Ignore the amplitude reading – I haven’t adjusted for the lift angle of 38 degrees yet. But the -41s/day and the patchy graph are for real. Having read George Daniels biography over the holidays, I am sort of curious how he would interpret this… He claimed that his watches could go 15 years without a service and keep their accuracy, and weren’t in need of lubrication. Surely his watches had a balance, jewels, jewel caps, etc. and needed oil in all those vital places.
I do of course understand his argument about the friction between the escape wheel and the pallet stones, and why the co-axial escapement is better in that respect. But all the rest is just a normal mechanical watch, with the same need for lubrication and cleanliness.
The balance roller is also different, as the power that is transmitted to the balance is transmitted in one direction by the impulse pin, but in the other direction by a jewel that looks very much like a pallet stone.The double escape wheel and the pallet fork of the co-axial escapement.
So – does the co-axial movement need less servicing? In principal yes, but practically, no.
Does it keep better accuracy over time? Not in this case 😉
Is it more accurate than the non-co-axial version? Not really.
But, it’s a technically interesting movement, and I can see the theoretical advantage of the co-axial escapement. Got to get my hands on an 8500 😉