On Fri, Jul 26, 2013, at 07:21 PM, andy pugh wrote: > On 26 July 2013 23:57, Jack Coats <j...@coats.org> wrote: > > It is similar to http://www.cadcamcadcam.com/toolchanger.aspx > > designed for the sherline. > > But the tools need to live inside the work envelope. I was wondering > about only having two tools in the work envelope and using the axes > and spindle to move the carousel or chain. > > I am not saying it is a good idea, just that it is _an_ idea.
I like out of the box thinking. > I already have the power drawbar (that I am particularly proud of :-) > Can your spindle drive orient the spindle? Probably required if the spindle taper is one of those with driving keys, otherwise not needed. If you have the kind of well-controlled spindle drive needed to orient the spindle, then maybe you can use spindle rotation to drive the tool carousel or tool chain. It could be much faster than using axis motion to do it one tool at a time. I can imagine a rubber ring (like a small tire) on the spindle, that can be brought into contact with the side of the carousel. You'd need an encoder on the carousel. Or a shaft near the tool change location, connected to the carousel with a chain or toothed belt. Choose the sprockets/pulleys such that one turn of the shaft advances the carousel by one tool slot. If your spindle has driving keys, the top end of the shaft could have mating slots, and you just come straight down at the shaft. That last one might be easiest to implement using a tool chain. The chain would require a driving sprocket anyway, and it probably wouldn't be too hard to have one revolution of the drive sprocket index it by one tool location. And the sprocket axis is likely to be near the tool change position. Or if your spindle drive isn't that precise, and/or you don't have drive keys, use a much higher reduction ratio. For example, a small worm drive, such that it takes a few dozen to a few hundred revs of the input shaft to advance the carousel by one tool. That doesn't require as much precision at the spindle, but it would require an encoder or sensors of some sort on the carousel. For the high reduction version, the connection to the spindle could be a flat disk facing up, with a sheet of rubber a few mm thick on top. Press the spindle end down on the rubber to spin it. Taking it a bit further - make the disk spring loaded upward. Surround it with a stationary ring, such that when idle, the spring pushes the outer rim of the rubber disk against the bottom of the ring, and it acts as a brake. The spindle pushes down on the center of the rubber disk (thru the hole in the center of the ring) to disengage the brake, then spins as needed. Pulling the spindle up could stop it very quickly even if the spindle itself can't stop fast. -- John Kasunich jmkasun...@fastmail.fm ------------------------------------------------------------------------------ See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
