It's been a while. I just completed a most-expenses-paid, five day stay at my local hospital, so it's a good time for blogging as I ease my way back into the shop. I'm feeling pretty good, but regaining stamina will take a couple weeks.
Just before my illness, I completed a run of dado planes. At about the same time, Richard Arnold, the eminent plane collector/toolmaker/joiner, did a nice series on Instagram about English Dado planes. He discussed the various types of depth stops used across the pond, but there are a couple different ones that show up in North America, including the one that I've adopted as my favorite. To varying degrees, these stops also show up on fillister and plow planes, so they're worth discussing.
The earliest depth stops, ca. 1700-1775, are simply friction fit. You adjust them with a hammer. Here's a screen shot of one of Richard's planes (I don't think he'll mind). This one's made by William Madox, one of my favorite early makers. The wedges are particularly lovely.
For those not familiar, the depth stop is the thing in the middle, between the main iron and the nicker. It's simple and elegant, but has obvious long-term problems. So the next step (in England, at least), was to secure the wooden stop with a metal screw, similar to today's lag screws. Usually a brass wear plate is inserted to protect the stop. Here's another of Richard's planes.
This type of stop persists into the 20th century. It was often the cheap option, because as we all know, if you tighten and loosen a lag screw enough times, the threads in the hole will just wear out. So, a more durable setup was needed.
By the late 18th century, the mature form of the English depth stop had come into use: An all-metal stop, with the depth adjusted by a screw, controlled by a knob on top. Here's one from my own collection.
There is much to recommend about this technology: It is simple to adjust, and pretty durable. Most of all, it allows for a large bearing surface, something that isn't practical with a wooden stop. However, there are also some drawbacks. All that metal gear is expensive and heavy. The stop is slow to adjust, and tiring on the wrist. And over the very long run, the screw gets corroded and hard to turn, metal parts bend, and problems ensue. It is common to find old ones from the late 19th-early 20th centuries that are in need of repair.
In North America, we find two interesting stops that just never seemed to be of interest to the English. First is the wedged stop. I can't read the maker's mark on the plane below, but it is definitely a commercially made plane.
To set the depth, you tap the top of the depth stop, then tighten the wedge. Three wedges in one plane! Here's a look at the stop and wedge:
This type of stop works well. It is simple and inexpensive to make, lightweight, and easy to repair or replace if needed. The main drawback is that it's finicky to adjust and can pop loose when you don't want it to.
Finally, we come to my favorite stop, and the one that allowed me start making dado planes for sale: The type secured with a wooden thumbscrew. A number of years ago, I acquired this plane by T.J. McMaster. It is a factory-made plane, probably from the 1820s or thereabouts.
Here's the stop and screw.
This stop is cheaper to make, and lighter, than a metal stop. It is faster to adjust. If the stop itself gets damaged, any competent user can make a new one. And the wooden threads will outlast metal ones by multiples. This one is about 200 years old and works perfectly, and I have examined plow planes at Colonial Williamsburg that have 300 year old threads in perfect working order.
Once I found the T.J. McMaster plane, I started making dado planes. Mine have a little nicer fit and finish, but in all essentials, they are the same design. Here's one that will be on its way to a customer tomorrow. First, two pics of the plane before finishing, after a test cut:
And two closeups of the stop, after finishing:
When I first started making wooden planes, I was convinced of the superiority of English planes, and when it comes to bench planes (jack, try, and smoother), that's largely still true. But for joinery planes (dado, plow, fillister), I think the reverse is often true. American planemakers, who had a harder time procuring expensive metal hardware, developed ingenious solutions that often work better than their English counterparts. And often, these solutions are more practical for the modern planemaker.
I've made a couple plows using wooden thumbscrews, and I love them, but the plow is a tough nut crack in terms of selling a plane that anyone could afford. More recently, I've made a slide arm fillister along the same lines, and that shows a lot of promise. The next task, after I get caught up on my order list a little, is to make a fillister available for sale. Stay tuned.