Question on mortises

[Mitchell Ristine]

All, I am working on my first workbench build. The legs will attached to feet with mortise and tenon joinery. The tenons with be 1.5" x 2.5". Question: When making the mortises can I remove most of the material at the drill press with a forstner bit and then clean up all the edges with a bench top mortiser? I just bought a delta 14-650 of off cl.

[ChrisA Edwards]

Yes you can do it that way, but the chisels on the mortiser will also do it fairly easily and probably leave you with a cleaner mortise.

[Jim Morgan]

Hollow chisels for mortises are guided by their drill bit biting into solid material. A hollow chisel used in the way you suggest would be prone to deflecting. You can drill out most of the waste and pare to your layout lines with a sharp bench chisel.

[Tom Bender]

I'd go with a 1/2" forester near each corner then go to the chisels.

If you try to hit the corners with the edges of the drilled holes they will not line up perfectly but if there is a shoulder to hide it that will be ok.

Depending on the wood I'd use a variety of chisels and mallets.

[Tony Bilello]

Why would you even want to do that?
The mortise machine is designed to do one thing well - make a mortise.

[Robert Engel]

Start with the corners, then go around and do the sides. The waste will fall out. You will have a much cleaner mortise and it will be far faster and more accurate. out.

Always start in the corners because the bit will tend to drift. Having material on both sides of the bit eliminates this. Then clean up between the corners.

I wouldn't go larger than 3/8" bit on a benchtop mortiser.

[Al Launier]

When using a benchtop mortiser, Robert provides good advice by suggesting starting at each end of the mortise as the chisel is supported on all four sides avoiding a tendency to drift while cutting the mortise. To take this a step further, you could leave a space between the remaining mortises to provide 4-sided support for each cut. Then when these are done you could go back & mortise the remaining spaces between the mortises. These would be supported on two opposing sides & would be easy to cut. Then a final re-mortising to clean out any remaining wood and you are done with a clean mortise.

[andy bessette]

Start with the corners...I wouldn't go larger than 3/8" bit...

^^^^^^^^^^This.

[Floyd Mah]

Just as a practical consideration, I've always found that work-holding can be difficult with tools like drill presses and mortisers on large workpieces. If you are thinking of mounting the legs after completing the top (the usual way), these comments might be applicable. If your benchtop blank is the typical size for woodworking, it might be at least 6 feet long, 20+ inches deep and 4" thick, weighing a hundred pounds or more. You need to consider how to balance this weight on either of these tools (drill press, benchtop mortiser) which might have a working table surface of approximately than one square foot. Also, you need to get your cutting tool perpendicular to the wood. These tools are really meant for working on wood that is on the order of 2x4's of variable lengths and manageable to wrestle into position, possibly with supports at the ends.

I would suggest the following technique. Use portable tools and hand tools to create your mortise. Tack a pattern for the mortise on the work piece and use a plunge router to create the vertical walls of the mortise. If it is a through hole, you can use a jigsaw or saber saw to cut out most of the bulk if the router's reach is exceeded. Pattern bits on a router can help you reach the bottom of the mortise. If you like, a forstner bit can be used on a hand drill, but I've found them to be slow (maybe my bits are dull?). A wide chisel with a guide block to keep you perpendicular will give you nice walls.

[William Hodge]

All, I am working on my first workbench build. The legs will attached to feet with mortise and tenon joinery. The tenons with be 1.5" x 2.5". Question: When making the mortises can I remove most of the material at the drill press with a forstner bit and then clean up all the edges with a bench top mortiser? I just bought a delta 14-650 of off cl.

I have made hundreds of mortises like this with that mortiser. If you can get the chisel sharp, you will be fine. If the chisel is improperly sharpened, it won't work.
A 3/4" tenon should be big enough for a work bench. That mortiser will take a 3/4" chisel. Depending on the material, the Delta mortiser will have a harder or easier time. Cutting the waste out with a forstner bit will make life easier. With a larger chisel, roughing out the mortises is required. I have found that with sharp chisels, deflection is minimal.
I

[Lee Schierer]

Use the mortiser to remove all the perimeter material first. Then remove the waste.

[Robert Engel]

William reminded me of something. Yes a sharp chisel is crucial.

I suggest a conical diamond honing stone specifically for mortising chisels. I believe Lee Valley has them.

Also, I recommend honing the outside of the chisel to a polish.

[Lee Schierer]

William reminded me of something. Yes a sharp chisel is crucial.

I suggest a conical diamond honing stone specifically for mortising chisels. I believe Lee Valley has them.

Also, I recommend honing the outside of the chisel to a polish.

Polishing the outside surfaces improves performance tremendously.

[Ted Phillips]

Personally, I use a very sharp "pigsticker" mortise chisel and a lump hammer. With a little practice, you can hollow out a mortise very quickly and accurately.

[lowell holmes]

I normally use a pig sticker if I can find one the proper size on my bench however, I am comfortable with this method.
I learned to do it while attending a Paul Sellers class at Homestead Heritage in Waco Texas about 20 years ago.

https://paulsellers.com/2012/07/chopping-mortises-bevel-edged-or-mortise-chisels-video/