On Thursday 02 June 2016 10:40:52 John Kasunich wrote: > On Thu, Jun 2, 2016, at 09:45 AM, andy pugh wrote: > > On 2 June 2016 at 14:15, John Kasunich <[email protected]> wrote: > > > Unless this is a mighty slow lathe, I don't think chain is the > > > appropriate drive mechanism. > > > > Silent chain has been used on a number of lathes historically: > > http://www.lathes.co.uk/southbend/page12.html > > That South Bend installation had a recommended motor speed > of 900 RPM. Gene's lathe uses a motor that I think runs 4000 RPM. > > My Van Norman mill used a silent chain from the 1/4 HP 1800 RPM > feed motor to the input shaft of the feed gearbox. Pulley and chain > were both worn and the chain would climb out of the teeth and > skip. There was enough meat on the large pulley that I could turn > off the silent-chain teeth and re-cut XL timing belt teeth. I put an > off-the-shelf XL pulley on the motor and back in service. > > > And the cam-chain in my motorcycle runs up to 14,000 rpm. > > Fully enclosed and oil lubricated. And properly engineered for > the task. > > > A conventional roller chain might well not be as smooth as one might > > like in a lathe application, though. > > > > I haven't posted this here yet: > > https://www.youtube.com/watch?v=woU927Tqoo8 > > This is my current project, which is using motorcycle cam-chains to > > drive the ball screws as an experiment. > > How fast do the ballscrews turn? > > I don't doubt that a chain could be made to work, but on a lathe > as small as Gene's I think it is far from the ideal solution.
Progress report: First, I cannot write gcode that really does what I want. I wanted to bore a 10.004 hole to fit my homemade 10mm shaft as the new pulleys come with only a 1/4 bore. So I planted a 1/4" tool in the hole, clamped it down and touched the machine off at x0y0. I had to keep asking it for a bigger hole which I did about 5 times before I managed to get a 10.010 hole, which fit the shaft until it ran into the burrs from the previously tightened set screws. So its in and turning the chuck but the bigger pulley is forceing to design a different method of setting a wedge in the jackshaft frame that I can use to tighten the belt until it sounds like froggy's magic twanger. That is to prevent the frame from lifting under a heavy cut, giving the belt slack enough to jump teeth. The increased diameter also means the angle bracket I put on the lathes casting to help hold the housing for the spindle electronics is going to need shortening about 5/8" and a new hole drilled for the screw. Piddly stuff but it still takes time. And I just found the jackshaft bearing thats doing all the grumbling recently, so once the wedge problem is solved, I"ll pull it back out and replace that bearing as I bought 4 of them. Its taken quite a beating two or 11 times changing this darned pulley. I've lost track of how many of the OEM plastic pulleys I've burned up. At that point, since machineing that wedge will be a bit of a project, I decided my back was done for the day, and since its almost midnight, its beer thirty too. And maybe even a bowl of ice cream. I got two stout neighbors and one supervisor, to help me pull the fiberglass tonneau cover off my GMC, so once I get it unloaed, I can load up a bandsaw I sold to an old friend in TN, and deliver it, spend the night since I've not seen him in person for about 15 years, then come back about 100 miles, rent a trailer from a local u-haul big enough to carry the bigger lathe I'm buying, and pull it home. And I'm not at all started on clearing out enough detrious to make a place for the lathe. Don't get old folks, it eats into your productive work time when it hurts to pick up 30 lbs these days. Its a right bummer. Takes too much time to rig a skyhook with a trolley and use a multisheave come-a-long to move something I could have picked up and walked off with 5 years ago. :( But I keep plugging along. Take care everyone. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic patterns at an interface-level. Reveals which users, apps, and protocols are consuming the most bandwidth. Provides multi-vendor support for NetFlow, J-Flow, sFlow and other flows. Make informed decisions using capacity planning reports. https://ad.doubleclick.net/ddm/clk/305295220;132659582;e _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
