On Thursday 18 June 2020 02:32:24 Chris Albertson wrote: > In the US, the traditional system uses teeth per inch. but the problem > with this system is "where do you place the tape measure?" The answer > is NOT around the outside of the gear. You need to place the tape > such that it runs inside the teeth. this is hard to do. Also here is > a quiz: You have two gears both 4 "pitch" both are 30 teeth, what > is the center to center distance? Can you figure this out in your > head quickly? I bet not. > > Outside the US everyone uses a simple system. They define "diameter" > as if the gear were a smooth roller. So two gears with 40mm diameter > would have a 40mm center to center distance. Then they define > "module" as teeth size that mesh. so any mod 1.0 gear meshes with any > mod 1.0 gear. A mod 0.2 gear meshes with other mod 0.2 gears. > > Then and here is the key... "module is the diameter divided by the > number of teeth" > > Example > (1) A 40 tooth 40mm diameter gear is module 1.0 it meshes with a > 20T 20mm diameter gear and the center to center is obviously 20+10=30 > (2) I just printed a Mod. 2.0 gear with 100 teeth. How big is it? > Well, some algebra: 2.0 = D/100 So D=200. It is about 200mm across. > it is HUGE and covers up most of the build plate on my printer. The > mating gear is 25T and you can easily work out the shaft distances > without the need of a table. > > In real life most designs use even number modules like 0.5, 1 or 2.0 > so there are only a handfull of sizes and you learn to identify them > by sight. > > So what is the "pitch" of a mod 1.0 gear? assume 10T and 10mm > diameter. The circumstance is 10*pi = 31.4159 mm with 10 teeth the > pitch is "Pi millimeters" for Mod one. For mod 2 the pitch is two Pi > mm and so on. > > You don't need a calculator to design stuff with metric gears. > > Today there exist countless US standard gears but I can't imagine > anyone using them in new designs. Even in the US, the industry is so > globalized that everyone has switched over. > > > > > On Wed, Jun 17, 2020 at 10:43 PM Gregg Eshelman via Emc-users < > > [email protected]> wrote: > > Module is the Metric version of gear pitch. A google for module gear > > chart will tell you everything you need to know. There are also > > module <> diametral pitch converters online in case you're using > > gear design software that only does Mod or DP but does allow input > > of arbitrary numbers. > > > > My you never ever encounter metric machinery with Mod 2.5 gears. > > It's Metric gearing's version of 14 DP, for which you don't want to > > have to come up with replacement gears.
Excellent tut. Makes perfect sense. Thank you Chris. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
