How do anti cupping grooves work?

[rsk]

?

 

[Phil Pascoe]

?

 

[Chrispy]

!

 

[John Brown]

TTTTTTTT

 

[joethedrummer]

Silently !!

 

[CHJ]

By reducing the mechanical integrity of one side of the board, this in turn counteracts natural stress relieving and/or the influence of moisture level effects on swelling/shrinking wood.

 

[SteveF]

Hi rsk

u may getter a better response if u introduce yourself
welcome to the forum

Steve

 

[Eric The Viking]

The back board of our 210-year-old grandfather clock has three large, tapering, sliding dovetails across it, with 2x1" battens in them going across the grain of the board. They're really beautifully made, with a snug fit all along the groove. I'd struggle to do them to the same quality with power tools today.

Sadly they didn't work - the clock case is significantly twisted. :-(

 

[RogerS]

The back board of our 210-year-old grandfather clock has three large, tapering, sliding dovetails across it, with 2x1" battens in them going across the grain of the board. They're really beautifully made, with a snug fit all along the groove. I'd struggle to do them to the same quality with power tools today.

Sadly they didn't work - the clock case is significantly twisted. :-(

That's because grandfather clocks are supposed to be screwed to a backboard attached to the wall!

 

[Eric The Viking]

The back board of our 210-year-old grandfather clock has three large, tapering, sliding dovetails across it, with 2x1" battens in them going across the grain of the board. They're really beautifully made, with a snug fit all along the groove. I'd struggle to do them to the same quality with power tools today.

Sadly they didn't work - the clock case is significantly twisted. :-(

That's because grandfather clocks are supposed to be screwed to a backboard attached to the wall!

It is.

It's actually keeping very good time, considering its age, +/- about 5 secs/day at this time of year. It doesn't have a Harrison pendulum so is rather weather dependent, and it's difficult to set exactly after the weekly winding session (I"m getting better at it). It's James Smith, Edinburgh, circa 1795 (sadly he was not the famous one from Pittenweem!).

It was restored really nicely at the beginning of last year by a local expert (Rick of Somerset Clocks). Prior to that I don't think it had run for 45 years, possibly longer. I vaguely remember it at my step-grandmothers but can't remember if it was running then.

It's the back board that's pulling the case out of true, I think, but I'm not going to risk messing about with it.

E.