On Monday 27 March 2017 00:17:19 Erik Christiansen wrote: > On 26.03.17 18:53, Gene Heskett wrote: > > But is 7 the correct factor? It should be fairly easy to jack it > > back out. > > Gene, I've never made one of them, but looking here: > > http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&ved= >0ahUKEwiE6q-q5PXSAhWGKWMKHeZIAf0QFgg-MAc&url=http%3A%2F%2Funiversalbear >ings.com.au%2Fdownload-subproducts%2Ftaperlock-bushes&usg=AFQjCNGOFIvAU >jPQ1JccxaHkdEjC0hT5oA > > the first bush in the table seems to be: > > atan((35.2 - 33.7)/11.1) = 7.7° included, near as dammit. > A bit steeper than my 7 degrees. I don'r recall now, although the code should still be in the nc_files directory on TLM, the angle or how I calculated it then as thats pushing a decade back up the log.
> They have a threaded half-hole on the perimeter, for a jacking screw, > so I figure that 8-ish degrees will not fall out as soon as you loosen > the screws. I've looked at those and wondered if that threaded half hole was enough to drive it tight. Thats also considerable thicker metal there, meaning it better fit very good because the crush is limited. So in the three I've made, Z on the sheldon is made with the external flange for the push/pull. 3 bolt version. Figured I had to as that 25x5 screw came with the driving end turned down to 10mm! I expected at least 14mm, but the thrust bearing was of a similar bore. Its also shloppy, 7 thou backlash, 5.5 of which is in the (mumble) thrust bearing. Fairly easy to get to, I intend to shim that for some preload before I do serious work with it. Doing it with the flange, I can leave thinner metal, which makes a good crush easier to get. I'll do this hub, then the pulley to the same angle, smack them together good, take it to the mill and locate the center of the hub, then drill the 6 holes, 3 with screw cleance, and 3 threaded for the screw but only the 3 with clearance get drilled by the tap drill into the pulley, and all 6 rigidly tapped. Due to a limited space between pulley face and flange I will probably have to eject it and finish tapping the flange for the jack screws. Then EDM the taper into 4 petals for an easy done death crush. Leaving room for the woodruff key internal as I don't know exactly where in the bore that key winds up being. The shaft can move within the pulleys and bearings some as its actual lengthwise placement is controlled by the right hand bearing boss, the 4 step pulley rides the right face, and this pulley rides the left face, effectively controlling the end play. A fibrous washer sits between the pulleys and the bearing boss. Those look to be in decent condition so they'll get cleaned and reused. The lower shaft of this is also spinning in the same bronze, but doesn't seem to be heating even when the vfd is up to 150 hz! It turns at a fixed ratio from the motor, perhaps 750-850 revs when the vfd is cranked. The upper shaft has much more radial loading, and dependent on the pulley sheave the intermediate drive belt is in, could be doing up to nearly 3k revs. So that one gets the Koyo needle roller bearings for sure. That ought to out-last me. I'm not done adjusting the shimming of the spindle bearings. In the final fit, and at a decent speed with fresh 10w in the oilers, I'd like to see only maybe 5F heating with it running on the hydrodynamic oil film. In backgear below 100 revs, that will leave a measurable slop. Currently it runs up about 20F on top of the bearing caps, and there is no measurable slop. I can see perhaps .0002" of springy wiggle at the spindle flange with a 3 foot pipe in the chuck and me pushing, pulling, or lifting on the far end of the pipe. Not bad for a machine close to 70 yo. :) Did I mention I love bronze spindle bushings? :) Unlike ball or timkins, much easier adjusted for wear, and these don't seem to be worn a bit. Some minor polishing, but plastigage can't see it. This one has the ball mounted right foot, and some Navy stamps on the back of the bed. > So long as both parts are made with the same topslide angle setting, I > wouldn't fuss about 7° or 9°, or something round about close to that. > If the shaft isn't too shiny, and your bush bore isn't too polished, > then there's probably no need to go for the smallest angle (for > tightest grip), and another degree or two (included) will be a bit > easier to dismantle. The shaft is well polished, and HARDENED and I'll have 3 jack screws, so the 7 degrees sounds about right. Tightening these is a matter of going around, hitting each screw in turn maybe 20 times before they're really tight. Jacking is the same, moveing each screw maybe 10 degrees as you go around them the first time, so you don't mushroom the point of the screw. Don't force it going either way and the screws if 8.8 or better, will last forever. TV transmitters, if air cooled, make one familiar with the care and feeding of a taperlock because on the GE's the pulley ratio get changed according to the season. RCA had a set of variable speed pulleys, wore rapidly IMO. > > I can see why you're making them. There's not much in them, and with > prices being mostly loony if the goods don't come from China, it's > well worthwhile. > > Erik And, I can have it done 3 weeks by the time the Chinese part arrives. :-) Thats about the time frame of getting a 4th bearing just for the upper shaft, so I'll have plenty of time to make the bearing pushers before they get here and I'm out of excuses to just "git-r-done". :) Thanks Erik. 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> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
