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Pcd Formula


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#1 Paul Burrowes

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Posted 12 May 2010 - 06:19 PM

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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Posted 12 May 2010 - 06:25 PM

Mind Explaining what a PCD is??

#3 Paul Burrowes

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Posted 12 May 2010 - 06:40 PM

Pitch circle diameter

#4 Dave Ball

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Posted 13 May 2010 - 01:46 AM

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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Posted 13 May 2010 - 01:49 AM

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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Posted 13 May 2010 - 04:51 PM

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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Posted 14 May 2010 - 02:29 AM

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

#8 LA CAMmer

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Posted 14 May 2010 - 02:43 AM

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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Posted 16 May 2010 - 04:41 PM

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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Posted 01 June 2013 - 01:29 AM

View PostLA CAMmer, on 14 May 2010 - 02:43 AM, said:

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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Posted 01 June 2013 - 01:30 AM

View PostPaul Burrowes, on 12 May 2010 - 06:19 PM, said:

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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Posted 01 June 2013 - 01:31 AM

View PostDave Ball, on 13 May 2010 - 01:46 AM, said:

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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Posted 01 June 2013 - 09:08 AM

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.