On 11/23/23 14:26, Chris Albertson wrote:
On Nov 22, 2023, at 1:06 PM, gene heskett <ghesk...@shentel.net> wrote:
I'd have to agree Andy. I need to design a disk brake for my A axis as there's
half a degree of slop in the worm drive which if it gets to the motor will be
held, but the slop in the worm makes for sloppy looking holes, but the
activation method is still in my head. Even that is only important when
drilling a hole for the handle. I'll come up with something.
Would a simple disk brake work? I think it might clamp the part any place
within that 1/2 degree of slop range. Ideally, you would have an index plate
and some way to place a pin in a hole to lock the table. But you could only
have a few holes and not enough holes for one at every place you might want to
stop.
What if the disk had “V” slots cut in the edge. Like a very large US Quarter
Dollar, but with maybe 360 grooves. Then you could wedge a shape (like a tiny
axe head?) into the slot and force the disk to stop on an even degree. You
could use more than one wedge, space them around the disk.
A wedge would need a lot less clamp force than a brake disk pad because it is a
mechanical lock almost like an index pin
If you still want a “disk brake” why not use an actual disk brake from a
bicycle? They are about the right size, have huge holding power, and don’t
cost all that much. The ones you would want to use are hydraulic so the
electric actuator could be a couple feet from the rotating table. They still
make cheaper ones that use cable but avoid those, they are too hard to adjust.
Or maybe both, Use the slot and wedge to aligh the table to the nearest degree
and then clamp it with a hydraulic disk brake. Cost is under $100.
Thanks for the ideas. In this case I think the disk brake is probably
the best idea, accuracy to the arcsecond isn't needed, just clamp it
where ever is is. I don't even have a legitimate "chuck" on this gizmo.
its a printed square socket with slightly tapered sides to corral a
square maple stick held by a live center at the far end. I can very
easily add a disk of arbitrary diameter to the front face & I'm sure I
could find a motorized driver to push the shoe and lock it for the
duration of boring the hole.
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Cheers, Gene Heskett.
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