Friday, March 15, 2013


I am back to clockmaking. I have been running into problems. Mr John Wilding wrote the instructions. But the drawings that come with the instructions do not reflect the modifications. Mr Wilding, as I have said, has built more clocks than I have passed power poles. He modified the pivots. Engineers call these things "bearings". He used pointy steel ends for his axles, which in clockspeak are called arbors. These pointy things run in brass tubes pressed into the clock frame, or plates. . We made the plates in episode 0 of this saga. So I have to make the arbors first, drill them for the pointy ends (called pivots in clockspeak, got that? Even in Italian they are called pivots) and then make the brass tubes, called bushings and this is engineerspeak too, so I can deal with it. Unfortunately the drawings (plans if you prefer) do not reflect his mods. Mr Wilding's mods are really very good; they cut down on friction, the deadly enemy of accuracy on any clock, wooden or otherwise.

 I first made the "center wheel" arbor as it is called. It calls for a 12mm dowel and (actually 1/2") and I had no such animal. So I turned down a 3/4" dowel. This was a Good Idea (TM). No commercial dowel is either circular or straight. It is not even dimensionally correct. Above, I am center-drilling the arbor to put a pointy thing (pivot) through it. Now this is no mean feat on the Taig lathe. You must support the outboard end so that the arbor does not whip about. I used my home-built steady-rest, mentioned elsewhere. This required boring out the center hole on the steady-rest to 12 mm + which was a project all by itself.

Finally I had the hole drilled. Now for the pointy thing (pivot) itself. This is a piece of steel hardware store rod with a 60 degree point on it.
 This was a breeze. I have finally learned how to turn points on things. I still have to work on my finish. I suspect my carbide tools are finally wearing out.  I am supporting my pivot on a collet. I have but the standard set of collets for the Taig lathe. But when you can use then they are marvellous. No runout (off-center) at all, unlike a standard chuck. Plus they will not take your fingers off, unlike the standard Taig chucks.

This pivot goes into the bushing -- or as Mr Wilding calls it, a bush. So we have to turn a bush from brass. This involves (1) cutting the thing, with a hacksaw, from my priceless stock of brass that I found at Fastnall in Anchorage, (2) drilling it through, (3) cutting a taper same as the pivot and (4) cutting to length.

Above I am at the stage of cutting the 60 degree taper on the bushing. I am using a priceless 60 deg. countersink picked up at Lowe's. 'Twill do. The other end of the arbor is a plain old piece of steel. Hardware store! I gave it a skim on the lathe to true it up. When all this is done, we can shove the wheel onto the shaft. This particular wheel has no pinions attached, a blessing. It will drive the minute hand.

So there we are. In the meantime we have have had lots of fun (and a great deal of trouble) making the arbors for the gear train that gets you from the escape wheel to this particular wheel. But the clock is beginning to take shape.

I am not in the least ashamed of my efforts so far. As the British say, the Words of my tune do not match the Music. Mr Wilding's variations on the clock (all for the good) do not match his drawings. And so I have to stop and figure things out. Worse, Mr Wilding uses RGU all the time. I refuse to work in RGU so I have to stop and convert, almost all the time. Then I have to deal with the RGU feed on the Taig lathe, but that is simple;  at least it's decimal and not absurd fractions of an inch. Next episode will detail (I hope) the rest of the "going train" which is clockspeak for the gearing that gets you from the pendulum beat to the hands on the clock.

No comments:

Post a Comment