On Friday 29 July 2016 12:21:31 Gene Heskett wrote: > On Friday 29 July 2016 11:20:57 andy pugh wrote: > > On 29 July 2016 at 16:06, Gene Heskett <[email protected]> wrote: > > > For those interested, it actually looks easy if a mill is > > > available. > > > > > > <http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12- > > >Pr ojects/TaperedSaddleGibs/> > > > > Or my way, which was even simpler: > > https://picasaweb.google.com/108164504656404380542/Gibbs > > > > First 14 pics. > > Picassa is in a shutdown mode, and nothing displays there now. > > There is a message link there now. > > > In brief: machine an angle. Set straight. Clamp some brass in there, > > machine both at the same setting. Fit. > > > > But it seems crazy to go to so much trouble to improve one lathe to > > make a part for the other. Why not make a not-so-good part on the > > little lathe, then use the Sheldon to make a better part for itself? > > Because the bronze crossfeed nut, has been bored out and cobbled up > with a brass helicoil insert, and is about 5 thou from stripped again? > Its a 10 tpi screw, and the backlash at the handle is about 90 thou, > so there is very little brass left to engage the square threads of > that screw. > > And the compound gibs are some sort of home brew that are too short to > allow proper adjustment? Ed Nisley was kind enough to supply some > shim stock, so I can tighten that up but they'll still be an inch > shorter than factory on the load bearing end > > And I've not a clue how much bed wear there there may be. That looks > good, but until I have made some longer turnings, no clue. > > But this is precisely why we need a cross-coupled screw comp that LCNC > has to cobble up with lincurve. What it really needs is a 3 var format > for the zcomp file at least, where the 1st var is the current zpos, > the next one is the real zpos, and the third one is a corrected xpos > at this zpos to be used to correct the xpos at this zpos. The only > thing that can't correct is the tool tip contact height as its > traverseing a worn bed. > > Using lincurve, it may be possible to arrive at something that is > useable because it can interpolate between points, but it seems it > would more properly be done by sending the xpos to the file input of > the x driver so it can be corrected at 50-100 points of the z range as > it fixes cheap screws where the pitch may even have a cyclic variant > per rev so you'd have multiple points per turn. > > Because there is so much to fix just to make it useable before it > grows motors, I may as well bypass that by tightening up the little > monster. It would be weeks faster to 1st swarf on the Sheldon at my > speed. :( > I got the jig made today, and cheated on the taper. I put the Sheldons tapered gib thats a bit ( about an inch and a half on the big end ) too short under it to set the taper, so at some point I can make a longer, thicker one for the Sheldon's compound on the same jig. Likely out of brass since I found a piece that should make all 3 of them in the bottom drawer. Went out to TSC to get the hold-down bolts for the jig, and found they had some stock on the metric stuff to finish up the little monsters conversion. Including a 3' bar of 1/2"x1" hot roll to make the gib clamps out of. That will need to be made 3/4" wide, but thats doable. I think I'm making progress anyway.
Motor bearings and RS-485 adapters haven't found me yet though. Too many projects... > Does this help explain it? > > Thanks andy. > > Cheers, Gene Heskett 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
