Replies

1. 
   flairwoodworks | Mar 17, 2009 04:13am | #1

   Tom,

   Either you or I are confused. A birds mouth bit is used to create positive registration and more glue area when doing coopered-style work, as seen here http://www.leevalley.com/wood/page.aspx?c=1&p=45160cat=1,46168,46174

   Chris @ www.flairwoodwork.spaces.live.com
   (soon to be www.flairwoodworks.com)

    - Success is not the key to happiness.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

1. 
   tom_47 | Mar 17, 2009 06:07am | #2

   Flair,
   I've attached a crude sketch of the tip. It looks like a bird's mouth to me. I believe it is intended to do mortising.

1. 
   flairwoodworks | Mar 17, 2009 04:13pm | #4

   Tom,I'm not sure what a MDI file is, but I can't open it. Charles' description of a mortising bit is accurate.Chris @ http://www.flairwoodwork.spaces.live.com(soon to be http://www.flairwoodworks.com)

    - Success is not the key to happiness.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

2. 
   charlesm | Mar 17, 2009 04:10pm | #3

   Tom,

   Typically what is referred to as a mortise bit is intended for shallow recesses like hinge mortises. For deep pocket mortises the best tool is probably the dedicated mortise machine which has a drill bit inside a square chisel. If you intend to use a router bit I would recommend an up cut spiral bit like the 75-106 (note that 1-1/4" is the max cut length with this bit and the cut should be made in multiple passes to avoid over stressing):

   http://www.freudtools.com/p-63-up-spiral.aspx

   Charles M

   Freud America, Inc.

3. 
   BOBABEUI | Mar 17, 2009 04:57pm | #5

   Tom,

   The mortising bits for the slot mortising attachment for my MM jointer/planer are called 'birds mouth', they are manufactured by Onsrud. Are these the bits you are talking about?

   I haven't used the slot mortiser a lot, but the technique I used was to cut from left to right, in 1/8" incremental passes. Very clean cuts and definitely the way to have to cut many mortise joints..

   
   

   ---

   Edited 3/17/2009 9:58 am ET by BOBABEUI

1. 
   RickL | Mar 17, 2009 05:53pm | #6

   Been using horizontal slot mortisers for 25 years plus.  I've tried the "birdsmouth bits".  The actual name is Oscillating mortise bit. I find the 2 flute  HSS endmills do a better job, have more size options and are cheaper. Look for the center cutting type for plunging but they work best if you go in 1/8" as you move side to side.  The oscillating and endmills wotk best at around 5,000 rpm. Not for a router.

   http://www.morriswoodtool.com/Tooling-Misc.htm#Oscillating Mortise Bit, Style 6HS

   Edited 3/17/2009 10:55 am ET by RickL

1. 
   BOBABEUI | Mar 17, 2009 07:36pm | #7

   Rick,Thanks.. The birds mouths 'came' with (kind of) the purchase of the slot mortiser.. They seem to work pretty good, but I will pick up a couple of HSS end mills to compare and contrast. The slot mortiser is a really cool addition my Minimax FS-41E jointer/planer..

1. 
   RickL | Mar 17, 2009 07:48pm | #8

   Make sure they are two flute. Four flutes are like ripping with a cross cut blade. Bogs it down.  Endmills are pretty inexpensive at http://www.use-enco.com and http://www.wttool.com

2. 
   tom_47 | Mar 17, 2009 10:13pm | #9

   Thanks all. Tom

3. 
   flairwoodworks | Mar 18, 2009 03:52am | #10

   Boy, that's confusing.Chris @ http://www.flairwoodwork.spaces.live.com(soon to be http://www.flairwoodworks.com)

    - Success is not the key to happiness.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

1. 
   tom_47 | Mar 18, 2009 07:49am | #11

   Thanks all (again).I tried the "oscilating bird's mouth" in my router at its lowest speed (5000 rpm), and made shallow (1/16") passes. This was in pine. Progress was slow but only had minor burning in the wood. This bit is HSS and shows a lot of pitch build up or burning on its two cutter tips. To do 40 mortises in maple not only be too slow to but I don't think this the bit will be able to stand up to the heat and harder wood. I ordered an upcut bit today.Tom

1. 
   RickL | Mar 18, 2009 05:56pm | #13

   What router do you have that goes to 5,000 rpm??? Lowest I've seen is 8,000 rpm.

   HSS in a router typically doesn't last long. I suspect the oscillating bit you bought was for a slot mortiser.

1. 
   tom_47 | Mar 19, 2009 03:05am | #14

   Rick,
   I was wrong about that 5K rpm, 8000 is the lowest speed.Tom

4. 
   DonC | Mar 18, 2009 07:51am | #12

   http://www.felderusa.com/

   They sell what you have.