Hand cutting mortises for plugs

[mark mcfarlane]

I bought a 9.5mm mortise chisel set and am learning to hand cut shallow square mortises to place plugs of a contrasting wood.

If I pre-drill using the included 9.5mm mortising bit it is very difficult to align the square mortise chisel perfectly and avoid a little smily face sticky out one side of the mortise.



Clamping a small metal square to one side of the hole seems to help with horizontal and vertical alignment of the mortise.
Using a slightly smaller drill (8mm) helps avoid the smileys, but creates more hand chiseling to clear the mortice.


Any other tips or trick y'all have learned?

I might end up driving a couple hours to Rockler and buying a Jet bench top mortiser...

Sharpening the cheap chisel I bought may help.

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[Brian Holcombe]

Mark with a knife and chop to the line. Chop end grain side first, then side grain. Chop small amounts with each chop.

A mortising machine does most if the work but in order to avoid the half round cutout I’ve hand shaped the auger on some and if they still do lightly I will chop the mortise slightly oversize to bring it to a smooth cutout.

Make your pegs slightly oversize (couple thousandths) to create a press fit which helps to minimize gaps.

[mark mcfarlane]

Thanks Brian

[Jamie Buxton]

If you want square mortises, buy just the square chisel intended for the hollow chisel mortiser. Sharpen it. Pound it into the wood with a hammer to mark the corners of the mortise. Proceed with your drill bit and straight chisels to remove the waste.

[mark mcfarlane]

If you want square mortises, buy just the square chisel intended for the hollow chisel mortiser. Sharpen it. Pound it into the wood with a hammer to mark the corners of the mortise. Proceed with your drill bit and straight chisels to remove the waste.

Thanks Jamie. I am using a square mortise chisel set but I was drilling the holes first. It seems like your suggestion of drilling after the square is cut may be a better way to avoid the smileys. I'll give it a try.

... cut the square, bisect the corners with a sharp line, drill at the intersection....

[Tom Bender]

This is a task not to be hurried. Make the peg first, use it to mark the mortise with a pencil then chop it out with a simple chisel. No drilling or mortice chisel. The first dozen or so are just for practice. With this method they can be made square, rectangle, parallelogram or whatever. These are meant to be decorative. Have fun with them.

[Jim Becker]

I agree with Brian...and make sure those chisels are uber-sharp. Once you carefully define the mortise, it's relatively easy to remove the little that really needs to come out. The edge is everything.

[Warren Lake]

buy the mortiser and make real ones that do their job, or waste time for fake news.

[Brian Runau]

Related how do you cut plugs that small? Thanks Brian

[Richard Coers]

Since we are in the power tool section, I'd make a template and use a guide bushing and 1/8" router bit or smaller to excavate out the waste. Then follow up with the square chisel. If you want to continue with a drill, you can also turn a dowel to use as a pilot from the square chisel to position and then pull the pilot and smack the chisel. If you want to align multiplies, clamp a board and use that as a straightedge.

[Jim Becker]

buy the mortiser and make real ones that do their job, or waste time for fake news.

For this style, they are often decorative items, not structural. It's an inlay that tends to be proud of the surface for effect. They are not tenons. They may also be used to hide metallic fasteners in some pieces, too. The differentiator here is that the plugs are square rather than round.

[Warren Lake]

so you mean like a hair piece?

[mark mcfarlane]

Thanks everyone for the help. After spending half a day hand cutting mortises I ordered a PM701 benchtop mortiser and some better mortice chisels. Then I spent 5 hours cleaning and setting up the tool, sharpening the chisels, and learning how to get precise square cuts. Anyway, this project is done but the mortiser will come in handy on a dining table planned for this Spring.

[Rob Luter]

I use a square chisel from a benchtop mortiser. I tap the chisel to make a crisp outline for the mortise then drill the interior out with a drill that's smaller than the mortice. Then I go back with the chisel and clean things up. It works pretty well.

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