John's grasshopper escapement

Short clip of clock mechanism

Category:

Science & Technology

Tags:

• Clock
• escapement

[john92037]

Sorry, but I cannot take any credit for the design. It is the one used by W R Smith in his very successful Grasshopper Skeleton Clock

[BenVanDeWaal]

Please see my comment with bshallard.

[RollaArtis]

With the 'grasshopper' escapement the recoil is intentional and indeed essential as it enables correction of the cycloidal error - it was developed from the anchor esc. with the big advantage that it doesn't need oil to work as there is no sliding action.

[KEvronista]

@RollaArtis

well, i feel a little foolish for having said the arnfield is superior to the grasshopper. it was the 'hopper's recoil that led to me think so, but after having built my own remontoire, i now realize that recoil isn't an issue for it, especially when harrison's own spring remontoire is utlized. add the fact that its motion is sinusoidal, where the arnie's isn't, and i have to concede, without reservation, the 'hopper's superiority.

KEvron

[KEvronista]

@RollaArtis

"Maybe the lego....?"

i'm not able to visualize the arrangement. i'd need to see it in order to give you an answer. aside from spring-loaded shock absorbers and rubber bands, they don't offer much in the way of springs.

KEvron

[RollaArtis]

@KEvronista All you need is a pivoted frame with suspension springs in an X shape which will twitch at the zero point giving just enough impulse. Maybe the Lego could be used after all?

[KEvronista]

@RollaArtis

interesting. if i recall correctly, b&w in fact moved the position of the escapement down the pendulum to reduce amplitude (not the way i'd have gone about it).

while impulsing through the suspension may be ideal, that would require a heavier gravity arm, which in turn would require more drive weight. that's where the limitations of lego come into play....

KEvron

[RollaArtis]

@KEvronista Ideally the pendulum should swing without physical interference such as an impulse arm but if this should be necessary, the further from the centre of oscillation the better. There are high precision pendulum clocks where the escapement gives impulse right at the top by flexing the suspension, so reducing interference with the pendulum oscillations to the minimum.

[KEvronista]

@RollaArtis

"through the suspension"

whoa. you lost me there.

KEvron

[RollaArtis]

@KEvronista Thanks - an interesting and ingenious gravity esc. variant, but it could be improved if the impulse was given near or even through the suspension.

[KEvronista]

@RollaArtis

@RollaArtis

"Er"

i sense a hint of amusement. consider this fine example by TheBellsAndWhistles (watch?v=ORo5aQ7_42o). in this design, the pendulum detaches from the grav arm prior to the grav arm engaging the detente. this arrangement eliminates the possiblity of the grav arm double-tapping the pendulum at detachment (a common ailment to arnies), and of the tension on the detente affecting the pendulum while it's in contact with the grav arm.

KEvron