If you can find an FHA drive then the servo and a very serious > crossed-roller gear is included. > http://bodgesoc.blogspot.co.uk/2017/05/harmonic.html
The guy who made the above video said he bought the 4" diameter harmonic drive on eBay for about $200. I checked just now and there are a LOT of these there but the ones you'd want start at closer to $300 although a few are under $200. There are quite a few available. I found another video where he puts the 4-axis drive to work and makes something I start the clip where he actually gets it working after solving some problems https://youtu.be/3g9IFnVDOTo?t=15m35s This is not bad for something that costs him in the $300 range to build (more like $400 if I had to do it.) Then I find that you can BUY the entire 4th axis for $250 with a 4" chuck include. This is the kind that uses a stepper and belt drive. /www.ebay.com/p/4th-Rotary-Rotational-Axis- <https://www.ebay.com/p/4th-Rotary-Rotational-Axis-Hollow-Shaft-3-Jaw-100mm-Tailstock-Nema23-CNC-Router/2177174372?iid=122197167744&_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D49566%26meid%3D599a1791062d493d969b6f22583b3951%26pid%3D100005%26rk%3D1%26rkt%3D6%26mehot%3Dpp%26sd%3D263050652003&_trksid=p2047675.c100005.m1851> The trouble with this is the poor resolution only 1200 full steps per revolution Not nearly good enough for engraving Need on the order of 20,000 steps per revolution to get 0.001 resolution in the outside of a 4" diameter part. For that on order of 1:100 reduction is needed with very low backlash. > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ 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
