On Friday, November 18, 2011 10:07:55 AM [email protected] did opine: > Hello Group, > > I have machined or purchased the necessary parts to duplicate Sherline's > Stepper Motor Spindle Drive Conversion Kit, P/N 6500 > > http://www.sherline.com/6500pg.htm > > I have all the mechanical parts together, and all is running well. Using > the standard Sherline controller and EMC2 with the supplied Sherline > files, I'm able to go through the motions of cutting threads. It > remains to be seen if adequate torque and accuracy are obtainable. > That is a #23 framed motor good for 120 oz/in. A bit puny for a spindle IMO. #23 framed motors are available for up to 430 oz/in. I got a 4 pack of them some time back from xylotex. I have one on my Z axis which seems to be able to turn nearly as fast as the shorter (lengthwise) 225's on the XY. With a 17/42 stepdown to a 10 tpi screw, 34 ipm can be had. XY can do about 22 ipm on 20 tpi screws
> Is there a way in EMC to command one stepper to run continuously at high > speed to drive the spindle, while the other 2 are running a normal 2 > axis lathe turning profile? An interesting question, and not that I know of. The problem is likely one of overflow in the emc internal counter, at which time emc has obviously lost track of where the spindle is, but not a concern for the relatively few turns a threading operation would be. The larger concern to me would be the loss of torque and stalls under load when spinning at the higher speeds. A spindle stall that was not detected, and without encoders feeding back it won't be, will equal a lot of broken, and expensive, solid carbide tooling, not to mention the wrecked parts as the stationary bit digs into the part before it breaks. I have wished for that in driving my rotary table when I have it setup like a lathe head, but have had to settle for driving it a few thousand degrees, first one direction, then the other. Geared 90/1, there is nothing 'fast' about it, but I can put a dremel diamond disk in my spindle and do a quite good job of polishing to exact size. A lights out operation obviously. This is not a problem when only turning a few dozen turns like a threading operation. I believe in your case, I would obtain enough parts to build a complete, and then quickly interchangeable spindle assembly so that threading could be done with this assembly, and normal milling done with the OEM setup. It is something I have considered for mine, but I have only gone so far as to purchase another Z axis casting, with thoughts of machining a stationary new spindle right into the casting. Something with R8 tooling perhaps. Then I start looking at the short ways, and get discouraged, it needs another inch of way length on both top and bottom as the existing lashup allows it to rock slightly. Cheap is cheap regardless of what one pays for it. And an HF micromill pretty well defines the word... :( > Thanks, > > David Clark in Southern Maryland, USA I am not that far away, N. Central WV, Weston TBE. It is about 3.5 hours to Harrisonburg from here. 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> If you're carrying a torch, put it down. The Olympics are over. ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-novd2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
