sawtooth-9
Established Member
I think the cause is " discovered "
Removed all shafts again and set these between centers on the Harrison lathe.
Found that both the "D" and "E" shafts had been bent by about 5 thou and careful inspection of the wear pattern on the 16 tooth gears was quite uneven. The result is the gear is running out of true, enough to create the tapping sound. There is evidence that this lathe has had a crash, so a bent shaft or two is not that surprising. The diagnosis was complicated by the fact that the bend on the "E" shaft was on the chuck end and the bend on the "D" shaft was on the drive side. So it was really hard to pinpoint where the noise came from.
So, now looking in UK and NZ for replacement shafts, or I will get these made locally.
I really did not think 5 thou run out would be enough to cause such a defined noise, but these gearboxes must be machined to quite fine tolerances.
Removed all shafts again and set these between centers on the Harrison lathe.
Found that both the "D" and "E" shafts had been bent by about 5 thou and careful inspection of the wear pattern on the 16 tooth gears was quite uneven. The result is the gear is running out of true, enough to create the tapping sound. There is evidence that this lathe has had a crash, so a bent shaft or two is not that surprising. The diagnosis was complicated by the fact that the bend on the "E" shaft was on the chuck end and the bend on the "D" shaft was on the drive side. So it was really hard to pinpoint where the noise came from.
So, now looking in UK and NZ for replacement shafts, or I will get these made locally.
I really did not think 5 thou run out would be enough to cause such a defined noise, but these gearboxes must be machined to quite fine tolerances.