[DrRobert]

Pardon my ignorance but I had not heard of this method. I like it. Found a video on youTube where similarly a guy, using a roughing end mill bit, drill fence, and stop block created some really nice mortises. Although he said it was slower than using a router...it created router like mortises (pretty clean) and would seem to be great for small parts.

I looked for 1/4 and 3/8 long enough to use in my horizontal mortiser but they were all too short.

I’ve heard people say use 4 flute end mill bits. In my hands not worth a darn.

 

[LilMtnDave]

I looked for 1/4 and 3/8 long enough to use in my horizontal mortiser but they were all too short.

I’ve heard people say use 4 flute end mill bits. In my hands not worth a darn.

They are "4 flute roughing end mill bits" the guy uses in the video and there is a bit of a technique to it concerning the start point, the direction, and keeping things clear of debris. Shows him doing down to 1/4" but he suggests nothing larger than 1/2" but that, I think, was based on the press's power....Mortises wider than the 1/2" can be made by just adjusting the fence.

Edit: The video also suggests having as much of the bit secured in the drill as possible to minimize deflection. I can see this as a bit limiting if you are looking for something more than 2" deep (although a 3/4" one I have seen is 4" in overall length..but the 1/2" ones are generally closer to 3" overall length.