Cutting mortises

[nanook]

I am hoping to build a cottage using at least partial timber framing construction[   open beam for cathedral ceiling ].In considering some of the difficulties this will present, one that concerns me is being able to cut clean,accurate mortises. I have read through much of the discussion on this forum on this topic.[boring machines,mortise chain saws, augers, chisels,drills, etc.]                                                                              Although I have never used a hollow mortise chisel and bit, I am guessing using one with a drill press and  doing some setting up to keep things square and level, might be my best bet. Use a 1" mortise chisel to do the corners and some of the wood on the sides, and finish the job with a framing chisel.                                Any advice or suggestions from the experienced readers would be greatly appreciated.

[ljmathias]

Welcome!  Glad you're going to try something new, or rather very old.  Timberframing is one of those things that very simple in concept and complex in execution.  I took (actually hosted) a timber framing class taught by Jim, the moderator of this section- learned a lot and actually feel I could go the next step and do structural timber framing (see the thread not quite a timber frame where we- my daughter and I- will be building a single bent with two floor beams to support the second floor and the rafters in a cathedral ceiling.  Will probably take me a solid week to get everything ready, squared up and all the parts fitted together so we can take it apart for raising on the foundation that will become her and her son's new home.

Anyway, there's a lot you need to learn and this is the place to learn the concepts and theoretical part- practice makes perfect applies to timber framing as much as any complex skill so that should be part of your learning plans.  Keep asking questions but try making something; I'd suggest a set of mortise and tenon sawhorses- heavy and solid for doing more of your work on...

Lj

[Brad_bb]

Actually a hollow mortiser is not the way I'd recommend.  If you're only going to do a handful to a few dozen joints, and money is tight, I'd get one of the lower cost mortising machines like a Snell($150-$250).  Jim Rogers a couple for sale.  He also sells good bits.  Just know what width mortises you are going to cut, and what size pegs and get the two bits for that.  Jim always sells good tools ready to use, unless otherwise stated, and the prices are fair.  He lists his inventory in the for sale section as "Hand Tools for Timber Framing".  You will also need a good framing chisel the same width as those mortises.  I'd recommend from Jim as well.
  It's not that hard to learn to cut mortises.  Just get an experienced framer to show you on one or two(the basics) and you'll be off and running.  You should learn layout technique as well.  Taking a workshop will teach you a ton and you'll be able to layout and cut your stuff after.  You'll lean more than just that specific stuff.  What you learn will apply to all woodworking as well.  Sharpening, visual grading/evaluating of timbers, tool use, etc.
  You don't need a chain mortiser.  It just helps in a more production setting, but makes a lot more dust and noise and requires a cord.  Regular boring machines are probably only 30 percent slower, but it has the advantages or no cord so more portable, no dust, quiet, and more enjoyable.

There are some good youtube videos on cutting a mortise.  Try these
http://www.youtube.com/user/MoonHillFarm#p/u/3/xQ1hPLNxBSc
http://www.youtube.com/user/MoonHillFarm#p/u/2/p_f51_ejghM

Tim likes to use an ax for some things, but not necessary.  Can be done with chisel and mallet.

[Carpenter]

     I'm glad you brought the subject up.  I was cutting mortises today for a coffee table.  They are a bit smaller than timber frame mortises but same principle.  Also, I am planning to build a timberframed shop this spring, so I have been looking at the tools available.  The coffee table has 3" x3" framing, so the through mortises are 1"x3".  I drilled the holes with a forestners bit and chiseled them square.  Didn't keep real good track of time but, I made two tenons and four mortises in under two hours.  Of course that is not warp speed, but then I always aim more for perfection than speed.  I really could have sped that up too, So I figure on a full sized timbered moritise in pine, I could probably cut them by hand in 20 minutes.  So, I should be able to cut 3 per hour.  My normal rate of pay as a carpenter in this area is $22 per hour, so, $7.33 / mortise.  Of course, that does not include housing or layout or anything else involved, just making the slot,  which is all a chain mortiser does. 
     I would love to have a chain mortiser, either a maefel or a swisspro, I'd even settle for a makita.  But, after looking at the numbers, I would have to cut over 500 mortises to justify one.  Since, right now the only timberframe I've got scheduled to build is for myself and it's just a 4 bent shop, I think I'll cut them by hand.  I do think I'll get a boring machine though.  They can bore holes amazingly fast if you don't mind working up a sweat and I think it would be a lot easier to get a boring machine to the timber than get the timber to my drill press. 
     If you've got a good way to get the timbers to you're drill press I would think that an actual mortising set up would work quite well.  Can you get an inch and a half or two inch hollow mortise set for a drill press and just do the whole thing with out having to clean it up with a framing chisel?  If so, I would probably figure out a system to get the timbers to the drill press.  ( I've never used a hollow mortise chisel either, just seen them on The New Yankee Workshop)

[Carpenter]

     Nice post Brad.  Maybe one of these days I'll be nearly that fast.  That was very inspirational.  You posted you're reply while I was writing mine.  I went ahead and posted it anyway.  It's odvious that he's cut a few mortises and while a chain mortiser would be a little faster, probably not enough to justify the cost of the machine unless one was planning to build several buildings. 

[Jim_Rogers]

Some general advice.

First of all make sure you layout is right. Knife the perimeter of the joint with a standard utility knife so that the wood doesn't chip out beyond your mortise or housing.

Bore the end holes first then the middle one(s).

Cut the housing after the mortise.

If your layout is 2" off the layout face and then 2" thick, then process the cleaning up of the mortise this way. That is cut the side to be truly 2" off the layout face first, then cut the opposite side until it is 2" wide. Use your framing square as a guide to the width of the mortise. Then process the end grain to make it as long as you need it to be, either end first, that really doesn't matter.

Make sure your mortise is the correct depth. Don't forget to add the housing if you don't bore it deep enough first it a challenge to get it deeper later. Very common mistake of beginners.

Usually we make mortise 1/8" to 1/4" deeper then the tenon length to insure that the tenon will never "bottom out" when drying shrinkage occurs.

If you layout and mortise is 1 1/2" off and 1 1/2" thick or even smaller, as mentioned 1" x 1" then follow the same process.

We do have a good stock of chisels, bits and boring machines on hand now.

Jim Rogers

[Dave Shepard]

Fourteen minutes for a brace mortise, add a minute for layout, fifteen minutes for a hand cut housed mortise.  8) Tim is a good axe man, I've seen him in action.

I think trying to cut a mortise with a hollow chisel mortiser will be difficult unless you have a specially setup machine. I have seen one that was custom built for timber framing on YouTube, but it was pretty complex. For a small, one time project, I think a boring machine or heavy drill and a sharp chisel will work quite well.

[nanook]

Thanks for the great feedback which I have already received. I don't anticipate cutting a whole lot of mortises in the future but want to give myself the best chance to have success with my cottage if I proceed. I will be milling the lumber at our mill and can either work on the timber there or transport to building site and work on it there. We have a farm tractor to help with moving it and have electricity at both sites. So far consensus seems to suggest using a boring machine and chisels[?].

[Brad_bb]

I've heard that hollow mortisers only go up to a certain size because, the larger you get, the larger the 4 corners are that the bit cannot get, and it gets too big for the chisel part to clear. 

[Jim_Rogers]

So far consensus seems to suggest using a boring machine and chisels[?].

It really depends on you.

A boring machine holds the bit truly 90° left to right and front to back. Some people can do this with a hand held power drill but it isn't easy, I know I've tried.

As mentioned, you can always sell off your boring machine after your project is done.

Part of the problems with using a hollow chisel mortiser is that the chisel/bit has to be aligned with the edge of the mortise. Trying to align a heavy timber with the bit attached to a drill press/mortiser machine, isn't an easy thing to do. And as mentioned chisel mortisers only come in certain sizes, and I've never seen or heard of one as big as one inch. (Other then the commercial ones previously made by Makita. And those cost as much as a chain mortiser.)

My brother bought me one and we never tried it to do mortises as it was so small. I think the biggest bit we could get was 3/4" and the smallest mortise we would ever do, in timber framing, was 1 1/2".

With a boring machine you set the machine on the beam and then bore the holes.
I did three videos on YouTube showing the parts of the Boss boring machine. And that did include some mortise layout and preparing the machine. If you do a search there you can see them. I'm not sure if I ever brought them here to this section of the forum or not. I don't believe I did as it was basically a commercial for our tool business, and they may not be allowed in this section.

Tim Beal of Moon Hill Farm also did some videos showing the cleaning up of a mortise, also on YouTube.

Good luck with your project and keep asking questions.

Jim Rogers

[Hilltop366]

Back about 12 years ago when I was trying to figure out how to make a bit of timber frame for the house I was building I had only seen the old boring machine in books and had no idea on where to find them and did not want to spend the $$ on a chain mortiser, I already had a drill press so I got to thinking why not make a boring machine with the drill press......... so I took the head off of the drill press and made a frame with some steel I had left over from other projects and also made a clamp that would go under the beam to hold it in place, and there you go a modern "portable" electric boring machine.

I used a saw tooth bit so I was able to overlap the holes about 1/4 of the bit which made for less chisel work and if I remember correctly I would take a hand electric drill with a small auger (maybe 9/16) and drill out the corners first so there would be less chisel work trying to get the corners cleaned out. Not too loud or dusty which was nice.

It worked ok, it drilled nice but was a bit heavy, also for some of the deeper mortises it did not have enough travel so I would drill as far as I could and then lower the bit in the chuck and make them a bit deeper, also because of the weight I never used the clamp part much unless the was a hard spot in the wood that would want to make bit walk or I was over lapping the bit a lot.

I still have the frame and if I needed to do a bit more I would use it again but if it was going to be a lot I would look for something else.

[Mad Professor]

Did I miss it or how come nobody said you NEED a slick?

Yes you do.....

[Brad_bb]

I would disagree.  I don't think you "need" a slick.  You can use your chisel like a slick. 

[krusty]

I would think every aspiring timberframe needs a slick!

Though back to the original question. I would get a bornman (sp?) layout tool. a 2" framing chisel with good steel in it, and a 2" Milwaukee bit from the BORG to drill your holes for the mortises. That will keep you cutting mortises until you have nightmares of them swallowing you .

[nanook]

Still trying to catch up on terms and acronyms. I believe the bornman is "Big Al" Borneman" layout tool. What do you mean by BORG?         With 8" timber I can see where a 2" slick would be an advantage in cutting/trimming the ends [and sides] of the mortises. When cutting a mortise what is the advantage of the 2" slick over an inch and a half chisel? Exact width? Leverage? Faster?    ???? In cutting a 2" wide mortise would you use a 2" bit or one slightly smaller[1  7/8]?  Again thanks for all the feedback.

[Dave Shepard]

Big Al layout tool was invented by Al Borneman.

BORG is Big Orange Retail Giant

Bore a hole exactly the width of your mortise.

American slicks are usually 3" to 4", Japanese slicks tend to be around 2" to 2 1/2". I use a 3" and a 3 3/8", and have a couple more in the 3" to 4" range. Slicks are heavier, making it easier to pare off more material. If you are just doing a small project, you probably don't need to invest in a Big Al, boring machine, and slick. However, if you are going to be doing a lot of it, then those tools will pay off in the long run.

[Brad_bb]

The reason I recommend one of the lower cost boring machines is that 1)I think they are much nicer to use than a big drill, they keep your bit square for you 2) a big drill costs more than the boring machine I mentioned if you don't already have it 3) If the big drill gets away from you and whacks your wrist or wraps you up, you'll with you'd went with the boring machine 4) a boring machine is more portable. 
   Typical slicks around here are between 3 and 4 inches.  They are much thinner than a chisel.  They have a curved edge(most often) for parring. You can easily clean up a mortise or tennon with your 2 inch chisel, that's how I learned.  You use it like a slick, without the mallet.  I'm trying to keep the original poster with the minimum to start.  If he learns with his chisel, and later wants to graduate to a slick, fine, but one step at a time.

[krusty]

I can't comment on what the maker is on my slick but when properly sharpened it is a treat to use, plus simply looks great! To be honest I don't think I really use a slick on mortises, mostly tenons. From a religious perspective every aspiring timberframer 'needs' one.

On the Borneman, I think even the Sobon shed sized project will save you hours and frustration of layout using this tool. It is simply $$ well spent.

Sorry Brad I would have to disagree on the boring machine VS drill. I have a cheap Dewalt 1/2" drill that has plenty of power. Yes it is scary to use if you are not cautious around knots, but is easy to handle otherwise. I also have a couple boring machines and as much as I love them on a summer day in the shade, I can drill faster and just as accurate with a drill and 2" bit.  The drill will work much better in knots than a boring machine, less bit wander.

[nanook]

Interesting last comment. Any more of you experienced people have anything to add re drill vs borer? I expect one advantage of the boring machine is that it keeps your bit straight front to back and side to side.

[icolquhoun]

I have a 1/2" hammer drill that the hammer feature can be disabled as well as a 1872 phillips boring machine I bought from Jim with 1.5" and 2" bits.  I have compared the two using a brand new 1.5" forstner bit that was about $50.  There is no comparison.
Not only is the boring machine quicker in actually boring, but for doing a typical mortise where you bore 5 holes, you bore a hole, clear the chips (watch your hand in relation to the end of the bit, don't ask me how I know  :'( ) set the machine for the next hole, and away you go.  With the drill, you need to extract the bit (not always easy), clear the chips, set it up, make sure it's 90degrees in every direction, and go again.  Set-up for each hole is faster with the old-school boring machine BY FAR.

Just my .02, so take it for just that, but timber framing is an art, just like wood turning, pottery, and glassblowing.  While you could certainly achieve the end result in many ways, it loses something in translation.  Just as I wouldn't turn a perfect bowl by using a CNC machine, I wouldn't use electric tools to cut traditional joinery.  There are few things more relaxing than cutting joinery using hand tools without dust, noise, or electric.  No need to rush anything, have extension cords all over, hearing protection, etc.  If there is a time crunch, just stick-frame it :D
....steps off soapbox(one made with hand tools  :D )
   

[Brad_bb]

Krusty's last comment is interesting I think regarding bit wander.  Keep in mind that there may be a number of factors that may lead to such an experience.  There are plenty of boring machines out there that have worn out bearing bores, this contributes play in the machine and can allow the bit to start off center.  Excess play in the guides can have the same effect.  The bit used can also play much into such a thing, especially when it comes to knots.  I can tell you that having a sharp bit makes a huge difference.  They are not difficult to sharpen/keep sharp when you understand how.
   Any boring machine I've used so far has had some amount of play, but not what I would consider excess.  I have purchased some machines that definitely have worn out bearing bores and way too much play.  I'm restoring those with sleeves and new shafts.
   There are a lot of framers here who definitely prefer the boring machine for a number of reasons, but if you do get one, you need to make sure it's in proper working order.  That's one reason I'd send you to Jim Rogers.  He will.