On Friday 08 March 2013 00:21:15 Igor Chudov did opine: > I had a disagreement with my employee today. I said that a retrofitted > CNC milling machine, like my Bridgeport Interact, is supremely useful > as a shop tool, but a CNC lathe has very little usefulness. I felt that > there is not really much that one can do with a CNC lathe. He > disagreed, but could not offer specifics. > > I want to see what you think, is a CNC lathe all that useful for someone > who is nota job shop or a manufacturing operation.
Absolutely Igor. I did do some work on my little toy from time to time, but I could never correlate the turn of the dial with what the micrometer said I had when I did turn the dial. None of the screws in it were usable or repeatable. But one of the things I needed to do was cut threads occasionally, and without 10x more motor and an encoder on the mill, that wasn't going to happen. So I made an encoder disk and an A-B-I opto kit, for the spindle, and put a 425 oz motor on the OEM lead screw. And a 50 oz on the back of the oem cross feed. With that, I cut my first few threads, and after calibration it was nice to be able to move it 0.003" and have it cut a fine sliver of steel off. But backlash was still a huge problem. Steve gave me a small ball screw suitable for the crossfeed. It took me a couple months to figure out how to do it since the 7x12 has very limited room for the nut, but this one was small so I did eventually get a mounting cage made, along with a double bearing thrust setup that I married to the end of the screw, turned the other end of it down for a 6.35mm coupling to a motor, first trying the 50 oz motor because that wasn't all that big or heavy hanging off the rear of the carriage, but wound up putting a triple stack 425 on it. The 50 could be pushed. Then the backlash in that half nut just had to go, so $135 later I was looking at a chinese 16x5mm C7 grade screw and trying to figure out how to fit it. Its now in and working fine, and my Z accuracy is now about a thou instead of 25 thou. Simply put, even for the onsies and maybe 3sies I might make as I play around at my own pace in my dotage, I can do them in 5% (including time to write the code) of the time that it would have taken me to do it by hand twisting the dials 5 years ago. It is a pleasure to use now, not a headache. And as long as my single tooth tool is properly sharpened, my cut threads are better than ever. I should have done it 12 or 13 years ago, but I hadn't heard of linuxcnc then. Because of the repeatable precision linuxcnc brings to the table, a thread it took me about a week to cut in each end (2 weeks total) of the nut carrier for the new z drive on my mill, could probably be done in 15 minutes if I had to do that again and I could keep that modified boring bar turned into an internal single tooth sharp. Chatter ate its edge dozens of times. 4340 steel is a bitch. So if the question is, is a cnc lathe worth it? Yes, yes, and yes. IMO, usefulness comparable to bottled beer, sliced bread, a pint of chocolate chip ice cream and a willing woman. 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> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> Only a fool has no doubts. I was taught to respect my elders, but its getting harder and harder to find any... ------------------------------------------------------------------------------ Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the endpoint security space. For insight on selecting the right partner to tackle endpoint security challenges, access the full report. http://p.sf.net/sfu/symantec-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
