|Forum topic by opalko||posted 03-04-2011 05:49 PM||1485 views||0 times favorited||20 replies|
03-04-2011 05:49 PM
Hi all, I am having poor results with my mortise & tenon joints, looking for advice on better ways to do these.
I am using a new Delta dedicated mortiser (which I have found out has a fence out of square – having Delta send a replacement after they told me “makes no difference if fence is square to table or not..”??).
For the tenons I make the cuts on a Delta Unisaw, single blade, no tenoning jig – just nibbling away the stock one pass at a time.
What happens is that after I make the mortises I then make the initial cut on all 4 sides to define the shoulder. I then nibble away one sawblade width at a time the edges on the two opposing sides to define the wide faces of the tenon. I then change the sawblade height to define the tenon side faces (narrow sides). I check the fit with the mortise. It is almost always too wide at this stage. So, back to the tablesaw. Lower the blade first to original height, then raise it a hair. Of course, the initial cut on all 4 sides has to be cut again, this time with the blad higher.
Invariably at this point I mis-cut and the line is now out of square along one or more edges (in other words if the piece were flattened to a two dimensional piece, and you followed the shoulder line, it would no longer be straight. Now, even if this step is done correctly, and the piece still is too wide, it must all be done again. On some cases I gest the shoulder line square/straight all the way around, but I make the tenon too thin! Now I have to start over….
The possibility for introduction of error seems almost insurmountable! How does anyone manage to get these right on the first try, or even the second try? What always seems to happen is I get a clean fitting joint on one side (hopefully the side showing!) but the opposite side is 1/32” or more too deep, so that there is a gap showing. Argh….! Help! Will a Leigh FMT jig make all these problems go away! Should I switch to dowels? Biscuits!??