I’ve not too long ago been engaged on this beautiful bracket clock by James McCabe. It was delivered to me due to an issue with the putting mechanism – when wound the clock would strike constantly till it ran out of energy. There are a selection of issues that might trigger this but it surely was agreed that the clock would even be serviced whereas it was within the workshop, because it was evident that there was quite a lot of very darkish oil and put on which could possibly be seen just by trying on the backplate.
One other apparent difficulty earlier than a full prognosis was some screws lacking from the brackets which might get replaced. Lastly, the case wanted some restore work: there was a dent on the again and apparent makes use of of filler from a earlier poor high quality restore which might be rectified.
Disassembling the clock made it clear it had not been handled effectively by the earlier repairer. Plates have been held collectively by previous nails, and components of the under-dial work had bits of wire wrapped round them to safe them in place. You can too see that the enamel of the good wheel are flooded with oil. No clock wants this quantity of oil, and it actually shouldn’t be right here. There was additionally a considerable amount of put on and tear on the pivots and pivot holes all through the clock which I’ll handle later.
Lastly, now the dial is off the reason for the problem with the putting mechanism will be seen – the tail of the gathering pallet has damaged off and is lacking. This could usually come to relaxation on a pin on the rack and arrest the putting practice after the suitable variety of ‘dings’, with out the tail there’s nothing to cease the practice and the clock will strike till there isn’t a extra energy. A brand new one will have to be made.
Service and overhaul
A core a part of any clock restore is a service or overhaul. At it’s most simple, this implies two core issues: cleansing all the parts completely to take away previous oil, filth and mud, and addressing mechanical put on and tear.
Under I’ve illustrated put on to pivots being corrected. Aspect by aspect you may see how totally different polished pivots look and the poor situation they have been in beforehand. With out sprucing, the friction from the pivot is enormously elevated and may trigger the clock to cease. The pivot should be free from scores or defects, and be completely parallel to permit the wheel to show as freely as attainable. The situation of clock pivots can differ wildly, however usually a clock will profit from having all pivots polished no less than a little bit.
Clock Plate Bushing
The opposite principal level of damage is the holes wherein pivots sit. The metal pivots put on away the brass plate which ends up in oval holes; this adjustments the space between the wheels and pinions, often called depthing, and impacts the effectivity of energy switch and within the worst instances could cause the practice to jam. To repair this, a brand new brass bushing is added to the clock. After I bush a plate, I take advantage of the smallest bush attainable as this makes it virtually invisible as soon as the restore is accomplished. You’ll be able to see within the earlier than picture the hole to the left, and the big dimension of a beforehand fitted bush. On the appropriate after restore the brand new gap is spherical, holds the wheel in precisely the appropriate place with out an excessive amount of ‘aspect shake’, and is sort of invisible to the bare eye.
A part of the clock which appeared to have been uncared for for a while was the barrel bearing: the place it rotates about its arbor. This can be a massive bearing, and really troublesome to restore with out the proper gear, which is maybe why it has not been repaired earlier than. A customized bushing was made and riveted in place earlier than adjusting to the proper form and dimension on the Schaublin lathe.
You’ll be able to see hammer marks on the barrel which is from earlier, inadequate and poor high quality repairs. An alternative choice to a correct bushing is to hammer what steel stays so as to fill the hole. That is unattainable to do precisely and solely makes the remaining steel thinner, which in flip hastens future put on. In my workshop if one thing must be repaired, it is going to be repaired correctly.
In addition to changing the broken gathering pallet, it was discovered that some screws have been lacking from the clock: the case brackets have been being held in place by one screw every reasonably than the proper two, so new screws would have to be made to match the originals.
A gathering pallet is a really complicated half with a lot of vital dimensions. Because of this, I elect to make use of my CAD/CAM amenities to rapidly produce an correct half based mostly on a number of key measurements. The 5-axis machine I take advantage of permits fast prototypes produced from brass to be made to substantiate all measurements are right earlier than a closing half is produced from metal then hand-finished, hardened, tempered, and polished the normal means. Combining leading edge expertise with conventional hand expertise on this means cuts out quite a lot of trial and error that may usually be required in clock restore.
Making Clock Screws
A pair of screws wanted to be made to match these already within the clock. After measurements of the previous ones have been taken, the brand new ones have been made, totally on the lathe, from silver metal. They have been then heat-treated to be hardened and tempered earlier than ending with a satin polish to match the previous ones.
Right here you may see the 2 new ones with the 2 originals, are you able to inform that are which? When making components for clocks it is very important select the proper methodology to make sure the brand new parts look right. Within the authentic components the slots would have been lower by hand, and so I did the identical right here. Slots can simply be machined, however these would have made the screws look too fashionable and misplaced.
Lastly, after all of the work is accomplished, the clock will be reassembled and oiled all through earlier than testing for 2-3 weeks. As soon as I’m assured the whole lot with the motion is nearly as good as it may be, the clock is able to be returned to the proprietor.