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Gold-Plated Hammers – Yes, Really!

Cleaning mortise bottoms

Posts

Cleaning mortise bottoms

#1

Cleaning mortise bottoms

Bill Lowrance in Geneva

>After you've chopped a mortise or other cavity to depth, you may want to clean up and square the bottom and corners, maybe even fairly precisely. In the West the verb for this must be "scronking" or some such, because it seems to be done merely by scraping the bottom with the mortising chisel. This is pretty crude and is not so nice for the tool.

The Japanese, no surprise, use cutters specialized for this -- the bottom-cleaning chisel, sokozari nomi (with a small acutely cranked cutting edge) and the harpoon chisel, mori nomi (shaped as the name indicates). Toshio Odate describes them in his book and Dick GmbH, among others, sells them. I haven't used one yet but am tempted.

Do the Japanese tools work only on soft woods? Is there some western equivalent to these Japanese nomi? Do people really just scronk away with their finely honed chisels, or do they use L-shaped corner chisels for part of the task, or do they sacrifice an unloved mortise chisel to scraping duty? Or, is there another approach?

Re: Cleaning mortise bottoms

#3

Re: Cleaning mortise bottoms

joel

>Why bother? End grain has no glue strength anyway and for a normal F+P mortise there should be no problem. chamfer the tenon slightly which will also make it easier inserting into the mortise. BTW if your mortise fits too long at the bottom you may have glue compression trouble anyway.

Japanese to most of the m+t into screens, and have shallow mortises where every bit helps. the lock mortise chisel (also called a swan necked chisel) were designed for cleaning mortises when installing things like locks, which need a fairly percision fit.

But for regular mortising - don't bother.

Re: Cleaning mortise bottoms

#4

wondered about this myself

bill tindall

>I have never heard why one cares about mortise bottoms.

but there must be some reason or "they" wouldn't make tools to do it.

Re: Cleaning mortise bottoms

#5

Re: Cleaning mortise bottoms

Dave Anderson Chester, NH

>I agree with Joel, the bottoms don't need to be clean. They do however need to be a slight bit deeper than the length of the tenon. If they aren't, there's no where for the excess glue to go and hydraulic pressure can make it almost impossible for the shoulders to be pulled up tight. I usually make my mortises about 1/16" longer than the tenon.

Re: Cleaning mortise bottoms

#6

Re: Cleaning mortise bottoms

Bob Smalser, Seabeck, WA

>I agree with Joel that there's no benefit to anality in mortise bottoms.

I simply index the bevel of the mortise chisel against the end of the mortise and lever backwards to scrape the bottom reasonably flat.

If I strike the ends normally to deepen the cut, then the above method also pares away bottom waste very well.

My other trick is using long, millwright's mortise chisels...thei increased length makes them easier to plumb and the added heft combined with a lead-weighted mallet makes short work of chopping mortises.

The 16 below, for example, were chopped from scratch in 45 minutes.


img

Re: Cleaning mortise bottoms

#7

Re: Cleaning mortise bottoms

Ernie Miller Topeka

>you place your work in a vice when morticing? I think using the bench top or better yet a morticing bench would be much better.

Re: Cleaning mortise bottoms

#8

Re: Cleaning mortise bottoms

Steven McKinley from Calgary

>Ernie,

though I can imagine what a mortising bench is, do you have any links to a picture of one?

Steven.

Re: Cleaning mortise bottoms

#9

Locks

Bill Houghton, Sebastopol, CA

>Joel,

Are we talking architectural locks here, like passage or entrance door locksets? If so, you may need to come out here and explain to my doors that the lock mortise is a "precision fit," since what I see when I remove the lockset has enough room in it to use for a secret compartment - and the old ones are usually marked by a series of bit circles - you know, the kind with the hole in the middle for the lead screw and the munged-up edges from the spurs.

Bill, who's made a couple of those precision-fit lock mortises himself over the years.

Re: Cleaning mortise bottoms

#10

Re: Cleaning mortise bottoms

paul womack

>A mortising bench (AKA mortising stool) is just a massive, narrow beam. Only the top face need even be smooth and true. The workpiece is commonly held by wedges between 2 small fixed uprights. The height is around 3 feet, and you sit on it whilst working.

It is far cheaper and easier to make a stable, solid and cheap dedicated mortising stool, than a workbench that will handle morticing activity to the same standard. A workbench is a jack of all trades, with the limitations thereof.

BugBear

Re: Cleaning mortise bottoms

#11

Re: wondered about this myself

paul womack

>but there must be some reason or "they"[Japanese] wouldn't make tools to do it.

IIRC it is a badge of pride to have mortice bottoms thin enough to see through.

Whatever floats yer' boat, I guess.

BugBear (who scrapes out the bottoms of mortices with chisels sturdy enough not be damaged by such use)

Re: Cleaning mortise bottoms

#12

Re: Cleaning mortise bottoms

William Duffield on the Cohansey

>I thought it was a stump :^)

Re: Cleaning mortise bottoms

#13

Re: Cleaning mortise bottoms

Don Thompson - Cutler Ridge, Florida

>I don't know about anal-compulsive cleaning, gluing to endgrain problems, etc, but I found that when I was making deep mortises in some 4x4 boards that the below-illustrated chisels helped to remove the chips (?) made by the mortise chisel, and to level the bottom of the mortise.

The left-hand chisel is a Sorby swan-neck; the right-hand chisel is a Jim Wilson Special. The first scrapes and pries, the second slices.

YMMV, but I found them helpful on these large mortises, which some may never make.


img

Re: Cleaning mortise bottoms

#14

Re: Locks

joel

>I'm thinking more like desks and stuff. but I suppose you don't need to be that precise. But then again in 20 years I have never felt the need to buy or even borrow a lock mortise chisel.

Re: Cleaning mortise bottoms

#15

Re: Cleaning mortise bottoms

William Duffield on the Cohansey

>That "Special" is certainly a good looking tool, an obviously well thought out design, and competently constructed as well. My memory has failed me regarding Jim Wilson, although the name seems somehow familiar. Was he previously associated with Steve Knight? Where do you go now to get his chisels?

While I don't see the need for flat bottomed mortises, I sure like to be sure they are cleaned out well enough that the tenon doesn't run into any trash during assembly. This is even more important if you are a left handed Neanderthal like me, and often use a hollow chisel mortiser in a DP for most of the heavy work. These things leave lots of junk at the bottom, and need to be cleaned up after.

Re: Cleaning mortise bottoms

#16

Re: Cleaning mortise bottoms

Don Thompson - Cutler Ridge, Florida

>Yes, Jim Wilson is the fellow that used to do some metal work for Steve Knight. He used to sell big mortise chisels through Steve. His company, such as it was, was named Paramount, or Paradigm - I am embarassed that I can not remember it. Anyway, for personal/professional reasons (he is a software guy), he got out of the tool making business.

I felt a need for a tool to slice at the bottom of large mortices I was working on for some yard structures, and I sent him a sketch. He pointed out that the profile in my design would be too weak, and the improved version is what you see.

If he were still making tools, I think I would get one or two smaller ones for furniture work. Not necessary, but I like it.

Re: Cleaning mortise bottoms

#17

Re: Cleaning mortise bottoms *LINK*

paul womack

>There just ain't nothin' new, is there?

BugBear


old chisel

Re: Cleaning mortise bottoms

#18

Re: better  *LINK*

paul womack

>


good detailed photos

Re: Cleaning mortise bottoms

#19

Re: Cleaning mortise bottoms *LINK*

Sean Evoy

>Don,

Jim Wilson made mortice chisels and did some work on Steve's infill plane bodies. He is on hiatus from active toolmaking, but he maintains his website which has some interesting info on heat treating and tool making.


http://www.paragoncode.com/toolmaking/

Re: Cleaning mortise bottoms

#20

There you go...

Don Thompson - Cutler Ridge, Florida

>That looks like a cross between the Wilson and a swan-neck. I like it.

Re: Cleaning mortise bottoms

#21

Question

Bob Hackett

>How would one go about chopping a mortice with that?I want to see a streaming video of the seller demonstrating the activity.:^)

Mainely,Bob-Who really shouldn`t complain,at least the seller knew it was used for morticing.

Re: Cleaning mortise bottoms

#22

Re: Question

Mike Lietzow

>I can say with a high degree of confidence that the descriptions Sandy (the seller) provides are _very_ well-informed.

Cheers,

Mike

Re: Cleaning mortise bottoms

#23

Re: There you go...

paul womack

>That looks like a cross between the Wilson and a swan-neck.

The old tool is far more complex than either. It cannot be made by simply bending and grinding bar-stock.

I guess they must have been very good at their intended task, since they're not killer rare over here in the UK. You certainly don't have to attend a specialist tool auction to find 'em.

BugBear

Re: Cleaning mortise bottoms

#24

Sooo...

Bob Hackett

>Any guesses as to how you chop with that tool?

Maybe Sandy just wrote THAT description before the coffee kicked in.I did give Sandy points for knowing about mortices after all.

I must admit is was a far better description than you`ll find on 90%+ 0f E-bay auctions.

Still want to see the demonstration though,I`m wondering mallet or specialized hammer.;^)

Mainely,Bob

Re: Cleaning mortise bottoms

#25

Re: Question

William Haun, Forest City, IA

>I believe that you would chop the mortise with a straight mortise chisel. Then use this chisel to just pry out chips from the bottom of the mortise. No pounding involed.

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