Marking Mortices: a suggestion for an enhancement.

[Andy Kev.]

Although I'm slowly getting better, I've always had difficulty when chopping out mortices in that I occasionally have the chisel skew to the long axis of the mortice. This obviously results in too much of a cut on one side and too little on the other. Do it a lot and the mortice can end up being physically very sloppy indeed.

I had an idea which I tried yesterday to counter this and the results were very good. I'm sure somebody else must have come up with the same thing but I've never seen an account of it anywhere so here goes. Once you've got the mortice marked, take the combination square and mark at the intervals at which you wish to chop - say 1/8" - at right angles to the length of the mortice and from one end to the other. You end up with it looking like a regularly spaced bar code.

What this more or less guarantees is that your first chop at each line of the bar code is dead straight i.e. not skewed. I still managed to get one or two little twists but far fewer than previously and as a result the completed mortices needed much less tidying up. The only penalty is an extra 30 secs or so in the marking of each mortice.

Does anybody else do this?

 

[thetyreman]

I find it's a feel thing, you've got to be able to tell when you're off centre, sellers makes a template which is just basically a block of wood with a brass plate on it that keeps the chisel square to the edge, but personally I found it a bit annoying and prefer doing it freehand knowing that there's a risk of some very slight twist, if you take your time though it should come out good, I can't claim to get it perfect every time but I'm a lot better at it now through practise.

 

[Andy Kev.]

I find it's a feel thing, you've got to be able to tell when you're off centre, sellers makes a template which is just basically a block of wood with a brass plate on it that keeps the chisel square to the edge, but personally I found it a bit annoying and prefer doing it freehand knowing that there's a risk of some very slight twist, if you take your time though it should come out good, I can't claim to get it perfect every time but I'm a lot better at it now through practise.

I'm getting better through practise as well and would hope to be one day reliably good doing it freehand. However, I wish I'd had the barcode idea ages ago as it would done away with a lot of frustration. By the way, I had no idea that anybody had developed a jig for this task.

 

[AndyT]

Andy, what sort of chisel were you using? I think if you used an oval bolstered mortice chisel, with the much deeper blade, you'd find it easier to keep the cutting edge at right angles.

 

[Andy Kev.]

Andy, I've treated myself to one of the new Veritas morticing chisels and its design makes the job significantly easier but nonetheless I still occasionally manage to twist a bit out of true. One of the reasons I'm so pleased with the knifed-in barcode idea is that it has resulted in even fewer off line chops.

 

[thetyreman]

I find it's a feel thing, you've got to be able to tell when you're off centre, sellers makes a template which is just basically a block of wood with a brass plate on it that keeps the chisel square to the edge, but personally I found it a bit annoying and prefer doing it freehand knowing that there's a risk of some very slight twist, if you take your time though it should come out good, I can't claim to get it perfect every time but I'm a lot better at it now through practise.

I'm getting better through practise as well and would hope to be one day reliably good doing it freehand. However, I wish I'd had the barcode idea ages ago as it would done away with a lot of frustration. By the way, I had no idea that anybody had developed a jig for this task.

it took a while to find it, then I realised I dont think he's uploaded it to youtube, here is the video I was talking about, it may be a big help https://woodworkingmasterclasses.com/vi ... technique/

 

[Andy Kev.]

Thanks for the link, Tyreman. To be honest I don't think I would need that jig unless I were using a wildly unsuitable chisel or fiendishly uncooperative wood and the barcode seems to be all I need because laying the tip of the chisel in each cut greatly reduces the risk of twisting although as I pointed out above, I haven't 100% eliminated my tendency to twist yet. I think that "yet" is the key word. I want to get to the point where my free hand morticing is so accurate that I don't need any kind of aid, as I imagine we all would. I just wish I'd had the barcode idea before I mangled my first mortice.

 

[MikeG.]

Are your chisels bang-on square at the business end? Having an off-square chisel is the thing which most throws me off when chopping mortises. If they're right, you don't actually need to put much force through the handle as they pretty much go where they need to go.

 

[Andy Kev.]

Are your chisels bang-on square at the business end? Having an off-square chisel is the thing which most throws me off when chopping mortises. If they're right, you don't actually need to put much force through the handle as they pretty much go where they need to go.

I've never checked. However, the fact that the mortice chisel is made by Veritas and the fact that I get a bang on square cut 9 out of 10 times (a success rate which represents a big improvement over time and which I hope to continue to better) suggests to me that the chisel is probably spot on. It's a bit like sawing tenons. The first time I tried it, I thought I would never manage a square result and yesterday I split all eight lines.

 

[woodbloke66]

Chopping the mortice square has nowt (or very little) to do with the chisel but where you stand. The job should be cramped to the bench top (never held in a vice) over the strongest part of the bench which is always directly over a leg. Then stand at the end of the bench so that the job is now facing away from you down the length of the bench. Place the chisel on the appropriate line (bar codes if needed), check to see that it's vertical (easy now 'cos you can see if it's tilted) and hit it hard with the biggest and meanest maul in your arsenal. The caveat is that the bench top must be level in both planes; if it's not you're liable to end up with a mortise that's out of kilter.
Chopping these things is easy, you've just got to stand in the right place - Rob

 

[Jacob]

Yes to Rob's suggestion above except I wouldn't bother clamping. All the cuts are vertical at all times so the thing stays well in place. An even better holding is to sit astride the workpiece on a saw horse, or even a purpose made morticing stool, so you are morticing between your knees.
Are the Veritas chisels slightly tapered (i.e. face to back) so that a cross section would be trapeze shaped? If so being slightly off square shouldn't matter - except for the last cuts down the end faces, which you'd do carefully anyway. If they aren't tapered it makes the job a lot harder.
n.b.the secret of rapid morticing is to take a thin vertical slice off the face of the previous cut - as deep as you can go without it getting stuck. First few cuts not deep of course. The wedge shape forces the waste out of the way and the tapered section frees the chisel when you pull it back a touch. Otherwise vertical all the time, no levering etc.

 

[woodbloke66]

Yes to Rob's suggestion above except I wouldn't bother clamping. All the cuts are vertical at all times so the thing stays well in place. An even better holding is to sit astride the workpiece on a saw horse, or even a purpose made morticing stool, so you are morticing between your knees.
Are the Veritas chisels slightly tapered (i.e. face to back) so that a cross section would be trapeze shaped? If so being slightly off square shouldn't matter - except for the last cuts down the end faces, which you'd do carefully anyway. If they aren't tapered it makes the job a lot harder.
n.b.the secret of rapid morticing is to take a thin vertical slice off the face of the previous cut - as deep as you can go without it getting stuck. First few cuts not deep of course. The wedge shape forces the waste out of the way and the tapered section frees the chisel when you pull it back a touch. Otherwise vertical all the time, no levering etc.

Agreed, Jacob; nice to see we're singing from the same hymn sheet (except I'd cramp the job down) - Rob

 

[MikeG.]

You're missing my point, Rob. If the end of the chisel is out of square, one corner of it bites into the wood first before the other if you hold the chisel vertical. That's just logic. That has the tendency to move that lower corner before the other corner catches up, putting a twisting force into the chisel, and making the whole job more of a fight. That's obvious because one corner of the chisel is taking a bigger wedge than the other, every time. Of course, it also attempts to tilt the chisel over, thus reducing your chance of getting the mortice being true (vertical).

So, I say again, one of the things to look for in chopping out mortices is that your chisel is true. If you don't believe me, feel free to grind the end off one and give it a try.

 

[woodbloke66]

You're missing my point, Rob. If the end of the chisel is out of square, one corner of it bites into the wood first before the other if you hold the chisel vertical. That's just logic. That has the tendency to move that lower corner before the other corner catches up, putting a twisting force into the chisel, and making the whole job more of a fight. That's obvious because one corner of the chisel is taking a bigger wedge than the other, every time. Of course, it also attempts to tilt the chisel over, thus reducing your chance of getting the mortice being true (vertical).

So, I say again, one of the things to look for in chopping out mortices is that your chisel is true. If you don't believe me, feel free to grind the end off one and give it a try.

Doesn't make a lot of difference Mike though I can see what you're saying and a square dead square chisel is obviously much more desirable, but at the end of the jour if you take control (where have we heard that before ) of the chisel by sighting it correctly and then giving it an almighty belt with huge, nasty maul, it should go in squarely - Rob

 

[Simon_M]

If all else fails, and you cut the mortice first, you can often mark a second line and have "have another go" and allow for a "fat" tenon to match. The short sides of the mortice aren't so important to get right.

 

[Jacob]

Well yes there's all sorts of messy and slow bodged jobs you can do!
Main thing is to mark it up properly with mortice-gauge lines to fit the chisel exactly, and stick to the marks. You have to if you are doing any serious work - you might have to cut 20 mortices first and then 20 tenons later and you want to be sure they'll all fit first time with no effin about!

 

[memzey]

Someone told me "If you could put an engineer's square into the mortice then you might see that something isn't quite right (except you can't). So, the next best thing is to drill a couple of holes using the pillar drill so that it's bang up against the marked area in several places. At least when you're done you can peer in and see if you went over the line (at depth) and next time it will get better".

If all else fails, and you cut the mortice first, you can often mark a second line and have "have another go" and allow for a "fat" tenon to match. The short sides of the mortice aren't so important to get right.

Very early on in my woodworking I did try drilling holes to help with morticing. It didn’t help at all and actually took longer than just doing it with a chisel. I did try a trick of removing a sliver off the top of the mortice first (one of Hayward’s books I think) which was helpful at first but still quite time consuming. Once I got the knack I realised that hand morticing is more about vigour and sweat than anything else. Wallop! Tennons on the other hand I still need to spend more time on to get right but that might just be down to my limitations!

 

[Jacob]

,,,,,,,
Very early on in my woodworking I did try drilling holes to help with morticing. It didn’t help at all and actually took longer than just doing it with a chisel.

Well yes - and it's harder to keep the chisel going straight when there are holes drilled

I did try a trick of removing a sliver off the top of the mortice first (one of Hayward’s books I think)

Robt Wearing. He comes up with lots of spiffing wheezes, good, bad and indifferent. That was a bad one!

.... Once I got the knack I realised that hand morticing is more about vigour and sweat than anything else. Wallop!

Yes, plus comfortable working position - best of all is sitting astride on a saw stool

Tenons on the other hand I still need to spend more time on to get right but that might just be down to my limitations!

Best tool for adjusting faces of tenons I found was a Stanley 78 (without fence etc obviously). Better control than just attacking with a paring chisel and removes material faster than a shoulder plane. Also does shoulders themselves if you haven't got a shoulder plane.

 

[memzey]

I’ve got a 78 (which I think is a great and underrated tool by the way) but I have never considered using it for adjusting tenons. I have come to the conclusion that the most efficient way of cutting tenons is to fit them straight from the saw (obvious I suppose). The only way I can do this is by being extremely careful and vigilant with my marking and cutting. This takes me some time to do but less time than fiddling with an over thick tenon to get it centred and to the correct thickness. If I practiced more or cut more by hand I’d probably be quicker but I am where I am with this (a crack-handed but enthusiastic amateur).

I’ve never tried sitting astride the piece as I mortice it but it sounds like a sensible practice. I’ve tended to hand mortice at my bench with the stock held down by a hold fast or cramp. If I were to start a project today against the clock (say for the wife or one of my daughters) I’d cut the tenons on my table saw and mortices with my HCM.

 

[MikeG.]

I tend to chisel tenons rather than saw them (well, other than the shoulders, obviously).