Sometimes Things Work Out

W.M. Ash Plow Irons

So I recently purchased a matching set of plow plane irons made by W.M. Ash. The idea was to either make a new wedge for my existing plow plane, or perhaps get crazy and make a whole new plow plane. There isn’t anything wrong with my current plow plane (except for a stripped depth stop screw), but I only have a 1/4″ iron for it.

Plow plane irons can be kind of funny though. Because of their shape, the plane and wedge are typically made with a matched set of irons. Irons from another plane may not necessarily fit because of differences in tapers. Of course one can compromise by making different wedges for each iron if you have a mixed bag of makers with different tapers, but I didn’t want the hassle. I wanted a matched set of irons.

So I got them today, and just for giggles, I pulled the current 1/4″ iron out of my plow plane. Guess what? The iron that came with the plane is a W.M. Ash iron with an identical taper. I tried all of the “new” W.M. Ash irons in the plane (made by Bensen & Crannell) and they are a perfect fit. So there won’t be any need to make a new plane or a new wedge. Perhaps I’ll just carve a new depth stop screw (and perhaps I won’t since I have grown used to just planing to a scribe line anyway). So now I have two 1/4″ W.M. Ash plow irons.

It doesn’t happen often, but it’s nice to catch a break once in awhile.


11 thoughts on “Sometimes Things Work Out

  1. Bob nice catch and I am sure very much welcomed. I am learning and getting into Wooden Planes myself which I am becoming very fond of. One thing I am not well versed on well actually 2 things, different set of irons and wedges if needed. How does one determine which or whose irons will work and the same issue with wedges. I am not sure on how to make or fit a different wedge and irons.

    I enjoy your blog and pod casts very much.


    • Thanks Steve! In a wooden plow plane, the iron has a significant taper. Because the mortise is also tapered, the taper of the iron and the taper of the wedge have to match and add up to the angle of the mortise taper or the wedge will not hold the iron securely. If you have a plow plane where the wedge will not hold the iron securely, it is likely that either the wedge is not original, or, more likely, that the iron is not original to that plane. It is possible to find other irons that will fit a plane well. But if they don’t, it’s possible to make them work by making a new wedge at a different angle. One just needs to make the angle of the wedge and the angle of the iron add up to the angle of the mortise.

  2. You could make an old woman’s tooth plane with it…. Lot of chatter about OWTs on the Oldtools list this past week.

    • That’s a really good idea actually. Thanks! I hand’t thought of that, but I do need/want one. Now to find a suitable chunk of beech.

  3. Bob- I’ve been playing with a plow plane lately and have trouble keeping the iron straight; it wants to wander towards either side of the plane body. Should it be aligned with the edge of the skate, or to one side? No matter how tight I drive the wedge, it still wanders… perhaps its just a bunk unit?

    Also, I have a spare OWT which is missing the iron. Email me if you are interested (yours for the cost of shipping).

    • Hi Bob, I too have just renovated a wooden plough plane (GOAD of London) . In response to RC’s trouble with keeping the cutting iron straight – the iron has a groove along the back of the cutter (the bevel side), this groove needs to mate exactly with the rear metal skate. It may be that the cutting iron does not have a groove, in which case it will float to one side or the other, or the wedge is not fitting correctly. One solution is to fit a cutting iron with a groove in the back and to run test cut and note the difference. The solution to an incorrect fitting wedge it to cut a new wedge. Measure the angles of the throat, which are likely to be 50 degrees on the back and 60 degrees on the front. Cut the wedge to a little over 10 degrees and gradually reduce the angle for a snug fit alog the length of the wedge top abd bottom.
      The GOAD plow had the wrong wedge fitted and no fence slide keys when I bought it, the wedge was skewed and only about a 1/4″ thick fitted into the 5/8″ throat, which I guess was taken from a Dado plane. It works fine now with new fence slide keys and a 5/8″ wedge tuned to fit with a sharp chisel.

    • Rob,
      There are several possibilities, but most likely, either the iron is wrong for the plane, or the wedge isn’t holding the iron securely. As Maurice said above (thanks Maurice!), there should be a groove filed down the back of the iron that should mate exactly with a double bevel filed on the front of the skate. If the groove doesn’t match the skate, the iron will not seat on the skate’s bevel. The groove should be centered down the length on the iron’s bevel side, centering the iron on the skate.

      The other possibility is an improper wedge. If the iron seats well on the skate without the wedge in place, but you can easily move the iron with the wedge installed, then either the iron or the wedge (or both) are not correct for the plane. If there is good wedging pressure at the top, but not at the bottom of the wedge mortise (caused by non mating angles), then the wedge could be pivoting the iron up off the skate, allowing it to move side to side, even though it feels like it is wedged well. You’ll need to check carefully if the iron lifts away from the skate when you wedge it up. Fit the iron first, and make sure it mates well with the skate. Then insert the wedge while observing what is happening where the iron and skate meet. If the iron lifts, even just a hair, when the wedge is fitted, then the iron angle and the wedge angle are not mating up well. Squeeze the iron and skate together after fitting the wedge. Does it feel like the iron flexes toward the skate, or does everything feel solid? If the iron moves at all, You will either need to find an iron that fits correctly, or you can try making a new wedge at the correct angle and see if that helps. But it will only help if the iron mates well with the skate without any wedging pressure at all.

      It is also possible that the wedge mortise has a hump in the middle of the bed. This is unlikely, but something worth checking anyway. If there is a high spot in the bed, use a fine file or paring chisel to work it down so the bed is flat, or ever so slightly hollow in the middle.

  4. Glad they worked for you, sorry it took so long to ship them. I notice when I packed them I called them MASH not WM ASH. I have always found handled plow planes to be easier to use, And I got better results from them. I found that the way I hold an unhandled plane allows me to roll my wrist a little. The handled ones I find easier to hold upright. But it’s probably just me.

    As far as matching the blades you can take a mis-matched set of iron to a machine shop and have them surface ground to the same angle. They can also put a new groove in the center. Or as mentioned you can make a wedge for each iron.

    The blades are traditionaly stored in a felt or leather roll this helps keep rust off them, keeps them together, and keeps them blade tips from hitting each other.

    • Thanks Tim! Shipping time was not unreasonable, no worries. I find keeping the plane vertical is easier when I balance the pressure more between my two hands. If I just try to push mostly with my right hand on the back of the plane, it can be tough to balance. However, when the left hand counters by pushing the fence firmly against the work and also slightly forward, I find the tendency to roll the plane much less.

      Having a machine shop grind a mismatched set of irons is a viable solution. Though it will still require making a new wedge to fit the new angle of the irons. But it would require only one wedge instead of one for each iron.

      One needs to be very careful doing this though. The irons shouldn’t simply be ground flat to the same angle, because the grooved side of the iron is not actually flat. Instead it has a very gentle concave eliptical arc to it. This is intentional and is designed to ensure that the iron seats on the skate tightly right at the very bottom. Flat irons will not seat as well at that critical point. Because there is no bed/mouth to these planes and the iron is largely unsupported at the bottom (the most critical area for it to be suported), this gentle concavity is necessary to prevent chatter and shifting of the iron in use. If one is to have irons machined like this, it would be wise to have the shop only grind the flat (unbeveled), ungrooved side of the iron, and leave the grooved side alone in order to maintain this gentle arc. I wouldn’t go this route without strict, detailed instructions to whomever was going to be doing the grinding, not to grind the grooved (beveled) side of the iron, and to keep it cool enough to not draw the temper or cause warping of the iron from over heating. Trusting the job to any old machine shop, is a risky chance to take on a set of irons that typically aren’t inexpensive to assemble.

      • You learn something every day. I have about a dozen sets and another 30 or so laying around. I grabbed my starret and all the ones I checked do have a slight arc on the back, and the face is flat.

        I have been using wooden plows for more than 10 years and I never noticed or heard of this. I did a little googling and clark and williams talk about this on thier blog. They say it’s for the reasons Bob mentioned above.

Comments are closed.