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# Pcd Formula

Started by
Paul Burrowes
, May 12 2010 06:19 PM

12 replies to this topic

### #1

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

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

Posted 12 May 2010 - 06:25 PM

Mind Explaining what a PCD is??

### #3

Posted 12 May 2010 - 06:40 PM

Pitch circle diameter

### #4

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

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

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

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

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

Posted 14 May 2010 - 02:29 AM

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

### #8

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

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

where

D = PCD (diameter you are after)

B = distance between holes

N = number of holes

### #9

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

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

Thanks

### #10

Posted 01 June 2013 - 01:29 AM

LA 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

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.

### #11

Posted 01 June 2013 - 01:30 AM

Paul 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

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.

### #12

Posted 01 June 2013 - 01:31 AM

Dave 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

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.

### #13

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.

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.