On Thursday 30 November 2017 19:40:32 Cecil Thomas wrote: > Gene, > If we are talking about the sheldon you got from Tom as I recall, it > had: (These are very approximate numbers based on an admittedly faulty > memory) > > a) Motor pulley about 4 inches > > b) countershaft Pulley (input cone pulley shaft) about 10 inches or > so. > > so with a "nominal" 3600 rpm motor the input countershaft rpm will be > "about" 3600 x 4/10 = 1440 > > for very rough approximation and motor slip call it conepulley input > 1200 rpm > > the cone pulley ratios as I recall were very approximately 2.5:1, > 1.25:1, .8:1, .4:1 > > so the cone pulley output speeds would be "about": > > 1200 X 2.5 = 3000 > > 1200 x 1.25 = 1500 > > 1200 x .8 = 960 > > 1200 x .4 = 480 > > As I recall, the double v-belt pulleys were about the same diameter > on the cone pulley output and on the spindle so the spindle rpms > would be approximately the same as the cone pulley rpms so it would > appear that the ratio between the motor and the spindle would be > "about" > > 3600 (motor) to 3000 (spindle) or 1.2:1 > 3600 (motor) to 1500 (spindle) or 2:1 > 3600 (motor) to 960 (spindle) or 3.75:1 > 3600 (motor) to 480 (spindle) or 7.5:1 > > Of course there is the Back gear which was very approximately 6:1 > so the speed range in back gear with a 3600 rpm motor would be "about" > > 500 rpm (spindle) > 250 rpm (spindle) > 160 rpm (spindle) > 80 rpm (spindle) > > So as I recall you have 8 different speeds available (with a constant > speed motor) not just two. > So you have 8 different motor to spindle ratios depending on which > cone pulley set you choose and which back gear position, all > controlled by belt position except the back gear whose ratio can be > confirmed by opening the cover and counting teeth. The final ratios > from motor to spindle would be "about" > 1.2:1 > 2:1 > 3.75:1 > 7.5:1 > 7.2:1 > 14.4:1 > 22.5:1 > 45:1 > > I don't remember any "Gear Box" except the quick change gear box > which only controlled the lead screw and you have removed. > > Again, this is all from memory and I haven't seen the machine in over > a year so.... > > The revs per MINUTE of the 1000 line encoder should depend completely > on your vfd setting but should be between 0 and say 6000 rpm for a > single pole motor or 0 to 100 revs per SECOND or 0 to 100K lines per > second or 0 to 400K edges per second. > There is nothing approaching Megahertz unless you want to wind the > motor up to speeds that would make me cringe all the way down here in > TN. > > Are we talking about the same lathe? > > Cecil > Actually, Cecil, no. All this is in re my G0704, which has also been cnc'd.
That Sheldon is now being run by a raspberry pi-3b, and only has one problem. All available rt or realtime preempt kernels have a horrible tendency to miss keyboard and mouse events, but the spi doesn't suffer from that, so once the code is written, it runs the machine great. This is also very very boot dependent in that you can keep rebooting it till the keyboard can be typed on, and it will run ok for weeks. The first of those rt kernels built for a jessie install is the best of the lot, all the later ones being worse to completely unusable no matter how many times its rebooted. Heres the uname -a for the best of them. Linux picnc 4.4.4-rt9-v7+ #7 SMP PREEMPT RT Mon Mar 7 14:53:11 UTC 2016 armv7l GNU/Linux I have a couple rock64's waiting in the wings for an spi driver. They do NOT have that architectural bottleneck in the internal data path that tries to kill the pi's. Running stretch, the speed of that little card matches this quad core phenom. An amazing little credit card sized computer. The major job its done for me is putting a new barrel in old meat in the pot, a 100 year old p-17, thats had 2 std mill spec barrels and 3 Ackley-06 barrels in it and shot out over the years, but now has a new 30" SS Bartlien barrel with a fast twist chambered for a 6.5 Creedmoor screwed into it, and I did all the threading etc except the extractor cut in the rear of the chamber, which I did on the G0704. And its been to the range just once, producing a 3/4 high, 2" wide 10 shot group in a very gusty cross breeze that day. With lots of room to tip the powder can a little higher, I expect it to do 1/2" groups on a quiet day. That 100+ lb oem 3/4 horse is in the boat house out of the weather, replaced by a 1 hp 3 phase that only weighs about 30 lbs, and a vfd. Works very well for rigid tapping except for the overshoot at the bottom of the hole, so I have to run it at about 100 rpms for that. I have some hal stuff that measures that overshoot so I know how much to subtract if the hole has a tap breaking bottom. I bought a 8" 4 jaw for it, even heavier. Rigid tapping would work well in a 5C collet, but haven't tried that yet. But that would get rid of 25 lbs of chuck to reverse. I have also rigged it with clamp collars so there's little to no chance of ever spinning a chuck off it. The vfd can make the belts yelp while reverseing it. Those things are adjustable! 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> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
