On Wed, Sep 8, 2010 at 7:35 PM, K.J. Kirwan <kjk_e...@ix.netcom.com> wrote: >>>> Igor Chudov wrote: >>>> >>>> Thanks to all for some clarifications that encouraged me to take some >>>> ginger first steps towards this (read, bought a servo motor on ebay). >>>> >>>> Guys, do you think that this servo motor will "do" to motorize the >>>> knee of my Bridgeport Interact: >>>> >>>> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390233108125 >>>> >>>> This is an "Italiano servomotori", with a 15:1 gearbox and a tach. I >>>> think that it can give me about 7 ft-lbs of torque on its chain drive >>>> at 200 RPM. That should be enough to move the knee with air assist. >>>> With 1:1 transmission, it would amount to 40 IPM, probably a bit less >>>> in real life. >>>> >>> Jon Elson wrote: >>> >>> Is this just a power elevator or a real servo axis? If servo, what will >>> you use to measure >>> W position? Probably not good to put an encoder on the motor, between >>> the worm gear on the motor, >>> the bevel gear in the knee and the Acme screw, the backlash will be large. >>> >>Igor Chudov wrote: >> >>Jon, good question. >> >>I think that the heavy knee will always sit tight on the acme screw. >> >>Other backlash may be at least repeatable. I will see. I am not >>totally averse to just putting an encoder on the knee handle shaft. >> > > Igor, your Bridgeport is similar to John's Bridgeport IIa NC except > his has the original Bridgeport II stepper motors (800 in-oz?). > John's uses the knee for Z and runs with the quill locked, because > it originally had Bridgeport's "Spindle Wizard" (trick quill-cycling > thing), and John took that off. It still has a manual lever on the > quill. We might add a "W" quill DRO to EMC2 at some point. John's > has the 4J head (4 HP/3 KW). The motor to ballscrew ratio on X and Y > is 2:1, and Z is 4:1. We can send you some photos and diagrams later. > I'll be in touch off list. > > The point is that (unless you just want a "knee up/dn" switch) I > believe you will have to get rid of that acme screw in order to have > proper control of the knee axis, even with the factory air > counterbalance. What John recommends is that you look for a BP2 > with a ballscrew knee and motor drive (motor mount, at least) that > someone is scrapping out. And if you can find one set, find two, as > John's 2nd BP2 (on the list of things-to-do) has an acme knee screw > as well. We'll look for two as well. All should bolt right in. > > Welcome to the BP2 club, and if you're in the Minneapolis area, John > says plan on stopping by for a look at his.
Kirwan, thanks. I may postpone this project for a while, but I will always keep in mind. I am in Chicagoland. Igor ------------------------------------------------------------------------------ This SF.net Dev2Dev email is sponsored by: Show off your parallel programming skills. Enter the Intel(R) Threading Challenge 2010. http://p.sf.net/sfu/intel-thread-sfd _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
