Today I received the Delta mortising machine I had ordered. I have never used a mortiser before. I set up the machine just as the very limited instructions directed. Tried out a 3/8 x 3/8 mortise on a piece of scrap white oak. Just exactly how much damn force is required to do this operation???? I used the chisel that came with the machine. I am not clear on the 1/16 to 3/16 protrusion of the bit from the chisel. I feel that I must be doing something real dumb and will wait until I hear some comments from someone.
Thanks!!!
Butch
Replies
Butch
When I first tried my morticer, I had trouble figuring out what the directions were trying to get done. What you have to visualize is that you don't want the back of the drill bit rubbing against the inside of the end of the square chisel. You need to have the drill bit positioned so that there is at least 1/16 inch clearance between the back of the cutting surfaces and the inside of the chisel. If the two parts rub, you will find that you burn up the chisel end from the friction of the two parts rubbing.
If you follow the instructions exactly you will find that what they are really asking you to do is to keep the drill and chisel together (no clearance) and then after you tighten the drill bit, you raise the chisel by the 1/16 and retightening just the chisel to give you the 1/16 clearance. It is kind of backwards logic- you could tighten the chisel all the way up and then tighen the drill bit in a lower position and accomplish the same clearance.
Regarding the pressure you need, it isn't too bad but there's a reason why it has such a long handle - it isn't a drill press and you need the extra leverage.
Not certain that my explanation was any clearer than Delta's but I hope it helped a little.
Peter
Actually, very little pressure when chisels are sharp. But it just so happens that Delta is shipping dull chisels made in china. I know, I got one a month ago and all but one of the four chisels wouldn't even cut through pine. Send 'em back.
Dave
I fully agree with Dave. I specifically bought the Delta chisels made in Austria. Even then, I lapped and tuned them. There are several FF articles on this, including the FF collection on Joinery Techniques. Just like most regular chisels or hand planes that you buy, don't expect to get very good performance right out of the box.
Against a previous note, start the chisel about 1/32 below the stop. Bring the bit all the way up, and tighten. Then move the chisel up that 1/32 to the stop. IMHO, if you need 1/16 or grater clearance, then you've got other problems that you should fix first.
I'm currently using them on a drill press, and just cut about 2 dozen 4" long mortices in cherry with only moderate pressure. Of course, he didn't mention the size, and if you're doing a 3/4" mortice, you've got to really lean on it.
Gerry
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