Mark V Speed Control

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dusty
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Re: Mark V Speed Control

Post by dusty »

JPG wrote: Fri Sep 09, 2022 1:45 pm The vanes should not come into play except for the control sheave, then their distance from the button bearing end matters(where the pork chop touches).

The od is minor since it only comes into play when the belt is OVER extended on the pulley.
Please explain the relationship between the button bearing and the vanes (slope of).

Is it ever recommended that the belt ride proud of the sheave?
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DLB
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Re: Mark V Speed Control

Post by DLB »

dusty wrote: Sat Sep 10, 2022 9:55 am ...
Is it ever recommended that the belt ride proud of the sheave?
I would think not. But at the same time, there is nothing to prevent it at the SLOW end. If the geometry of the belt, sheaves, and eccentric work out that way it may ride slightly proud unless the operator limits it. Completely different on the FAST end of course, since we set a stop to prevent it. I tried a few combinations and they all ran slightly proud at slow.

As someone pointed out earlier, it is probably not the original intent of the design to fully compress the spring at SLOW either. And it probably IS the intent of the design to be able to run at or under 700 RPM.

- David
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dusty
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Re: Mark V Speed Control

Post by dusty »

DLB wrote: Sat Sep 10, 2022 5:17 pm
dusty wrote: Sat Sep 10, 2022 9:55 am ...
Is it ever recommended that the belt ride proud of the sheave?
I would think not. But at the same time, there is nothing to prevent it at the SLOW end. If the geometry of the belt, sheaves, and eccentric work out that way it may ride slightly proud unless the operator limits it. Completely different on the FAST end of course, since we set a stop to prevent it. I tried a few combinations and they all ran slightly proud at slow.

As someone pointed out earlier, it is probably not the original intent of the design to fully compress the spring at SLOW either. And it probably IS the intent of the design to be able to run at or under 700 RPM.

- David
Because of the dimensions of the sheaves (upper) they can go only so far closed. When they his the hard stop, the sheaves are 1/2" apart at the perimeter. With a belt that is 1/2" wide riding in that sheaveI I would think that the belt would stop there.
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JPG
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Re: Mark V Speed Control

Post by JPG »

dusty wrote: Sat Sep 10, 2022 9:55 am
JPG wrote: Fri Sep 09, 2022 1:45 pm The vanes should not come into play except for the control sheave, then their distance from the button bearing end matters(where the pork chop touches).

The od is minor since it only comes into play when the belt is OVER extended on the pulley.
Please explain the relationship between the button bearing and the vanes (slope of).

Is it ever recommended that the belt ride proud of the sheave?
Consider what is controlling speed. The porkchop that bears against the button bearing that is a distance from the sloping vanes. That distance will affect the resultant speed.
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
DLB
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Re: Mark V Speed Control

Post by DLB »

dusty wrote: Sat Sep 10, 2022 5:42 pm
DLB wrote: Sat Sep 10, 2022 5:17 pm
dusty wrote: Sat Sep 10, 2022 9:55 am ...
Is it ever recommended that the belt ride proud of the sheave?
I would think not. But at the same time, there is nothing to prevent it at the SLOW end. If the geometry of the belt, sheaves, and eccentric work out that way it may ride slightly proud unless the operator limits it. Completely different on the FAST end of course, since we set a stop to prevent it. I tried a few combinations and they all ran slightly proud at slow.

As someone pointed out earlier, it is probably not the original intent of the design to fully compress the spring at SLOW either. And it probably IS the intent of the design to be able to run at or under 700 RPM.

- David
Because of the dimensions of the sheaves (upper) they can go only so far closed. When they his the hard stop, the sheaves are 1/2" apart at the perimeter. With a belt that is 1/2" wide riding in that sheaveI I would think that the belt would stop there.
That makes sense. Sample of one, that 1/2" on the sheaves is pretty precise though and 1/2" on the belt is worn out. Belts I'm using are all 1/2" plus. I don't have a new SS belt to measure, but my belts are wide enough to ride slightly proud in a 1/2" Vee. Presumably a new SS belt would ride even higher than the ones I'm using if the rest of the geometry allows the Idler sheaves to close all the way.

- David
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Re: Mark V Speed Control

Post by dusty »

DLB wrote: Sun Sep 11, 2022 9:25 am
dusty wrote: Sat Sep 10, 2022 5:42 pm
DLB wrote: Sat Sep 10, 2022 5:17 pm I would think not. But at the same time, there is nothing to prevent it at the SLOW end. If the geometry of the belt, sheaves, and eccentric work out that way it may ride slightly proud unless the operator limits it. Completely different on the FAST end of course, since we set a stop to prevent it. I tried a few combinations and they all ran slightly proud at slow.

As someone pointed out earlier, it is probably not the original intent of the design to fully compress the spring at SLOW either. And it probably IS the intent of the design to be able to run at or under 700 RPM.

- David
Because of the dimensions of the sheaves (upper) they can go only so far closed. When they his the hard stop, the sheaves are 1/2" apart at the perimeter. With a belt that is 1/2" wide riding in that sheaveI I would think that the belt would stop there.
That makes sense. Sample of one, that 1/2" on the sheaves is pretty precise though and 1/2" on the belt is worn out. Belts I'm using are all 1/2" plus. I don't have a new SS belt to measure, but my belts are wide enough to ride slightly proud in a 1/2" Vee. Presumably a new SS belt would ride even higher than the ones I'm using if the rest of the geometry allows the Idler sheaves to close all the way.

- David
It is my belief that if the high speed stop is adjusted with the belt riding within the perimeter of the sheave it will not ride proud at either high or low speed. Remember that the belt moves in equal but opposite directions on the sheaves; if you make a speed adjustment that moves the belt 1/4" on the floating sheave it will simultaneously move 1/4" in the opposite direction on the idler sheave. With a belt of the proper length it is mathematically impossible to get the belt proud.
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Re: Mark V Speed Control

Post by dusty »

dusty wrote: Sun Sep 11, 2022 3:32 pm
DLB wrote: Sun Sep 11, 2022 9:25 am
dusty wrote: Sat Sep 10, 2022 5:42 pm

Because of the dimensions of the sheaves (upper) they can go only so far closed. When they his the hard stop, the sheaves are 1/2" apart at the perimeter. With a belt that is 1/2" wide riding in that sheaveI I would think that the belt would stop there.
That makes sense. Sample of one, that 1/2" on the sheaves is pretty precise though and 1/2" on the belt is worn out. Belts I'm using are all 1/2" plus. I don't have a new SS belt to measure, but my belts are wide enough to ride slightly proud in a 1/2" Vee. Presumably a new SS belt would ride even higher than the ones I'm using if the rest of the geometry allows the Idler sheaves to close all the way.

- David
It is my belief that if the high speed stop is adjusted with the belt riding within the perimeter of the sheave it will not ride proud at either high or low speed. Remember that the belt moves in equal but opposite directions on the sheaves; if you make a speed adjustment that moves the belt 1/4" on the floating sheave it will simultaneously move 1/4" in the opposite direction on the idler sheave. With a belt of the proper length it is mathematically impossible to get the belt proud.

I do not have unmounted fan and floating sheaves to play with but I do have a couple sets of the other sheaves. With these on the bench, mounted on an idler shaft, it becomes obvious that the sheaves were designed "with hard stops" that limit the sheaves from going closed any further than 1/2" measured at the perimeter of the sheave.
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DLB
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Re: Mark V Speed Control

Post by DLB »

dusty wrote: Sun Sep 11, 2022 3:32 pm ...It is my belief that if the high speed stop is adjusted with the belt riding within the perimeter of the sheave it will not ride proud at either high or low speed. Remember that the belt moves in equal but opposite directions on the sheaves; if you make a speed adjustment that moves the belt 1/4" on the floating sheave it will simultaneously move 1/4" in the opposite direction on the idler sheave. With a belt of the proper length it is mathematically impossible to get the belt proud.
I normally adjust the high speed stop so the belt is an estimated 1/8" to 1/16" inside the perimeter of the motor sheaves. But the stop only does one thing: limits pork chop travel in the high speed direction. The only thing the high speed stop setscrew is doing at low speed is providing an axle for the idler gear for the indicator ring.

It still seems to me that a belt wider than 1/2" which includes new SS belts, will ride slightly proud if the sheaves fully close. And that is what I've observed. Is your idea of a 'proper length' belt one that prevents the Idler sheaves fully closing at the stop? The only other stop I see in the system is full compression of the motor shaft spring. I though there was general consensus that full compression of the spring is not a particularly good stop. While I agree a slightly shorter belt would prevent the belt from running proud, it would do so by fully compressing the motor shaft spring and therefore preventing the Control Sheave from full range of travel and closing to that 1/2" gap. IMO the low speed mechanical limit is always going to be either full compression of the spring or full closing of the Idler sheaves. Unlike high speed, there is no other limiter to the travel. IMO it follows that the ideal belt length will allow full closing of the Idler sheaves with almost full compression of the motor spring and therefore will run proud at the stop.

I'm not suggesting it is a good idea to run the belt proud. What I said is that there is nothing in the design as currently implemented to prevent it. Perhaps with original belts there was, I suspect this is the case. (Narrower belts.) It is a simple matter for the user that is concerned about it to observe the belt position at the slow stop and to choose not to use the slow stop if warranted. I ran mine to the stops during this thread to support discussion of how slow the machine will go, I seldom run the machine at the slow stop, but if you want to know the slowest achievable speed you kind of have to.

- David
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Re: Mark V Speed Control

Post by JPG »

+1

I consider the only "good" (durable) limit stops are the pulleys fully closing. The high speed stop prevents an interference at fast of the idler sheave and the speed control itself. Positioning the belt position on the motor pulley only establishes an approximate range for the high speed stop's adjustable range. Only the screw length/projection is then left to limit the range.

P.S. Annnd belt width/length WILL affect the end result.(speed range)
╔═══╗
╟JPG ╢
╚═══╝

Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
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dusty
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Re: Mark V Speed Control

Post by dusty »

DLB wrote: Mon Sep 12, 2022 10:20 am
dusty wrote: Sun Sep 11, 2022 3:32 pm ...It is my belief that if the high speed stop is adjusted with the belt riding within the perimeter of the sheave it will not ride proud at either high or low speed. Remember that the belt moves in equal but opposite directions on the sheaves; if you make a speed adjustment that moves the belt 1/4" on the floating sheave it will simultaneously move 1/4" in the opposite direction on the idler sheave. With a belt of the proper length it is mathematically impossible to get the belt proud.
I normally adjust the high speed stop so the belt is an estimated 1/8" to 1/16" inside the perimeter of the motor sheaves. But the stop only does one thing: limits pork chop travel in the high speed direction. The only thing the high speed stop setscrew is doing at low speed is providing an axle for the idler gear for the indicator ring.

It still seems to me that a belt wider than 1/2" which includes new SS belts, will ride slightly proud if the sheaves fully close. And that is what I've observed. Is your idea of a 'proper length' belt one that prevents the Idler sheaves fully closing at the stop? The only other stop I see in the system is full compression of the motor shaft spring. I though there was general consensus that full compression of the spring is not a particularly good stop. While I agree a slightly shorter belt would prevent the belt from running proud, it would do so by fully compressing the motor shaft spring and therefore preventing the Control Sheave from full range of travel and closing to that 1/2" gap. IMO the low speed mechanical limit is always going to be either full compression of the spring or full closing of the Idler sheaves. Unlike high speed, there is no other limiter to the travel. IMO it follows that the ideal belt length will allow full closing of the Idler sheaves with almost full compression of the motor spring and therefore will run proud at the stop.

I'm not suggesting it is a good idea to run the belt proud. What I said is that there is nothing in the design as currently implemented to prevent it. Perhaps with original belts there was, I suspect this is the case. (Narrower belts.) It is a simple matter for the user that is concerned about it to observe the belt position at the slow stop and to choose not to use the slow stop if warranted. I ran mine to the stops during this thread to support discussion of how slow the machine will go, I seldom run the machine at the slow stop, but if you want to know the slowest achievable speed you kind of have to.

- David
No matter the width of the belt, if you run the speed control up until the belt is near the perimeter of the sheave but not above it and then set the high speed stop, the belt should never ride higher than that.

Having set the high speed stop, if you adjust to low speed the belt should ride in about the same position on the idler sheave. I say that with the understanding that if using a non-standard belt - all bets are off.

This illustrates what I believe the belts do as one moves from one extreme to the other.
Attachments
Belt Distribution on Sheaves at different speeds.jpg
Belt Distribution on Sheaves at different speeds.jpg (136.29 KiB) Viewed 593 times
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