Metric bench chisels

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Forum topic by HermanKuhn posted 10-07-2019 08:59 PM 566 views 0 times favorited 6 replies Add to Favorites Watch
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11 posts in 3398 days

10-07-2019 08:59 PM

Will a metric size set of bench chisels make a difference if im measuring tenon cuts in imperial?

6 replies so far

View Mike_in_STL's profile


1443 posts in 1774 days

#1 posted 10-07-2019 09:15 PM

Before someone comes along and berates you, No, the chisels don’t care what size the cuts are . Just make your marks and stay in the lines. Use a chisel that is the appropriate size for the job. Don’t try to force a bigger chisel in a smaller hole. It won’t end well for you.

-- Sawdust makes me whole --Mike in STL

View OleGrump's profile


581 posts in 1584 days

#2 posted 10-08-2019 12:55 AM

True that. Unless the set of mortise chisels happen to be handy, even when I use “Imperial” (aka “SAE”) sized chisels, I always go one size smaller than the mortise opening. One can always make it a bit wider, but we can’t make it more narrow.

-- OleGrump

View JayT's profile


6431 posts in 3451 days

#3 posted 10-08-2019 01:01 AM

Totally agree with the others. I actually like Metric chisels for mortises for the same reason OleGrump mentions. You can get a metric size that is just slightly undersized for an imperial measurement and it makes it a lot easier to work and adjust.

Marc Spagnuolo, the Wood Whisperer, did a post a while back where he talks about that, as well, and says it better than I ever could.

-- - In theory, there is no difference between theory and practice. In practice, there is.

View Lazyman's profile


7943 posts in 2627 days

#4 posted 10-08-2019 02:16 AM

Of course, as mentioned above, you can always use smaller chisels to cut your mortises. Traditionally, especially when using mortising chisels, the mortises and tenon widths were determined by setting the marking gauge to the width of the chisel. With practice, this can be a big time saver as you will have much less cleanup to do after chopping away most of the waste. While I have not done many M&T joints lately, with this approach, I always find it easier to get the mortise to be exactly as wide as your chisel. For me, I find that I was much more likely to make the mortise wider than planned when I used a chisel smaller than the mortise and then I had to remark the tenon to match the oversized mortise. When the width of the mortise matches the chisel width, the sides help keep it square as you work your way in.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View SMP's profile


4816 posts in 1145 days

#5 posted 10-08-2019 04:43 AM

The funny thing is I found out that some are actually metric, even though labeled and sold as imperial. Like my old marples, etc. I measured them with a micrometer to verify, sure enough the article i read was correct. But as has been mentioned, you mark out by hand anyways so it doesn’t really matter.

View BubbaIBA's profile


545 posts in 3616 days

#6 posted 10-09-2019 11:33 AM

Will a metric size set of bench chisels make a difference if im measuring tenon cuts in imperial?

- HermanKuhn


First question is: Why are you measuring your tenon width? Are you using a “tenon” marking gauge? If you are, just set it to the width of the chisel you use to chop the mortise then it will not matter what standard your chisels are sized to.

My shop is a mixture of Western and Japanese chisels. Some of the Western chisels are metric, all of the Japanese chisels are. Which I use for what job is never a factor of imperial vs. metric.

Full discourse, I run a metric shop and have for a number of years and can not imagine going back to a imperial shop but that is another story.


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