On Tuesday 16 August 2016 05:55:21 andy pugh wrote: > On 16 August 2016 at 03:36, Gene Heskett <ghesk...@shentel.net> wrote: > > If anyone has links to pix I can steal ideas from, plz post them. > > I did have some that were embedded in a cnc-zone post, but it looks > like that hosting service has disappeared, and taken the images with > it. > > The trick I used on my mini-lathe was to have a relatively small > toothed-belt pulley that could fit under the cross slide with a > needle-roller to resist the belt tension, and then put the > thrust-bearings rather further outboard in the manual-handle > extension.
Both of these lathes can come out past the front of the carriage, but if I restricted that, no biggie. My thrust bearing is in the original shaft bearing, a set of ball washers in the little monster. What I haven't measured yet in the Sheldon is the room under the z screw to hide a short nema 34 motor like you did in that pix. Is that amount of reduction fast enough for the ins and outs of a G76 threading operation? Thats one of the considerations that made me put the motor on the rear of the little monster so I could direct drive a longer nema 23. Rapids are right snappy, even the z with its 2/1 stepdown can make 60 ipm. Thats an 8 wire, in parallel, 425oz motor, whereas the x is a 272, 8 wire, parallel. > The Holbrook was easier because the cross-slide never came further > than the front of the apron. > https://goo.gl/photos/ZA19udQrNAoTnRUv7 Thats neat, using the bikes timing chain cut to size. Is that a servo or a stepper behind the apron? I need to take some pix so you all can see what I am up against here. The x screw was anchored at the far rear, on the taper attachments slider. All that is coming off, but unless I rebuild the x handle, thrust is not its strong point as it is connected to an extension of the X screw by its slotted shaft, with a hardened pin engaging the slot in the extension to turn the X screw. It essentially floats in the screwed into the saddle edge plain bearing. With no heavy thrust, it has now worn. I've ordered and have ball thrust washers for that handles shaft, and could buld a new shaft running on torrington rollers to take the side thrust, and if I build that shaft again, the pin drive and handle would leave, and another of my compression couplings could grab the shaft for both turn and thrust. And a gear on the inside end that can be driven by the gearshift in the apron. Its very difficult, needing prybars, to effect that gear change, and the clutch is very weak, so that whole apron will be history. I may as well figure on moving it with the computer, or not at all. If there's room on the back of a new apron for the motor, I believe thats what I'll do as it rather handily removes all the gingerbread of the taper attachment without creating a motor mount nightmare. I'll go take another look/see as to making room for the torringtons in that screw in X handle carrier. And how much room for a motor if that apron is replaced by some 1/2" alu I have. Thats in the plans since its not usefull as is. Thanks Andy. 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
