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Posted

I'm working on an oldish French clock, barrel movement, with a Thevenet platform escapement. I'd guess it is late 19th century so it probably has natural jewels. It's not precious but it is valued by it's owners. The clock has been knocked to the floor. Luckily it was carpeted. Less luckily, the owner had left the winding key in the barrel. The escapement wheel  was bent out of true, but this was easy to rectify. It looks like the balance took the brunt of the impact as the lower cap jewel was smashed and the lip of the bezel setting was torn. I made a replacement setting using a pressed in jewel: 

DSC_1256.thumb.JPG.7f111dfe864e443e996f33982c88e59f.JPG

The difficulty come with assessment of the condition of the remaining jewels. I've examined them closely with my old microscope and took some photos through the eyepiece with my phone. I'm not familiar with how much damage or wear and tear is acceptable. Whilst I'd be able to  replace them with pressed in jewels in brass chatons, I'm not equipped at present to deal with rubbed in jewels, nor do I have a source of them. So my multifaceted question is this: would you replace these jewels, and if so, with what and from where would you source it?

Upper escapement jewel:1606944962_Upperescapementjewel.thumb.JPG.20b1f4840dd7ecca35ad5457c22e4740.JPG

Upper balance cap jewel. A bit chipped at the edge but nicely polished in the middle

2144530139_Uppercapjewel.thumb.JPG.2829c0d794ca18784b55eb6aa232a20e.JPG

Upper balance jewel. Looks smooth in its centre bore but the edge of the hole shows chipping

 

1020552624_Upperbalancejewel.thumb.JPG.435ecee649a06e84cae8712e998167cf.JPG

Lower pallet fork pivot jewel. Bit rough around the hole

 

1989923026_Lowerpalletforkjewel.thumb.JPG.91df1e54466f55ef1e444e3e7e868a5f.JPG

Upper pallet fork jewel cracked and chipped

 

1975384650_Upperpalletforkjewel.thumb.JPG.37fc8c976c21cc8a0ce9a5f37e8daf81.JPGLower balance pivot jewel, looks pretty good

1242793318_Lowerbalancejewel.thumb.JPG.eceacbf56c255dc47d8d2c43d2458a51.JPG

Upper pallet fork jewel, cracked.

Lower escapement jewel, pretty good

328676667_Lowerescapementjewel.thumb.JPG.2b72ce203c29aa4690634683a3411677.JPG

Fitted together as is, the clock runs for eight days at a wind. The pivots mostly look in need of a bit of TLC.

Balance upper, looks a bit scored. Also is it normal for these pivots to be cut without a square shoulder?  Isn't the arbor rough looking

 

Upper.thumb.JPG.fb7baa4c858bf1031ab00d2fa078d65d.JPG

Balance lower, seems to have survived the impact

 

1282636754_Balancetableside.thumb.JPG.399af70129cdceab9a572878070d4496.JPG

 Escapement pivots seem better. Lower:

1508407623_Escapementlower.thumb.JPG.21d07f828d110559527dce0b1690019e.JPG

Upper needs a polish:

1610352927_Escapementupper.thumb.JPG.f7f7c6bf78848d5c317e1428d56d5846.JPG

And finally the pallet for pivots. Upper corresponding to the badly cracked jewel:

928096166_Palletforkupper.thumb.JPG.07c4c2d02bfa2a13c77ff29e50e8b134.JPG

And lower looking a bit grubby:

123797168_Palletforklower.thumb.JPG.ff37582aa600d9f233e8d1d152687e12.JPG

Balance upper pivot.JPG

Lower pallet fork jewel.JPG

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Posted

All pivots need to be polished and burnished.  The one but last of the bunch of jewel holes need replacing, plus the very last jewel photo. You should be able to buy jewels from a good supplier, have a look on ebay for jewels old stock is always for sale. 

Posted
6 minutes ago, oldhippy said:

All pivots need to be polished and burnished.  The one but last of the bunch of jewel holes need replacing, plus the very last jewel photo. You should be able to buy jewels from a good supplier, have a look on ebay for jewels old stock is always for sale. 

Thanks @oldhippy Do you think given the low value it would be acceptable to use pressed jewels as I have the tools to do that, plus I can find that sort of jewel readily? 

Posted

I would always replace the rubbed in jewels for friction fit, unless it was about restoration or preservation of the timepiece.

As you said, sourcing the jewels will be relatively easy. anything that is of questionable integrity, replace. That's a pretty big job, as it looks like a lot of replacement jewels are needed. The pivots/arbors will burnish and polish up nicely, as there only slight wear on them.

  • Thanks 1
  • 1 month later...
Posted

Thanks all your your advice on this. It was good practice using the Jacot tool on less fiddly pivots, and the replacement jewels were simple to fit in pressed in brass mountings. There is no significant change in the appearance of the escapement except the slight change of colour from the old jewels to the new synthetic ones such as the lower jewel in the picture below. The movement works perfectly. 

DSC_1274.thumb.JPG.7d2b0bb8136db878567ecb51aca23020.JPG

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