Loose M&T

[John Leech]

Ok, I give up! I'm attempting my first ever loose M&T joint. Try as I might I just can't seem to get the mortise square on the piece. I've tried making a jig to rout the mortises with a guide bushing and a 1/2" bit, but one of two things happens: either the fence is not quite square or the grove in the jig (which was routed on the table to accomadate the 5/8" bushing) is crooked. What gives? Am I approaching this all wrong when there is a much easier way to do this, or is this just a case of operator error?

Thanks, John

[Ken Salisbury]

John,
It is really hard to say. The jig you have created naturally has to be very accurate as does your method of using the jig. If you plan on making many more tenons consider making what I use for 98% of my tenons (http://www.klsal.com/tenon jig.htm)

[John Leech]

Is this something that I can do with a basic straight edge attached to my router?