On Saturday 07 November 2009, Erik Christiansen wrote: >On Sat, Nov 07, 2009 at 10:21:29AM +1100, Frank Tkalcevic wrote: >> While on the topic of toothed wheels, is there a standard forumula for >> timing belt pulley tooth profiles, in particular MXL style? > >Looking in my local suppliers catalogue, there's only dimensions for HTD >synchronous belts. i.e. those with the semicircular teeth. > >One of the first things I'd like to make, once EMC is going, is some >matching pulleys. Since their gullets seem to be a semicircle centred on >the tooth tip diameter, I thought it might be possible to make a pulley >with cheeks as follows: > > Turn a groove in the circumference of the pulley blank, sized to > accept the body of the belt. > > On the rotary table, on the mill, drill the gullets through one side, > at the turned diameter, stopping at the opposite cheek. > >Even a slot drill would probably leave tiny burrs on the through hole, >some roughness on the opposite cheek, and sharp edges on the tooth tips, >so perhaps such a pulley would chew up at least the first belt run on >it. > >Turning after drilling would eliminate the burrs, but what a racket it >would make! Now, would the semicircular tooth snag the sharp tooth edges >on entry and exit, I wonder? > >Erik
If you are a handloader, and have a case tumbler/rumbler for cleaning and polishing your fired cases, and your parts are alu, a day in that should pretty much take care of the really sharp burred edges. I have used it for steel parts too, but it takes several days for steel to polish up. Another thought would be to turn the profile with the flanges, then put it on a rotary table mounted 'A' style, and carve the grooves with a ball nose mill. The slight radii at the ends where you stop at the flanges will probably just wear in both the belt and the pulley without even damaging the belt, if the sharp edges are rumbled off as before. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> Education is the process of casting false pearls before real swine. -- Irwin Edman ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
