On Monday 25 May 2009, Rainer Schmidt wrote: >Haha.. The Belt Stiffness fools many. It's a PU timing belt which is >steel loaded. I tensioned it to 160lbs and the think sounds like a >guitar string. There is NO flex whatsoever. If there would be... most >cars would sink their valves into the cylinders more often than not. >The ratio is 1:3 and the stepper has 10 steps micro stepping. So I get >2000 steps per revolution times three. So I get 360/6000 degree >resolution which I could reproduce. If you would use a servo then you >can easily tripple that resolution with the right encoder. I chose a >stepper there because I wanted the high holding torque for unbalanced >work. Did I mention that it is FAST..... > >I also hae a sherline table on my Taig mill. And that's where it >belongs. I mill pen's with it and for that it's nice and very precise. >However, it does wear as all the stuff does which is not designed for >CNC kinda moves (which means a LOT of moves). And for the price of it >I milled my monster 4th. The timkin bearings are sitting in those 3 >Inch AL blocks 8))). Derived from the shaft all measurements became >slightly beefy lol. > >I also milled a groove into the bottom of the head and the tailstock >so alignment is easy. The biggest challenge was to bore that hole for >the MT3 sleeve. Compared to the tailstock I must say that the sherline >tailstock resembles a toothpick. > >If you wish to mill tiny stuff and not to often then go for the >sherline table combo. If you need a quick turning cnc solution then >build one. I took a look at all sorts of tables and the ones suitable >would have been precision US or European made rotary tables which >would have cost me several thousand dollars and that for no other >reason but backlash. Na.... building one or having one build is >probably the best way to go as there are no affordable CNC tables. > >Yesterday I used it to cut a thread into a larger hole in a wood >block. No way to do that with the slow turning regular tables. it has >to go 'swish swish swish' and not scraaaapeeee, screeeeeechhhhhh, >squeeeeaaaalllll..... haha. > >Have a good memorial day and recall what others did for your >particular country so they did not do it in vain. >Rainer
I looked at your 'rotary table' and must say I'm impressed. Unforch, it would take up the whole x table of my expanded micromill. So ATM, when I need a 4th, I have a $100 4" grizzly I put a 425 oz stepper on, and it can make 4 to 7 hundred degrees a minute depending on the mood its in. Backlash is highly variable, and this unit is so cheap it doesn't even have a socket for a center. I also had to do some finish machining to take the wobble out, the table did not sit tightly enough against the base as shipped. Using edm, I put some holes in a 10" carbide saw blade that was way too hard for conventional drilling a few weeks ago so I could fasten it to this table, rigged a dremel with a diamond wheel off the regular head, and did a decent job of sharpening that dull saw blade. The thing didn't seem to have much if any cyclic errors, either in the worm or in the bullgear, at least in comparison to the spacing of the teeth on the blade, a Freud made, chrome plated avanti. Sweet blade, but a few thousand feet of cuts in cherry will sour any blade eventually. I don't have any provision to lock the table, but make sure it always attacks the work rather than backing into it. I haven't had it miss cut yet because of that, at least not that I've seen in the work. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> What, after all, is a halo? It's only one more thing to keep clean. -- Christopher Fry ------------------------------------------------------------------------------ Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of tech-side developers & brand creativity professionals. Meet the minds behind Google Creative Lab, Visual Complexity, Processing, & iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian Group, R/GA, & Big Spaceship. http://www.creativitycat.com _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
