Sewing Table #3: Using the Mortising Machine (for the first time)

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Blog entry by Blake posted 06-10-2008 10:10 PM 4220 reads 0 times favorited 12 comments Add to Favorites Watch
« Part 2: My First Fine Furnature!!! Getting Started... Milling the Lumber Part 3 of Sewing Table series Part 4: Mortise and Tenons for my Birthday »

I have had this little Delta Mortiser for about a year and have never used it. So I am exited to finally give it a workout. I learned a lot.


I put a lot of time into laying out the joinery. I’ve never done this before. Here are some of the sketches I made including a printout of my sketchup drawing and a birds-eye view sketch of the joinery.

Vertical measurement sketch:

When I had worked out the details I drew it out on a scrap cut from one of the legs:

Test cuts:

I figured out pretty fast that you can’t use the benchtop mortiser unless it is bolted to your bench or it will fall forward when you pull down on it. So here it is bolted to a temporary tool stand and you can see the first test cut being made:

The first several holes were trial and error for getting the depth right. This picture shows the depth and how close the mortises come to each other:

One thing I learned is that it is good to have a pick handy for clearing chips out once in a while:

The first test run came out Ok but I realized that my mortise chisel was not perfectly square to the fence. It made several little ridges on the inside faces of the mortise.

So I squared the chisel to the fence with a machinist square.

I had to shine a flashlight under it and turn it until there was no more sliver of light between the chisel and the square:

The last lesson I learned the hard way is that a mortise chisel gets VERY VERY HOT. I burned my finger. It is hard to tell in this photo because it was taken just after I did it. But today (the next day) I have a perfect square on my finger the shape of a mortise chisel.

The test cuts went well. Now I am set up and ready to make the real mortises. I’ll keep you posted.


-- Happy woodworking!

12 comments so far

View PaBull's profile


969 posts in 4743 days

#1 posted 06-10-2008 10:31 PM

oh, wow that answers some questions, you are going to town with this sewing table. I hope my wife is not seeing this, I need to finish the house before she gets her quilting furniture.

-- rhykenologist and plant grower

View Tony's profile


995 posts in 5108 days

#2 posted 06-10-2008 10:50 PM

Here is a tip for you Blake.

The mortise chisels straight from the box are sharp, but they could be sharper. I polish/hone the 4 outside edges of the of the chisel on my tormek. There is a huge difference in the ease of cutting. I also noticed discolouring of the cutting edge due to heat, but after honing it remains perfect mirror finish and runs cooler.
(My chisel dropped from the chuck whilst in the installation process – gravity over 6”, my finger underneath and a neat square cut into my left index finger down to the bone – the chisel was sharp at least)

Watch the spacing between the auger and the chisel – this makes a big difference in the performance, I find about 2 to 2.5 mm spacing works for me.

The mortise chisel is well known for clogging inside the chisel – try taking lighter cuts, especially during the first full plunge. Ensure that the waste material can escape.

Hope this helps you a little

-- Tony - All things are possible, just some things are more difficult than others! - SKYPE: Heron2005 (

View Blake's profile


3443 posts in 4952 days

#3 posted 06-10-2008 11:02 PM

Thanks Tony!

I’m open to as much mortising machine advice as you folks can give me. Keep it coming!

-- Happy woodworking!

View teenagewoodworker's profile


2727 posts in 4846 days

#4 posted 06-11-2008 12:11 AM

cool Blake, this is coming along great. my favorite part of any project is the glue up because you see everything come together and i can’t wait to see this one come together!

View Karson's profile


35273 posts in 5478 days

#5 posted 06-11-2008 12:50 AM

Blake their are diamond hones for the inside of the chisles. They are available from Rockler i believe. Around $20.00. I mount the cones in a drill press to none the inside of the chisles.

When you chuck the drill and chisel into the mortise machine leave about a gap of a nickle above the shoulder of the Chisel. Lock in the drill tight against the chisle and then loosen the chisle and move it up tight to the machine. That will give the required clearance.

Here is Mark DeCou’s blog on Mortise machines.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Appomattox Virginia [email protected]

View Betsy's profile


3394 posts in 4974 days

#6 posted 06-11-2008 02:16 AM

Bake – I think you need to swing your bit around so that the opening is to the side. That will cut down on the clogging. If the opening is toward the front or back of your cut the chips have no where to go but into the body of the bit, where it will clog and eventually stop the bit altogether. Turn it sideways, towards the open portion of the mortise and it won’t clog so much.

-- "Our past judges our present." JFK - 1962; American Heritage Magazine

View Beginningwoodworker's profile


13345 posts in 4751 days

#7 posted 06-11-2008 01:48 PM

Very nice work.

View Al Navas's profile

Al Navas

305 posts in 4953 days

#8 posted 06-11-2008 02:27 PM


You are doing great!!!

I wrote this short post on Tuning a Hollow Mortise Chisel (Episode 7a.) on my blog some time ago. As others have pointed out, it helps to have really sharp chisels! One of the most useful items I have found to do the tuning is the conical sharpening kit, which does a terrific job of sharpening the inside surfaces of the chisels.

-- Al Navas, Country Club, MO,

View Blake's profile


3443 posts in 4952 days

#9 posted 06-11-2008 08:55 PM

Thanks for the tips!

-- Happy woodworking!

View GaryK's profile


10262 posts in 5066 days

#10 posted 06-11-2008 11:20 PM

The only advice I can give you is to not be shy about having a lot of drill bit sticking out. When I first got mine I tried to set it perfectly and over heated the bit. Looks ugly now. :-)

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View Dorje's profile


1763 posts in 5075 days

#11 posted 06-12-2008 02:08 AM

All above suggestions are great…

I’ll reiterate the importance of sharp chisels! Honing the four outside faces and honing the inside with a cone is a must. Also, sharpening the actual bit should be done with an auger bit file. You’ll get really good results if all aspects are well tuned.

I second or third the notion of leaving a ton of room between the bit and the chisel. More is more. Less stinks, or would that be sticks…

One other thing about the mortiser. You’ll want to be sure that you take out as much slop as possible from the ways. This is adjustable. You should have little to no play in the dovetailed ways.

Keep it up!

Here’s a link to a Roland Joihnson FWW video on the topic, if you have access to it…

-- Dorje (pronounced "door-jay"), Seattle, WA

View gizmodyne's profile


1785 posts in 5168 days

#12 posted 06-12-2008 02:45 PM

My tips.

1. square the chisel to the fence by bringing the chisel down to the actual work piece/ fence/ or square scrap) while loose, then tighten
2. At class we set the spacing with a dime (between the auger and the chisel)
3. On your first cut go slow, on move the cut 1/2 a chisel step over. This way you cut half into wood and half into air. This helps to minimize the chisel from twisting and giving you diamond shaped cuts as you showed above.

Good luck.

-- -John "Do I have to keep typing a smiley? Just assume it's a joke."

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