2024-09-26

Last modified: 2024-09-27 09:06:26

• Clock
• CAD model of house
• Sovereign scales

Clock

I'm making a new anchor with a bit less lift, 2 deg. now. Will see if I can get this thing to convincingly work.

Also reducing the safety margin, the angle in CAD was 1.8 degrees, now reduced to 1 degree, which I think makes for 2x that amount in safety margin, because it's applied to both pallets.

Still not working very satisfactorily. I put some Sharpie marks on the wire and found that I couldn't get the clamps tight enough to stop it slipping at high amplitudes, so that could basically 100% explain why the amplitude is so low. If it gains any more energy then a clamp slips and it loses it again. So next step is definitely to improve the clamping.

CAD model of house

I think I need to just persist with FreeCAD being slow. The only remaining operations on the roof are putting the gaps between the tiles on the perpendicular piece, adding some bodge part to join the perpendicular bit back to the main bit more solidly, and cutting out holes for the chimneys. Then I don't need to touch the roof again, can potentially even move it to a different file.

Sovereign scales

Paul suggested making "Sovereign scales".

They look like this:

You can put a gold sovereign in the left-hand circle and if the scale balances then it has the correct mass, and if it fits within the circle and through the slot then it is of the correct dimensions.

There is a second slot twice as far away from the fulcrum for a half sovereign.

But they are all old and nobody seems to make them any more, so good condition ones are expensive.

Paul's idea was to make a simpler version where there is no hinge. It's just one piece, and when there's no coin loaded it sits flat on the "counterweight", and when a coin is added that is heavy enough, it is just enough to tip the thing over and lift up the counterweight. The fulcrum is just the edge of the counterweight.

But the downside is that that only works if you have a flat and level surface to put it on, whereas the hinged version can be used freehand at car boot sales etc.

Probably best to make a hinged version.

I designed this one:

The idea being that the hinged part can fold up to fit in a pocket more easily. But it has the drawback that it won't sit on a flat surface without falling over if you set it down carelessly.

So then I came up with this:

We make a big foot that is just barely tall enough, and thin down the seesaw so that it fits inside it.

This is then made out of 3 pieces:

• 3mm aluminium sheet, 91mm long by 16mm wide
• 8mm aluminium block, 20mm long by 16mm wide
• 15mm stainless steel rod, ~4.5mm long

You calibrate it by facing off the stainless steel rod until it is correctly balanced.

The CAD model I have at the moment is not ready to use because the half sovereign slot is not exactly 2x as far away from the pivot as the full sovereign, so it can't possibly be correctly calibrated for both.

Adding a quarter sovereign might not work so well:

It has to be 4x as far away from the pivot as the full sovereign is. If I put the full sovereign any closer to the pivot then the beam will have to get wider else the hole for the half sovereign won't constrain it any more. And if I put the full sovereign too much closer to the pivot then it will start adding mass to the other side.