Hole Calculation

[john dakinParticipant @johndakin59277]

I need to find out how to work out how many 1mm holes will fit onto a 160mm diameter circle, I am trying to make a watchmakers indexing plate that has 360 1mm holes on the first circle, and need to know if they will all fit without the holes being to close and breaking into each other, I am new to this so go easy on me, is there some sort of formula or calculator?

[john dakinParticipant @johndakin59277]

[Neil WyattModerator @neilwyatt]

Circumference = PI x diameter = 3.14 x 160 = 502mm, so 502/360 = 1.39mm per hole,. I don't think .39mm between holes leaves you much room for error.

To have 1mm between holes (still challenging) you need a circle 360x 2= 720mmm circumference.

720/PI = 720/3.14 = 230mm diameter

Alternatively you could put the holes in two rings, one at 160mm and an inner ring at, say, 150mm, offset by one degree.

[john dakinParticipant @johndakin59277]

Thanks very much for the information I will give it a go,, I'm using cambam by the way to do the program for my cnc mill

[JasonBModerator @jasonb]

Same answers also in the thread from when you asked before? Here

If you have a CAD package then just draw one circle and then use a circular pattern to spread the holes around the circle. you will be able to see what spacing and numbering works just by scrolling the number of holes up or down

[John HaineParticipant @johnhaine32865]

Do you really need 1mm holes? Is this for direct division of a degree scale? The thing is, drilling a 1mm hole in a bit of plate thick enough 360 times without the drill wandering, breaking, or getting blunt sounds a bit of a challenge.

[SillyOldDufferModerator @sillyoldduffer]

Fingers crossed this is right!

Dave

[not done it yetParticipant @notdoneityet]

If the given disc size is 160mm, there is not a lot of point in trying to cram 360 holes, of 1mm diameter, into one ring and no point in suggesting a disc in excess of 287mm.

Neil has provided one simple solution to the problem (odds on one ring and evens on a second, or more rings). The other alternative is to reduce the hole diameter.

[SillyOldDufferModerator @sillyoldduffer]

Posted by not done it yet on 22/07/2017 10:23:11:

If the given disc size is 160mm, there is not a lot of point in trying to cram 360 holes, of 1mm diameter, into one ring and no point in suggesting a disc in excess of 287mm.

…

I'm not suggesting actually using a disc in excess of 287mm, that's just an example of the 'How big does the disc need to be' formula in action. The formula addresses John's Original Post which asked 'is there some sort of formula or calculator?'

Dave

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