# Centre finder.



## Derek Willis. (18 Jul 2009)

Been using one of my centre finders yesterday, marking up a number of mortise and tenon joints, certainly makes for ease and accuracy.






Derek.


----------



## Woodmagnet (18 Jul 2009)

They certainly come in handy at times Derek. :wink:


----------



## Mailman14 (19 Jul 2009)

Hi there, any explanation on how this marks the shoulders? I can see how it marks the centre of any width rail / stile, but for shoulders, I'm lost...


----------



## Derek Willis. (19 Jul 2009)

Mailman, can't see any post saying it would mark shoulders at all.
Derek


----------



## Mailman14 (19 Jul 2009)

Hi Derek - I can see that by slipping the block over a rail (for example), and rotating on the centre pin, that would show the centre of the rails width. How do you know where to place the shoulders (I'm working on a general 1/3, 1/3, 1/3 spacing)? :duno:


----------



## Derek Willis. (19 Jul 2009)

Mailman,
I havn't tried it, but I suppose, if you put a spacer behind one of the pins it would place a mark 1/3rd. of the way ffrom the edge, then do the same the other side, for me I use a mortise guage.
Derek.


----------



## skyechem (19 Jul 2009)

If you make a new guide, and put a nail at 1/3 and 2/3 across the gap between the guide pins, that will mark out 1/3 and 2/3 on the wood for shoulders. It works with any fraction. I don't know if it's any more useful then a mortice gauge though...


----------



## Derek Willis. (19 Jul 2009)

Makes sense doesn't it!! May give it a try on20mm. stock as that is the size used so much in the sort of cabinetry that I do a lot.
Derek.


----------



## Night Train (19 Jul 2009)

The thirds rule is fine but I generally set the mortise for the nearest chisel width to a third rather then an exact third. Unless it looks wrong of course in which case your thirds divider could be useful. I still divide up using a steel rule set at an angle.


----------



## Steve Maskery (19 Jul 2009)

I'm a bit of a heathen when it comes to Thirds. It always looks too thin, especially on ex-1" stock. I always err on the fat side (no making up your own jokes, please). So for nominally 1" boards (which, if I'm lucky have finished at 21mm) I would use 5/16 or 8mm tenons.

A jig like this is fine for finding the centre of a piece (provided you don't want to get too close to the end), after that, you do with it as you please 

S


----------



## xy mosian (20 Jul 2009)

I was taught that the tenon/mortice should be slightly thicker than a third of the thinest component. Still whatever works.

xy


----------

