Tapered moulding plane irons

creasman

Board of Directors, Development Director
Jim
Staff member
Corporate Member
I'm making a set of snipe bill moulding planes. For the irons I figured I had three choices: order blanks from some place like Lie-Nielsen, recycle a set of irons from other planes, or make my own. I decided on the latter using O1 tool steel. The shape of these irons is nothing special, but they do need to be tapered in order to work right. I have a couple of other moulding planes where the irons are not tapered. These are a real pain to adjust and remove the irons.

First task was to cut the irons to shape. In my case I was able to cut both from an 8" section of 1/8" x 1" O1 bar stock. The flag on each is 2" x 11/16" and the tang is 6" x 3/16". Total length is 8". Here I have the two marked out in the layout fluid and have started sawing the first tang. The center (unused) rectangle requires a bit of drilling and filing to remove.

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And these are the two blanks after a bit of filing to smooth the saw cuts.

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At this point they are still 1/8" thick from end to end. The goal is to taper these from 1/8" at the bit down to 1/16" at the end of the tang. It needs to be a continuous taper, meaning that both sides should end up straight and true.

I'm sure there are a dozen ways to attack this, depending on the equipment you have. I have files and a spindle sander so that's what I used. I began the process by filing a series of reference notches every two inches and checked these with a dial caliper. The first is at the tang end where the thickness should be 1/16". Two inches from this the thickness is 5/64", two inches more it's 3/32" and then just above the flag it is 7/64".

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With these as reference marks I used a coarse file to take away the metal in between. At that point most of the material is removed. The remaining work is to smooth the entire length so the taper decreases evenly and continuously from 1/8" down to 1/16", something that would be difficult to do with files.

I switched over to a jig I made for the spindle sander. It's a simple fence with a fine adjustment knob that allows me to dial in a precise thickness. The key, however, is the holder for the iron. If I simply pushed the iron through it would sand it to a uniform thickness. Instead, I made a holder from a scrap of plywood that has the proper taper. The iron is held in his block of wood using some rare earth magnets. A few passes through leaves a smooth surface and perfect taper.

Note, the cavity is about 3/32" deep at all points. The back of the holder block is planed to be 1/16" less at one end (slightly more actually since it's longer than the iron). You can see the taper forming as the only remaining layout fluid is near the bit, and is fading as you move away from this end.

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This is the jig I used with the spindle sander. As you loosen the knob a spring pushes the fence towards the spindle.

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The final step is to use a #400 diamond stone to smooth and polish the sanded side of the iron. After that they are ready to shape. Next picture is of one fully tapered and the other ready for the rough filing.

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I have the irons shaped to match their respective profiles. Next step is to harden and temper them before the final sharpening.

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Hmerkle

Hank
Corporate Member
@creasman You said "The shape of these irons is nothing special, but they do need to be tapered in order to work right. I have a couple of other moulding planes where the irons are not tapered. These are a real pain to adjust and remove the irons. "
Since the wedge is tapered, why does it matter if the iron is tapered?
Why are the flat irons a pain to adjust?
Or
Why is a tapered Iron easier to adjust than a flat iron?
 

creasman

Board of Directors, Development Director
Jim
Staff member
Corporate Member
Why are the flat irons a pain to adjust?
Or
Why is a tapered Iron easier to adjust than a flat iron?

Sometimes adjusting the iron means removing it and starting over. This requires releasing the wedge. With tapered irons this is as easy as tapping the iron forward (i.e., through the mouth). Because of the taper this action frees the wedge. For irons that aren't tapered this doesn't really help. In fact you might even tighten it slightly by doing so.

There are other ways of removing the wedge such as whacking the front top of the plane on the workbench, or tapping the wedge. You can also back the wedge up slightly by the first method. However, these risk damaging the plane.
 

Robert LaPlaca

Robert
User
Hank, with a tapered iron, if the wedge has a ‘death grip‘ on the iron, all one needs to do is tap the iron down from the tang, the tapering of the iron will release the death grip the wedge has.
 

David Turner

David
Corporate Member
I respect all those above that have expressed their opinions and experience but I must say poppycock !
I have 10 pairs of hollows and rounds and numerious othe side escapement planes that I have built that have 1/8" 01 flat steel blades/irons. None of them are hard to adjust or take apart.

There are at least two experts in the side escapement plane building that say there is no need for tapered blades/irons. They are Tod Herrli of Mississinewa Plane Co. as depicted in his "Classic Plane Making" DVD and John M. Whelan in his book "Making Traditional Wooden Planes"
 

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