Chopping Mortises

[Jim Foster]

I chopped my first mortise in White Oak today, 3" x 1/2" x 1-1/4" deep. It's for the leg vise on my Roubo bench. It came out reasonably square and to size. Keeping the chips clear was the biggest challenge during the chopping, and I had a lot of trouble getting the bottom flat as I finished. I'm curious how others get the bottoms of blind mortises flat?

[Bob Lang]

Why do you want the bottom flat, and how flat do you want it? If you chop to a consistent depth, and a bit deeper than the tenon you're good.

Bob Lang

[Jim Foster]

Maybe it does not need to be flat after all.
Why do you want the bottom flat, and how flat do you want it? If you chop to a consistent depth, and a bit deeper than the tenon you're good.

Bob Lang

[Jim Barrett]

No reason to be flat...just deep enough for your tenon and glue.

Jim

[steven c newman]

IF you WANT it flat, you will need a special chisel for that job. Shank is curved. Slide it down to the bottom, the curve will help you scrape the bottom flat. Otherwise, if there is enough room for a tenon and some glue, you be fine.

[Jim Koepke]

IF you WANT it flat, you will need a special chisel for that job.

As others have mentioned, if you are going to glue a tenon into it, you want a bit more room and it doesn't matter that the bottom isn't flat.

If you are installing a lock into the mortise where a flat bottom may be wanted, then a special chisel, called a lock mortise chisel or a swan neck chisel, is the tool.

See one by clicking here. (http://www.toolsforworkingwood.com//Merchant/merchant.mvc?Screen=PROD&Store_Code=toolshop&Product_Code=EE-500-21.XX&Category_Code=)

jtk

[Jim Matthews]

I was under the impression that the cheeks of the tenon provide the long grain glue surface. Unless the tenon is wedged, the exposed endgrain can't provide much bonding strength.

[Jim Neeley]

You are correct, Jim M. This is the eighth post and I'm the fifth Jim.. Sheesh! :-)

[Jim Foster]

After reading all the comments, I have to agree, I was assuming that there might be a quick step to get them pretty flat at the bottom, but I will just focus on getting the depth a little deeper than the tenons and let practice improve my efforts.

[Terry Beadle]

I use very lite little chopping strokes with the chisel when I get to the bottom. Then I use my Japanese bottom cleaning chisel to put the cuttings out and scrape the bottom fairly smooth.