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David S Newman
08-23-2009, 02:54 PM
I have aquired a dividing head which has a ratio on the worm of 60 to 1. I need to make a 360 degree scale on a project. Sat down and tried to work it out, came up with using a 66 hole plate I would need to advance 11 holes at a time for 360 degrees, is this coirrect? Please is there a simple formula to work these things out? David

TGTool
08-23-2009, 03:15 PM
I find it easiest to do these thing as fractions, dividing to the lowest common denominator, then mutiplying to find a hole plate series that will work. With the 60:1 ratio and your needing 360 holes, the ratio is 60/360. That is, the number of turns per full rotation offered by your dividing head, divided by the number of positions you need. If you think about it, one turn each time would give you 60 holes. One half turn each time would give you 120 holes etc.

So you need a turns proportion of 60/360 or 6/36 or 1/6 - that is, one sixth turn of the crank each time to get your 360 division. Now any plate circle that has a multiple of 6 will work. One hole in a six hole plate, two holes in a twelve, three in an 18 etc. If you've got a 24 or 36 hole plate that would work out to every 4th hole or every 6th hole.

Pherdie
08-24-2009, 01:20 PM
Sat down and tried to work it out, came up with using a 66 hole plate I would need to advance 11 holes at a time for 360 degrees, is this coirrect?

While TGtool's response is absolutely correct and contains excellent information, I think you may be looking for a more direct answer. The answer is "Yes".

Don't forget that you will have 12 holes between your sector arm spacing. One hole will be your current working position and 11 more holes to advance to your next working position.

Good luck.

Fred

Glenn Wegman
08-24-2009, 01:34 PM
This may be of help.

Instructions:

Indexing Chart:

Uh Oh......40 to 1 chart!

Sorry!

old-biker-uk
08-24-2009, 02:15 PM
My 1941 Machinery's Handbook has the indexing settings for a 60 tooth dividing head, I could scan them no problem.
Mark

David S Newman
08-24-2009, 03:12 PM
My 1941 Machinery's Handbook has the indexing settings for a 60 tooth dividing head, I could scan them no problem.
Mark

That would be great Mark if you will do that for me. David

old-biker-uk
08-24-2009, 03:41 PM
David