Replies

1. 
   Lataxe | Sep 13, 2008 12:56am | #1

   Bonka,

   I make through mortises with a 4" long (2" cutting edges) CMT upcut spiral bit in a router. The spiral bit cost a good bit more than a forstner bit but it makes perfect through mortises every time.

   The woodrat used to be the tool employed to guide the router with this bit in it. However, I now use a pair of opposing fences mounted on the router to sit astride the part to be mortised and move the router freehand. You can easily make a simple jig instead of using double fences, to guide the router.

   If the mortise is a lot deeper than 2 inches, flip the part over and go in from the other side. The fences (or jig) will ensure the two mortises meet properly in the centre - if the workpiece is square.

   For one-dided plunges, it takes 4 - 6 passes (depending on the depth of the mortise) before the bit breaks through to the other side. Because the bit is spiral and upcut, there is never any breakout. Using such a bit in a router gives perfectly straight, clean, 90 degree walls of an exact width (i.e the width of the bit). Move the fences or jig (fences have micro-adjusts) and you can widen the initial mortise slot to an accuracy of 0.2mm.

   This seems a far better way to make through mortises than any other I've tried, because of the clean, exact dimensions and the absence of any breakout. Once those initial through slots are made, a chisel can be used to square the ends (or round the ends of your tenons). The end of the mortise where a wedge may go can also be chiseled easily to make the required trumpet shape in the mortise where the wedges will spread the tenon.

   If you can spring for the spiral bit and you alredy have a router, I recommend putting aside those other methods and tooling. They are harder to accomplish, cause glitches such as breakout and tend to make mortise walls that are not too clean or accurate.

   If you must use a forstner bit, go in from the show side as the breakout will hopefully then be hidden by the shoulder of the tenoned part where it abuts the mortised part.

   Lataxe

1. 
   Bonka | Sep 13, 2008 05:01pm | #10

   Lataxe;

   I have searched the Net and cannot find a router bit as you describe. Would you please direct me to a vendor with a bit as you have?

   Thank you.

1. 
   Boogalee | Sep 13, 2008 05:28pm | #11

   http://www.whitesiderouterbits.com/wm_catalog_2007.pdf

2. 
   mwenz | Sep 13, 2008 05:36pm | #12

   Hi Bonka,

   Just another piece of advice from the internet...

   When you say you used a marking gauge, you are marking both sides? And, if you are marking both sides, is the face of the gauge being used against the same face of the stock, just on opposite sides of the wood?

   Take care, Mike

2. 
   Bonka | Sep 13, 2008 06:00pm | #13

   I don't see any 3/8" spiral upcut bits with a cut longer than 1.5 in. on the CMT site.

1. 
   Lataxe | Sep 14, 2008 12:09am | #17

   Bonk,CMT do a 3/8" spiral bit of 1.5" cutting length (as you desribe)and a 1/2" bit of 2" cutting length. I also have an 8mm (5/16") spiral bit from woodrat that has a 1/4" shaft and is 4" long. This will cut very deep as the cutting end is wider than the shaft. However, I haven't seen this woodrat bit for sale for a while now. Perhaps it was deemed unsafe (too long and thin).I have tried the drill bit and chisel method of cutting mortises in the past but suffered something of your problem - it's difficult to get rid of the scalops without overcutting or causing other damage to the edges of the mortise hole. Also, it takes ages.If you're accurate in your marking out (I like titemark gauge with a dedicated double-cutter wheel for mortises) a mortise chisel is surprisingly accurate and fast, at least compared to the drill and chisel method. I use 2-cherries mortise chisels with a 35 degree grind having a 2 degree microbevel. This edge seems tough enough at these angles to stand up to some heavy blows from the mallet. It isn't easy to cut a mortise to meet exactly from both sides though. Only a slight deviation from the vertical will cause a ledge where the two mortise holes meet in the middle. Using a 90 degree guide block as you start the cut helps. Once the mortise chisel is on track it will stay that way - once the mortise hole has a bit of depth.Lataxe

1. 
   Bonka | Sep 14, 2008 01:54am | #18

   Thank you for your reply. I finaly bit the bullet. I am chopping by hand. I am nearly through my first one but ran out of ooomph. I am going to have a go at it tomorrow. I used a mortise guage to initially set up the mortise on both sides. I then used a straight edge and followed the marks left by the guage with a very sharp marking knife. I did this on both sides. The first cuts were the most nerve racking for me. Once I got some depth to it it goes better. So far it looks good. This is the show side where the tenon comes through and it seems as if it will fit tight. If not I can always slap some Bondo around it.:)  I have a total of eight to chop through 1.5" maple. If this does not make a man out of me nothing will.  I do not find these excersized that rewarding even after it is all said and done. The rest of the  M&T are going to be floating where applicable.

1. 
   derekcohen | Sep 14, 2008 11:10am | #19

   Hi Bonka

   Let me give you a sure-fire method. It is a little overkill, but good when starting out.

   1. Mark out the mortice from both sides using a mortice gauge and square, as you have done.

   2. Knife the lines deeply, as you have done.

   now ..

   3. Pare away the inside with a paring chisel (not a mortice chisel). The closest picture I have is this one, which is of creating a fence for sawing a dado

   View Image

   Imagine that you are paring away to the sides from inside the mortice.

   This is what you are after (remembering this is a dado, not your mortice) ..

   View Image

   4. Now pare away the top layer of wood, down to about 1/8", using the mortice chisel held bevel down. Keep knifing the lines as you go. The deeper you go, the easier it is since the chisel registers inside the knifed lines. This is the idea.

   5. Now is time to start chopping. Do not - repeat NOT - chop to the ends. I stop about 1/4" short and clean the ends up at the end. Chop down vertically with the back of the blade facing forward. The next chopping stroke is about 1/16" towards yourself. The wedge on the chisel will drive it foward and pop out a chip. As you get close to the rear (end closest to youself), reverse the chisel and do it all from the other end.

   6. To square the ends, use the mortice chisel to pare gradually until you get to the knifed end line. NEVER place the chisel end in the knifed line and attemp to chop it out this way. The chisel will always be driven back a fraction, and will end up over the line.

   7. For through mortices, only work to half the thickness. Then work from the other side of the stretcher. Mark the chisel (with tape of a felt tip pen) so that you know how deep to go.

   Last point. I use vintage oval bolstered (or Englsih bolstered) mortice chisels as well as a couple of Ray Iles (same trapezoid design). As pointed out, it is very difficult to chop into pre-drilled out mortices with these chisels.

   Regards from Perth

   Derek

   Edited 9/14/2008 4:13 am ET by derekcohen

2. 
   philip | Sep 14, 2008 12:17pm | #20

   Yah Derek, that will work slowly but surely and be instructive as well.
   However, it is not the method as laid down under the Apprentice's Training Act, section xy dated 1757 : now defunct, due to the electric motor, but still rabidly enforced by renegade elements of the Woodworking Taleban, who are re-grouping as we speak. (small joke).Philip Marcou

3. 
   dkellernc | Sep 14, 2008 05:26pm | #21

   Bonka -

   Your observations about the difficulty of chopping mortises in maple by hand are spot-on.  Regardless of how good you are/aren't with a mortise chisel, it's going to take a while in maple (either the soft or hard variety).  If at some future point you decide to build a project out of a more forgiving wood, such as mahogany or walnut, you will find that it goes much faster.  Softwoods, of course, go faster still.  Generally speaking, I can chop a 1-1/2" deep by 1/2" wide mortise in eastern white pine in less than a minute (not counting the marking out - that takes the same no matter what the wood is).  Doing it in Mahogany takes slightly longer - about 3 minutes.

   And, of course, I avoid doing it in maple or (heaven forbid!) rosewood like the plague.

   Derek's method is a good one - I'd study the steps closely.  What you're observing with a corner or bevel paring chisel is normal - the wedging action of the bevel will force the flat back against (and sometimes beyond) the marked line.  It's something that you learn to compensate for when using hand tools.

4. 
   Bonka | Sep 14, 2008 10:49pm | #22

   I have chopped three through mortises in maple that is harder than Woodpecker lips.  I have yet to get the last two pared with a chisel but they seem to be OK.  If there are any irregularities on the show side I will be using hide glue and I under stand that will take dye/stain and may help.  Then again I doubt few will stick their nose down there to look for small irregularities.  I have a total of eight to cut and I am only on the practise stage so far.  I feel if I learn to do this with maple anyother wood should seem easy. It takes some good wallops to drive the chisel any depth.  My garage/shop is over +90*  with hight humidity. Even with a fan blowing on me I am not putting out chips as fast as a beaver. Thanks for your interest as well as all of the others who have nursed me along on this step into the unkown.

2. 
   philip | Sep 13, 2008 01:19am | #2

   Bon, if you showed a picture it would help a lot. We could see if , for example, you have incised the lines enough , and what you mean by scalloping.Are you using a very soft wood? Drill press?

   Philip Marcou
1. 
   Bonka | Sep 13, 2008 01:33am | #4

   I have incised the lines very well.  I am using a drill press and the wood is maple. I think one of my errors is trying to shave off the scalloping from the bit from the top of the mortise. I need to start cutting down from the presenting side flip it over and repeat. I have no tear out problem on the bottom from the bit. All I want is the presenting side to look good and be even and snug with the tenon. At this point I am taking a break. Tired and woodworking are not good partners. I even tried to chop one by hand. It seemed that the chisel was more or less crushing the wood. I read that mortise chisels should not be too sharp and no microbevel as the edge would break down. Any thoughts on how sharp the tool should be. The chisel I am paring with will shave end grain on pine. Do I need my mortise chisel to be that sharp? Thank you.

1. 
   dkellernc | Sep 13, 2008 01:59am | #5

   Bonka - You're right.  Tired and woodworking (particularly with power tools) doesn't mix.  There are a lot of guys knicknamed "stumpy" that made that mistake.

   The quotation about the sharpness of mortise chisels you referenced came from the instructions accompanying the Ray Iles mortise chisels from Tools for Working Wood.  Note that the Christian Becksvoort technique will not work with these chisels.  There are two reasons - one, the sides are ground into a paralellogram (so the top edges of the chisel will not engage the work), and two, the arris formed by the sides and the top is not sharp.

   To make Chris' technique work, you need chisels with a square section such as Lie-Nielsen's mortise chisels.

   And - ignore any advice you get about any woodworking tool not needing to be sharp.  It's true that you don't need to be able to shave with a mortising chisel, as a lot of the work is the impact of the mallet transfered to the wedging action of the bevel of the chisel.  But - any chisel will work better if it's razor sharp.  In the case of a mortise chisel, it means fewer blows required from a mallet and with less force.  There is, however, a balance between the toughness of the steel, the sharpness of the edge, and the angle of the bevel.  Too sharp (shallow) an angle combined with a brittle steel results in the edge chipping while under the force of the mallet blows.

1. 
   Bonka | Sep 13, 2008 11:22am | #7

   As luck would have it I have a Ray Iles mortise chisel. If one cannot use them to square up the corners what good are they?  Am I now going to have to get a LN chisel?  I would think a bench chisel would not fair well.  The mortises are 1.5" and in maple. I can't round over the tenons as the 5/8' tenon protrusion would look odd. I hate to spend anothe $65 on a chisel in light of having spent that much on one I can't use.  Can on chop mortises with the Iles chisel and square up the ends? I just don't under  stand making a chisel in that manner.  

1. 
   BG | Sep 13, 2008 02:02pm | #8

   Bonka,Give yourself a break and cheat a bit. The objective is a nice tight face joint...so undercut it at the start and pare to the desired outcome. I always cut in both sides about 1/16" so my edges stay sharp. Once you've done all that work chopping out the innards can be faster than drilling.No mater how hard I try to keep my chisel vertical and perpendicular I tend to lean to the left about 1-2 degrees. The list only becomes apparent when fitting the piece together at the end. Before I would just force the piece into square, now I pare one side of the tenon and add to the other side. My point is don't kill yourself trying to be machine like, give yourself some flexibility.

2. 
   joelm | Sep 13, 2008 03:18pm | #9

   Even Mr. Moxon writing 350 years ago knew that the simple way of making a mortise is to chop it slightly narrow and then pare to scribe lines. Read the instructions that come came with the chisel.
   For a through mortise lay out carefully from both sides and when you chop the second side put in a plug so that your chisel won't continue to the far edge and damage it. Square sided sash mortise chisels work well for shallow cuts like sashes but for deep mortises you can't beat a real mortise chisel. Pre- drilling is neither here of there but if you do pre-drill use a smaller sized drill bit than the width of the mortise.
   Any mortise 1/2" or narrower it's faster to just chop it than pre-drill. on really wide mortises - wider than your chisel - pre-drill then par up the sides or treat it as two parellel mortises and then waste out the middle lastJoel
   http://www.toolsforworkingwood.com

3. 
   dkellernc | Sep 13, 2008 07:57pm | #14

   Bonka - Yes, of course you can use the Ray Iles mortise chisel for chopping mortises - that's the specific reason I purchased mine.  My point is that you can't use the Ray Iles with Chris Becksvoort's technique - drilling out most of the waste, driving the chisel down to the bottom against the end of the mortise, then tilting it forward to break off the cresent-shaped remains from the drilling operation.  That, as Chris notes, requires a mortise chisel with a square blade section so that the top of the blade has square and sharp corners.

   The Ray Iles chisels are designed to function as effectively as possible using the traditional technique for chopping mortises.  That is, carefully marking the mortise, then chiseling out the waste by alternately driving it down into the mortise and levering it against the bevel to break out the waste.  Note - this technique does not involve drilling out the waste.  In fact, drilling out the waste would make using the chisel very difficult other than squaring the ends of the mortises.

4. 
   Bonka | Sep 13, 2008 08:30pm | #15

   I sharped the mortise chisel until it is very keen. I lapped the back.  I proceded to chop a mortise. I do not get any wood to pop out when I lever the tool toward the bevel. I have gotten probably 1/2" deep in 15 min.  My nervous system will not tolerate that speed. I am able to now use my "Mortise Pal" once the wife figured out how to cut over lapping mortises so I can make a 2.75" mortise. My problem is still squaring the ends. I deeply score the end and the little arc area is squared off with a deep score. I first tried my 3/8" corner chisel. The edge was popped into the score and it still cut to the back of the score. I tried a bench chisel with dismal results.  These were all done several times with less than acceptable results for the presenting side of a through tenon.  I am loathe to buy a LN mortise chisel because I will probably be throwing money down the rat hole.  I just need someone physically at my side to show me what to do and there is no one that I know that does woodwork in this area. I coffed table and end tables I am making are not going to have through tenons. Thanks for your help.

5. 
   mwenz | Sep 13, 2008 09:33pm | #16

   I just need someone physically at my side to show me what to do and there is no one that I know that does woodwork in this area.

   The great thing about the internet is that while you personally do not know anyone in your area, I can guarantee there are woodworkers near where you are.

   A step would be to modify your profile to show at least your general location or put it in the thread. That way if someone in your area happens to see your post, they have an opportunity to offer help.

   Larger forums such as WoodNet and Sawmill Creek have a much larger contingent of woodworkers scattered around the world. Asking for personal help at either or both forums mentioned may well get a positive response if someone here doesn't.

   Mike

   Edited 9/13/2008 2:33 pm by mwenz

3. 
   dkellernc | Sep 13, 2008 01:29am | #3

   Bonka -

   If you want to use the technique you're using (drilling out the waste and popping the rest out with a mortise chisel), I might could offer a few observations that might help out.  All of the mortises I cut are done by hand - I gave up on the router solution a while back as too inefficient, as I don't cut more than 2 or 3 at a time.

   1)  If you're going to cut a through mortise, it is essential that the piece be perfectly rectangular if you want a mortise cut from both sides to line up accurately.  That by itself is not sufficient, but it is necessary.  Without a square piece, there's no way you're going to have layouts on both sides that correspond with each other.

   2)  Once you've ensured that your workpiece is perfectly rectangular, it's necessary to make sure that you're registering the marking gauge fence on the same face of the workpiece - it's easy to mess this up.  I'd suggest putting a penciled "X" on the face you choose to register the fence on.  And, of course, you must ensure that the mortise gauge setting doesn't move between cutting the mortise lines on each side of the workpiece.

   3)  The best looking through-mortises result from carefully and deeply cut mortise lines on both the sides of the mortise and the ends, because without these the mortise chisel will break out fibers from either face side, which will give you a very ragged look.  And, of course, the mortise needs to be exactly the width of one of your chisels.

   4)  If you're going to drill out the waste, you must choose a slightly smaller forstner bit than the width of your mortise, and your drill press must drop the bit precisely square to the face of your mortise.  And naturally, the intial driving of the mortise chisel into the end of the mortise prior to dropping it forward to break out the waste must be done without any twist.

   5) Finally, I find that it's dang difficult to get a good-looking through mortise unless it's chiseled from both sides.  It may be possible to do if the workpiece is tightly backed up by a scrap block, but inevitably the mortise chisel will wander slightly off of 90 degrees, and will break out the back side because it crosses over the incised mortise lines.  A little mis-alignment in the interior of the workpiece is OK - a little bit of paring chisel work will take care of two holes that are slightly off-axis in the center.

   Also, I'd comment that Chris Becksvoort's technique, while clever and fast, isn't going to work very well if you're using stock that has curly or twisted grain.  The grain irregulaties will likely pull the mortise chisel off line when it's driven into the end of the mortise.

4. 
   Samson | Sep 13, 2008 03:24am | #6

   Through mortise are tough to make really clean. As others have said marking is essential. I don't like the idea of marking with a mortise gauge for through style. Use a marking or xacto knife. Your really need these clear lines to pare to. Make two very well and very carefully marked rectangles on the opposing sides. If you wish to drill out most of the waste, that's fine, but use a backer at the drill press to eliminate any possible blow out and don't try to get any closer to any line than 1/16th. Then carefully pare out the remaining waste with regular bench chisels working from each side. Always keep the show side in mind as the priority for "pretty." Here are a couple of pics for what they are worth:

   http://farm4.static.flickr.com/3085/2806744167_02dedf102f.jpg

   http://farm4.static.flickr.com/3052/2850075798_de06a212ea.jpg

5. 
   user-1119429039 | Sep 15, 2008 12:23am | #23

   Dear Bonka,
   Check this video:
   http://www.taunton.com/finewoodworking/SkillsAndTechniques/SkillsAndTechniquesArticle.aspx?id=30382
   It shows a method for cutting through mortises, using a template, a router, and guide bushings. Gives you clean, straight through mortises with no tearout.
   Good luck,
   David Heim
   Managing Editor
   FineWoodworking.com

1. 
   Bonka | Sep 15, 2008 02:31am | #24

   Dear David;

   Thank you so much for that.  Using a router to cut the mortises was not my main problem. It was squaring the ends. That movie shows how to do it.  I know one thing, by golly I can hand cut a mortise now.  I have cut a bunch for practice but with eight staring me in the face and in maple to boot I do believe I will get out the old router this week end and have a go.I have so many maple scraps I am even going to fire up the smoker and do some baby back ribs.  Thank again.