Member postings for Graham Compton

With all this damping, not shaky enough!

Graham

I'm in the (prolonged) process of building a seismometer. Any chance of a bit more technical detail? Mine also uses a capacitance sensor but I have problems with damping (ie much too much).

regards

Graham

There's the god news and there's the bad news:

The clock has only made one loud noise (in my hearing) in the last few days. All other switching events have been quiet. So it sounds as if the toggle no longer sticks on the edge of the notch block.

However, I connected a 'scope across the solenoid. The pulse is generally about 130ms with most events between 110 and 150ms. Occasionally though there are 300ms events. I recorded two of these and I was watching the second. The toggle caught on the exit edge and so pushed spring lever further down and closed the contacts for longer. It was quiet because the toggle didn't slip off.

So, the noise is cured, but not the fault. Has anyone out there made similar measurements on a Hipp toggle?

regards

Graham

Having only recently joined the forum I'm coming late to this thread.

It's true that clock makers generally avoid worm gearing because of the friction, but elsewhere I've been describing bits of my Wilding Hipp clock and this successfully uses a 1:60 worm gear to divide down for the minute hand. Music boxes often use worm gears in the step up direction but they are too lossy for the step-up needed in a mechanical clock, particularly since they really do need lubrication for step-up and that is avoided between gears in clocks. My clock's step-down worm isn't lubricated and shows no sign of wear after some 18 years. In terms of tooth form. Wilding specified straight flank teeth, which for the worm is, I think, an involute form, the equivalent of a rack. The wheel is cut with something looking like a symmetrical ratchet cutter, probably not ideal in terms of the involute form but it has worked ok.

regards

Graham

Thanks Michael. Sorry, "if all else fails, read the instructions". I'll try your instructions to show a wider view of my version of the Wilding Hipp clock switch mechanism.

Thanks for the link to that Hipp clock on Youtube. Rather more elegant than mine, although part of my excuse is that I've tried to minimise the weight of moving parts. My first notch blocks were very much lighter than the one at issue, which was born of desperation. I think my criticism of the Wilding design, viewed from where I am now, is that some of the moving parts are a bit massive.

The image was taken with a Lumix on the widest angle, so the perspective is a little odd. The arrangement of the pieces of spring in the lever may be visible, although as I'm typing this it looks as though the resolution has been reduced. The observant may notice the BlueTac preventing the screw on the left from moving.

The notch is offset to the left by rather more than I intended (yes, I should have measured more carefully) and the result is that the pendulum arc is quite large. However, it works! And without sticking for a good day and a half now, so I'm loathe to interfere. As a watch repairer said to me when I'd managed to re-assemble my wristwatch "quit while you're ahead". Maybe next time it comes off the wall for the decorating. Or sooner if the large swing continues to offends me.

regards

Graham

I've come rather late to this posting but:

I have a G&S Conference microscope. It's a hernia job to move as it has a generous 100W built in power supply. I also have a G&S inverted microscope (that's equally heavy). More to the point, I have some G&S literature that a member of the Quekette (spelling) Society was kind enough to provide. It's a while since I looked at it but I think it's advertising literature. I can send you a copy.

regards

Graham

My daughter tells me that this is a link to a picture of my toggle mechanism:

**LINK**

I tried clicking on the likely looking icons but couldn't work out how to post an image using the tools on the forum page. Not intuitive for me I'm afraid.

Meanwhile, she also lost all my text so here we go for the second time.

I feel a bit of a fraud. The toggle mechanism has healed itself and in a few days it has gone from sticking every other impulse to not sticking at all for the last 6 hours while I've been monitoring it. It remains to be seen whether this is permanent. One reason for using a hard notch block was that any material removed might make things better rather than worse - but it might be luck.

Assuming the image is available: It's fairly self explanatory. The notch block is a corner of 3/16" silver steel, milled to clean up the edges and add a 90 degree notch. Polished in the immediate vicinity of the notch. Tapped 3mm and then coated with soft soap, heated and quenched in brine with some oil on top. The lever is a piece of clock spring, a hole punched in the middle for the block. There is a shorter piece of spring below it that extends a bit less then half way from the mounting and another shorter piece between the main piece of spring and the block to change the way it bends. The contact is at the left end. The toggle is a bit of brass sheet (not engraving), soldered to a brass tube drilled 1/16" for the arbor. Brass hammered to harden and filed to thin the edge. In the image, the pendulum is moving left to right.

fingers crossed

Graham

I'm envious of that agate notch-block. Before I made my steel version I was contemplating some sort of jewelling, but I decided that it would take me too long to master the technique. I'll try to get a picture of mine, but my macro photos never look very good. The differences in shape from the agate version are: the notch is a right angle whereas the agate one looks rather more than 90 degrees; my entrance ramp is linear rather than a curve; my exit edge is another right angle - this is the most interesting difference, the agate version clearly has a flat top. I'll try that on my next version.

Yes, the decay between swings measured at that exit edge is going to be very small. I wish I could think of a non-invasive way of measuring the pendulum position, but I've yet to think of one, especially one with that sort of resolution.

Yes, leaving it alone might have been the best advice. The clock was working reasonably well until my wife wanted it off the wall to make way for decorating. While it's off the wall, I thought, I'll just have another go....

The slightly mysterious good news is that over the last 24 hours the proportion of impulses where the toggle sticks has gone right down, not to zero, but probably now only once an hour. I can think of only two explanations: the steel edge has trimmed off some of the brass toggle and improved its shape or the draining battery has changed the magnitude of the impulse to a level where, by chance, the decaying swing doesn't hit the edge but drops neatly on either side. Time will tell, but one reason I swapped the materials was that the steel toggle was cutting grooves in the notch block, making the sticking worse, the new hard steel version should avoid that, but possibly at the expense of the brass toggle.

regards

Graham

Thanks for your comments. Since my post I've thinned down the edge of the brass toggle and it has helped a bit; it now only sticks on the edge about once in 5 or 10 (approximate, I know, but I've spent an uncomfortably long time staring at the clock; a hidden cost of infrequent pulsing). My collection of Model Engineers occupies a number of cardboard boxes in random order so finding Wilding's article on improvement will take a while!

My clock differs from Wilding's design in a number of places, mostly to reduce friction and raise the pendulum Q a bit, but the only variations that affect the toggle action are making the lever springy (I don't think that will come into play until after the the toggle has caught on the edge or not) and lightening the toggle. On thinking about it, by removing most of the brass around the toggle base and therefore shifting the toggle's centre of gravity away from the pivot I will have lowered the frequency of it's swing and slowed it's movement away from the the edge of the notch. However, a bit of blue-tack at the base doesn't seem to have made any improvement.

If all else fails, I may try adding a light spring to the toggle.

regards

Graham

Rather a long time ago I made my first clock. It was the Wilding Hipp Clock, published in Model Engineer. It was my millennium clock. It has been going more-or-less continuously since then but I can't say I'm happy with the Hipp toggle action, so I'm looking for ideas/advice. The toggle and the notch were both made from hacksaw blade material, which I think was as originally described. Occasionally the toggle would would stick on the exit edge of the notch, making a loud thump. I made the spring lever that holds the notch more resilient and that improved things a bit, however, steel on steel is not a great idea and so I replaced the notch with one made from phosphorbronze. Not bad for a while, but the steel gradually cut grooves in the notch and it started to play up. I went through two versions of the phosphorbronze notch, with different exit edge geometry - no improvement. I then decided to change it all around and I've recently made a notch from silver steel and left it dead-hard. The toggle is brass. It still grabs the exit edge a lot of the time. I guess my next move will be to return to the steel hacksaw blade for the toggle, but has any one solved this problem? I've watched the mechanism in action on the tower clock in the BHI museum. Works every time, despite fairly gentle curves on the edges. Why does mine sometimes stick and that not?

regards

Graham