On Tuesday 16 August 2016 11:41:37 andy pugh wrote: > On 16 August 2016 at 16:02, Gene Heskett <ghesk...@shentel.net> wrote: > > Is that amount of > > reduction fast enough for the ins and outs of a G76 threading > > operation? > > The 9x20 lathe has a 1:1 geared NEMA23, and actually works fine. > ( https://www.youtube.com/watch?v=nIYMfyf4jDI ) > > > Thats neat, using the bikes timing chain cut to size. Is that a > > servo or a stepper behind the apron? > > It's a 900W servo. I decided not to mess about with that lathe :-) > It's quite quick, and I haven't actually done much tuning yet (It > probably ought to have cascaded PID as it runs torque-mode)
Well, I am trying to use what I "brung to the party" if I can. IF I drill & tap the front of the saddle for half a dozen 6mm screws, and hang the new apron on the front of the saddle, I have enough room for a 262 oz stepper if I cut the back shaft off. With a center cutout for the crossfeed, iot will come flush with the face of a half inch thick apron. Projected size of the new apron is 11.5" long, 7" or a bit more high, & 1/2" thick. Its weathered quite a bit, so will need painted. Color? YTBD. :) There's only one problem, the Z screw, if mounted where the old on is, will be nearly 3.5 inches from the back face, so I'll have to make a big long pad for the Z nut to interface with it. I have an alu block or 2 that will do that. The X screw handle housing can be cut back to where a timing pulley will align with one on the motor. Do that while I am fitting it for bearings. Set a pulley ratio of 2/1 and it should still be fast enough for G76 threading. The new apron will be somewhat ventilated as I'll take it out of the relatively clean center area of an ampex VR1200 deck plate which had some sort of inserts for screws installed in slightly bigger holes. None project above the face of the alu on either face. So, since everything is being cut to fit, thats the next piece of this project. I'll need to plug a few holes where parts were mounted but thats NBD. Everything else has to fit it. As far as the top cover over the X screw goes, once I am driving it with the motor, (and this motor has been spun at 3k rpms on the table with a good high voltage supply) I'll run it to the back side limit, and saw off the surplus 8" with an angle grinder. Then cover the open top with a sheet of 1/8" alu. With a swarf shield hanging down to just below the rear end of the screw. I just tried to remove that crossfeed extension, but apparently the gibs are one piece so the dog screws have it solidly stuck. Thats adjustable with the angle grinder of course. Now, where did I stash the hacksaw blades for my saber saw... I'll cut it out, then make it neat on the mill. Including an oblong recess in the lower face the motor, with a jackscrew to adjust belt tension. Oops, that screw will need to be available from the front when its installed. Mental redesign of motor mount in progress. How about a total cutout 1/32" wider than the motor to set a 1/8" thick slider with full length holddown strips on the front. A 1/16" deep, 1/4" wider than the cutout relief in the front of the cutout, and the 1/8" holdowns cleared 1/16" deep & 1/8" wide on the back face to guide the slider. Slider long anough to cover the hole regardless of where the motor is pulled to. Fugly but with a draw screw from the bottom, it should work fine. This will definitely keep me out of the bars for a while. ;-) Thanks Andy, your pix made me think. Where did you wind up putting the cable chain to carry motor power and limit/home switches? I like it on the rear, but I'm not in love with carrying them across the saddle. But with the inevitable tool collection laying in the chip pan, down in front is a disaster waiting to happen, like cracking concrete. 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
