On Friday 29 July 2016 05:07:02 andy pugh wrote: > On 29 July 2016 at 02:49, Gene Heskett <[email protected]> wrote: > > There does appear to be a flat on > > the tip, perhaps a thou wide. > > Should there be? > > What exactly, is this tapered thread? > What I am attempting to do is have, at the end, a wrapper for G33, that will cut a tapered thread to make both outside, and a nut to fit it, to serve as a compression gripper to, in this case, extend the end of a metric teeny ball screw to fit in the hollowed out (by Sheldon) shaft of the front handle, which has an internal drive pin/key that if a slot is machined in this 3/8" diameter extension, can drive the handle from the motor attached to the rear of the carriage, or if motor power is off, allow by hand operation. I intend also to put a similar setup on the Z drive, so that it also can be hand operated. But that will likely be on one end or the other of the Z screw. Probably the right end once I engineer the motor mount for the Z drive. Unfortunately, there is not a suitably flat spot to bolt anything to on the right end of the bed, so I expect I'll excise all the gears on the left and make a shaft extension, probably using this code again, to extend the Z screw far enough to the left from its thrust anchor, mounted where the gear shift was, about 9" to a third bearing left of the change gears, or coupled directly to the big motor mounted of the change gears panel via standoffs. I figure a 1050mm 20x5 screw can drive it, but that hasn't been ordered yet.
This whole thing is at this point, being delayed to up the precision of the little monster I have to use to make this stuff. I had the pages bookmarked for Rick Kruger's conversion of this series of lathes to a tapered gib setup, so I printed that whole thing last night. I have a block of alu plenty big enough to make the jig, so all I need to round up is a foot of 1"x.250" brass for the gibs, and some 1/2x3/4" stock for the gib clamps. And a bunch of screws. With that, I'll be off to the races. The current problem with the little monster is it cuts a different size by 4 or 5 thou, depending on which way the carriage is being driven. This is due to looser than optimum front gibs allowing the carriage to climb the slope of the v-way. And short of removing the z screw, no way to properly access the gib adjusters so the proper adjustments can be made. So an attempt to make Ricks tapered gib setup is going to be made. For those interested, it actually looks easy if a mill is available. <http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12-Projects/TaperedSaddleGibs/> I have that motor, psu and driver in Nema 34 size, that I removed from the G0704 because it was too slow, and will see if that psu can handle that 8 wire motor wired parallel, because it simply cannot spin more than 20 or 25 rpms wired series. Its a 1600 oz/in monster, and buckets of inductance when wired series kill its speed. > Note that in the US there is a flat on the thread, but the flat size > is modified to eliminate the spiral leak path: > https://en.wikipedia.org/wiki/National_pipe_thread > > In the rest of the world the thread-form is Whitworth, with rounded > peaks and troughs: > https://en.wikipedia.org/wiki/British_Standard_Pipe > > To add to the fun, one is 60 degrees and the other is 55 degrees. Which may be the better form for ultimate tensile strength. Not to mention that the rounded tips and valleys make a stress distributer, so it has to be stronger. But I'd imagine those taps and dies are a bit pricy due to the more precise machining involved. To complete that why not, there is the N.I.H. factor here in the states, and obtaining them is probably only from off-shore locations, with, except for China, prohibitive shipping costs. 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
