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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
Posted to rec.crafts.metalworking
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Stacked set screws?
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? |
#2
Posted to rec.crafts.metalworking
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Stacked set screws?
"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 |
#3
Posted to rec.crafts.metalworking
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Stacked set screws?
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. |
#4
Posted to rec.crafts.metalworking
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Stacked set screws?
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. |
#5
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Stacked set screws?
"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. |
#6
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Stacked set screws?
"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.) |
#7
Posted to rec.crafts.metalworking
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Stacked set screws?
"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. |
#8
Posted to rec.crafts.metalworking
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Stacked set screws?
"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. |
#9
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Stacked set screws?
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 --- |
#10
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Stacked set screws?
"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. |
#11
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Stacked set screws?
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. |
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