So I’ve got a goofy issue tuning my block bench plane. It’s one of the Pony Jorgensen #4 smoothing planes they’re selling at Lowe’s in the States. Works pretty well with one exception: Moving the frog forward to bring the iron closer to the mouth also advances the iron.
I can’t get it anywhere near as closed as you’re supposed to with a smoothing plane before I can’t retract the iron sufficiently. The mating surface in the sole that the frog rests on is slightly angled downward, so the frog is lowered as it is moved forward. I can’t realistically bring the iron any farther on the chip breaker than I’ve got it.
As I had it apart, I noticed the finish on the bottom of the frog, the surface that mates with the sole, was as cast, it isn’t machined or lapped. Should it be?
Try setting it up with the mouth at about 1/16" and the chipbreaker really close to the edge
Depth of cut is too deep at maximum retraction. I think the chip breaker is slightly too long for the mouth to be that closed. I might grind it a little shorter at some point. I can’t fully retract the iron unless the mouth is 1/8" or more
Does the blade have multiple notches to allow adjustment as you sharpen it? Are you using the notch that makes the blade shortest?
No notches. Well, one notch. It’s a pretty much standard Sanley-Bailey pattern bench plane. Here, I’ll show you how it works.
Here’s the iron (blade) by itself. That long slot is ultimately what allows you to adjust for sharpening. It attaches to another piece of metal called the cap iron or chip breaker like this:
With a screw through the back:
The chip breaker has two functions here: the very tip sits flush against the front of the blade just behind the cutting edge so that when the shaving meets it, it is curled forward causing the cellulose fibers to snap and stop any wedging action. This has the effect of rolling the shavings into curls in a way that bevel up planes tend not to. It also interfaces with the depth of cut adjuster on the plane.
Here is the sole and frog assembly:
On a simpler plane like a block plane, the iron would rest on a machined surface built into the sole (the main body of the plane), a bench plane like this has an adjustment feature for setting the blade not only deeper or shallower, but forward and backward to control the size of opening the shavings will emerge through. The wedge shaped thing the blade rests on is called a frog, apparently named after a structure in a horse’s hoof with a similar shape. The depth of cut adjustment is a screw operated lever, you can see the top of the lever poking through in the above image just below the disc shaped thing near the top (that’s part of the lateral adjuster). The iron and chip breaker assembly mounts on the plane like so:
The chip breaker is on top with the iron sandwiched between it and the frog. The depth adjustment lever pokes up through that long slot in the iron and catches that notch in the chip breaker. As the user turns an adjustment wheel on the back of the frog, it tilts that lever which causes the iron and chip breaker assembly to slide up and down the face of the frog, advancing and retracting the cutting edge through the sole.
One last part, the lever cap:
Some have a toggle lever at the top, this one has a thumb screw, either way what that does is pinch the iron and chip breaker assembly against the frog by putting tension on that screw that sticks up through the middle of it all. Changing the tension there changes how hard it is to move the depth of cut or lateral adjust.
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At least on this particular plane and I assume on other similar ones, the mating surface between the frog and the sole is angled downward, so moving the frog forward also moves it downward, which advances the depth of cut. So to move the iron forward/close the mouth, you would have to also retract the iron with the depth of cut knob. Except with the frog adjusted forward, the depth adjuster hits its limit of travel before the iron is retracted far enough. I’ve got the iron choked up about as far as I can reasonably go on the chip breaker, which makes me think the chip breaker would need to be shortened to operate this plane like that, since I can’t make the blade shorter than the chip breaker.
And while investigating this I found the bottom surface of the frog isn’t machined. Been using it for a year like that so I suppose it’s not that critical but still.