Rebushing a Forestville escapement platform

[HectorLooi]

I posted about repairing the cracked mainspring barrels of tbis clock last year. The clock worked fine for a few months but it stopped completely a couple of weeks ago. There was totally no power transferred to the balance wheel. I removed the balance and found that the pallet fork would not unlock anymore. On examining the escapement, I found that the pivot holes of the escape wheel are worn.

I haven't done any rebushing work before. I can't even tell if this hole is original or has been rebushed before. The hole on one of the plates is in a very narrow strip of brass. I'm wondering if it is even possible to rebush this hole.

I hope more experienced members can take a look at the photos and advise me. Thanks.

[watchweasol]

Hi Hector   Both holes look original and dont appear to have been bushed.  The method in doing these is the same as any re bushing job, making sure you broach or drill the hole central. the attaced noted will explain the procedure.  I use a small drill in the drill press drilled under size (bush Size) and breach to fit thn broach the pivot hole.  when done try the wheel and the adjacent one for smooth running. 

1002416176_BushingUsingHandTools.pdf (2).pdf

[HectorLooi]

I reamed out both holes and tapped in the new bushes last night. Went quite well. Now I have to get a round bur and create the oil sinks.

[oldhippy]

That's good for a first attempt, always check for end shake and make sure the wheels run free, it's a good idea when all is done to put the wheels between the plates  and tighten then check on the running as I said to make sure they run free try it at different angles and if all is well that will be a good job done. 

If you have a clock movement with lantern pinions that is this type the holes for the wheels are meant to have a loose fitting. That is this type.

 

[HectorLooi]

The first clock that I serviced had lantern pinions. I learned how to repin a lantern pinion from watching YouTube. 

I drilled out the oil sinks this morning. I'll test the escape wheel on its own first before fitting the pallet fork and balance wheel when I get home from work.

[HectorLooi]

When I reamed the hole for the bush with my five sided cutting broach, it raised a bur around the edges of the hole. Is that normal or is it because the broach is blunt or am I using too much force?

My Seitz jewelling set also has D shaped broaches. Can they be used for bushing or is the taper angle wrong?

[oldhippy]

Bur around the edge is normal a simple way of removing it if you don't have the right tools is a simple pen knife blade. A D shaped broach is OK providing you have the correct size. Lantern pinions can be fun to replace and it's so easy. I have seen some nasty work done on them, instead of closing the hole with a punch they have run soft solder around, so if just one pinion needs replacing you have a task on your hands. 

The one on the left is the sort of tool to get hold of for removing bur you can get all different sizes 

[watchweasol]

Hi Hector  Nice job  To remove the burr and create an oil sink I personaly use a drill bit in a pin vice for more control the same applies to the burrs posted by Old Hippy best used manually on delicate jobs.  Ok in the dremel for milling etc.

[oldhippy]

Never use hand power tools when repairing clocks. You have very little or no control and they can do irreversible damage.  

[HectorLooi]

The clock has been running overnight. Thanks everyone. 

I now understand what OH means by soft modern brass. The brass of the bush is much harder than the brass of the plate. When I was reaming the hole, I could feel the broach biting into the brass, but with the bush, I had to use a little more force to cut into it.

If I get bushing rods from Cousins, is the brass soft modern brass or hard vintage brass?

I could hardly see the taper on the pre-manufactured bushes. What is the taper on a typical bush?

[oldhippy]

I always used bushing rods as I prefered to make my own bushings. I had no trouble with the hardness of the brass, I am talking back in the 70's and 80's there was a lot of stock already in the workshop. Buying replacement from my supplier which was Southern Watch & Clock Suppliers from  Orpington Kent sorry to say they no longer exist.  

[watchweasol]

Nice one Hector. A bushing pro now.

[rodabod]

On 2/24/2021 at 1:21 AM, HectorLooi said:

If I get bushing rods from Cousins, is the brass soft modern brass or hard vintage brass?

This is a very good question. Cousins may state where it is from. Personally, I would not use it if it isn’t European or USA-made. 
 

I have made bushings from scrap antique clock movement pillars in the past. Partly to get the colour correct for antique movements, but also to ensure good quality brass. 
 

I also have a set of Bergeon pre-made bushes which can obviously be adjusted to fit. 

[HectorLooi]

This is really becoming a neverending project. After rebushing this clock, I succeeded in coning and tangling the balance hairspring when I forgot to unpin and unhook it from the regulator before removing the plates of the escapement platform.

I finally straightened it and got the hairspring to almost flat again. I put everything back together and fixed it on my test stand. It ran for a few days without any issues then stopped. 

When I put the movement face down, it'll start running again. But when I put it face up or vertical, it'll stop again. The cone pivots looked fine even under a 10X loupe. But when I put it under a microscope, I could see that one end of the pivot was damaged. I tried sharpening it on my lathe but my HSS cutters simply wouldn't cut it. My tungsten cutter was also blunt from cutting a previous project. 

I used a ceramic stone to reshape it slightly and put it back in the clock. I could now get it to run face up but the amplitude isn't great.

I'll sharpen my tungsten cutters today and try again tonight. I wonder what would crop up next.... 

[oldhippy]

All you need is a small  Arkansas stone with a drop of oil. That is what I used, I had a three sided one and a small square one.   You need it to look like a new sharpened pencil.  See the difference between yours and what it should be.  

 

Here is a link

https://www.zoro.co.uk/shop/abrasives/oilstones-and-whetstones/150x13mm-three-square-abrasive-sharpening-stone---silicon-carbide---medium/p/ZT1034324X?utm_source=google&utm_campaign=pla%2B|%2BAbrasives&utm_term=ZT1034324X&utm_medium=pla_css_3&targetid=pla-392797652293&loc_physical_ms=9045300&dev=c&gclid=CjwKCAjwqIiFBhAHEiwANg9szmu4KxU54bzji0xLIgIXlBN1cn5LahuB4PBHYpvWU2Yy-4-7-YWGTBoCLnMQAvD_BwE

[HectorLooi]

I sharpened the pivots to a point last night. The amplitude has improved and is stable in all positions. But I noticed that the amplitude is nowhere near that of a watch movement. From the slow motion video, it looks like it's not even 180°. Is this normal or did I miss something else?

[nickelsilver]

Looks fine to me. First of all the balance is vertical, which increases pivot friction, then you have relatively massive conical pivots in steel bushings- you will never get near watch amplitude.

[oldhippy]

I would have expected a better action then that. I trust you have oiled the cups and escape wheel teeth and pallet pins. What oil did you use?  Don't expect an amplitude like a watch.  Make sure the hairspring moves between the regulator and not just resting, it needs to move so the regulator works properly at any position.   

[HectorLooi]

I used Windles clock oil in the cups and also on the teeth of the escape wheel. I have adjusted the end curve of the hairspring until the regulator can ride the entire travel without distorting the hairspring. 

I suspect the hairspring is not original because the coils were very loose and even when the regulator was all the way at the end, it was still running fast. And the 2nd coil of the hairspring was rubbing against the regulator. 

When I accidentally "coned" the hairspring, during the straightening process I reshaped it so that the coils at the centre are tighter and I had more room in the end curve to prevent fouling the 2nd coil. I also took up the "excess" spring beyond the stud and effectively lengthened the hairspring to increase the period.

[oldhippy]

That is the best oil to use. If the hairspring in not the original, then that is your answer for the poor action of the balance.  

[RogerH]

Is it the angle of the picture or are the bushes worn on the left hand side of the regulator? I agree with OH that the movement doesn't look right, it may be worth looking at a replacement spring.

[oldhippy]

I would say as it's on the going side it should be rebushed. Well done RodgerH I completely missed that I was far too engrossed watching the the action of the balance.

[HectorLooi]

7 hours ago, RogerH said:

Is it the angle of the picture or are the bushes worn on the left hand side of the regulator? I agree with OH that the movement doesn't look right, it may be worth looking at a replacement spring.

Thanks Roger. It is a little worn out. And so am I. I've been a little under the weather lately. I went for a swab test last night and confined at home till the results come back.

I would love to replace the hairspring. The lot of clock hairsprings that I got from Cousins is a load of rubbish. None of them look like they belong in a clock.

Any idea where to find a replacement? 

[RogerH]

I use Cousins and they can be a bit hit and miss sometimes. Ebay is always an option, again it's risky but if you can find similar type clock / movement then you might get lucky. This could be a long game but worth persevering as you've come this far.