make - forge? - wedge for feathers-and-wedge rock-split Featured

How would you go about producting wedges about 2mm to 3mm thinner than the current ones?

------------------------------------------- The wedges in my 1/2" set are 0.50" thick at the large end. When a set is placed in a half inch drill gage hole the wedge freely enters about 1/4 its length.

Without annealing them 2-3mm isn't an outrageous amount to grind off, relative to the alternatives. With annealing it's easy on a milling machine (again), and they are small enough to reharden without a proper forge. Mine from T&H mushroom slightly with use, they definitely aren't brittle hard.

Do you plan to make or buy them? They should be a fairly easy shape to forge from round stock which is more available than bar in higher carbon grades. I made my first wedges from mild steel which doesn't hold up well, they do need to be hardened. Wedges can be bandsawn from plate by shifting the guide fence to half the angle and flipping the stock after each cut. The difficult part may be finding hardenable steel bar stock in a small, inexpensive quantity. Perhaps the worn cutting edge from a road plow or bucket loader?

I took a night class in blacksmithing to gain access to instruction, a larger anvil and a better forge than my woodstove, which isn't really hot enough. I have the parts for a forge but not a safe place to use it.

I'd probably use O1 ground flat stock, but only because it is readily available. Can be cut on a bandsaw in as-it-arrives condition. Not cheap, but you can sometimes find a deal.

Slowly heat to red-orange, soak for 15 minutes. Quench in hot oil, then immediately temper well, don't let it cool from hot oil temperature: you don't want it too hard - maybe an hour or two at 250 C. You'll still be around 60 Rockwell C.

Not sure if you can spring temper O1. I wouldn't try it here.

That old favourite EN24T might work too, but it is hard to find except in round bar.

It's great for hard stuff like knives or screwdrivers: but if you need impact resistance you have to temper it so much it gets soft; or at least that's my limited experience, ymmv. I know some people have used it for punches.

Another problem is, again, it's only really available in round bar.

Peter Fairbrother

What about S7 steel:

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Or 1045 steel:

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Or 4340 steel:

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Joe Gwinn

The question:

How would you go about producting wedges about 2mm to 3mm thinner than the current ones?

Doing something to the current wedges would be okay.

Making them anew with something like forging could be a good project. If so what steel would you use? AISI1075? (C-Mn; 0.75%C). If so - "spring-temper"?

We have something called "silver steel" which is "(centreless-?) ground

Always appreciated the range of knowledge here.

Regards, Rich Smith

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All good choices.

Ah yes the wonderful McMaster-Carr. Unfortunately they only sell to VAT-registered businesses in the UK, and shipping starts at about $300 (ouch!!).

You can get 4340 and S7 in the UK, but I don't know where you could get suitable flats to make wedges in reasonable small quantities.

EN9 would do better (quench-hardens, unlike EN8), but again I don't know where to buy suitable flats.

Anyone?

The only reason I suggested O1 ground flat stock is because it is readily available in the UK, eg on ebay, in small quantities. And it's suitably strong and hard, it's obviously flat not round bar, and can be had in the right size for about £40 for 500mm delivered. Not cheap, but I don't know where to do better, especially if you include carriage. There are occasional bargains to be had too.

Actually, I'd buy wedges rather than make them, but ymmv.

Peter Fairbrother

Making them anew with something like forging could be a good project.

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I'm only a novice blacksmith. Much of my practice was in drawing out a round bar into a long tapered one of square cross section. The idea is to compress the whole width of the bar under the hammer, since flattening a solid round section applies internal tension to areas protruding outside the hammer strike that can open voids. If desired it can be rounded after tapering.

As thinning an area widens as well as lengthening it, the thickness had to be reduced gradually and evenly on all sides, keeping a square cross section and immediately correcting bending, twisting and the tendency to become a rhombus. For me lengthening with a cross peen hammer caused more trouble than it was worth.

The height of the anvil top affects how squarely you can consistently hit. My anvil is too light for serious forging which I can't and don't need to do anyway so I raised it to a more convenient bench height for less strenuous work on sheet metal etc. It cured the temptation to hammer on the milling machine table.

For a wedge my guess, based on pre-curving a single edged froe blade to end up straight, is that the blank might have to be started with a square taper before converting to a parallel sided wedge. Undoubtedly a real smith could tell you more. Modeling clay is said to be good to practice with.

The wedge can be cut/broken from the bar by notching it all around on a chisel standing upright in the square (Hardy) hole. The instructor was amazed at how square and even the tenon on my attempt was, until I told him I had used my milling machine. They have an ethic of using only traditional methods, which is fine for artistic work but not the machine parts I wanted.

It was remarkable how many shapes the smith could form with only a hammer and anvil. I didn't progress past drawing out a taper, stepping down a shoulder and bending over the horn. My efforts at twisting can't be called progress, or art.

----------------------------------------- Their cost suggests Black Forest elves make them by hand. We're spoiled by the economy of mass production, of items whose sales volume justifies it. Custom hand work is still expensive to buy, or to obtain the equipment to make. I justified mine because it let me control all of a project at work.

I bought my wedges and shims after trying to make them, mostly because the shims/feathers are a difficult shape to hold while machining.

Eek!

We're spoiled

Are the insides of the feathers straight?

Hmm, a clamp couple of feet of 1/2" round bar in a good pipe vice, use a thickish slitting saw on t'mill, cut off when you have them long enough, reclamp, rinse and repeat..

noisy though :)

Peter Fairbrother

Round bars only.

Hmmm, £40 for 80x12x500mm seems not that bad..

Peter Fairbrother

Ouch for sure.

Well, I don't know UK markets, but I would expect that there are European makers of these steels by one name or another. And they may have an even better answer.

As Jim W says, hot forging is probably the better way to make these feathers. I think that most of the other alloys can be forged and maybe forge welded as well, but didn't really dig into it. Maybe the solution is to choose and bring alloy steel rod to a local blacksmith.

Joe Gwinn

I've got some 6mm EN8 plate that I could part with some bits of. I've had items profiled out of it so some sections aren't much use for much else and would easily make the wedges I expect.

Are the insides of the feathers straight?

Hmm, a clamp couple of feet of 1/2" round bar in a good pipe vice, use a thickish slitting saw on t'mill, cut off when you have them long enough, reclamp, rinse and repeat..

noisy though :)

Peter Fairbrother

-------------------------------- No, they are tapered to match their side of the wedge, and the end that protrudes from the hole is quite thin. I think chatter would be a problem unless they were supported near the cut, and extended plus lowered in steps as it proceeds. Or they could be slit from mild steel rod stock in a jig that supports them at the angle.

They need to apply pressure evenly over their length, else the rock will just chip off at the hole mouth.

OK, a bandsaw then shaping in a fixture on the mill then.

Matey next door says they can be made so that either the bottom is slightly thicker than a simple wedge, or the wedge is thinned at the top, so that the maximum pressure is at the bottom. I don't know whether that is necessary, trowandholden don't seem to do it, some others do.

I was watching a video about Hilti capping rock, seems easy enough, if a little energetic.

You don't need a license to buy Hilti cartridges in the UK, though maybe you shouldn't if you have a criminal record.

Peter Fairbrother

It occurs to me that there is a standard way to hold such awkward items for machining: embed it in solid epoxy, which is later burned off.

Or, soft-solder the workpiece to a larger bit of mild steel. When complete, unsolder and shake the excess off - the remaining solder will lubricate things.

Do we have any idea what kind of steel they use?

Joe Gwinn

These aren't that expensive via Amazon:

Do we have any idea what kind of steel they use? Joe Gwinn

---------------------------- The feathers are soft and flexible, the wedge harder, such that it puts scrape marks on the feathers but not vice versa. The wedge heads have become slightly mushroomed. The feathers are all warped from use, I'd have to carefully straighten some to reconstruct the original geometry.

The feathers for the 5x 1/2" set and the single 3/4" were all made from 3/8" round rod. The large end is a half circle. I chose 1/2" after finding several new 1/2" spline drive bits from an auction in a second hand tool store (that's closing).

I suppose the feathers could be cut freehand endwise on an upright bandsaw if the stock was tightly clamped in an inverted toolmakers vise to keep it from twisting when the blade was off center, then beltsanded to smooth ridges. I bandsawed some oak slab scrap into a batch of wedges freehand to pencil lines that came out straight and smooth enough for the carpenter neighbor to think I bought them until sunshine revealed the saw marks.

The feathers for the 5x 1/2" set and the single 3/4" were all made from 3/8" round rod. The large end is a half circle. I chose 1/2" after finding several new 1/2" spline drive bits from an auction in a second hand tool store (that's closing).

I suppose the feathers could be cut freehand endwise on an upright bandsaw if the stock was tightly clamped in an inverted toolmakers vise to keep it from twisting when the blade was off center, then beltsanded to smooth ridges.

--------------------------------------- On closer examination they appear to have been diagonally split lengthwise with a horizontal bandsaw, the scratches slightly angled too, leaving the large end about 1/4" thick, plus or minus several hairs.

I think a horizontal bandsaw plus a drill press could make this fixture:

Perhaps two short end blocks drilled 11/32" through and 3/8 part way, to axially clamp the 3/8" OD blank. The space between them allows inserting and removing the part. The bandsaw cuts its own slot. The shutoff tab is extended to stop the saw before it slices the fixture base, thus the slightly angled kerf marks. The base might be tilted closer to the blade angle. Turn the vise to the diagonal angle.

Initial setup centers the blade over the middle of the blank, afterwards lower the blade into the slot before tightening the vise.

To simplify machining the moving end clamp block could be on a pivot arm instead of a slot, which also moves the toggle clamp away from the blade. An eccentric pivot bushing would permit small angular error correction.

If one can solder the wedge to something solid, all manner of machining operations become easy.

Use eutectic tin-lead solder for lowest melting point.

Or just forge them. My bet is that the commercial wedges are made of

Probably in Roman times, they were made of wrought iron.

Joe Gwinn

Probably in Roman times, they were made of wrought iron.

Joe Gwinn

-------------------------------------- Or bronze, the Romans were masters of it.

Holtzapffel Book II, Chapter XXVI describes the history of laying out and forming threads by simple methods before the modern screw-cutting lathe was introduced. I have an old die stock with grooves for gradually pressing threads into a rod by tightening the two halves together that appear to have been cut with a chisel.

A great advance was a lathe with a sliding spindle with several thread pitches cut on it, so it would advance the work past a stationary cutter at the pitch selected by lowering a follower into one of the spindle threads.