Making A Socket Firmer Chisel

[Preston Baxter]

Some folks were interested in seeing the details of how I made my mortise chisels. I made a 3/8" firmer chisel yesterday and took some photos along the way to show the process.

The round blank is chucked in the lathe and the socket is turned to a taper using the compound slide set to 5 deg.
This lathe is not really well suited to turn tool steel. It lacks the rigidity to make all but light cuts. I'm eventually going to install a compound slide on my Hardinge Mill so it will be able to quickly do this task instead.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab1.jpeg

Here the shoulder being roughed out:
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab2.jpeg

Here is the completed socket after polishing:
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab3.jpeg


The part is now being supported by a steady rest, and the socket hole is being drilled out to the root size using the tailstock:
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab4.jpeg


After drilling, I switch to a boring tool mounted on the compound slide which is set to 5 deg. This pic was taken after taking the final finishing cut:
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab6.jpeg


Here is the part with all the lathe work done. The small round shoulder was turned to the proper diameter to give me a reference check point during the milling process.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab8.jpeg

Since messages are limited to 15 images, I'll add rest in a separate post.

[Preston Baxter]

The part is now clamped in a vice in the mill. There is a spacer under the part to give support.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab9.jpeg

The first side has been milled with a couple of roughing passes and a final finishing pass. This nearly 60 year old machine can really hog off metal.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab10.jpeg

The second side is complete.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab11.jpeg

The third side is done, it's starting to look like a chisel.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab12.jpeg

Next, I layout the taper for the face side of the chisel:
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab13.jpeg

Milling the final, face side.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab14.jpeg

The part straight off the mill:
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab15.jpeg



The tip is then hardened with a MAPP torch and peanut oil. The dark color on the first third of the blade shows the extent of hardening. From here, the chisel will be tempered in the kitchen oven for thirty minutes at 350 deg.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab16.jpeg

After tempering, the chisel is flattened on a cast iron lapping plate. Here I am charging the plate with 120 grit compound. It just takes a little. Too much, and the part just slides around without the grit embedding in the plate once lapping commences.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab17.jpeg

The plate will start to get sticky as the steel residue mixes with the grease. Just wipe the plate off with a little Kerosene or Mineral Spirits and continue lapping until the grit breaks down, then recharge. I keep meaning to try just some plain dry grit and Mineral spirits since the compound has a bad sulfur smell. After lapping all faces, I finish up on oilstones.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab18.jpeg

I turn and fit the handles pin to the socket first, then complete the handle:
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab19.jpeg


Here is the finished chisel. It works beautifully.
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab20.jpeg

http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab21.jpeg

Here it is beside its big brothers:
http://personal.bellsouth.net/p/s/psbax/ww/firmer_fab/pb_firmer_fab22.jpeg

[george wilson]

That's a lot of work! I'm surprised that that 6" lathe will cut the steel. I started out with a 12" Atlas,and it was a pain to get anywhere with. I couldn't take off more than 1/32" at a pass!

[Jim Koepke]

Thanks for showing this.

I wish I had taken metal shop when I was in school. This makes it look easy enough that maybe I could book learn if I had the machines.

Sure is an interesting subject for the neanderthal galoot.

jim

[harry strasil]

I took metal shop while going to school even tho the school didn't have a metal shop, I was still an apprentice blacksmith under my father and uncle. LOL

[Preston Baxter]

I would like to learn some basic blacksmithing skills someday. It would come in handy for projects like this. In this case, I could start out with a much smaller bar and upset the socket end to the larger diameter and have a less machining and metal waste.

[harry strasil]

the old method was to upset a bit, then flare out the end and form it into a socket then forge weld the seam, lots of old chisels you can see the seam inside the socket. Also the socket and chisel were made as seperate pieces and then forge welded together. Tang are much easier to make so there were a lot of them in the real early days.

I have used ordinary black pipe to replace broken off or really mutilated sockets by first swaging out one end, then fullering down the other end and welding to the old blade socket stub.

[harry strasil]

FWIW, Preston Upsetting is one of the harder things for most Smiths to do, as they tend to get too much of the end hot and then all the hot end wants to do is bend over when they hit it. I have made what I call an Upset Helper that makes the task much easier. Its just a 2 inch square piece of hot rolled with gradually larger holes drilled in it and a square shank that fits into the Hardy Hole of the anvil. To use you install the upset helper and then heat only about 1 inch of the end of the piece you want to upset and drop it into the hole as quick as you can and start striking the top end while holding with a pair of tongs, it will want to bend over but the hole restricts it to only so much bending, you then take it out straighten up the end and then you reheat and drop in a larger hole, they progress by 1/8 inch larger and do it again. It works rather well, just remember to only heat the very end of the piece.

http://img.photobucket.com/albums/v81/irnsrgn/smithing/upset001.jpg

[Keith Christopher]

SIGN ME UP FOR A SET ! Thanks for the play by play. I loved it. It is funny with the flash and all they almost look like copper. :)


Keith

[Jonathan McCullough]

Fantastic work. Two questions: what kind of tool steel are you using? And how were you able to get the taper on the lathe? Did you just set the compound on an angle and advance the compound instead of the carriage?

[george wilson]

He said 01 somewhere else.

[harry strasil]

Angled Compound = Independently Poor Machinists Taper Attachment.

[James Taglienti]

That was really cool.

[Roy Wall]

Preston --

Sensational Thread......Awesome work.

Those are beautiful chisels - thanks for sharing your talent!

[Jim Koepke]

Harry,

With your upset helper, could you then have a similar helper only with a cone inside to start the formation of the socket?

jim

[harry strasil]

My Cone Tool, made from a piece of angle iron with a Hardy Shank.

http://img.photobucket.com/albums/v81/irnsrgn/smithing/conejig003.jpg

http://img.photobucket.com/albums/v81/irnsrgn/smithing/conejig006.jpg

http://img.photobucket.com/albums/v81/irnsrgn/smithing/conejig008.jpg

[Matt Radtke]

Some folks were interested in seeing the details of how I made my mortise chisels. I made a 3/8" firmer chisel yesterday and took some photos along the way to show the process.

I don't suppose if we ask extra-special nice, you'd be able to give us some exact dimensions? Like how thick the socket is, what scale you use between chisel size and handle/socket size and turned shoulder size to chisel size.

[Preston Baxter]

I don't suppose if we ask extra-special nice, you'd be able to give us some exact dimensions? Like how thick the socket is, what scale you use between chisel size and handle/socket size and turned shoulder size to chisel size.
.

The initial Mortise Chisel socket dimensions were based on the socket of an old Ohio tool 1-1/2" framing chisel. It had a 6 deg taper (12 deg included angle) and .1" wall thickness. Try to look at all the old chisels you can. Take what aspects you like, make some sketches of the top and side profiles, and adjust to suit your needs.


These are probably by no means the optimal dimensions for a mortise chisel, it was just an approximate formula I came up with for a first pass design. Some manufactures made all their socket and handle sizes the same throughout a set. I prefer graduated sizes because they look more balanced and feel more balanced in use.

For my 1/4", 3/8", and 1/2" width mortise chisels, I used socket top diameters of 5/8", 3/4", and 7/8" respectively. Wall thickness is 0.1" on the two larger ones, and is about 0.070" on the smaller one to accommodate a little more wood in the socket. The 5/8" socket on the 1/4" chisel may be too small depending on how hard you intend to pound or pry on it. My chisels will be used for light work in cabinetmaking so it works for me.

Blade thickness is socket top diameter - 1/16".

The diameter of the small end of the taper (and small end of rounded shoulder) is equal to: socket top diameter - 13/32"

The diameter of the large end of the rounded shoulder is = sqrt( T^2 + W^2 ) where T is blade thickness and W is blade width. This is just basic Pythagorean theorem to find the cylindrical diameter needed to accommodate any given rectangle or square.

The handle sizes were just what looked right and what I could get off the lathe. I'm still new to woodturning, but I am getting better with practice at hitting the shape I intended. After making the 1/4" mortise chisel, I found that the 3/8" mortise chisel handle looked like it should be a little larger to match the set. It also feels a little small in use. The 1/2" and 1/4" handles feel fine.


I came across three old bench socket chisels after making the mortise chisels and found their socket angles were all 5 deg. (10 deg included), so I decided to try this angle with my bench firmer chisel. The handle seems to wedge in tighter, and the shallower taper makes the socket longer for a more elegant look.

I haven't yet decided what would be the optimal dimensions and socket sizes for a full 1/4"-1" set of bench chisels. I do know that the sockets will probably go from 5/8" to 3/4." 5/8" is about as small as you can go and not have a weak point at wooden peg of the handle. 3/4" is as large a socket size I would want for a 1" bench chisel.

The 3/8 chisel I made was a prototype to check the proportions. The socket top is about 5/8" and the neck is 5/16". However, I think I will re-formulate my preliminary set of dimensions to make the neck a little smaller and blade thinner.

[Matt Radtke]

So I threw together a quick CAD drawing to make sure I understand your dimensions right. Based on your 3/8" firmer, does seem about right? Anything you would change/improve on?

[Preston Baxter]

Matt,

I made the angle of my socket 5 degrees based on old bench chisels I have. If you decrease the angle to much, it could cause the handle to expand the socket. The 4.6 degrees you have shown is close enough and should be fine.

The dimensions are not critical other than how they affect the length of the socket and how the blade meets the socket. I try to keep the angle fixed and adjust the socket top and bottom diameters to keep all the socket lengths approximately the same for all chisels in the set.

I didn't have the 3/8 chisel in front of me yesterday so I was off a little on the bottom dimension. The socket bottom on my firmer chisel is 0.3" and the blade thickness if 5/16". The next chisel I make in this size range will have will have a smaller socket bottom to accommodate a thinner blade. My firmer chisel turned out a little too firm, more like a sash mortise chisel.

Your bottom shoulder diameter of 25/64 is too small for a 3/8" chisel unless you intend on the blade thickness being .109" at the top.
If the blade is any thinner than the bottom of the socket, then you have to cut into the socket to make it work.

To keep the blade below the socket, the blade thickness has to be at least as thick as the socket bottom. So, if your bottom of socket is 5/16 and your blade will be 3/8" wide, then the shoulder diameter would need to be a minimum of sqrt(5/16^2 + 3/8^2) = .488" to keep out of the socket. However, some chisels were designed to leave the socket bottom thicker and mill up into the socket. Especially with narrow 1/8" chisels. This can make the chisel stronger if the socket bottom is sized large enough to increase the effective area of the blade/socket junction. I attached an image that shows different methods.

Its best to make both side and top view drawings of the chisel complete with the blade to make sure everything lines up correctly. Otherwise, there my be surprises when going from the lathe to the mill. I would also add to the drawings, dotted lines around the blade showing the cylindrical waste material of the round blank before being milled.

[Matt Radtke]

Your bottom shoulder diameter of 25/64 is too small for a 3/8" chisel unless you intend on the blade thickness being .109" at the top.
If the blade is any thinner than the bottom of the socket, then you have to cut into the socket to make it work.


Heh, you're right. Dunno where that number came from. I checked my hand written notes and that's what I started doing, but clearly my answer was wrong.

Sorry for all the questions, but I'm pretty sure I have access to everything I need to take a crack at this.

-Matt

[Kenneth Hakansson]

wow that's impressive works, I wish I could make chisels like that :)

//Ken

[David Weaver]

I can't believe i missed this..

Would there be any benefit to heating and hammering the blank after the chisel was formed in order to forge it? Would the chisel be tougher after milling it?

I was reading someone's advertising spiel a couple of days ago (for turning tools) about still making forged tools instead of the milled turning tools most people make.

Or am I completely off and is there something mechanical is done to the bar and round stock already (before it's ground and sold) that makes that a wasted effort?

[george wilson]

I have made carving tools by forging them. If you hammer the tool steel until it is below red heat,it is called "packing",and compresses the steel down. you can release the packing effect by heating the tool up red hot,and sharply striking the end of the tang.

Otherwise,you can go ahead and heat treat the steel,retaining the benefits of packing.

Maybe Harry has a different name for this process. I learned it from an old text which I have given away to an aspiring younger blacksmith.

[David Weaver]

I have made carving tools by forging them. If you hammer the tool steel until it is below red heat,it is called "packing",and compresses the steel down. you can release the packing effect by heating the tool up red hot,and sharply striking the end of the tang.

Otherwise,you can go ahead and heat treat the steel,retaining the benefits of packing.

Maybe Harry has a different name for this process. I learned it from an old text which I have given away to an aspiring younger blacksmith.

That's exactly what I'm referring to, but I am armed only with one materials science general elective from college, and no idea what happens to the bar stock in the real world before it's on my doorstep.

I've heard the packing term before, which I'd assume is the same thing as compressing the grain structure?

[george wilson]

You are correct,David. There is also pack hardening,which is the same as case hardening. You pack the object into a crucible full of carbonaceous material,and lute the lid on.

I haven't thought about these things for a long time,and could be a bit off on definitions.

[John Toigo]

Good tip Harry - I'm going to make an Upset Helper for me.