Mortise Walls Rough or Smooth?

[J_SAMa]

This came up quite a while ago. Now I finally got around to posting it :roll: .

The titles pretty much says it all. Should one bother smoothing the walls of a mortise or just leave them rough?

Whilst chopping mortises, I noticed that the walls have a lot of small "bumps" and irregularities. I think this is because I used conventional B/E chisels (which tended to twist when chopping into the mortises) instead of mortise chisels. I tried paring those irregularities off and had mixed results: on some of them I actually widened the mortises or even worse, made the mortise taper in its width (or is that called the "thickness").
So is are the bumps and fuzz better left alone or should they be pared?

Sam

 

[woodbrains]

Hello,

I wearies me to say this, as I know there will be some of the usual suspects saying different, but the answer is, not to chop with BE chisels. They are for paring, so chain drill out the waste and pare to you scribe marks. This is pretty much the standard method of making mortices if you have not got mortice chisels. I didn't for years and the method served me well.

Mike.

 

[Reggie]

if the tenon fits, I don't think it matters in the slightest, if it doesn't, then you've got room for manoeuvre, I don't think the type of chisel particularly matters, just the technique, from what I've seen http://www.youtube.com/watch?v=q_NXq7_TILA

 

[J_SAMa]

Hello,

I wearies me to say this, as I know there will be some of the usual suspects saying different, but the answer is, not to chop with BE chisels. They are for paring, so chain drill out the waste and pare to you scribe marks. This is pretty much the standard method of making mortices if you have not got mortice chisels. I didn't for years and the method served me well.

Mike.

Like most of my woodworking skills my mortise-chopping skills are derived from Paul Seller's methodology...

 

[Jelly]

Hello,

I wearies me to say this, as I know there will be some of the usual suspects saying different, but the answer is, not to chop with BE chisels. They are for paring, so chain drill out the waste and pare to you scribe marks. This is pretty much the standard method of making mortices if you have not got mortice chisels. I didn't for years and the method served me well.

Mike.

Really? You really want to advocate drilling out small mortices? if you need a 1" mortice, then it makes sense, but 3/8" or 1/4" and it becomes a stuggle to keep the bids straight (and get the depths right) without a drill press costing more than buying a mortice chisel would, and certainly more than buying a beefy firmer chisel would.

I'd have thought investing in a firmer chisel or two (doesnt have to be anything special, a cheapy from toolbank [not sure if there's a european equivalent] would be just fine, so long as it's got parallel sides), would be the best bet.

Actually, if you're wiling to pay postage I think I have some duplicate firmer and sash mortice chisels that came in a big job lot, if you tell me the size or sizes that would be most useful to you currently I'll see if there are any going spare.

 

[G S Haydon]

I think if your joint is snug avoid paring too much. I guess in my mind you use a toothing plane to key the surfaces for veneer in old school work. Those rough edges you speak of in the mortice will probably key nicely once glued (within reason).

On the topic of the best chisels. The chisel that is used in the video is best described as a general purpose chisel that happens to have beveled edges. It's main users would be mainly but not exclusively carpenters and joiners. They are therefore quite robust and would hold up to light morticing well. They are not paring chisels, or in my mind at least not that light weight. It was common to for joiners to use a firmer chisel, sash chisels for smaller mortices. That said if a joiner back in the day had loads of morticing to do a heavy weight chisel would of been a wise purchase. Nearly all workshops for the last 100 years or more have or had a morticing machine making this part of the joint.

The method is well demonstrated but it is old news. Seen here published in the 1920's

 

[Cheshirechappie]

So long as the mortice is reasonably close to the desired width, leave it rough. Even in the best class work, it's normal to leave the tenon surfaces 'from the saw', and not to trim it unless the joint won't fit. As neither mortice nor tenon are 'show' surfaces, finish doesn't really matter (within reason), as you'll never see them again once the job is glued up. All glues will cope with a bit of roughness, so that's not a problem, either.

The better class of B/E chisel have very narrow edges between the side bevels and the chisel's flat face. These will leave a VERY rough finish if used for morticing, so it may be better to use the more general class of modern mass-market B/E chisels with quite thick edges between the bevel and flat face - the sort of chisel that is more like a firmer with the top corners knocked off if you look at it end on. They should clean up the mortice walls a bit more effectively.

All in all, however, I'd agree that it's best to cut a mortice with a mortice chisel, or with a morticing machine if one is available. Using a B/E, despite Mr Sellers' recommendation, is definitely second best - the sort of thing you should only resort to in an emergency, or if you have to work with a very limited kit of tools.

 

[J_SAMa]

Hello,

I wearies me to say this, as I know there will be some of the usual suspects saying different, but the answer is, not to chop with BE chisels. They are for paring, so chain drill out the waste and pare to you scribe marks. This is pretty much the standard method of making mortices if you have not got mortice chisels. I didn't for years and the method served me well.

Mike.

Really? You really want to advocate drilling out small mortices? if you need a 1" mortice, then it makes sense, but 3/8" or 1/4" and it becomes a stuggle to keep the bids straight (and get the depths right) without a drill press costing more than buying a mortice chisel would, and certainly more than buying a beefy firmer chisel would.

I'd have thought investing in a firmer chisel or two (doesnt have to be anything special, a cheapy from toolbank [not sure if there's a european equivalent] would be just fine, so long as it's got parallel sides), would be the best bet.

Actually, if you're wiling to pay postage I think I have some duplicate firmer and sash mortice chisels that came in a big job lot, if you tell me the size or sizes that would be most useful to you currently I'll see if there are any going spare.

I've got some cheap beveled firmers by Faithfull. Now with some practice I get acceptable results 8)

 

[Reggie]

As long as the mortice and tenon are a good enough fit then I don't think it matters myself, it's on a set of inside faces that aren't seen.
also, if you do yourself a favour and cut the tenons slightly fat then you give yourself some wiggle room for trimming if you're not that confident.

The video was merely a demonstration of using either a b/e or a real mortice chisel and it not making the slightest bit of difference (except the b/e chisel producing a smoother finish!) and my point was to watch the technique, there's no twisting going on and it doesn't change between the chisels.

 

[longinthetooth]

Depends on the application (type and scale of the overall structure). For a chair, if you needed maximum glued strength and the mating surfaces were small, I would counsel precision. For a vernacular (eg green oak) roof frame, there are no glued surfaces and it's just a mechanical engagement, so fibrous surfaces are less important. An external house door may be a more complex case: you would want to avoid unfilled voids within the joint that would be moisture traps (I believe that the Victorians used fungicidal white lead paste in this connection), but given certain tolerances on the tenon / mortice cheeks (on a finer scale than the roof frame just mentioned), the main mechanical (& glued) engagement is from the wedging of the tenon in its height.

Horses for courses, always.

 

[Jacob]

If it fits the tenon nicely thats as good as you can get and any smoothing will make it a looser and poorer fit. Best to leave it alone and try and improve your technique on the next ones. I wouldn't prioritise better chisels - it's good to be able to do it with whatever you have to hand and to adapt your technique to the tools available.
Definitely no to drilling - this makes for a very messy job and quite likely to be slower.

 

[GazPal]

If it fits the tenon nicely thats as good as you can get and any smoothing will make it a looser and poorer fit. Best to leave it alone and try and improve your technique on the next ones. I wouldn't prioritise better chisels - it's good to be able to do it with whatever you have to hand and to adapt your technique to the tools available.
Definitely no to drilling - this makes for a very messy job and quite likely to be slower.

Very true and a good route to pursue along a consistent learning curve.

------------

Sam,
For novice and experienced hand alike, wasting out mortise with the drill can leave you with more problems than it resolves, unless you have a good bench mortiser, or have had lots of practise working freehand. Skew the drill slightly to one side during use and you find one side of the cut stands proud of the intended wall/cheeks - in need of paring - and the other has eaten into them. Undercut mortise cheeks weaken the mechanical joint and increase the amount of glue used in comparatively weak compensation.

Using reasonable quality firmer chisels - if mortise chisels aren't among your kit - is perfectly fine and you'll find many new bevelled chisels are of the firmer type rather than the more lightweight paring type with finer lands.

Purpose made mortise chisels aren't vital to good mortising. While the fit of the joint shouldn't be overly tight, you should work as cleanly as possible - and make a habit of it - and be able to press the snug fitting, dry joint firmly home by hand. This type of fit leaves you with a well glued - unstarved - joint that relies primarily upon it's mechanical properties and not the glue to hold it together.

 

[Richard T]

To chop out a mortice with a chisel, be it a made for purpose mortice or other, is to split each chip along the grain. It relies on the direction of the length of the slot being in line with the grain. So the walls will never be smooth unless you chop it smaller before paring to size - a pointless exercise as, as said above, nothing of it will be seen and it is probably a near impossible task to perfectly fit a smooth sided M&T joint as well as a rough (ish) one that fits where it touches.

To use a non - mortise chisel (a la Paul S) requires more concentration on keeping the blade square to the slot, whereas a well - started slot will keep the thick body of a mortise chisel square.

The sides will always be the rough product of the splitting action though. The straighter the grain the smoother the finish I guess but it makes little odds. I tried a mortise in a scrap Elm recently to see what happened with that crazy grain - perfectly decent result.

The thing I find the hardest discipline is keeping exactly to the line over and over again. Much easier I would think when having a sheet of glass acting as one side to perfectly butt up against all the time.

 

[Phil Pascoe]

They didn't have much trouble with the mortices in the hubs of cartwheels, did they? They were elm.

 

[Reggie]

I guess the glass could keep it straight and certainly won't allow gouging into that glass, the glass extending above the piece must have an influence on proceedings too, as you say though, it's entirely down to technique and how well he's concentrating on keeping the blade straight. I've got to say, I didn't have any issues when I tried that method with a b/e.

 

[Jacob]

T.....
The thing I find the hardest discipline is keeping exactly to the line over and over again. ...

It helps if you do it on the end of the bench so you are looking along the length rather than across.

 

[woodbrains]

Really? You really want to advocate drilling out small mortices? if you need a 1" mortice, then it makes sense, but 3/8" or 1/4" and it becomes a stuggle to keep the bids straight (and get the depths right) without a drill press costing more than buying a mortice chisel would, and certainly more than buying a beefy firmer chisel would.

I'd have thought investing in a firmer chisel or two (doesnt have to be anything special, a cheapy from toolbank [not sure if there's a european equivalent] would be just fine, so long as it's got parallel sides), would be the best bet.

Actually, if you're wiling to pay postage I think I have some duplicate firmer and sash mortice chisels that came in a big job lot, if you tell me the size or sizes that would be most useful to you currently I'll see if there are any going spare.

Hello,

Yes I do and I'm not the only one. Cutting mortices for locks in doors are done this way. There are many hand tool skills books that show mortices done this way. (Roger Holmes, and excellent maker trained by Alan Peters shows it done this way, my dad did it this way) There is evidence in lots of old furniture that it can be done this way.

Speed was not the question ( that comes with practice anyway) but how to achieve smoother walls. This will do it. Other ways may do rougher faster, but that was not the question.

Toothing planes are a spurious analogy as hide glue in veneering does not work the same as PVA type glues. Modern glues work best with smooth, close fitting joints. Best is planed finishes, so the closer we can get to this ideal the better. I'm not saying that mortices are ever that smooth. But since we don't know how rough the OP's mortices are, we have to assume they are rough enough to worry about.

A couple of proper mortice chisel will be the best course to take for future work , but this wasn't the question either. If we are just going to recommend more equipment, then a hollow chisel Morticer would be good too, and bench top models are quite affordable these days. But the question was how to get smoother with BE chisels. Using the chisels as designed to, rather than trying to do something they are not ideal for would be the most logical course of action.

Mike.

Edit,

If you can't keep a drill brace upright, then you might not be able to keep a BE chisel upright either. both just require a bit of application and practice and a bit of tape will gauge the depth, that is not uncommon.

 

[Roughcut]

If you look at the shape of a mortise chisel it's easy to see why it will alway's cut the bulk material out of a mortise much easier than a conventional bevel edged chisel.
Although a bevel edged chisel can be used it is not the ideal tool, and is best used for final paring as has been said.

http://www.macwood.com.au/index.php?mai ... cts_id=635

 

[Jacob]

.... Cutting mortices for locks in doors are done this way. There are many hand tool skills books that show mortices done this way. (Roger Holmes, and excellent maker trained by Alan Peters shows it done this way, my dad did it this way) There is evidence in lots of old furniture that it can be done this way......

Deep lock mortices are an exception but it's still better to get well started with chisel alone before you start drilling, so that you have a clean hole and straight sides as a guide.

 

[G S Haydon]

"Toothing planes are a spurious analogy as hide glue in veneering does not work the same as PVA type glues"

I will do my best to avoid spuriousity in the future. I try to make a reasoned point whenever I can.

"get well started with chisel alone before you start drilling, so that you have a clean hole and straight sides as a guide."

To coin a phrase "not so" . Never needed a shallow mortice to drill straight, even on deep horizontal sash locks. Seems like an extra step that's not required. Each to their own though. Just been itching tho use the "not so" for so long :lol: