Thoughts on the Hollow Chisel Mortising Machine (updated 11-14-2007)

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Blog entry by Mark A. DeCou posted 03-02-2007 06:05 PM 12087 reads 1 time favorited 18 comments Add to Favorites Watch

In a recent Blog by Obi, he discussed using a router to cut mortises, and this started up a discussion, in which Don cautioned against getting a Hollow Chisel Mortiser. I think there are good thoughts on both sides of this debate, and I don’t mean to do anything other than offer some more experience about purchasing and using a Mortiser, and other methods of cutting mortises.

As in anything, the more money you spend, the better tool you get. If I were buying just what I wanted, not what I could afford, I would get a big mortiser, and the floor model Powermatic looks like a good one, especially the one that allows me to angle the cut, and offers a hand screw clamp to hold the work piece tight. However, in my business, money is an issue, and so I must compromise between cost, speed, and ease of use.

I have done successful mortising several ways:

1) Hand chiseling out the mortise, using only a chisel to remove material.
2) Hand chiseling out the mortise, using a drill bit to remove the bulk of the material
3) Routering the mortise with a hand-held plunge router
4) Horizontally mounting a router in a shop built fixture (ended up in the burn barrel).
5) Using a bench top hollow chisel mortiser.
6) Using my Legacy Ornamental Mill to router out mortises in table legs.

Another method I have not tried yet:
7) I want a “Multirouter”.
Here is a link to see what it looks like

Saving Time?
I think the joints I am most proud of are the hand chiseled ones, but nobody else can tell, as each of the methods I have used over the years has provided accurate, nicely fitting joints. However, I know which ones I am most proud of, and it is always the chiseled ones. So, what’s the difference in choosing one method over another? I think it is mainly in the time required to do each of the processes, and how hard a person wants to work.

For most of us, I think “saving time” is probably the biggest factor in our decision in choosing a method for cutting a mortise. In my mind, “Accuracy” is the most important criteria, but I always “hear” people talk about “speed first.” I am reminded of those Summer Driver’s Education Films, and so I still think that “Speed Kills” to some degree even in woodworking. So, if I can hand cut a mortise with a chisel, but the joint is sloppy and loose, then I should have used another method, as Accuracy is the Criteria that I feel is most important.

To beat a dead horse (Kansas Figure of Speech) I think for most woodworkers the speed of cutting a mortise should not be such a high priority concern. If you love working wood in your hobby time, and you are making an heirloom piece, why does it matter if you make a mortise in 15 minutes, or an hour? The experience and chest-thumping might be worth the time using only a chisel.

Speed Pays?
For those making a living on the craft, speed pays the bills to certain extent. More importantly, I think it is a mattern of what a craftperson is selling that pays the bills. Are you selling a piece of furniture that fills a need in the home, or an heirloom piece of functional-art? These characteristics aren’t the same in my book, and so the joinery methodology should reflect the goal you are wanting to achieve.

Do Customers Really Care?
One time I met a guy in central Colorado that had a niche of making large carved pieces of furniture without any electricity in his shop. His pieces were massive, and expensive, and “old-school” in every attribute. He heated the shop with wood, worked by oil lamp, and crafted only with hand tools. Did the customers say that the work was too expensive and that he should get electricity and buy some power tools to speed up his work? No, they flocked to his door, as they wanted what he built, and how he built it, and were willing pay for his time to do it that way.

He admitted to me that he started out using only hand tools as he was too poor to put electricity in the rented building, or buy power tools. What he discovered was a hand-crafted niche he had not anticipated. That work led him into timber framing, and then into expensive log-homes where he would live at the job site for a year, cutting down the logs from the site, hand squaring them with an adze, cutting dovetails joints for the corners with a hand saw and chisels. Sure, the customers could buy cheaper logs from a log-mill plant, but they were paying for this methodology of work. I met him in 1997, and he strongly encouraged me to do my best work, regardless of the effort, or time required to do so. I’ve tried to do that since then.

One More Example:
In my last major Commission, the Refined Rustic China Cabinet and Table/Chair Set, my customer (actually just the wife) indicated in every early meeting on the design criteria, that the final cost was a major limitation for us. So, I considered how to accomplish the “look” of what they wanted while saving labor hours. I came back and asked whether they wanted me to biscuit joint all of the joinery, including the door frames and drawers. I offered to them that it would easily save $1,000-$2,000, maybe more. They thought about it a week, and decided they wanted all long tenon joinery, and added “no plywood, and no biscuits”. Enough said. As “Handy Manny” on Nick Jr. says, ”...ok tools, let’s get to work!”

So, it has been my experience over the past two years, that when faced with the decision to save money versus old-school mortise and tenon joinery, the customer has picked the most expensive route. They want to pound their chest as well about what they own.

My recommendation for a hobbyist is that it is hard to beat the chest-swelling pride you can get by hand cutting mortises with a chisel (the same goes for dovetails, but that is another discussion). Just come see my work bench some day, and that is what I will show you, the through tenons with tusk tenon ends and wedges, all cut with a chisel and mallet (before I knew any better). I specifically decided to use that method of cutting the mortises, as I wanted to practice the skills of using a chisel. This skill has been helpful over the years, and I am glad I made the decision to practice the method back in 1998 or 1999.

So, Why Did I Buy a Mortiser?
I purchased a Jet bench-top hollow chisel mortiser because I had just been awarded a large commission to do several Arts & Crafts pieces, and I didn’t want to route, or hand chisel that many joints. I talked with the customer first, and as long as I used traditional style tenons and mortises and no biscuits and no pocket-screws, they were ok with using power tools. So for me, the decision was based on the economics and the quantity of mortises required for the commission, but I checked with the customer first.

I’m glad I made the decision I did to buy the Mortiser, as the extra time allowed me more hours to work my carving into their commission, which eventually is what made the big impact on the pieces. People notice the joinery, but only after they admire the lettering and carved panels.

Looking back on it, I could now see that a more expensive tool would have been easily justified. I think the most important aspect for a professional is simply sell to a customer what you do, and then do what you sell. For instance, if you sell them on tenons, don’t do biscuit joinery. If you sell them on hardwoods, don’t try to hide veneering. Enough said.

Why the Jet?
My decision to buy the Jet was in response to a review I read on mortisers in some magazine (I can’t remember which one now). The magazine article suggested finding a machine that turns at 3450 rpm, and one with twin support towers, as they worked better in their testing.

I looked hard at the Harbor Freight machine, but it was just too cheap looking to assure me that it would cut accurately, and I had about 2 years of work to do with it on the Arts & Crafts commission.

I decided to listen to the magazine’s “unbiased” opinion (is there ever an unbiased opinion?) and looked seriously at the Jet machine, as it was given a “best choice” rating as I remember it.

So, I looked for a 3450 rpm machine and compared prices between a couple of brands and several retail sources, eventually ordering my Jet through Grizzly’s website for around $250, plus shipping, and something like another $100 for the extra chisel bits I wanted. If I would have had $1,000 to spend at the time, I would have gotten the Powermatic, or an equivalent quality machine. I figured at the time that I could always eBay my old Jet when I could afford a bigger machine in the future.

Did I Get My Money’s Worth?
Here is a list of some of the projects I have previously posted at LJ, in which I used the Jet Mortiser:

There have been other projects, but I think you get the point. When I add up the sales volume for each of these projects, the time saving, efficient, and accurate Jet Mortiser was a small investment compared to the payoff. This is why I suggest that I should have purchased a more expensive floor standing model. Still, the Jet has performed well, and it is working fine still, ready for service every day.

The Multirouter:
If money had not been an issue at the time, I would have purchased the “Multirouter” rig, which I learned about watching David Marks on his DIY Woodworks show. This fixture based machinery starts at about $2700, with an easy extra $1500 spent on the accessories that are necessary to have to really get the full potential of the tool.

I met another furniture maker at the Western Design Conference that shelved his hollow chisel mortiser when he bought a Multirouter, and gave testimony that the machine paid for itself quickly. However, the Multirouter does not cut square corner mortises, as it uses a router bit. So, if you want old-school “looking” joinery, you still have to square up the corners by hand, or use a Hollow Chisel mortiser for the job. I mostly want the Mulitrouter to do angled mortises, and for cutting tenons. I would like to build more carved chairs someday, and I think with the Multirouter I could get the labor costs down enough that people would consider buying my work in that medium.

A Multirouter for Hobby Work?
I don’t feel that for most hobbyists in the craft that the Multirouter is really a consideration for them.

Square Peg in a Round Hole? Never.
After having the hollow chisel mortiser in my shop, I think I would like to have both the hollow chisel mortiser, and the Multirouter. There are many situations where I like to quickly set up and “punch” a square hole in a piece of wood. If for no other reason, it just looks cool. I never use round dowels for pegs, I use square holes and square pegs. It just looks cool to me.

I even started making it a design point to always leave my pegs proud of the surface about 1/8” and then hand carve the end a little to give it some texture. Why? I don’t know, everyone else either sands them flush, or cuts a little bevel edge on the end, I just wanted to be different. The texture of the carved end shows up well in the shadowing of light, and it adds an element of “richness” that doesn’t show up in photos, but is apparent in person.

I bought the Jet mortiser about 4 years ago, and I have truly enjoyed using the machine and it has way more than paid for itself in my business. I have liked it so much; I have pondered buying a couple more of them and setting each up with a different chisel to save time in the set up. If I had a bigger shop, this would be a serious consideration.

As with any power tool, there are things to learn, techniques, tricks, do’s and don’ts that seem to be learned best by experience. Some things are pretty routine like, keeping the chisels sharp, the bit sharp, holding the wood tightly, not pushing the chisel ahead of the auger’s ability to keep up, and not putting a mortise where you previously put a nail (ruins your day), etc.

I have learned that if my work piece, such as a table leg, is not perfectly square on all four faces, I am just asking for trouble. Before I had my jointer, I had a lot of trouble with this. The parallel faces don’t have to be off by much to cause problems.

I have also learned to do angled mortises on the Hollow Chisel machine for chair making by using an angled wedge under the work piece. I suppose in about 30 minutes, a smart operator could most likely learn about all that I have learned in using this machine 4 years if they could take in all of the words I used in that 30 minutes.

Smoke Anyone?
I have found that setting the auger with more clearance to the chisel barrel helps with the problem of smoking the wood, although it still gets plenty hot. If I am cutting ¼” or 5/16” square mortises, I can cut them as quickly as I could run a drill press/drill bit of the same size. As the bit gets larger, the slower it goes though, the more heat is generated, and the longer I have to wait in between mortises for the bit to cool down.

Karson and I talked on the phone about a month ago and we covered several topics, one of which was mortising. I mentioned that I had trouble with smoke and burning, and that the chisel gets very hot when I am using it. He made the suggestion that I leave more clearance between the bottom auger and the chisel head, and that simple suggestion made a big difference. I was setting up my machine tight enough that the auger bit was pulling out chips that were bigger than the gap they were to exit the chisel barrel through, and so they would get stuck and then would burn. I had tried a lot of different things, but not what Karson had suggested. It was one of those proverbial “forehead slap” moments, and I am thankful for the suggestion.

I am not a stickler for keeping anything super-sharp. I like tools that are super-sharp but they don’t stay that way long, and I just don’t like to spend the time doing it. Karson suggested I get a pyramid hone for the end of the chisel, and I know this would surely help, so this accessory is on my list to buy. I should have ordered one at the start.

The chisels are hard to sharpen, except with the pyramid shaped hone that is built to fit the end of the chisel. I have used a Dremel grinder bit to hand dress the edge, but it is not an exact fit, and so the results weren’t perfect. I have learned to dress up the auger-cutting blade with a file ever-so-often, and I like using dry silicone spray on the auger/chisel. I think if a person would take the time to hone and polish the outside of the square chisel the same as we all prefer our hand chisels to be, it would definitely improve the performance.

When I ordered the Jet, I bought every chisel Jet offered with the machine. I mostly use the ¼”, 5/16” & 3/8” chisels. I have used the ½” chisel to some degree, but as the chisels get bigger, I seem to use them less and less. I think I have used the 1” chisel just one time, never the 3/4” bit, and probably would not recommend purchasing them. I can very efficiently cut two ½” holes side by side to get a 1 inch mortise, and that is what I tend to do now. I used some hefty 1” mortises on the large dining table base I made for the Western Design Conference last year, but other than that, I have not used the 1” bit.

When I did the sliding stepped tenons with square pegs for the floating bread board end of that Dining Table (I hope to write up the process some time), I elected to use a plunge router to make the mortises in the bread board end lumber. So, I guess in summary, it is good to know more than one method, and use whichever method is best for the situation to accomplish the design. A Hollow Chisel Mortiser is best in some places, not in others.

If I was Teaching…
If I was teaching a one-day course on “How to Cut A Perfect Mortise & Tenon,” I think I would choose only the old drill bit/hand chisel method to teach and have the student practice with that only. In that one-day class, I would demonstrate the hollow chisel mortiser, and the hand routering method, but probably wouldn’t focus much time for practicing those methods during the class time.

Even with a Mortiser, you will need to accurately clean up the joint some with either a chisel, or a file. Through-Tenons are much more difficult in this respect than blind tenon joints. Through-tenons look cool, and people notice them, so I tend to use them whenever I can.

If you have questions, comments, or want to see some photos, let me know.
Mark DeCou

(this writing is protected by copywrite, M.A. DeCou 3-2-2007, 3-3-2007)

-- Mark DeCou - American Contemporary Craft Artisan -

18 comments so far

View dennis mitchell's profile

dennis mitchell

3994 posts in 4551 days

#1 posted 03-02-2007 07:06 PM

Ok I’ll put one on the list..been wanting to any way. Thanks Mark!

View Dick, & Barb Cain's profile

Dick, & Barb Cain

8693 posts in 4536 days

#2 posted 03-02-2007 07:32 PM

I have a hollow chisel attachment for my drill press, & I like it. I bought it at Harbor Freight. When I was in high school the hollow chisel mortiser was one of the most popular machines. There was always a line of kids waiting their turn. I guess drilling a square hole fascinated us.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN.

View Bill's profile


2579 posts in 4398 days

#3 posted 03-02-2007 07:44 PM

This is a great write up Mark. What is the multirouter you were talking about? A particular tool, or ?

-- Bill, Turlock California,

View Don's profile


2603 posts in 4414 days

#4 posted 03-02-2007 11:01 PM

Mark, thanks for this good information.

There is one other method of doing mortises that you have not mentioned, Festool’s new Domino.

This tool offers the ease and speed of a biscuit jointer with the accuracy and strength of a traditional mortise.

I don’t own one, but have used one. They are an amazing tool and have revolutionized mortise making for many Australian cabinet makers. Everyone I’ve spoken to that owns one swears by them and laughs at my reluctance to spend the rather high price tag, aprox AU$1200. Maybe someday.

-- CanuckDon "I just love small wooden boxes!"

View Mark A. DeCou's profile

Mark A. DeCou

2009 posts in 4642 days

#5 posted 03-02-2007 11:46 PM

Hey folks, I was in a hurry this morning when I tried to write this up and get to an appointment to see the surgeon about my gall bladder problems. I just got home, and I am now on my way to meet with the tax accountant, so I’m out of time now also.

I will give some more information, photos, model numbers, and more info on the Multirouter. If you are curious before I get back, I know you can see information on it at David Marks’ website, which I believe is He’s a rep for them. You need to mount a router motor to it, but it is mainly a large platform that you clamp your work piece to and then use the router in a horizontal milling format. They have a video you can watch, but they want a $20 deposit to get a copy.

Surgery is scheduled on Tuesday next week, so I’m going to be pushing hard to get as much work done before then as possible. I will not be able to work in the shop for a few days, so I am hoping to get a chance to write up some of the other ideas I have had, but haven’t taken time do yet.

Thanks Don for the info on Festool, I was not aware of that equipment. There is a fixture jig set up for tenons, and I think it does mortises also that Leigh makes, the folks that make the Leigh Dovetail jig. I’ll try to round up that data when I get back.

Send me more comments and questions so I will know what more information to cover about the Mortiser.

As Phil says in the Old Country, Cheers,

-- Mark DeCou - American Contemporary Craft Artisan -

View Karson's profile


35152 posts in 4637 days

#6 posted 03-03-2007 12:00 AM

Mark: Very good.

Let me add this bit of information. Woodworking Magazine Spring 2007 in their review of mortise chisels states that the Powermatic 701 mortiser has a built in spacer to set the gap between the auger and the chisel. Their spacer measured .117” – considerably thicker than a nickel at .072” setting the gap to the .117 spaces caused the chisel to run 40 to 50 deg F cooler than with the gap created with a nickel.

But they caution that leaving the bit extended any further will likely result in bit breakage.

They then removed all visable grinding marks on the outside of the chisel with 150 sandpaper, then 320 grit and then 30 strokes on a medium and fine diamond stone. They then used a sharpening cone to sharpen the inside of the chisel. This reduced the tumperature again between 50 and 60 deg F.

Bits that smoked out of the box, with this tweaking operated in the same range as the most expensive bits. They then polished the outside with 8,000 grit ceramic stones and it only reduced the tempature by a few degrees.

Their recommendation get rid of the grinding marks, sharpen the inside and set an effective gap.

They also tried filing a relief cut in the corners, which is a feature in some of the chisels but it made no measurable difference, in the torque to initiate the cut or in the operating temperature.

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

View dennis mitchell's profile

dennis mitchell

3994 posts in 4551 days

#7 posted 03-03-2007 12:05 AM

Tuesday next week. Wish you the best…I’ll keep you in my prayers.

View schroeder's profile


702 posts in 4362 days

#8 posted 03-03-2007 10:45 PM

Mark, I think your right on the money. Most furniture I make encompasses a through mortise & tenon. After starting out with chisels & drill, I decided to save up for the floor model Powermatic hollow chisel. It took me a while to get it, but-man what a nice machine for accuracy, tolerance and speed.

One of my good friends had a Multi-router he offered to let me try out. I couldn’t see how it would benefit me, as I nearly always use square tenons, but I appreciated the gesture. To my pleasure (and dismay – I’ll explain that in a moment), the thing cuts wonderful square tenons. I just don’t use the template jig and set it up twice, (once for all the horizontal cuts and then again when I’m ready for the vertical cuts). Compound angles are just a pleasure to cut and duplicating angled tenon setups is easy. It sets up scary-easy and the tolerance is unbelievable. That’s where the dismay came in – I decided I must have one. It perfectly compliments the mortiser, but as you said, it’s every bit of all of $2,700. I talked it over with my wife and she was “less” than supportive, but tolerable with the idea of saving for a new tool (gotta love the little hen!)

I told my friend thanks for letting me try it out, and my plan to save and buy one. He said he would come and get it if he needed it and to wait on buying one – that was two years ago and it’s still in the shop, (what a good guy!). For what it’s worth, I think these two machines are worth saving for – They are, in my opinion, the perfect compliment to one another. The friend who loaned me the Multi-Router advised me long ago to not necessarily buy the best tools, but always buy the top of the line of what I can afford. That credo has always served me well if I can find the patience to wait.

Anyhow, my two cents worth.

Gods speed on your recovery next week Mark – My thoughts will be with you!


-- The Gnarly Wood Shoppe

View Mark A. DeCou's profile

Mark A. DeCou

2009 posts in 4642 days

#9 posted 03-04-2007 06:53 AM

Schroeder: crap, you have both of my dream machines. Glad they are working well for you, makes my opinion sound substantiated (is that a word?).

If you get time, you might take some photos of the Multirouter and post them, seems that many of the folks here have not seen it before. It was one of the items I asked for in my grant proposal, that got shot down.

Your work is great looking, quality machinery has to help a quality minded craftsperson build quality stuff.

I’m only a little mad about your friend leaving you the Multirouter to use. Jealous I guess.


-- Mark DeCou - American Contemporary Craft Artisan -

View Bill's profile


2579 posts in 4398 days

#10 posted 03-04-2007 07:04 PM

Good luck Mark, and a speedy recovery.

At least you will be able to catch up on some of your writing since you won’t be in the shop!

Yes Schroeder, please add some pictures of the tools. I am interested in tools that improve my results, makes them consistent, and saves time. Of course, there is always that issue of money to resolve..

-- Bill, Turlock California,

View schroeder's profile


702 posts in 4362 days

#11 posted 03-04-2007 07:39 PM

I’ll take some pix this afternoon Bill and see if I can figure out how to post them…

-- The Gnarly Wood Shoppe

View Dick, & Barb Cain's profile

Dick, & Barb Cain

8693 posts in 4536 days

#12 posted 03-04-2007 07:47 PM

Here’s a link with videos#.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN.

View Bill's profile


2579 posts in 4398 days

#13 posted 03-04-2007 07:50 PM

Pretty nifty machine!

-- Bill, Turlock California,

View Duane Kohles's profile

Duane Kohles

40 posts in 4537 days

#14 posted 03-09-2007 03:33 PM

Schroeder and Mark
If you could only buy one, which one would it be. I have some table and chair work coming up later this year, and I am planning on buying one or the other. I am tempted to buy the Multi router as I have the drill press hollow chisel attatchment set.

-- Duane Kohles

View schroeder's profile


702 posts in 4362 days

#15 posted 03-09-2007 09:41 PM

In my opinion, the Multi Router – for making tenons and angled tenons, and especially for repetitive tasks, it’s a great machine.

-- The Gnarly Wood Shoppe

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