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Re: Published proof of concept for new ratchet design... Feb 19, 2012 2:04 PM
Posted in group: MakerBot Clock Makers
Need orange gears for Halloween! Not sure about the drum yet, I haven't printed that far up! Although it has maybe 40mm of plastic supporting the screw it will mount on. Hopefully i'll find out later tonight! Also, I was originally envisioning the front panels as being the anchors for the fronts of the screws. So worst case I can just add a partial front panel.

Yeah, i saw the coffin thing too. For the case, i'm contemplating extending the top and bottom to make it more diamond shaped. I've also been contemplating ditching the hard angles altogether and going with arcs for the sides (keeping the top and bottom the same). The gear arms may change too. They're actually arcs, but the facets are turned down real low so they look angular. =)

Also, i've been envisioning this contraption sitting in a floor standing case sort of like a grandfather clock! The bottom half would just slot down into the stand and shouldn't need any additional mounting hardware.

On 02/19/2012 04:41 PM, Mathieu Glachant wrote:
That just looks amazing! I like both the idea of the printed numbers on a ring of the gear, and the idea of leaving the clock's coffin - err, case - open. Will the drum not need a little extra support in that case tho?

On Sunday, February 19, 2012, wrote:
Working weekends all around! Fortunately i'm in a printing phase so not alot of time is required.

The one thing that occurrs to me with the ratchet sketch is the ratcheting head will move in an arc like fashion (not a pure arc given the arm will be flexing, but close enough) so the well may need adjusted a bit. I Iike how the head has depth so that when its fully compressed the head is resting against the outer ring adding to the support for the inner ring.

One other thing that occurred to me is the angle of the head engagement. I've run into a problem with my most recent drum prints in that the print had rounded the teeth and ratched heads enough that they can slip backwards with enough force. Making the engagement face a little angled so there is a positive engagement angle should help.

Current progress (doing center and right side first, will follow up with the left later):

When finished it won't have concentric hands, but it looks like the screws are mounted firmly enough that I may be able to leave the face open which could be nice. Also the escapement wheel here is backwards and the panelization so far works great! I'll definitely have to make a library of it.

I'm contemplating adding rings that will attach to the minute and hour gears that have all the numbers printed on them with an indicator circle above that to help in identifying which hour/minute is currently selected.


On 02/19/2012 10:24 AM, Mathieu Glachant wrote:
I doodled a lot on the ratchet design over the week and was hoping to have time to commit it to code over the weekend, but this is turning into a full blown working WE... So here is one of those doodles.

The basic idea is to move back the attachment point for the arm but provide a wedge under it to minimize the area where the outer and inner rings are not in direct contact.

This works best if the arm is at a fairly steep angle to the tangent, and perhaps the face where the arm butts up against the notch needs to be kept perpendicular to that same tangent. Alternatively, the arm could face the other way and instead of pushing against the inner ring, it could clip on with a hook.

Lastly, the gap left in the outer ring so the arm can bend out of the way could be gently curved so that the arm is never forced to bend sharply in a single spot.