On Thursday 18 April 2019 04:20:37 Roland Jollivet wrote: > On Thu, 18 Apr 2019 at 01:22, Gene Heskett <ghesk...@shentel.net> wrote: > > On Wednesday 17 April 2019 15:06:02 Chris Albertson wrote: > > > > [...] > > > > > But if maybe you lock the spindle and turn the nut. > > > > This is the case, except you are turnbing the nut by using the xy > > steppers to drive the carousel which is turning the nut. > > > > > Then your spindle > > > lock needs to have a torque gauge fitted. The gauge is either a > > > spring and switch or a load cell. The switch is much easier to > > > interface with. > > > <https://lists.sourceforge.net/lists/listinfo/emc-users> > > Hi Gene > > To recap; small steppers 'drive' the carousel around to tighten the > motor. Bad idea. I tend to agree, given the power limits available from the steppers. > > Here's a different way of looking at it; > Keep the current stepper arrangement, but drive the carousel instead, > with a windscreen wiper motor. > You now have as much torque as you like in the carousel. Add a > reduction drive if you like. If you mount this under the bed you can > go to town on it. > > The process would be to move into tool position, Z down, then either > track the motion of the carousel,
Difficult to synch, but probably doable. > or disable the stepper drives and > let them coast as the carousel takes the spindle with it as it > loosens/tightens. Once you've reached your target Amperage on the > motor, stop, and Z up. The X,Y is now a 'don't care', so home the > machine. That would likely mean moving the tool changer at least to the middle of the Y range, or a long move to get y homed again. And the carousel becomes half a wheel that has to be in its own home position to allow the gantry risers to get past it. The windshield wiper motor with a big geardown, say 6/1, could then use the wipers parking switch to position the carousel at one of 6 tool positions, with one more home switch. What I had in mind was to borrow the right rear 200mmx200mm so a gunstock blank could fit beside it. Then the gantry risers could clear it regardless. And of coarse there's the y offset of the z mount, making the rear 80mm in-accessible. Currently the coolant tank occupies the space but theres nothing saying I can't make a riser for it to make 18" of working room for a swing in carousel under it. The limited Z range will be a problem for long tools in any event. I'd like to steer clear of useing a transfer arm to reach into the working area, but powering a rotating socket on the end of it to do the tightening and loosening of the collet nut has a certain cachette to it. That way the xy remains at the tool change location so a rehome won't be needed. And the transfer arm stays outside the path of the gantry when parked at the next tool. And so do the arm driving motor(s, one to drive the arm and one to drive the socket). Driving the socket with a rack, with a bearing to back up the rack at the point of contact sounds good, and beats a whole chain of spur gears I saw in one design. So it sticks out but if the stickout is only when in position there shouldn't be anything but air for it to hit. Design length enough in the rack to allow a full turn of the nut, and run it to one end or the the other depending on whether you are removing or inserting the tool before engaging the nut. Get the gear ratio needed by a bigger spur gear on the sockets base and a smaller gear on the wiper motor could do that. Thats 3 wiper motors to run. Thinking... > You then further rotate the carousel to home with a single switch so > it's always ready. Or put the tool back in the pocket it came out of so the tool table can track it w/o that codeing hassle, then rotate to the new pocket before the arm picks up the next tool. And with all that, the tool changer is going to use up quite a bit of i/o. And a sheet of 1/4" ply cut up just to make try patterns. :) All that bs makes buying an atc equipt spindle seem like the cheap option. Frankly, neither R8 nor the various sizes of ER's were made with tool changers in mind. Either style demands a TLO calibration once the new tool is in place. But I keep letting my imagination out to play. Code is a lot cheaper than hardware. Thanks and take care, Roland. 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> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
