Holy smoking mortises!!!

2/2/07, 1:47 AM #1

Eric Kuehne
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Holy smoking mortises!!!

Eric Kuehne

>Well, I'm at the mortising stage of a project and have never liked the performance of my mortise chisels so I decided to follow the instructions in the Bob Lang article on the PW blog. Seemed like a good idea and, in spite of the fact that I have sprung for Clico chisels I have been getting a lot of smoke. So I tuned up the chisels and sharpened the bits per the instructions.

Did a test run in an old 2X4 (Which I know is not much of a test but you have to start somewhere.) and, viola! It worked beautifully. (BTW, this is with a 1/4" chisel for a 1" deep, 2" long mortise.) So now it's show time. Maple. Fire it up. Pull the handle and....holy smoke there's smoke. Curses! Now I can tell you that the chisels seem to go in (and out) more easily than before and they have have gone from OMG dull to pretty darn sharp. But still the smoke. Is this something I just have to live with in harder woods? Any ideas would be appreciated.

Eric, high up in Los Gatos

Re: Holy smoking mortises!!!

2/2/07, 2:49 AM #2

Garrett in Victoria BC
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Re: Holy smoking mortises!!!

Garrett in Victoria BC

>You should see no smoke with a sharp 1/4", even in maple. A few of suggestions:

Slightly increase the gap between the chisel and the bit;

Ensure the chisel can - and does - exhaust the shavings; and

Slow the feed rate and clear the chisel from the work as you feed.

Cheers, Garrett

Re: Holy smoking mortises!!!

2/2/07, 3:21 AM #3

Neal in San Jose
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712 posts

Registered: 5/2/06

C'mon down

Neal in San Jose

>Eric, if you'd like, bring your chisels down to my garag...I mean studio and we can put them thru their paces on my mortiser, and we can see how my chesels handle your stock. There are a few tricks I've picked up along the way that we can try and see if we get better results. Ping me off-board (remove an "o") if you'd like to meet up.

Off the top of my head, as already mentioned, increase the clearance between the chisel and the auger. I polish the inside of the chisel, and the auger as well. Be sure your chisel is as sharp as you know how - with a 1/4 chisel you are pushing a 1 inch chisel thru your stock. You are trying a pretty demanding wood. Cherry and Maple both have a lot of sugars, and tend to burn and smoke even with pretty good tools and technique.

Re: Holy smoking mortises!!!

2/2/07, 7:15 AM #4

Ryan Dicker in Renfrew, Ontario
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Re: Holy smoking mortises!!!

Ryan Dicker in Renfrew, Ontario

>You might consider using a bit of a lubricant help with the extraction of shavings from the chisel. The smoke is from the dust and chis getting jammed in the end of the chisel/bit and burning up. Also, if you have an air compressor, consider using it to blow the shavings out of the mortise at all times during the cut. You could use a dust collector hose, but it would have to have enough power to suck the chisel and mortise clean. Blowing the chips out makes for a little more cleanup, but it is much more effective.

The first hole that you make will almost always smoke and burn, since the only direction the chips can go is up. It seems like the burning goes away when there is a space beside the mortise you are currently cutting.

Thats my experience anyways...the chisels we use at the shop (highschool shop) are dull as a flat head screwdriver. (The bits being about as effective as a Phillips). The mortiser however is a tank. It is a floor mount Wadkin-Bursgreen that's been around since 1926....ok not really, but it is a beast.

Ryan

Holy smoking mortises!!!

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