On Wednesday, June 13, 2012 07:24:53 PM Przemek Klosowski did opine: > On Wed, Jun 13, 2012 at 10:39 AM, gene heskett <[email protected]> wrote: > > Nook has an 8x2.5 screw & a 'keyed' ball nut > > They have a nice selection and pretty informative website, but no > prices. You need to 'get a quote' so I called and talked to a rep, and > felt that they are not a small/hobbyist customer oriented. The guy was > nice but it was clear that they don't care for the low cost/entry > level market. > I got that impression very clearly several years ago when I bought a length of 1/2x10 Acme bolt, and 2 bronze nuts. They were damned proud of those nuts too, just under $40 each in bronze. Shipped the screw in a round cardboard tube that wasn't much stronger than newsprint, so of course the screw was bent about 1/2" in the middle by the time it got to WV. I straightened something less than half of it for my first pass at a Z drive but found that with the screw in the OEM position behind the post, that no amount of torque on the screw would put more than 5 lbs of downforce on a drill bit, even more worthless than those famous tits on a boar hog.
So I turned the head housing 90 degrees on the spindle sleeve, making room for the screw to come down the front of the post about 2" away from it, sank it into the top of the sled casting with a nut on the inside, then moved the nuts to a sleeve with a ball thrust bearing top & bottom, put a toothed belt pulley between them, and the bronze nuts threaded into the sleeve above & below the bearings and the motor on a plate off the bottom of the top bearing block. The same motor that was slipping cogs at 5 lbs on a bathroom scale now puts 155 lbs on the bathroom scale. All in the geometry. > I did find some interesting things: he confirmed what we knew already, > that the most popular and therefore best value ball screw size is 5/8. > Another useful information was that there are three manufacturing > classes, in order of increasing accuracy and price. Standard rolled > thread is accurate to 0.004in/ft; precision rolled good to 0.001/ft, > and ground thread better than 0.5mil/ft + or - tempco I'd have assume. :( How do you find anything on the Roton site? Cheers Przemek, 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> I've got an IDEA!! Why don't I STARE at you so HARD, you forget your SOCIAL SECURITY NUMBER!! ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
