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Tag Archives: LONGCASE CLOCK

Counterwheel strike longcase clock

Before photos:

counterwheel4

After photos:

The chassis

chassis

After a few evenings I have my chassis assembled tight.

I milled square, two pieces of engraving brass – 5″ x 6 3/8″.

I found the centre datum line and ‘registered’ the plates together using small taper pins.

The pillars are 3″ long and have a spigot both ends.

One spigot gets faced off for a 4 B.A tapped hole, the other gets rounded off for ‘quick release’ taper pins. Each pillar is made for each hole respectively, I give a small, hidden mark to signify pillars l, ll, lll, and lV.

Spot through the plates with a centre bit then clamp it all down real tight to stop it grabbing as the pillar-drill pops through.

I’ve made rings to decorate the pillars.

I made the steel screws and brass washers.

Next:

Next I would like to make the pallet arbor crutch. But this can’t be fitted until I cut out the top slot in the back plate. Because once it’s soldered on I won’t be able to get it out unless that slot is cut. But; one of my registering pins is right there in the way, and I need it to help me position and depth the striking train. So the striking train has to be done next all the way up to the fly. Then I can cut out the back plate, so that I can work down towards the pendulum.

Marking the anchor

To mark out the steel for the anchor I either clamp the scape wheel directly to the high carbon steel sheet or mark it on paper then scribe from that. This Escapement is a square recoil escapement, square because the pallets span 7 1/2 teeth of the scape wheel which has 30 teeth.

So mark (on the paper) the 7 1/2 points (with a dot of your pen)

Coincidentally (and this is not critical) the inner circle of your crossed out wheel is approximately right for finding the degree of angle for the two impulse faces (radius= .71). So scribe/draw a line from your dots and across the inner circle so it just touches it, one across the top from the left pallet and one down the right from the right pallet. Next put in the drop-off face angles; from the centre of the wheel draw a line outwards directly to both dots and past, shade in to make clear this is metal to keep.
Next find the position for the anchor arbor. The distance between the arbors is X.

X divided by the radius = 1.41 ~ so the radius multiplied by 1.41 = X.

In this case 1.15.

Use a compass to scribe this line, it doesn’t matter too much where along the anchor the arbor hole goes. Place it centrally to look good.
Carve all this out of the steel keeping clear of the scribe lines as it can be shaped little by little in the depthing gauge. Hopefully it should jam as you have made it too big and when it is nearly there finish it off by planting it in the clock. When it is nearly there remember to file/polish down the drop-off faces which shortens the pallet instead of taking too much off the impulse faces making it ‘drop’ too far.

 

Rachet click, spring and screw

rachet

Completed barrels and great wheels:

completed-barrels

Barrels, end plates, slipwasher and rachet:

barrels

For the barrels I used 2″ drawn brass tube. 1 3/8″ long. Faced off nicely in the three jaw chuck.

The four endplates are out of 3/16″ sheet. All the centres are drilled and reamed to the 5/16″ for the arbors. Two of them will be the ratchets and are turned down to 2 1/8″ dia. The other two are 2 1/4 dia with a spigot turned to fit the barrel by using a mandrel in a collet. A spigot is also turned on the ratchet ends only 1/32″.
Next I groove/screw cut the barrels. Silver solder on the endplate, mount it back on the mandrel with the tailstock applying pressure in the endplate hole.
Set the lathe up to do 14 threads per inch and take very light cuts remembering backlash so you have to come out furthur (towards the tailstock) to keep on track.

Barrel arbors:

barrel-arbors
My barrel arbors are machined from 5/16″ dia silver steel. Again I fabricate. Each about 5″ long I turn down the small spigot 1/8″ at 1/4″ dia. Then the other end I turn down 1 1/2″ to 1/4 dia.
Then I make some steel shoulders. (note: make them extra large so its not too fiddly to braze. They can always be turned smaller later)
A groove needs to be cut with the parting-off tool for the slip washer. It’s all not too critical as the shoulder will soldered after the barrel, ratchet and endplate is mounted. Then I square off 7/8″ in a ‘roller filing rest’ in the lathe, using a division plate giving me four quarters. (pics attached).

Wheel, collet, arbor and pinion:

wheel

The going train

going-train

The mounted great wheels:

The screw cut:

 

Mounting the great wheels and going train:

Disassemble the chassis and put the two plates together in the register pins. Scribe out the positions for the great wheel arbors, at 2 1/4″ from the bottom and 1 9/16″ either side of the centre line. Drill and ream to fit.
Next depth the 96tooth great wheel to the centre wheel pinion on a simple homemade depthing tool. Scribe an arc across the centre line, drill and broach. Then depth the centre wheel to the Scape pinion and scribe that arc which will be 2 1/16″ furthur up the plate.

Division plate and lathe mod for roller filing rest

division

 

Collets

collets

Pinions:

pinions

Here I make pinion wire. All of my pinions are made out of 5/16″ diameter stock on the milling machine. When I have cut all my leaves I can cut off a pinion one at a time at the required length, drill the hole and position on the arbor. A main advantage of fabricating instead of turning the whole arbor & pinion from solid is so that it is much easier to depth the pinions to the wheels using a simple homemade depthing tool. 3 pinions are to have 8 leaves and 4 have 7.

The 3rd and Centre pinions are 8 leaves and both are turned down to the 3/16″ to hold their wheels respectively. The Scape, Fly, Warn, and Pallet are 7 leaves. And the Pin is 8 leaves. Pinions and pivots should be hardened and tempered to prevent wear.