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Pcd Formula

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12 replies to this topic

#1
Paul Burrowes

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Hi all can anyone help with a simple formula to calculate the pcd of a set of holes...
i know how many holes i have and i also know the center distance between the holes
i just need the formula to find what pcd it is..

i just wanted a quick way of working out a pcd without drawing it up in mastercam
thanks paul

#2
Ron Branch @ Verisurf

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Mind Explaining what a PCD is??

#3
Paul Burrowes

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Pitch circle diameter

#4
Dave Ball

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A PCD is more commonly known as a bolt circle.


B = D x sin( 360 / (2 x N))

where

B = distance between bolt holes
D = diameter of bolt circle
N = number of holes in circle

#5
Rstewart

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Just click the bolt circle button in the "create" tab. You just need the radius and number of holes.

#6
Paul Burrowes

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thanks for that but its not what im after.
if i have a part that has say 5 holes in it i can measure between the holes and i know how many hooles there are but i dont know the dia that the holes are on..its this unknown diameter that i want to find..
thanks

#7
Bryan Johnson

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Create a Circle through the center of 3 of the holes?

#8
LA CAMmer

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From Dave's equation above:

D = B / (Sin(360/2N))

where

D = PCD (diameter you are after)
B = distance between holes
N = number of holes

#9
Paul Burrowes

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Thats it La CAMmer...
Now for another quick question.. how do i put it into a vb script file that i can run?
Thanks

#10
mohanish

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From Dave's equation above:

D = B / (Sin(360/2N))

where

D = PCD (diameter you are after)
B = distance between holes
N = number of holes


The esiest way to find the PCD is :
Find circumference of PCD then divide it by numbers of holes on PCD.

For Example :-
(508 X 3.14) / 30 = S

where S = center to center linear dist. (not curve wise) between r holes.

By this formula u can easily find the degree also.Posted Image

#11
mohanish

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Hi all can anyone help with a simple formula to calculate the pcd of a set of holes...
i know how many holes i have and i also know the center distance between the holes
i just need the formula to find what pcd it is..

i just wanted a quick way of working out a pcd without drawing it up in mastercam
thanks paul


The esiest way to find the PCD is :
Find circumference of PCD then divide it by numbers of holes on PCD.

For Example :-
(508 X 3.14) / 30 = S

where S = center to center linear dist. (not curve wise) between r holes.

By this formula u can easily find the degree also.Posted Image

#12
mohanish

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A PCD is more commonly known as a bolt circle.


B = D x sin( 360 / (2 x N))

where

B = distance between bolt holes
D = diameter of bolt circle
N = number of holes in circle


The esiest way to find the PCD is :
Find circumference of PCD then divide it by numbers of holes on PCD.

For Example :-
(508 X 3.14) / 30 = S

where S = center to center linear dist. (not curve wise) between r holes.

By this formula u can easily find the degree also.Posted Image

#13
MotorCityMinion

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No math-o-majics needed.

1) Create arc end points, using the circle centers as end points.

2) Create arc 3 points, using the circle centers as points.

3) Create an arc tangent to 3 entities and add the hole rad to that arc value.
  • Foghorn Leghorn likes this