On Monday 15 June 2015 17:46:40 Eric Parsonage wrote: > Gene > > Isn’t this simply a case of doing the maths for at a small section of > the shaft/hub? So imagine you have steel incline with an aluminum mass > on it with a vertical force exerted on the aluminum mass. The reaction > against the slope induces a force in the horizontal plane. the only > thing that stops the aluminum mass (your hub) from moving along the > slope is the coefficient of friction between steel and aluminum. > > So put simply the angle where you will have equilibrium (i.e. the > point at which the shaft becomes self locking) = arctan(coefficient of > friction between the two metals) obviously to make it self locking you > would deduct a couple of degrees from this and to make it self > releasing add a couple of degrees to this to account for variation in > materials. > > > A quick google found me a table of coefficients of friction of various > combinations of brake materials > http://www.engineeringtoolbox.com/friction-coefficients-d_778.html > <http://www.engineeringtoolbox.com/friction-coefficients-d_778.html> I > would use the greasy oily column. In fact steel on steel in this case > gives arctan(0.16) which is approximately 9 degrees for the point of > equilibrium (neither self locking or self releasing) subtract a couple > of degrees to ensure it is self locking and the result is as you > predicted. > eg the same 7 degrees. And at that angle it should be relatively easy to tease apart should I want to later.
Now to get the GO704 XYZ converted as its the only thing I have that will do a 6+ inch circular cut. 6.7875 according to the stock screws. But the ball screw kit did not show up today. And I am wondering if I can worry a piece of 1"x.125" bar stock into a rim for it. Or if I have to make two, and superglue them together to get the width to use the whole, nearly an inch wide treadmill belt? Either way it will take the GO704's full Y motion to make it, the lathe simply hasn't enough swing even if they have claimed 7" for the last 40 years. What I am trying to do is get the power I have dependably into the spindle since I am out of transmission ability when the alu workpiece exceeds 2.5 to 3" in diameter now. Or about 1.125" in steel. The power is there to break or burn up the plastic parts now. And I am running LMS out of spares. :( Local guy has a 110+ yo Porter, about a 16x96 bed, sitting out in the weather but the last time I grabbed a carriage wheel it could be turned as could the spindle. Assume babbit spindle bearings, they are capped. Its mine for $500, maybe less. But how much are ball screws big enough to move that old hog? The existing carriage screw is about a 1.375" acme. If I have to ask, I can't afford it... Needs at least a 10 horse for the spindle too. Current, rusty chuck is about a 14", 6 jaw, I assume a scroller but didn't look that close. Tool post etc I'd have to make. I'd guess its weight at about a "Merican" ton as its on fancy cast iron legs. But I keep dreaming of having a lathe that big, someday... > Eric > > > On Jun 16, 2015, at 5:03 AM, Gene Heskett <ghesk...@wdtv.com> wrote: > > > > Greetings; > > > > Building on an idea Andy suggested earlier today. > > > > Somewhat entending a thread on tapers I started a couple years ago, > > now I would like to be advised on the taper angle to use, where the > > tapered ring being wedged in to the hub is steel and the hub is > > moderately hard alu. > > > > I've done quite a bit of googling, and read the older threads here, > > but the closest I've come is an included angle in the 14 degree > > area, or 7 degrees off axis in cnc terms. No one has discussed the > > effect of dissimilar metals that I have noted in skimming about 65 > > old messages or in the google outputs. > > > > My copy of #27 is out in the shop, and the weather is wet and noisy > > and I'm still pretty well crippled up. I could get there, but it > > would likely cost me another painful, sleepless night. > > > > Is it in there (#27), or are there some general rules of thumb that > > govern this to a "first pass that will work well enough" accuracy? > > > > Thanks everybody. > > > > 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) > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > -------------------------------------------------------------------- > >---------- _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > ---------------------------------------------------------------------- >-------- _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
