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I'm not finding a way to determine what spur gear I can run on a rack I have?

DMSentra

New member
The tooth angle is 14.5deg per side, linear pitch is .448" (edited) averaged from 9 teeth using .25" endmills in the gullets, if I remember right. All the videos and websites I've gone though the last week either have confused me to the point I missed it or hasn't taught me how to work backwards from rack to spur gear. Am I right in figuring the .488 isn't a nice, pretty round number because the circular pitch of the original mating gear made it so? Would that have started out at a .5"cp and I can work the linear backwards from that somehow, or is that just silly?
 
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john.k

Active member
If the rack is off a machine,the makers match gearing up to the design requirements of the machine.....not to a standardized gear chart.....in any case .488 seems like 12mm to me.
 

DMSentra

New member
It is off an old HBM. I think I have to correct myself in that I think it's .448" pitch, not .488. I just found Pi/CP=DP. That takes me to a 7DP gear? Is my math at least correct?
 

Mark Rand

Active member
Yes, that'll be 7DP. It's not, actually, all that uncommon for racks for quills and similar on machine tools (meaniing that my Beaver milling machine uses the same pitsh on it's quill :D).
 

DMSentra

New member
Yes, that'll be 7DP. It's not, actually, all that uncommon for racks for quills and similar on machine tools (meaniing that my Beaver milling machine uses the same pitsh on it's quill :D).

Woohoo! Confirmation I actually have something gearing figured out.
 








 
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