All,
I picked up a 3/8″ mortice chisel up at the tag sale yesterday for $5. The bevel is almost convex and the tip is not square. I figured I just regrind and square up the point as well as put a concave bevel on the tool…( I say that like I know what I’m doing …I’m actually playing pretend).
Before sharpening, I decided to play with it this morning and a piece of oak. It really cuts well and I’m wondering how sharp shoud a mortice chisel be?…and, does the convex shape help preserve the point?
Experience is a wonderful thing. It enables you see recognize a mistake when you make it again…
Replies
It should be sharp enough to cut hairs on your arm,sharp enough so it looks sharp under a good magnifying glass.The concave shape normally found on chisels is there to facilitate easy sharpening quickly;only two points contact the stone.
lol
Jackplane,
Ok, nothing unusual then. thanks
The face of a mortice chisel should be ground and honed flat (I like about 30 deg.) in order for it to cut it's best and to preserve the cutting edge.
$5 is a good deal.
Jeff
Jeff K,
Ahh..yes, 30 degrees...
It seems like it's a keeper. No ID and has a funnel type thing for the handle. I was surprised how well it cut while not being very sharp.
The guy I got this from comes up from Alabama every week or so and brings a ton of tools. I also bought four chisels for a buck a piece (Nicholsons)...the handles were worth more than that..the rasp had a rosewood with brass collar handle...
Hi BG,
I can't remember where I saw it, but I recall seeing that a convex grind on a mortice chisel aided in breaking out the chips.
I've never tried it myself - I've always hollow ground them
Cheers,
eddie
eddie,
That was my distant recollection also...a convex face. However, I'll start with the 30 degree on a flat face and see where we go from there.
I have been using a Japanese chisel for morticing that is a little less than 3/8" and the face is concave. I noticed that when hit with mallet the Japanese chisel kinda lets you know when its gone far enough. Not so with my new $5 dollar baby..it just keeps going and going. I suspect the difference is the concave increases the resistence as you drive farther in...
BG,
Where is this tag sale?
jk
Maybe I am wrong, but it seems to me you don't really want a superfine, razor sharp edge on a mortise chisel. If you are going to pound on the back end with a mallet, and then prise out big chunks, it would seem you'd want a thicker edge. Now a bench chisel is a different matter.
Frank
John K,
Every Sunday up in Rowley on Route 1A at Todds Farm.
This past Sunday, for the first time, they had some huge old wooden vises (3). ...the wood screws were about 3" thick..said they came from a ship building barn up in Maine...
Edited 9/22/2003 9:30:34 PM ET by BG
BG,
I've been to a few auctions there. Didn't know they had a regular gig.
Thanks
jk
JohnK,
Don't want to mislead you...there are about 4-6 tool only type vendors up there. Many vendors will have some tools but don't specialize in tools only. The point being it's kinda hit and miss....
BG,
Didn't think it was tools only, but thank you for the clarification.
jk
BG, I flicked through a book on sharpening about a month a go. The price/information equation wasn't quite within my pocket at the timw. From what I recall, the recommended angles for a mortice chisel was a 25 deg bevel with a 30 deg micro bevel. Over time, with hand sharpening and sloppy technique, this could easily appear as a convex surface. The physics of this arrangement would appear to be a sharp wedge to easily enter the timber with a "blunter" cutting edge to stand up to the pounding. Don't know if the recommended angles applied to all mortice cutting, only mortices in easily worked wood, or to mortices in hard to work woods.
Ian
Ian,
I've kinda gotten in the habit of using at least two chisels for mortices (and dovetails too). I do a light initial cut on the line with a sharp microbeveled hard chisel, the Japanese fit that description and purpose quite well. Using a true mortice chisel for the initial cuts is probably okay but I'm concerned that the shoulder line may be lost with hard hits and a strong angle. So I establish that shoulder with the japanese forst.
However, you don't want to pry with the Japanese very hard cause the tip is brittle. I have some old Stanley's for prying...but they are not long enough to get good leverage.
I think I'll leave off the microbevel initially and continue to use the Japanese chisel to do the cut in and clean up.
BG, Eddie is more experienced at this than I and hopefully will comment some more. However, my understanding is that a mortice chisel is deliberately muck thicker than it is wide to help you stay square in the mortice. In use you start about 1/8" in from one end of the mortice, with the bevel facing toward the waste, and chop straight down until "you encounter slight resistance" you then lever out the waste. This creates a pocket into which subsequent chips can move. You then reverse the chisel and start chopping toward the other end of the mortice, stopping just short of the end. The last 1/8" on each end of the mortice is only removed after you achieve the depth you require. Given that the mortice has been marked out to match the width of your chisel, I tend to think that swapping chisels for cutting different parts of the mortice would be more trouble than necessary. But hey, I don't earn a living at this.
Ian
Ian,
Using two chisels is a problem, especially, as in my case, they are of slightly different widths. That is one of the reasons I've been shoping for mortice chisels. I've cut a bunch of mortices using only the Japanese ...which is okay, but the shortness of the chisel is a problem....get a bo-bo on the palm of my hand. Also, the Japanese chisel I have is a bench chisel that is quite thick...however, the tip is brittle and can't be used for prying. So my current technique is to cut in the line and remove about a 1/16" of stock off the top, then I move in from the shoulder and chop, chop...using a Stanley to clean out the waste...and finally cleaning up the with the Japanese chisel to the line.
The technique that you suggest sounds a lot faster. I'm going to try it once I sharpen this puppy
I have been waiting for the LN's and trying to find a place I can see the Two Cherrie/Hirsch live around here. I don't really want to buy a set of chisels but rather one or two at a time...
BG
Know what you mean about wishing to see the tool in the flesh as it were. the following might help:I spent last Christmas's tool money buying a few Two Cherries from Dieter Schmid (Berlin, Germany). He had a set of 6 bench chisels (6 / 10 / 12 / 16 / 20 / 26 mm) on special for about 70 Euros, even with shipping it was under 100 Euros. Also purchased two mortice chisels from the 1306 series. The wooden handles on these are just NOT TOO big for my hands, I've got what I think of as average sized hands and if the handles were much fatter, the chisels would be hard to hold, which is not to say that I find them difficult to use, just that I would prefer a slightly smaller handle, say a diameter about 1/8 in smaller. Note this issue with handle size is only applicable to the mortice chisels, the handles on the bench chisels are fine. For comparision, my dad has a Two Cherries Mortice with the fibre covered beechwood handle - if anything I find its handle too small, requiring too tight a grip.
As for the Japanese chisel, several years ago I spoke to Japanwoodworker (may even have been Ted Dansen, sp?) about the brittle tip issue and was advised to increase the micro bevel to 35 deg.
Hope this helps
Ian
Ian,
It does help, thanks. I too saw that Two Cherry sale and almost jumped on it...except Santa brought me a TS...and I was focused on miter guages, tennon jigs, and blades....
Correct me if I'm wrong, but I think with chisels, there is a tendency to use the same ones over and over again. In some cases its because the work is the same dimension, etc. but in other situations the individual tends to pick the tool they are used to and feel confident with. Also, for the most part, as long as the sharpness holds for a reasonable amount of time, you get used to certain chisels and the rest just sit there. A set is good because you have a consistent look and feel with only the size changing.
If my presumption is correct, then to avoid filling up my tool holders with tools I don't use, I need to figure out what my needs will be and select appropriately from there. For instance, most of my mortices will be 1/4 or 3/8"...possibly 1/2" every once in a while. Doing dovetails the Two Cherry set would probably cover all my needs. I do like the feel of the Sorby for paring. I have not figured out where or when you use a 'firmer' chisel.
I have not figured out where or when you use a 'firmer' chisel.
BG, you really should start a new thread for this one !
I'd really like to see the responses.
Ian
Ian is EXACTLY RIGHT.
thank you
I'll provide an answer to your question in a round-a-bout way: the last thing you want to do when actually chopping a mortise is drive it too deeply on each pass. Doing so makes levering out the waste more difficult and almost guarantees bruised ends. I don't sweat it if the thing is not razor sharp. It doesn't have to be.
Boss,
I did put a new bevel on it and took it through the sharpening steps including stroping. Two hits with the mallet and the tip rolled a bit. Removed the burr and wnet back to work...its fine. So, your right, sharp enough! thanks
You hear a lot these days about edges rolling over - especially when it relates to newer chisels and supposed 'inferior steel' and overall inferior workmanship. I believe you have an older chisel whose steel should be less 'suspect' than newer chisels. However, I think the whole argument is academic bordering on silly. I chop perfectly fine mortises all the time with off-the-shelf, current production mortise chisels available from a range of suppliers. I submit that surgical sharpness never has been a necessary criteria to chop a mortise with a real mortise chisel. If your technique is to drive the chisel to half the finished depth on the first pass (bad technique) then you need a supersharp mortise chisel.
I'm not saying that I don't keep the edges in reasonably decent shape, I do. I am saying that I've done a lot of chopping in a day's work, without a lot of fretting at the stones during the day, and the last mortises cut were as good as the first. And they were all pretty damn good.
Rest easy, let your tools work for you instead of you working for your tools.
Edited 10/1/2003 1:21:08 PM ET by BossCrunk
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