sprocket dimensions

Discussion in 'Frame Mounted Engines' started by choppermke, May 22, 2012.

1. choppermkeMember

does any one know the 44 toth sprocket 9 hole diameter or radious from center. thanks

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2. Al.FishermanActive Member

Tip of tooth to tip of tooth 7 1/4"

3. choppermkeMember

thanks for the reply al but i need the bolt hole pattern, ie the diameter of the holes or the radius from center of the sproket to the center of the hole or slot for the bolt. this is done by taking calipers, measuring the center hole, measuring the bolt hole or slot, measuring the material between the empty spaces. than taking the last dimension and adding half of the first two measurments. and this will give me the bolt circle radius.

4. choppermkeMember

inches or metric works i can convert them. thank you.

5. Al.FishermanActive Member

Hope this helps.

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Last edited: May 23, 2012
6. choppermkeMember

sir u are the man thank you. now i can start my production on my hub adapter

7. loquinActive Member

Al, those dimension don't seem exactly right. If the bolt-hole mounting circle is 3.25 inches, with 9 holes, the center-to-center spacing on the holes should be 1.112 inches.

But, if the bolt hole center-to-center spacing is 1.25 inches, then the bolt-hole circle diameter should be 3.65 inches.

Last edited: May 25, 2012
8. choppermkeMember

can we combine these threads. i did multipule serches befor posting and never seen that thread. i am a machinist and the easiest way to find the diameter is to take the diameter of both holes or center hole and lenght of the slot, if the sprocket is sloted, divide them seperatly by 2 and use calipers to measure material between them. than you take that dimention adding half of each hole, or half the center hole and half the slot lenght. i would have already done this but my sprocket is on my bike and it is a stingray so it is a pain taking the sprocket on and off. i was hopping someone or even a vender might have one not on a bike that they can measure. i talked to one vendors tech support, i think kings, but the info they gave me was bad

9. Al.FishermanActive Member

Correction..... I came up with close to 1 1/16" (1.0625") not 1.25"

10. choppermkeMember

i see what u mean. i triged it out, but with a 2 legs at 1.625 and 40 degrees i got 1.1116 so was the correction an actual measurement of a phisical sprocket? Because now im suspicious of all the dimensions. for one they are in inches and not metric. i suposse that they might have rounded the metric dimensions or just converted wronge because if u convert 1.625 it equals 41.275 and 1.25 is 31.75. but if u put those nubers into a trig calculator they dont even come close.

11. Al.FishermanActive Member

The problem using a caliper as I did, the points are not exact, as they are drawn out from the sprocket. So the measurements are as close as I could get. It's not like measuring a shaft or bearing as they are not varied points

Last edited: May 26, 2012

kewl thanks

13. choppermkeMember

so from that pic it looks as if they are not equaly spaced correct?

14. Al.FishermanActive Member

No they are. When you put the rag joint together, the metal spacers that go behind the rubber can be rotated. If you don't understand I'll take a picture of the sprocket with the metal plates over the sprocket.

The 9 holes form a nonagon....Degrees in a nonagon 180(n - 2)
n is the number of sides
n=9
180(9-2)
180(7)
1260 degrees

Each hole being a vertex, you have 9 angles each of 140 degrees.

Last edited: May 26, 2012

16. choppermkeMember

see my problem is that the last rag joint i had tosted my rim and through me during a 10mph turn because of the torque on the spokes. so now im trying to put together an adapter. so the distance from x to the center of the slot should be all i need to make a 9 hole bolt cercle, but u might be beter able to tell me if this is true. u seen to be an engineer and know your stuff. im used to havng a cad file and mastercam. sorry about that

Last edited: May 26, 2012
17. Al.FishermanActive Member

I can't figure out what you are saying. one time you said the rag joint touched your rim (how can this be?), then you say you were throne off because it touched your spokes (all rag joints touch the spokes). Not all 44 tooth sprockets have the same 9 hole pattern. I'm working on one I have to make the center hole so the dust cover will fit into, but the mounting holes are different and I have to drill 9 new holes.

Is this what you want to make?
.........Both sprockets are 44 tooth--->

Last edited: May 26, 2012
18. choppermkeMember

sorry again i guess that answers it at the same time if they can be different patterns than i need to pull mine and put calipers on it. thanks for the help though. i will post my results when i do. thanks again

19. loquinActive Member

You could consider the width of the 'slots' in the sprocket to be the hole 'diameter' d. (ref the edited pic, attached)

If you measure the center hole diameter (which you did) and the distance between the edge of the center hole and inner edge of a slot (S1), you could calculate the innermost possible mounting circle. And, if you measure from the edge of the center hole and the outer edge of the slot (S2), you could calculate the outermost possible mounting circle diameter.

It's my guess that the slot is configured so that the middle of the slot corresponds to the desired mounting hole circle, but, they knew that the tolerances they were getting were poor...

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Last edited: May 31, 2012