With my dividing head is this possible

[David S Newman]

I have a dividing head 60 to 1 ratio I need to divide 125 divisions, the two plates I have are 60,46,38,34,31,29 and 78,66,42,32,27. My old brain can't seem to work it out or is it impossible with these two plates ? Can't seem to find a common denomenator with these. David

[oldtiffie]

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[dm1try]

I have a dividing head 60 to 1 ratio I need to divide 125 divisions, the two plates I have are 60,46,38,34,31,29 and 78,66,42,32,27. My old brain can't seem to work it out or is it impossible with these two plates ? Can't seem to find a common denomenator with these. David

it's not possible. with your plates you can't do

37 41 43 47 49 53 59 61 67 71 73 74 77 79 82 83 86 89 91 94 97 98 101 103 106 107 109 111 112 113 118 119 121 122 123 125 127 129 131 133 134 137 139 141 142 143 146 147 148 149 ...

i have a little calculator at http://mmcd.meditprofi.ru/machining/dh.html you can save the html code to a hard disk if you like, it will work from there just fine.

[SGW]

I think you're dividing the wrong way. It's 60/125, or 12/25, so you need a 25-hole circle (or some multiple of 25) to do it.

[lynnl]

Oldtiffie, I think you have your fraction inverted, ie. should be 60/125.

With a 60:1 ratio 60 turns will yield one round-trip. And we want to DIVIDE that into 125 pieces. ergo, 60/125 or 12/25. So we'd go 12 spaces on a 25 hole plate (or 24 spaces on a 50 hole plate, etc).
But alas, to David's great disappointment, he doesn't have one with a factor of 25.

[David S Newman]

Thanks for your replies. made me quite happy, thought I had signs of my brain needing a rebuild. David

[John Stevenson]

One reason why on our division plates we put three extra hole sets, 25, 63 and 127.

125 division is a common one if you want a dial for an 8 tpi screw.

Failing this Evan has posted a way using a sticky label strip.

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[edit] And before anyone asks, yes I am doing the special 5" plates once we get this last show out of the way this weekend.

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[oldtiffie]

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[David S Newman]

One reason why on our division plates we put three extra hole sets, 25, 63 and 127.

125 division is a common one if you want a dial for an 8 tpi screw.

Failing this Evan has posted a way using a sticky label strip.

.
[edit] And before anyone asks, yes I am doing the special 5" plates once we get this last show out of the way this weekend.

.

Yes John, that's what I need to do , make a dial for a 8 tpi feedscrew. David

[oldtiffie]

As said

Sorry.

You are right and I am wrong.

Thanks for the check and advice - appreciated.

I sure am glad that David did not proceed on my advice!!!

I have "re-worked" the figures which confirms my error and that everyone else is correct:

1/125 = N/60 (N = number of turns of indexing arm)

60/125 = N/1

12/25 = N

So to use indexing arm requires row/s with multiple/s of 25 holes. So cannot be done with existing set of plates.

[oldtiffie]

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[John Stevenson]

Tiffie, About halfway down, there is a mis print ..


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[Lew Hartswick]

oldtiffe, That is the way "real" machinists do it. :-) Or is that engineers??
...lew...

[oldtiffie]

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[oldtiffie]

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