On Wednesday 11 July 2012 07:42:56 andy pugh did opine: > On 11 July 2012 02:14, Gene Heskett <[email protected]> wrote: > > And that seems to have worked, for this particular final size. Is > > there any way to effectively predict which will give the correct > > result > > One function rounds up, and one rounds down, so which is correct > depends on the calculation being performed. > (The behaviour with negative numbers needs to be checked too, I think > they round away from zero and towards zero respectively, rather than > actually up or down) > > > Either that, or make me another taperlock hub. That at least would > > allow me to take it back apart, which the roll pins would make a > > right PIMA if not impossible. > > Here is an idea stolen from Wohlhaupter (a screw with two different > thread pitches) [ first 3] I made a similar screw to hold a taper together: > https://picasaweb.google.com/lh/photo/fOViOE1sue9y5d2MWi_w-9MTjNZETYmyPJ > y0liipFm0?feat=directlink And then a screw extension goes on > https://picasaweb.google.com/lh/photo/XKsl4J8YIO6HccM04_sr8NMTjNZETYmyPJ > y0liipFm0?feat=directlink And you then tighten the taper up by turning > the screw _antoclockwise_ through this hole
I think you meant anti-clockwise. The screw I assume was a long stock sized allen socket setscrew with the newer, smaller thread cut on the end? Having toured the lumber yards and tractor supply locally, that is something I'd have to get from amazon or ?? > https://picasaweb.google.com/lh/photo/uM-sArsbLcD6GVG_nqK0LNMTjNZETYmyPJ > y0liipFm0?feat=directlink I like that idea, but I'm working with an 8mm screw, not the 20mm or more in the last 3 pix. So by the time I grind the taper on the end of the ball screw, and drill & tap the end for this special screw, I expect the maximum practical thread into the end of it will be no more than 5mm. Tensile strength of that would be about equ a 4mm rod, not exactly an unbreakable item. But it certainly looks to be do-able if I can get the tapers to match. I have drill rod in 1/2", but no tools to do the allen socket for tightening it, so I'm thinking of making the screw out of drill rod, and long enough to reach all the way through the extension so it could become a cap screw, or for knuckle safety since that would then be in the middle of the miniature hand crank (its pretty, and impresses the local frogs when it spins all by itself, but putting it back on is 100% optional at this point), an acorn nut. Once its pulled into that very low angle taper, does that same differential thread have the cojones to eject it again after 4+ years for it to get good and stuck? Since I don't have to transmit the motor torque thru that taper, I am tempted to use a shorter, higher angle taper since the important part is constraining the ball screw against any longitudinal slippage. OTOH, a similar setup at the rear, where my motor is, looks like a good way to make it dis-assemble-able from that end. I have a flexible coupling back there, but the screw could just as easily be ground to .250" and the coupling used directly instead of the roll pin and slotted to fit the roll pin cup there now. That slightly restricts the cross-slide motion by about 1/4" now and I would not mind getting that back a bit. The OEM screw could have been about 10mm longer. And that couplings clamp screws were removed and coated with never-seize easing their tightening and are 1/32 of a turn from broke/stripped, plus some locktite super glue by the time I had stopped the slippage. That is a 425 oz motor. It should have had a 10mm shaft, but its .250", D flatted. PIMA to keep the setscrews tight where I did use them. All food for thought, and as has been said, the pix are better than 1000 words. Thank you Andy. 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! BOFH excuse #262: Our POP server was kidnapped by a weasel. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
