Friday, June 19, 2015

Roubo's Irons Don't Taper??!!!

I am flabbergasted. What is up with this? Roubo's irons don't taper?!!!

There I was, just flipping through the several pages of planes in The Book of Plates that LAP produced - as I do just about every day, it seems. (I tell ya, this book is worth its weight in gold to me.) So, this particular day, I was meticulously studying the plane irons because I am delving further into making planes that are based on Roubo's drawings. I'll actually be contributing an article to  Popular Woodworking in the near future on this subject. I promise that all of you aspiring planemakers out there will love it. It doesn't require any specialized tools and they are very simple to make.

Roubo style plane based on the Book of Plates

Anyway, I have been trying to decide how I wanted to go about making the irons. I just assumed that his irons were tapered from thick at the cutting edge to thinner at the opposite end. Then I just happened to flip to some pages showing some of his earlier drawings and BAM! there it was - a side view of the irons clearly showing both the bench plane and the side escapement plane with parallel thickness irons! No taper!

I know what you are thinking, "He just didn't draw the subtle taper of the irons." This is possible, but he clearly knew how to draw a tapered iron because the plow plane irons on plate 16 are clearly tapered. However, the irons shown on plate 13 are not tapered even the slightest.

Roubo - Plate 13

This sort of rocked everything that I assumed about antique irons. Most of those I know who think on this subject believe that the irons were tapered to save metal. So what is going on here? Could it be that the tapered irons of the British and American planes were made that way because it, in fact, added functional value? I believe this is the case. I think this actually gives reason to believe that the added functional value of tapered irons wasn't just an unintended benefit of a frugal planemaker. Maybe it was an accidental discovery, but continuation of the practice was surely intentional. After all, if the reason was only to save metal, then why would the planes Roubo knew of have even-thickness irons from toe to heel? Wouldn't they be interested in saving iron too? Wasn't it just as expensive for them at the time? And, wouldn't it be more difficult for a blacksmith to make an even-thickness iron? Lots of unanswered questions here, but I wanted to share my findings with you all. I personally hate to speculate too much, but it is interesting, nonetheless.

One thing is answered, though: I have wondered why there was a sneck on his irons. This explains it! I am still sold on tapered irons, but this gives some food for thought.


18 comments:

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  2. Have you seen the French hand planes on the European web sites. I think it was French ebay and maybe dutch site. I enjoy your blog please keep the fine content coming. Waiting for the book on hand planes that you should write.

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    1. LOL. Robert, I might just have to do that. Thanks for the encouragement.

      I have seen a number of these online but only after I looked at the plates from Roubo. It got me to thinking seriously about them.

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  3. Cool! I agree that these planes are much easier to make. I find on mine that the un-tapered blade I used holds just fine. Could it be since the iron is full width that there is more wedge holding it in place than on a comparable English plane?

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    1. Brian,

      I think that the flat irons hold just fine. They just don't adjust very well. I'll try and put together a post at some point explaining what is nice about a tapered iron in comparison.

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  4. There are other modern makers that use "flat irons" and they seem to work successfully (and don't require as much re-setting the wedge with adjusting). One area where tapered irons help, is outlined here http://www.handplaneforums.com/viewtopic.php?f=19&t=63 where flat irons can become stuck in the body over time. In the open mortise of Roubo'splanes this is less of a factor as the wedge can exit out the side, or as shown in plate 19? may have a sneck on the side of the wedge to allow a good whack with a mallet. I'm interested to see how well that tiny escapement works. I have a real ugly design I've been itching to try out that has a small escapement but haven't gotten to the making shavings point with the design (big remodel in process). If you want to see more plane wreckage, flip through the last few posts on my blog.

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    1. Jeremy,

      As I was saying to Brian. I think that the flat irons hold just fine but they are problematic when it comes to adjusting. I'll post more about it at some point. Thanks for your thoughts.

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  5. French makers such as Peugeot Freres continued to offer parallel irons well into the 20th century, but only on premium tools. Tapered irons (and beech wood stocks) were used on lesser tools.
    I mostly use parallel iron on my own moulders, but the wedge needs careful fitting. Even plough planes don't require thick tapered irons--think about the simple cutters used in metal ploughs, such as the Stanley 45.
    Although I don't know for a certainty, I think that the tools that Roubo illustrates are patterns or suggestions that craftsmen could use to make their own tools. The professional tool maker didn't dominate in France the way he did in England.
    Thanks for great post.

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    1. Yes Roubo gives instruction on what the plane sizes construction should be like. That would suffice for someone to make there own just from that.

      As for the traditional plough planes they have to be tapered to compensate for the groove that is cut into its back for registering it to the skate. Also an iron that is fixed in place with a wedge requires different mechanics compared to the Stanley 45. That said a flat iron will work for wedged planes just fine but there are some draw backs to consider when it comes to adjusting them.

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    2. Appreciate your thoughts on the history as well. Thanks

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  6. I've made a couple of the roubo style open sided planes (after Warren Mickley brought it up in discussion as a suggestion to someone), and like many of us, my first moulding planes had flat ground stock just because it was easier. In a grooving plane, it's probably a little less inappropriate since it's a bulk use plane where you don't want dainty work.

    But in the moulders and everything else that doesn't have a lever cap, it was quite a pain!!! No taper means the wedge can really get a death grip on the iron with even a mediocre quality bedding.

    (but the grooving planes of the style you show are something everyone should make, even if they make a 1 hour version out of a brick of shop scrap and the wedge is nothing more than a triangle).

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    1. David,

      You hit the nail on the head. The flat irons are a pain to adjust. When you drive the iron in to increase the depth it will tend to draw the wedge in as well and make it even tighter. Conversely a sneck would allow a wedge to be removed or loosened by tapping it backwards and drawing the wedge out. Thanks for your input.

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  8. Upon closer examination, it looks like that one has a moulding profile. My mistake!

    Same sentiment. At some point, you have to get comfortable making quick accurate tools if you're going to progress in hand tool work. The open sided plane for quickies is great, and permanent (not a throw away tool) at the same time.

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    1. I agree whole heartedly. And yes it is a 1/4" moulding plane

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  11. I have never had much difficulty adjusting parallel irons, I started out on Krenov planes and Japanese planes, that in a sense are both reverse tapered. It's just different, not difficult. The tapered iron is easier to unload if the plane gets stuck but the dogleg on those irons should take care of that.

    What I do is set the wedge enough to get a cut, but not fully. Adjust the blade, then I tap the wedge home. The initial wedge set is not enough to make it tough to adjust the blade, and yet there isn't enough left to set that it drags the blade out of position when I set it. The other thing is that I use pretty nice blades, O1 or modern made stuff, they are pretty smooth. Some of the older blades are pretty rough, which might be an issue, though I have some of those and haven't really had a problem.

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