What is a Shoulder Plane and How to Use It
I would consider myself a dabbler in hand tool woodworking. I know how to use them better than most anyone on the street, but compared to other wood workers I’m still weak. The shoulder plane, and really all planes, are nothing more than chisels in a jig. In this case, the plane body ensures a consistent, 90 degree cut, sharpening the inside corners of rabbets and shoulders of mortise and tenons.
This is a shoulder plane.
Simply put, it’s a small plane, generally coming in three sizes, small, medium, and large, with a blade the width of the body. You use them like most planes, going in the direction of the grain, but instead of doing lots of work they are meant for delicate, clean up jobs after using a bigger tool to make the initial cuts. Their main purpose is to trim the end grain shoulders of a tenon, hence the name. It’s also the reason why the iron is bevel up, giving it a low angle, making it easier to trim end grain cleanly.
I didn’t have a shoulder plane for many years, but decided, as I started doing more traditional joinery, that a shoulder plane would be nice to speed up the process. Yes, you can use a chisel, but achieving consistent results is tough.
Enter my plane, the Bench Dog 92, a low cost option, for shoulder planes at least. There were a few reasons why I selected this plane. One, price as this was my first shoulder plane. Two, size. This is a small plane, which is easier to control for small applications such as cleaning up tenons, where large planes can be unwieldy. Third, this particular plane has a split body providing for extra adjustability, making the plane versatile and enabling a special, hidden feature.
In this article I will show you the basics of how to disassemble the plane, what the parts are and why they are there, how to use it, and I’ll leave you with a secret use which turns this tool into two with one simple trick.
Plane Parts
A disassembled shoulder plane. From left to right, the body, iron, chip breaker, and top. My words, not official
Like most planes, the sole of the plane needs to be flat. A shoulder plane also needs the sides to be 90 degrees to the sole, otherwise it won’t cut at 90 degrees, it’s sole purpose.
Next, body types. My plane is a split body, meaning it comes apart to access the iron. You can do that by loosening the top screw and sliding the back and front apart.
The other types include solid body with or without an adjustable mouth. I don’t know much about which is better, I’ve only used the one I have, but I find it important to be able to adjust the mouth, enabling you to take bigger bites in long grain rabbets while also closing up for trimming end grain to reduce tear out.
The rest of the plane is simple. The black part is the chip breaker, used to hold the iron in place. The iron is the chisel looking thing that does the cutting, the bevel goes up in a shoulder plane, that’s important but we’ll talk about it later.
Adjustment Screws
This particular plane has four screws. Don’t quote me on the names, this is what I am calling them.
Thrust adjustment. This large screw in the back moves the plane iron back and forth to take a shallow or deeper cut.
Body screw. The top screw, it holds the body together. Much like the thrust screw it looks like it could be finger tightened, but is slotted to tighten with a screwdriver. Tighten it with a screwdriver, otherwise the body can slip apart in use.
Tension screw. This is accessible from the top of the plane. By tightening this screw the tensioner is lifted slightly in the back, pushing down on the front which holds the blade in place. Tighten this too much and you won’t be able to adjust the thrust screw, leave it too loose and your iron can move side to side or slide back.
Throat adjustment. This little, hidden screw controls how open the throat of the plane is. It does not need to be adjusted often after initial setup, unless of course you want to open up the throat for larger passes.
Setup and Using a Shoulder Plane
To put the plane together, first we need to take it apart. Simply loosen, but don’t remove, the body screw. You’ll now be able to slide the plane apart by pushing the top off toward the front, this is going to take some force. Once loose, you can lift it off.
Now remove the tension screw completely and you can slide the iron and chip breaker out of the front. You can also simply loosen the chip breaker and slide the iron out, you’ll need to do this to sharpen.
And speaking of sharpening, now’s a good time to go through that process, if you want.
Now to put it back together. Simply do the reverse. Iron goes in the slot and on it’s holder. Next, in goes the chip breaker, insert the screw so it doesn’t slide out and then move it back to position. I’m no expert, but don’t put it too far forward else it will capture shavings, clogging the throat and making it difficult to use the plane.
Lastly, put the to back on, navigating the screw through the slot and sliding the plane back together. Slide it all the way back so the body screw hits the throat adjustment screw. If you need more throat, back the throat adjustment screw out, if the gap is too wide, tighten it. I like to leave a slightly open throat at this point so I can adjust the iron to close it. If, in operation, the plane is cutting too shallow I have space to move the iron forward using the thrust adjuster. If I don’t have enough throat space I will adjust the throat screw until I have it right for the operation.
Which brings me to my next step, adjustment of the iron. A shoulder plane’s iron is the exact same width as the body such that it cuts right up to the corner of the plane. So first things first, make sure it’s even on both corners of the throat. If you have trouble moving the iron, loosen the tensioning screw slightly.
Next, make sure it’s even across the throat, as pictured. If it is crooked, hold the front of the iron and back, wiggling the iron back and forth slightly until it evens out. Once set, tighten the tensioner again, just a little, and check it again to make sure nothing moved.
You have done it. That’s the whole process. Using the plane is simple, stick it into a rabbet and slide it forward. If it isn’t cutting, advance the iron. If it’s taking too much of a cut, back it off. If it’s jamming, open the throat a tiny bit. And I mean tiny. The picture here is for illustration, in use the throat will be virtually closed, but shavings should still go through.
The reason for this is this type of plane is for end grain, and a closed throat will do a cleaner job.
Chisel Plane
Okay, now to my promise, the secret use. Since this plane splits and the top comes off you can use it as a chisel plane. It’s not the most comfortable to use this way, but it is possible.
A chisel plane is a plane with no throat, the iron hangs out the front. It is used in an area where a chisel would be difficult to control. I used it recently to trim the corners of a rabbet. I cut them square initially with a chisel, but evened them out with the chisel plane.
So there you go, a two for one tool. A shoulder plane isn’t essential, it isn’t a work horse, it isn’t a lot of things. But it sure does do it’s job well, provides consistent results, and is easy to use.
If you’re interesting in buying this plane, here’s a link to it on Amazon. I only recommend things I use in my shop and I’ve had this plane for over a year, it’s been a great investment!