V belt, How buy?

[MEASURE TWICE]

Originally Posted by MEASURE TWICE

I was careful to see if that equation worked so I measured the outside as you mentioned, but the equation worked quite well.

Calipers across the outside edge of the pulley or the teeth of a sprocket and the shaft bore diameter size and the distance between shaft centers may be easy to measure. This could pardon me, but not just measure twice (my handle), but measure different ways both correct, and use as an error checking (correlation).

MT

Example

4.48” Pulley with 5/8” Shaft

2.00” Pulley with 5/8” Shaft

Distance between both pulley shaft centers =
Distance outer edge of both shafts – [ (½ X shaft 1st pulley diameter) + (½ X shaft 2nd pulley diameter) ]

In my case the Distance between both pulley shaft centers = 4”

4.48” X (constant 1.57) = 7.0336”

2.00” X (constant 1.57) = 3.1400”

7.0336” + 3.1400” = 10.1736”

2 X (Distance between both pulley shaft centers 4”) = 8”

10.1736” + 8” = 18.1736”

This is what I heard and seem to work out nice. Something else just noticed and sort of unique: the 2" pulley times the constant 1.57 = 3.14 as that is Pi (Greek Letter for that constant that it is)

MT

[goog]

Tool Makers method with old belt is great.If you could find a adj. pulley cheap enough you could have even more adjustment.Good luck.

[MEASURE TWICE]

Originally Posted by MEASURE TWICE

Example

4.48” Pulley with 5/8” Shaft

2.00” Pulley with 5/8” Shaft

Distance between both pulley shaft centers =
Distance outer edge of both shafts – [ (½ X shaft 1st pulley diameter) + (½ X shaft 2nd pulley diameter) ]

In my case the Distance between both pulley shaft centers = 4”

4.48” X (constant 1.57) = 7.0336”

2.00” X (constant 1.57) = 3.1400”

7.0336” + 3.1400” = 10.1736”

2 X (Distance between both pulley shaft centers 4”) = 8”

10.1736” + 8” = 18.1736”

This is what I heard and seem to work out nice. Something else just noticed and sort of unique: the 2" pulley times the constant 1.57 = 3.14 as that is Pi (Greek Letter for that constant that it is)

MT

[QUOTE=MEASURE TWICE;443557]Example

4.48” Pulley with 5/8” Shaft

2.00” Pulley with 5/8” Shaft

Distance between both pulley shaft centers =
Distance outer edge of both shafts – [ (½ X shaft 1st pulley diameter) + (½ X shaft 2nd pulley diameter) ]

In my case the Distance between both pulley shaft centers = 4”

4.48” X (constant 1.57) = 7.0336”

2.00” X (constant 1.57) = 3.1400”

7.0336” + 3.1400” = 10.1736”

2 X (Distance between both pulley shaft centers 4”) = 8”

10.1736” + 8” = 18.1736”

This is what I heard and seem to work out nice. Something else just noticed and sort of unique: the 2" pulley times the constant 1.57 = 3.14 as that is Pi (Greek Letter for that constant that it is)

MT

Correction: Although this is what I got from the help at Grainger, this is not completely correct unless the pulleys are of the same size.

I would add this to make up for the difference in size of pulleys. We are usually using different size pulleys to gear down the ratio so it is important to get it exact.

Additionally I realized what 1.57 constant I was told is. Since as above I saw that 2 X 1.57 = 3.14 which is Pi constant, I now know it was just the same as using [Circumference = 2 Pi X radius] and then dividing the circumference by 2.

The above I already knew and this using 1.57 was just another way of doing the same.

Here is what was missing for the two length portions of the belt between the pulleys at their greatest distance from shaft centers to be the exact. It’s not going to need trigonometry since we are dealing with right triangles an easier way is the Pythagorean Theorem.

Sorry for my drawing being not the best. Please imagine there being a second right triangle beneath the first one for the belt going along the bottom of the two pulleys. If I drew that it would get too cluttered.

Putting 1st pulley the smaller one first as I’m gearing down….
Starting with my pulleys a calipers measures outside edge of pulleys:

1st Pulley Diameter = 2”
1st Pulley Radius = ( 2” / 2 ) = 1”
2 X Pi 3.14 X Radius = Circumference
1st Pulley Circumference = ( 2 X Pi 3.14 X Radius 1”) = 6.28”
1st Pulley ½ Circumference = ( 6.26 / 2 ) = 3.14”

2nd Pulley Diameter = 4.48”
2nd Pulley Radius = ( 4.48” / 2 ) = 2.24”
2 X Pi 3.14 X Radius = Circumference
2nd Pulley Circumference = ( 2 X Pi 3.14 X Radius 2.24”) = 14.0672”
2nd Pulley ½ Circumference = ( 14.0672 / 2 ) = 7.0336”

In the right triangle in the picture attached:
a = absolute value of [ (1st pulley Diameter ) – (2nd pulley Diameter ) ]
a = absolute value of (2” – 4.48”)
a = absolute value of (-2.24”)
a = 2.24”

In the right triangle in the picture attached:
b = distance between centers of shafts on pulleys
In measuring with calipers the distance on farthest edges of shafts you just subtract ½ the shaft size of each of the two shafts and that is the distance between shaft centers.
For my motor bike I have b = 4”
b = 4”

The hypotenuse (longest side of the of the right triangle) = c
This is as in the picture c in the drawing.
This is where a more exact calculation is done.
Pythagorean Theorem [ (a X a ) + (b X b ) ] = (c X c )
Rearranging (c X c ) = [ (a X a ) + (b X b ) ]
Simplifying for c:
Square Root of ( c X c ) = Square Root of [ ( a X a ) + ( b X b ) ]
Square Root of ( c X c ) = Square Root of [ ( 2.24” X 2.24” ) + ( 4” X 4” ) ]
Square Root of ( c X c ) = Square Root of [ ( 5.0176” ) + ( 16” ) ]
Square Root of ( c X c ) = Square Root of [ 21.0176” ]
c = 4.5845“
c two times for the 2nd right triangle not pictured, but needed for the bottom of the pulley belt as well is:
c two times = ( 2 X 4.5845”)
c two times = 9.169”

Putting it all together:

Belt Length = ( ½ of 1st Pulley Circumference ) + ( ½ of 2nd Pulley Circumference) + ( c two times )
Belt Length = 3.14” + 7.0336” + 9.169”
Belt Length = 19.3426”

The error without using the additional steps and seeing that the length is longer is the difference between 19.3426” and previous length 18.1736” which amounts to 1.169” longer belt length.

I will write a program to do this so each time it will not be so tedious, and then measuring a few setups I would like to see if it is right on!

1.169" is significant so without the additional step the available adjustment may not be enough. In any case best to measure it and if the math agrees so be it

MT

[MEASURE TWICE]

Goog yes as I mentioned as well Tool Makers point on how to measure is right!

On Goog's note about being able to adjust:

Here is a picture of one side of the dual jack shaft brackets with pillow bearing holders. Note I slotted the bracket for bottom pillow bearing holder as there is enough room for the pulley to move further down and tighten up the belt sufficiently.

MT

[MEASURE TWICE]

Nehmo, Goog mentions about adjustable pulleys and I think they have them at Grainger, but I thought I was going to at first be able to adjust length with the section belts where links of the belt can be removed or added to adjust length. Only thing is that the tension I needed and that the belt stretched so adjustment that way did not snug up enough. The belt slipped on the smaller of the two pulleys. The regular v-belt that I got at the auto parts store Kragen was a Gates belt and does have very little stretch. I made a slotted adjustment and move the whole bottom jack shaft up or down, which for my dual stacked jack shaft allows the tension between top an bottom jack shaft pulleys to be set just right without slipping.

I will look to see what kind of cost there is involved in adjustable diameter pulleys, as it may be in the future for me if in the big picture it is easier.

MT

[Nehmo]

In my case, I also can drill new holes and move either the shaft bearings or the engine. Basically, I need something short enough. I was hoping a local parts store would stock one, but so far no luck. (My pulley's label states type A, and Gates gives 0.5" top width for A.)
Yes, there is a Grainger (I bought the bearings there) in Kansas City, but I have to take a couple of buses + bike to get there. Plus, today is Friday.
Right now, I have the engine mounted on the bike as cargo. I have the shaft and pulleys detached in the bucket I use as a front basket. The first free moment I get, I'll head to a parts store.

[MEASURE TWICE]

Grainger has this: Adjustable pulley and with a little math I calculated that with an A section belt for adjustment diameter of the pulley 2.1" to 3.1" you could have one half the pulley where the belt seats in going from a length of 3.297" to 4.867". The adjustment being length change of 1.57" which for around $13.28 I now think it would have been the way to go instead of slotting the bracket as I did.

One last thing though as I called and spoke with a rep at Grainger, the adjustment is done by rotation the threaded half portion of the pulley and tighten down in the key-way. This means whatever one revolution equates to in diameter, that is the increment of the adjustment and you would have to live with. I will stop by one of their store to bring calipers and see what the increment amounts to, but I suspect it could have easily worked in my system.

MT

http://www.grainger.com/Grainger/CON...448?Pid=search

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CONGRESS V-Belt Pulley, 3.25 OD, 5/8 Bore, Var Pitch

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V-Belt Pulley, Variable Pitch Fixed Bore, Bore Dia. 5/8 In., Outside Dia. 3.25 In., 1 Groove, 4L, A, or AX Belt Pitch Dia. 2.1 to 3.1 In., 5L, B, or BX Belt Pitch Dia. 2.4 to 3.2 In., 3/16 x 3/32 In. Keyway, Die Cast (Zamak #3) Material, For Use With 4L, 5L, A, or B Type V-Belts

Grainger Item # 1X448
Price (ea.) $13.28
Brand CONGRESS
Mfr. Model # VP325X062KW
UNSPSC # 31171804
Ship Qty. 1
Sell Qty. (Will-Call) 1
Ship Weight (lbs.) 0.9
Availability Ready to Ship
Catalog Page No. 143
Country of Origin
(Country of Origin is subject to change.) USA
Qty.

[MEASURE TWICE]

For a while on and off in the past I was without a welder, so this meant sometimes I could have made things easier and better if I had a welder available all the time.

My jack shaft brackets for the pillow bearing holders could have been made much better, but I have so much time already invested in them, I am leaving it as is. The problem I was at first concerned about was that for adjustment the slotting lengthened the area that already was thinned out to allow the bellow bearings to not hit the bracket which the holder was mounted on.

For fear of the slotting taking too much of the overall metal in the bracket away, I beefed it up by welding a thicker one side to make up the difference. Working with what you have available at the time is just the way it is, but we get by anyhow.

The adjustable pulley I am still really thinking of using in place of one of the pulleys that goes from my bottom jackshaft to the rear wheel drive pulley. This is so can tension the rear wheel drive belt.

I do not feel it right to adjust that belt by having the threads on the rear wheel axle anywhere but where it should be farthest back and tightened down. I may even weld over so there is no drop out and for removal you have to disassemble the hub. Or at least recreate what has already been done on kid bikes that will not allow the wheel to come off very easily without first removing a clip on both sides of the front and rear drop outs.

Cost for the adjustable diameter pulley well worth the safety factor!

Thanks for the hints all!

MT

[curtisfox]

Originally Posted by Tool Maker

The inside diameter of the belt is meaningless.

Belts are measured at the gauge line that is just below the Top surface of the belt.

Are your pulleys wide enough at the top of the Vee to hold a 17/32 wide belt? The wider belt rides up higher, so it uses a larger belt.

If you have an old V belt, you can cut it then wrap it around both pulleys for a measurement. Pull it snug, and where the 2 ends overlap, draw a line across the back of both pieces in a straight line. Then lay the belt out flat & measure between the two marks. That is the closest measurement you will get.

.

There was a tip in a car book just a month ago. Do like ToolMaker says and when you get it to fit thke a staple gun and put a couple staples in it, then you can take it to the store and get one just the right size.........Curt

[MEASURE TWICE]

I once had the auto parts store allow me to bring in the whole bike in that back where all the belts were hanging on the racks. I took my tools as well with me and I was allowed to try on as many belts as I liked and only buy what fit. That I don't expect to happen all the time but it did back then.

MT