I don't think I'm ready for yet another hobby (3-D printing), so I think I'll just put an oversized motor and pulley.
Gene -- What stepper family are you using for the lathe? (A link, please.) Regards, Ken Kenneth Lerman 55 Main Street Newtown, CT 06470 On Fri, Feb 4, 2022 at 12:25 PM gene heskett <ghesk...@shentel.net> wrote: > On Friday, February 4, 2022 10:31:23 AM EST Kenneth Lerman wrote: > > Chris -- At my house, computers are all over the place. I think I have > > a spare atom floating around. Also a couple of other machines. > > Gene -- The grinder is here. > > <https://drive.google.com/file/d/1L8JiX0rtDZO99rVnQKNjUH7m-ZgFz2Un/view > > ?usp=sharing> The > > ways look pretty clean. The only accessory I have is a magnetic chuck. > > > Cute little thing Ken. And with a mag chuck, you stole it. > > > I don't really need a surface grinder, but no shop is complete without > > one. Once I started to use it, I realized that my right arm and > > shoulder really aren't suited to this type of manual work. > > As the senior member here, I get to complain first :) But you're excused > ;o) > As to you gear ratio problems, I agree, which is why I designed a small > variation of a harmonic drive for use on the A axis of my 6040 mill. But > its too small I think for what you want to do. But the 3d slicer "cura" > can scale, and if you've a 3d printer that can handle PETG, one of the > higher temp plastics, on an everyday basis, this thing scaled up 200% > should do the job for you ok. Gear ratio, about as high as it can go at > the native size is 50/1 but could be as low as 30/1. > > I'm driving it with a 1NM version of the new 3 phase stepper/servo's, but > that family of servo's can be had at 3NM or about 425 oz/in, as all have > an 8mm diameter d-flated shaft, which I put on my milling machine, power > up to lock it and make the flat bigger, so the measurement from flat to > back of the round is 6.5mm. With a printed armature hub that grips the > whole shaft its strong enough in PETG that no hard to machine metal hub > insert is needed. In my size, I can make 2 of them out of a $20 kilo of > PETG, and a small bottle of crosman bb's, or about 15$ a drive. At a > scaleup for what you need, about 200%, will x4 the amount of filament, > and probably x4 the print time too but I don't see why it won't work if > you wanted to try it. My whole idea is cheap, if it breaks, print > another. > > > The longitudinal travel is just over a foot, and it takes about 3-1/2 > > turns of the crank to go that distance. I'm thinking around a second > > per turn would be about the maximum. So, that's 60 RPM. I'm thinking > > of a 1:6 ratio on the timing belt pulleys, so that's 360 RPM at the > > stepper which is pretty slow. A full stepping rate would be 200 * > > 360/60 => 200 * 6 which is only 1200 steps per second. > > > > An alternative would be to provide more gearing, but I don't think it's > > practical to get more than about a six to one ratio in a single belt > > reduction and I'd like to avoid mechanical complexity if I can. > > OpenSCAD, which I used to design this, is quite capable of doing any part > that fits on the bed of your 3d printer. And if at 87 I can learn it, I'm > convinced you could too. > > Two OpenSCAD master files, are text files, and this drive and the driver > sprocket to replace the alu crap that came on this A drive originally, > total about 1400 LOC, several hundred of which is comments so I can > figure out a month from now, what the heck I was doing. Lots of it is > from thingiverse, and modified by me. But the final version hasn't made > it to my web site, yet... Something about the only time a program is > finished is when someone shoots the programmer. > > I am also driving my converted 11x54 Sheldon lathe with the 3NM and 2NM > versions of this motor/driver stepper/servo. And driven by LinuxCNC > running on a rpi4, its doing dance steps that it could not do 80 years > ago when it was shipped to the navy. Including correcting for the 13 thou > of bed wear right in front of the chuck. This lathe has been rode hard, > thrown across the truck bed going around a corner too fast and put away > wet long before it followed me home in a cargo van. > > If interested, give me you PM address and I'll email the .scad to you. > > > Thoughts? > > Take care and stay well. > > > Ken > > > > Kenneth Lerman > > 55 Main Street > > Newtown, CT 06470 > > > 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, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > 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 > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
