Tuesday, January 31, 2017

Drawbored mortice and tenon

It is a joint easy to realize as well as very strong and traction-resistant; it permits of making joints without glue, too. The secret are offset bores through mortice and tenon: when the pin is inserted, it forces the tenon in the mortice and keeps it strongly in place.

I utilized this tecnique for inserting a Jack plane wooden handle in its mortice
Normally, I use to glue the handle in place and secure it by a screw, driven through the handle foot, but the drawbored mortice and tenon seems to me a good alternative, utilized in the past for this purpose.

In this case I have had to utilize an handle with the grain oriented perpendicular in respect to the body grain (I thank Paul Bouchard for his very good advices) and with little lateral projection (the horn is just outlined for avoid its breakage)

First, we can drill through the mortice one or more bores. 
In this case I utilized 6 mm pins for a tenon (the handle foot) 25 mm thick and ca 30 mm long. 
After the bores have been done, the tenon is well inserted in the mortice and the position of bores is marked by the 6 mm drill bit. 
Then, the tenon is extracted and the bores are marked again, this time slightly further back
1 mm ca offset and no more in order to avoid troubles with pin insertion.

We can round and lubricate the pin tips by a little bit of candle wax.


From last images you can see the plane having an offset handle, an old practice, today no more in use and that seems to give a better ergonomicity to the plane, although the precise reason is unknown. The offset is on the left but normally is on the rigth (of course I am left handled).



Monday, January 23, 2017