause may be the large
inertia of the
bandsaw wheels, which are from a motorcycle. When the
vee-belt-tightening drive clutch is loose the belt slips
freely over
the pulleys, but when stopping the belt still grabs
enough to spin the
engine after it's shut off. Thus the couplers see torque
in both
directions.

This suggests that adding a second set screw to lock the
first does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?




I remember something like that being done for an air
metering screw on a PCP air rifle. First set screw
obstructs the passage, and the second one backs it up and
locks it in place.

It takes two screws in the thread to obstruct passage. They
push against each other so both sides of the groove are
sealed. Plus, the screws lock each other in place even if
the inner one is not in contact with something. phil k.

"Phil Kangas" wrote in message ...


"Bob La Londe" wrote in message On 6/11/2019 6:49 PM,
Jim Wilkins wrote:
My home made sawmill uses L095 Lovejoy couplers to connect the engine
to the transmission, and their set screws loosen unless I pull very
hard on a long hex wrench. The cause may be the large inertia of the
bandsaw wheels, which are from a motorcycle. When the
vee-belt-tightening drive clutch is loose the belt slips freely over
the pulleys, but when stopping the belt still grabs enough to spin the
engine after it's shut off. Thus the couplers see torque in both
directions.

This suggests that adding a second set screw to lock the first does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?




I remember something like that being done for an air metering screw on a
PCP air rifle. First set screw obstructs the passage, and the second one
backs it up and locks it in place.

It takes two screws in the thread to obstruct passage. They
push against each other so both sides of the groove are
sealed. Plus, the screws lock each other in place even if
the inner one is not in contact with something. phil k.

***

In this case, no. The set screw protrudes into a passage way and that is
the passageway that is obstructed or cleared by adjustment of the screw.
The passageway the set screws are in is incidental for the purpose of having
a place to put the screw. Even if it was not sealed the air loss around the
screw would be incidental or parasitic at worst. It would not be major.
Some guys are eliminating the second screw and just using vibratite on the
first screw so they can adjust the gun easier.

However, my whole point was that I had an example of how two set screws are
used to lock themselves in place. I can tell you that it does not work
quite as well as hoped. Its possible to drive the first screw with the
second in a case where its not stopped up against an object. You have to
have a "feel" for it and know when to stop so as to not change the
adjustment of the gun.

We are talking about sudden discharge of a small amount of high pressure air
(3000 psi to start) with a hammer and a knock valve. (I think knock valve
is the right term.)

"Bob La Londe" wrote in message
...
On 6/11/2019 6:49 PM, Jim Wilkins wrote:
My home made sawmill uses L095 Lovejoy couplers to connect the
engine
to the transmission, and their set screws loosen unless I pull very
hard on a long hex wrench. The cause may be the large inertia of
the
bandsaw wheels, which are from a motorcycle. When the
vee-belt-tightening drive clutch is loose the belt slips freely
over
the pulleys, but when stopping the belt still grabs enough to spin
the
engine after it's shut off. Thus the couplers see torque in both
directions.

This suggests that adding a second set screw to lock the first does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?

I remember something like that being done for an air metering screw
on a PCP air rifle. First set screw obstructs the passage, and the
second one backs it up and locks it in place.

https://www.lovejoy-inc.com/wp-conte...010catalog.pdf
I hadn't noticed Chart 1 which gives a Service Factor torque
multiplier of 2.2 for a 1-cylinder engine driving a bandsaw mill. A
larger coupler is on order.

My log splitter (SF=2.0) came with an L095 and hasn't given trouble
running almost at the limit for a black Buna rubber spider. The same
engine and coupler on the sawmill (SF=2.2) damaged the spider.

"Jim Wilkins" wrote in message
...
"Bob La Londe" wrote in message
...
On 6/11/2019 6:49 PM, Jim Wilkins wrote:
My home made sawmill uses L095 Lovejoy couplers to connect the
engine
to the transmission, and their set screws loosen unless I pull
very
hard on a long hex wrench. The cause may be the large inertia of
the
bandsaw wheels, which are from a motorcycle. When the
vee-belt-tightening drive clutch is loose the belt slips freely
over
the pulleys, but when stopping the belt still grabs enough to spin
the
engine after it's shut off. Thus the couplers see torque in both
directions.

This suggests that adding a second set screw to lock the first
does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?

I remember something like that being done for an air metering screw
on a PCP air rifle. First set screw obstructs the passage, and the
second one backs it up and locks it in place.

https://www.lovejoy-inc.com/wp-conte...010catalog.pdf
I hadn't noticed Chart 1 which gives a Service Factor torque
multiplier of 2.2 for a 1-cylinder engine driving a bandsaw mill. A
larger [L099] coupler is on order.

My log splitter (SF=2.0) came with an L095 and hasn't given trouble
running almost at the limit for a black Buna rubber spider. The same
engine and coupler on the sawmill (SF=2.2) damaged the spider.


So far the Lovejoy L099 coupler appears to be working well. The saw's
new engine is a Harbor Freight 6.5 HP Predator.

I've spent the recent sunny days sawing oak logs into beams, with a
tiny baby bunny watching from about 10' away.

On 2019-06-12, Jim Wilkins wrote:

[ ... ]

This suggests that adding a second set screw to lock the first does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?

The web site insists that I register or log in, so I've seen
nothing of that site.

I know that in the Bridgeport spindle for R8 collets there is
one place where a dog-point setscrew is topped by a setscrew which is
ground short enough so the Allen key can pass though the top one to
adjust the protrusion of the dog point. Then you back out the key so it
turns only the fully hollow setscrew to tighten it to lock the other in
place.

I also have used a square-headed setscrew over a normal setscrew
to lock it in place in the squirrel-cage blower in my furnace. That has
worked well compared to using only the original setscrew.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"DoN. Nichols" wrote in message
...
On 2019-06-12, Jim Wilkins wrote:

[ ... ]

This suggests that adding a second set screw to lock the first does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?

The web site insists that I register or log in, so I've seen
nothing of that site.

I know that in the Bridgeport spindle for R8 collets there is
one place where a dog-point setscrew is topped by a setscrew which
is
ground short enough so the Allen key can pass though the top one to
adjust the protrusion of the dog point. Then you back out the key
so it
turns only the fully hollow setscrew to tighten it to lock the other
in
place.

I also have used a square-headed setscrew over a normal setscrew
to lock it in place in the squirrel-cage blower in my furnace. That
has
worked well compared to using only the original setscrew.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703)
938-4564
(too) near Washington D.C. |
http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

After upsizing from an L095 to an L099 Lovejoy coupler I haven't seen
any trouble. The L095 which has been satisfactory driving a log
splitter hydraulic pump for 20+ years was apparently overstressed at
the higher load service factor of the bandsaw mill. The setscrews kept
loosening and the rubber spider that connects the driving and driven
couplers disintegrated. Changing from the 5.5HP engine borrowed from
the log splitter to a 6.5HP 212CC HF Predator made it worse. That's a
very nice engine for $99, though.

The drive clutch is a belt tightener between the engine and the speed
reducer. With the engine off and clutch disengaged the belt slips but
when it's running the heavy motorcycle wheels continued to spin the
engine after shutting it off, until the new belt and pulleys wore
smooth. This reversed the direction of torque on the couplers' shaft
keys and may have loosened the setscrews.

I fixed and hooked up the (crashed) bike's speedometer and let the
wheels coast down to 10MPH before shutting off, which seems to reduce
the torsional shocks. The speedo is also useful to show the speed and
load on the blade and how far it runs before dulling. The recommended
5000 feet per minute is a little over the 55MPH line.

I don't understand why the loose belt behaves like a centrifugal
clutch that engages above some belt speed. It does this whether the
engine or the wheels are driving, but slips when turned by hand or
during gradual engagement at startup, with the engine at idle. It
seems to lock up around 20MPH wheel speed.

I didn't use a centrifugal clutch because I want to be able to
disengage the drive instantly if anything goes wrong.

On 06/07/2019 02:40, DoN. Nichols wrote:
On 2019-06-12, Jim Wilkins wrote:

[ ... ]

This suggests that adding a second set screw to lock the first does
help.
https://www.hobby-machinist.com/thre...-screws.36903/

What's your experience?
The web site insists that I register or log in, so I've seen
nothing of that site.

For me I can see login and register but the rest of the thread is
readable without doing either, maybe it's because I have a script
blocker active so Javascript is disabled for the site.


I know that in the Bridgeport spindle for R8 collets there is
one place where a dog-point setscrew is topped by a setscrew which is
ground short enough so the Allen key can pass though the top one to
adjust the protrusion of the dog point. Then you back out the key so it
turns only the fully hollow setscrew to tighten it to lock the other in
place.

I also have used a square-headed setscrew over a normal setscrew
to lock it in place in the squirrel-cage blower in my furnace. That has
worked well compared to using only the original setscrew.

Good Luck,
DoN.