Laminated Molding Plane Irons

A couple of months ago someone dropped off an old molding plane in my shop that was missing the iron and wedge. A plane missing its iron is like a book torn in half, so unsatisfying…

Lie-Nielsen happens to make tapered molding plane iron blanks from solid 0-1 steel that you can buy annealed and ready for profiling for not too much money, but how about making your own by forge laminating some tool steel? For anyone interested in Japanese tool blacksmithing forge welding is an important skill, one that I don’t really have ideal conditions to practice, having to set up my forge in the out of doors. But I’ll be damned if life just goes on and on without giving it a try.

For the main body of the iron I used 3/16 mild steel. Hollow and Round molding planes are generally made as matched sets, so it makes sense to make two irons at a time. Hence a way of cutting the steel to rough shape and pre-forged dimension with little waste.

I plunge cut the middle with an angle grinder and finished by hand with a hack saw. If you don’t have an angle grinder you could just leave a little extra room on the reigns of the iron and cut a slot wide enough to get the hacksaw blade in for the vertical cut.

The tool steel I used was forged down from an old file to about 1/8″ and tapered on the back end. Any less than that and I found that the tool steel in my lamination tended to become quite uneven. I tried so, so many times to get the tool steel to stick properly after fluxing with borax to the mild steel and stay in place while bringing up to welding heat in the forge. Its tricky, to say the least. Luckily I have a MIG welder so just tack welded a tiny spot in the back, brought up to fluxing heat, and separated the pieces enough to get some borax in there, then back in the fire for welding heat. The mating surfaces had previously been ground bright and clean.

Previously I had been dubious about my ability to get a good welding heat, its hard to judge outdoors, even with a big piece of plywood casting shade. Using hardwood charcoal I practiced forge welding mild steel back on itself, and found that yes, that shit gets hot enough to melt away and form little bloom nuggets around the tuyere. The key for me was making a (relative) large fire where I had clearer oxidation and carbonization zones. Judging when the steel is hot enough…still a matter of experience.

Three welding heats and two forging heats to get down to thickness and taper from 3/16″ at the cutting edge to a little less than 1/8″ at the back. Mild steel is much more forgiving of cold forging than tool steel, and the reigns of the iron draw out quite a bit. Get them as close to finished dimension as possible! The lamination I didn’t forge on edge, just squashed out like a pancake and cut, ground, and filed to shape.

The laminated part will warp a bit during quenching, and some of it will come out after tempering, depending on how hard you are going to leave the steel you might consider forging in a little bit of the opposite bend before quenching. A decent ura would help too, that might come later for me.

I like using old files for tool steel, you can find them really cheap in junk and antique shops. That said, now that I’ve met with some small portion of success forge welding I went ahead and bought a stock of 0-1 tool steel 2″ wide by 1/8″ so that I could practice with steel of consistent properties, and it saves a good bit of work and charcoal compared to forging files to the right shape and thickness for lamination.

I need this sign, my shop is a slow work zone.

Indeed it was a very slow work zone out on the road, nobody was there.

I like “Wooden Planes and How to Make Them” quite a bit, but you won’t know shit about how a proper side escapement plane is made by reading only that one book. Larry Williams DVD “Making Traditional Side Escapement Planes was great, and lists all the requisite molding plane iron dimensions for any give size of plane.

If I get the chance I’ll make some sen and the plane blade and knife for a Japanese dovetail plane I’ve wanted to put together ever since trying one out at Mark’s. Easy sliding dovetails in my future!

3 thoughts on “Laminated Molding Plane Irons”

  1. Nicely done! Amazing what you can accomplish, given the will and desire. A pile of bricks, a couple of handfuls of homemade charcoal and your awesome fuigo…..

    Forge welding is fun and a surprisingly practical means of constructing cutting tools, especially given the constraints of using such a modest forge setup. And it’s cool! A trick you see in some of the Japanese blacksmith videos is to add a sprinkle of iron shavings onto the fluxed iron, then lay on the steel. Initially, the iron filings give traction to the steel which otherwise wants to skate around and fall into the fire, then when you are getting up to welding temps, the small size of the filings allows them fuse at a lower temperature and give a quicker grab to the tack weld. I’ve done this a handful of times. It works, but I suspect it contributes to a slight decarburization right at the weld line, visible as a faint blurring at the boundary that is aestheticly unsightly. Next chance I get, I plan to try using cast-iron shavings instead, see how that works out.

    I’ve been using a roughly 50/50 mix of Borax and roach powder (99% Boric Acid) as a flux. The two melt at slightly different temps, giving a broader window of protection against oxidation. Some of the old texts discourage the use of Boric acid in the flux mix when joining high carbon steel to low carbon iron, claiming it tends toward de-carb but I’m not sure. More references recommend the two, so…. I just got some Ammonium Chloride to add to the mix (called Sal ammoniac in the old books) but haven’t tried it yet. I also got an old hydraulic hammer bit to use as a post anvil….450 lbs of iron moving goodness, a welcome supplement to my little 86 lb farrier anvil. Overkill?

  2. While I look forward to whatever you write about your experiences with planemaking, I do want to suggest that a dovetail plane is not strictly necessary for making sliding dovetails. I used to think the same way so this is a bit of a confessional and my own declaration to commit to posting about the process on my own weblog in time.
    I found that putting the taper in the female side of the joint is simply a matter of using a angled wood block as a guide. For the male (tenon) side of the joint, a shoulder plane with corresponding guide block is a very adequate solution; on end grain, another guide block supports a paring chisel that slices into a stop cut. Shims under the guide block can allow for a taper sliding dovetail joint.
    I’ve thought about the LN molding plane blanks but have not bought any due to concerns about properly tempering them after shaping. Any advice on how to do so while using a minimal amount of hardware will be appreciated.

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