Power gear sets with spur gears (as opposed to worm gearing) are usually
designed with non-integral ratios to assure that all the teeth on one gear
end up contacting all the teeth on the other gear. This promotes uniform
wear and longer life for the gears. Therefore it is good to "count the
teeth" when using such a gear reduction unit if accuracy of ratio is
inportant in your application.
Wannabee Taig CNC Mill Owner
----Original Message Follows----
From: "Larry Richter" <cattaraugus@...
Subject: Re: [taigtools] DIY Dividing Head Question
Date: Sun, 29 Feb 2004 21:12:15 -0800
Really depends. Helical gears are nice, but is it absolutely, positively,
exactly 24 to one? Intended to stick a small Dayton gear box into a marine
drive-turret position indicator once, but it turned out the stated gear
ratio was only nominal. Had to build a custom indicator gear box after all.
----- Original Message -----
From: "e3pi" <e3pi@...>
Sent: Sunday, February 29, 2004 7:59 PM
Subject: [taigtools] DIY Dividing Head Question
> I've zero experience with dividing heads, but I am excited with
> their 40: 60:1 precision leverage and ease for general dividing the
> circle; and possibly used for linear ruling too; I imagine.
> I've a Dayton 24:1 Gear Reducer.
> This has helical gears with negligial backlash that I can tell.
> It is small enough to be "Taigable".
> From reading I see 60:1; 40:1 are common for dividing head worm gears.
> Note also worm gears lock position on the non-"pinion" main gear
> axel - i.e.; the main gear angular displacement cannot drive the
> "pinion" or "worm" - which is a benefit for machinery set up.
> This Dayon gear reducer will drive either axel; i.e., 24:1 or 1:24;
> as desired. This could be a problem.
> One small grace advantage:
> "24" is a "highly composite" integer(24=4*3*2*1=4!); makes for easy
> arithmetic shared among common fractions of 360 degrees.
> So aside from half to a third the precision of other DH's - is this
> a reasonable source on the start of my first DIY dividing head?
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