2 x 5" mortises

[Greg]

Hi all,

I am cutting the joinery in my sill plates, and in the four corners of my garden shed, it calls for a 2 x 5 inch mortise. This is where the stub tenon of the corner posts will sit. I will have the same problem with a 2x7 mortise on the middle posts.

So, my problem is using a 2 inch boring bit, I drill out each end of the mortise, leaving a ~ 1 inch chunk of materal in the middle.

Maybe its just my crappy boring machine, but I cannot keep the bit from wandering out of the middle and falling into the nearby hole. There seems to be no way to space out the bit to get three complete holes drilled. So I end up going back in with a 3/4 inch bit and a hand brace to remove the excess material. What a pain in the a#$!#@!!

How in the world did the old timers do these 2 x 5" mortises?

Thanks,
Greg

p.s. I have noticed watching eBay of late that pretty much any hand cranked boring machines now routinely go for $300 !!!! Seemed like not too long ago, you could find a decent one for closer to half that.

Wow, for that kind of dough I could just do it the easy way and buy a makita chain mortiser for $1200...

[raycon]

Use a 3/4" or 1"  boring bit in the center holes. Chuck it up in an electric drill. Drill the two middle holes first then the two 2" holes.
Don't know if that will work for you or not but thats what I've done in making blind mortises. Combination of  brace boring machine and power tool.

[Timber_Framer]

Does your boring bit have a spur? (for lack of the proper word)
I use self feed saw toothed forstners bits and have very little trouble staying at home http://www.toolsteal.com/store_images/DeWALT/l_RAF-DWT-NEW-DW1633.jpg

Click link above to see image at http://www.toolsteal.com
You see that screw point protruding past the cutting edges? Using the prper speed that little screw keeps my bit right where I need it to be.

[ohsoloco]

Timber_framer, how do you like those self-feeding bits for making mortises?  I had a 1 1/2" auger bit I got from Lee Valley to make a small frame, but the lead screw snapped off when I started a white oak frame  >:(  My next shot was one of those self-feed bits with an extension like you have.  Problem is, if I bore in more than an inch or two, there is so much packed-in sawdust above the bit that I snap the screw holding the chuck on my drill  :(   So it's, drill an inch or two, and back it out, drill some more...back it out  :   Those screws have a left-hand thread, so they're not cheap, and luckily there's always been enough of the screw (BARELY) sticking out of the hole for me to get my vise grips on.   If I were going to cut a substantial frame like a workshop, I think I'd invest in a chain mortiser.  Unfortunately I've used one before, so I know how great they are  ;)

[Jim_Rogers]

I was told a long time ago about lead screws on bits. Course threads are for softwood, fine threads are for hardwoods. Fine threads pull the bit into the wood slower and give the bit a chance to cut the wood.
If you're going to use a bit for hardwoods look for one with fine lead screw threads.
If the lead screw is replaceable replace it with a fine thread screw.
Good luck,
Jim Rogers

[ARKANSAWYER]

Greg,
  I was taught to start my outside holes and cut about 1/2 inch deep.  Then start my middle hole and go about 1 inch deep.  Now go and do the outside holes about 1 inch deeper and come back and finish the middle hole to depth and then the outside holes.  Try this.
ARKANSAWYER

[Timber_Framer]

ohsoloco, I've only used them on white pine and aspen so i have no experience with self feed bits and hardwood :-/
ARKANSAWYER's technique works very well.

[ohsoloco]

I had the same problem backing the bit out of the tamarak I used for the sill.  I started making my mortises kinda like Arkansawyer described, but they were all 6", and I just did them like a step with some overlap so the chips could pile up in the previous hole so I wouldn't have to back out so often.  

I couldn't wait to finish the sill on the smokehouse so I could quit cutting that DanG sappy tamarak and get to the white oak.  I've read WO was a favored wood for timber framing, and now I know why, it's a joy to work with