Marking mortices (Part II)

[Derek Cohen]

The other day I received an email inviting me to purchase the latest one-time tool from Woodpeckers, a mortice and tenon centre gauge ..


http://www.woodpeck.com/media/main_1_mt_center_gauge.jpg


Here is the link to their website for those interested: woodpeck.com/ottmtcenterpwwp.html?et_mid=643179&rid=237299788


My first thought was that this was brilliant - what a great, quick way to mark a mortice (or tenon) in the centre of a stretcher. Then I looked at the price ($150), and that one had to pre-order now for 5 months time. I put away the credit card.


I still think that it is a terrific idea, and I must admit that the concept haunted me for some days. Today - Sunday - I decided to build my own version. So I looked around the workshop for something to cannibalise.


I found an old dovetail marker that had never worked and had been tossed into a drawer ...


http://i13.photobucket.com/albums/a262/Derek50/Marking%20mortices/8_zps7f97e960.jpg


This is the centre gauge I built ...


http://i13.photobucket.com/albums/a262/Derek50/Marking%20mortices/9_zps4040be94.jpg


It slips over the stretcher this way ...


http://i13.photobucket.com/albums/a262/Derek50/Marking%20mortices/10_zps7748312e.jpg


Marking out for a 3/4" wide stretcher calls for a 1/4" wide mortice. This one will be 2" long.


Step #1 is to mark off the 2" length (with room to avoid blowing out the end) ...


http://i13.photobucket.com/albums/a262/Derek50/Marking%20mortices/11_zps1fb46341.jpg


Now place the centre gauge between the two end lines (anywhere, it is not critical). Set the 1/4" mortice chisel against the centre, eyeballing it square ...


http://i13.photobucket.com/albums/a262/Derek50/Marking%20mortices/12_zps64d29392.jpg


Press done hard so that you leave a clear imprint of the chisel ...


http://i13.photobucket.com/albums/a262/Derek50/Marking%20mortices/13_zps81a96c89.jpg


Now you have a choice - either use two single blade cutting gauges to mark each line individually (you will need to set these aside for the tenon) ...


http://i13.photobucket.com/albums/a262/Derek50/Marking%20mortices/14_zps11bb2790.jpg


... or use a mortice gauge, aligning the blades with the outer edge of the imprint ...


http://i13.photobucket.com/albums/a262/Derek50/Marking%20mortices/15_zpsf1196abb.jpg


It has never been critical to centre the mortice, but this method does speed up the process (even though this is all a bit tongue-in-the-cheek). Is it accurately centred? I did three or four. None were perfectly centred. Some error creeps in. It does not matter. As long as you use the same gauge(s) and score from the reference side, each mortice/tenon will be marked at the same distance from the sides.


Regards from Perth


Derek

[David Weaver]

Humorous to market a gadget like that for $150. Woodpeckers does seem to have a following marketing a lot of little gadgets that will probably show up with not much wear on them in 20 years (strangely enough, a lot of the bridge city items have started to show up at MJD listings at a high projected price, but i don't know what they sell for and they have a significantly different aesthetic).

At any rate, I don't think I've ever marked a mortise dead center on anything, just keep track of the face of everything. To use a gadget to mark center on a mortise and then on a tenon would almost certainly be less accurate than referencing the face side of a joint and ignoring the fact that a mortise might be slightly off center. And doing the latter is free.

[Jessica Pierce-LaRose]

Accurate mortises seems too much like work, but I want to make sure I stay neanderthal "pure" - how about a hand-crank Domino for the next project, Derek?

(This comment is in total jest)