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bound201

Question regarding laminated timber framing chisels

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I'm making some chisels for timber framing, that means the blade will be ~10 inches and the handle will be 8-9 inches. These will be ~1/4" thick with a slight taper to the edge ranging from 1.5-2.5" wide. I'm wanting to laminate/forge weld steel on the back to a mild steel face, it saves cash to keep the costs lower due to the overall size of these. 

 

Any suggestions for how thick the tool steel edge should be? I'm likely to use O1 but I'd like to make similar to a japanese style chisel with a slightly harder edge say closer to 60-62 range.

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How much forge welding have you done? You have a lot of specifications to meet if you're not proficient and by your questions I'm thinking this is a new venture. How long have you been making blades?

Seriously, a "slight taper?" Do you want the blade  widen or narrower toward the edge? OR are you referring to the edge bevel?

You don't tell us if these are push or struck chisels? Heck nor even the blade shape. What kind of handles and attachment method? All these things are interrelated and it's important to take the pertinent details into account. The type of edge steel is less important than the other factors so long as it's competent for the work. If you put a wood chisel bevel on an 01 edge hardened and tempered to rc 60-62 it's going to be fragile.

My best suggestion for you at this point is to read up on making wood chisels, pick up some leaf spring and practice before you take the big leap of welded bits. Spring steel is more forgiving in a number of ways, cost and heat treat. better still spring steel is and has been making top shelf wood tools for better than a century, probably a couple.

I made a set for a fellow a couple three decades ago, a: slick, gouge and a draw knife so he could build his dream log cabin. I hardly knew what I was doing but being what it is leaf spring cut me enough slack I was able to make working tools. They had, (have?) full width and length tangs so he could either push or strike them as he needed.

Save the welded bits till you don't need to ask us how and you'll be much more likely to succeed.

Frosty The Lucky.

 

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The historic examples I have were generally quite thin on the steeled edge; a nice commercially produced foot adze I own has a high C pad of about 1/8" thick forge welded to the back for steeling.

As 5160 is pretty much free from leaf springs I don't see the savings and do see the greater difficulty in producing them in the "It took me 8 hours to get one to work but I saved a dollar in materials, and spent several times the saving in extra fuel costs."

Now doing them to replicate earlier items using real wrought iron for the bodies and steeling the edges is a functional goal.  You will of course need the forge welding skills down pat before working on the chisels.

If you have access to any such tools in museums, collections or use you can usually see how thick the  layers were made by careful examination of them.

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There is a recent "woodwright's shop" where smaller chisels are forge welded.  There might be some snippets of advice and tricks to be found there http://www.pbs.org/video/2365386383/

If that link doesn't work, search on woodwright's shop episodes and look for one labeled "tempered steel"

Nothing fancy but a couple of morsels to be had.

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i gotta mention, that having forge welded a bit, I cant see this method saving any money.  Fuel would cost more than using a good 1095 or 5160. and I normally find welding easy and fast for me.

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Even as late as the American Civil War high carbon steel could cost 6 times the cost of plain wrought iron so it made sense back then.  Now I can wander through my scrap pile and I have more high C stuff than I can use in my lifetime and the reason I do it the old way at times is just because it's the old way or for ornamental reasons.

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12 hours ago, Frosty said:

I've forge welded more than a few items so welding isn't much of a concern. This is a chisel not a slick so it will be used with a mallet. Timber slicks are hand use only.

 

The blade would have two tapers, many old timber chisels have two tapers and could have a slight conical shape on top. Taper in width by about 4/100 from edge to heel to prevent jamming.

 

I am likely to do a socket for the handle though a full tang is easier to do. 

 

5160 would do ok I'm looking for more edge retention in these. I typically aim for 59 with my knives in most circumstances. I'm likely to use O1 in this situation for ease of heat treatment and availability but I'd like a harder edge in the range of 60-62. I've tested some older timber chisels and they fall in this range.

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I don't have much to say regarding making framing chisels, but I do use them every day, both new and old. 

 

The tool steel plate on my antique chisels are a little more than an 1/8" thick, probably more like 3/16" or a hair more and and roughly 3/4 the length of the blade. 1/4" sound to thin for the blade as well, maybe tapering down to 1/4" before the bevel at the cutting edge, you might also want to consider a central ridge so that the chisel blade has a nearly triangular cross section but roughly 1/8" at the edges, this makes it much easier to remove it when it's jammed.

I would also strongly recommend a socket handle, more time forging, but much easier to rehandle and much less likely to break the handle.

Just my 2 cents, let me know if you want me to take some pics and actual measurements.

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