Stanley No 20 Compass Plane question

[Matt Hunstiger]

I just got a compass plane off eeeebaaay and was wondering if someone here has a measurement for the chip breaker/cap iron so that I can know if I have the correct one, and not the chip breaker from the #3, which I understand is sometimes substituted. My understanding from Patrick Leach's website is that "the slot that engages the adjustment fork is situated nearer to the top of the cap iron than it is on the bench planes." It's 1 3/8" from the bottom of the slot to the top of the cap iron on the one I have (see photo below). The cap iron also has a "PAT FEB 7' 93" stamp on it, which matches the "PAT'D 2-7-93" patent date on the body casting found on a lot of these. Mine does not have the casting date on the side of the body near the adjustment wheel.
20230902_212435.jpg
20230902_194843.jpg

Here is the plane as received.
20230902_184538.jpg
and mostly deconstructed.
20230902_195146.jpg
The rest of the plane's parts seems to be of the correct vintage, and a lot of them have a "B" cast into them. Here are some of them. Ran out of attachment spots, but the lever cap has a "B" on the back too.
20230902_194723.jpg
20230902_194733.jpg
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20230902_194818.jpg

[Stephen Rosenthal]

Matt,

Mine is a later model #20 - black japanning, No. 20 Made in USA on top of the sole’s adjusting wheel. Purchased in the box at an estate sale - all original. The distance from the bottom of the slot to the top of the chip breaker is 1 1/8”.

[Matt Hunstiger]

Oh, oh no. #wompwomp

(Thank you for letting me know!)

[Jim Koepke]

The distance you should be worrying about is from the bottom of the slot to where the bottom edge of the chip breaker contacts the blade.

It is doubtful Stanley had more than one chip breaker with the same patent date.

The question is whether or not the plane functions properly with this chip breaker. If it doesn't, is the problem caused by a too long or too short chip breaker or something else.

From what Patrick Leach says you likely have the correct chip breaker. The casting may be one of the early castings without the patent date.

jtk

[Philip Glover]

Here is a comparison of my no. 20, circa 1899 - 1902, to a no. 3 type 13 cap iron.
IMG_1949.jpg

The no. 20 is on the bottom.
IMG_1950.jpg

The dimensional differences are so small that the functional difference is negligible.

Phil

[Matt Hunstiger]

Thank you for the replies guys. Photos, measurements, helpful comments; you all are the best. I have cleaned the plane parts and have worked on the blade a bit. We'll see how it performs soon I hope. I'm surprised to see the No. 3 is so close.

Matt

[Philip Glover]

The main difference is the location of the cap screw.
As seen here; the No. 20 is on the left and No. 3 on the right.

IMG_1956.jpg

Phil

[Matt Hunstiger]

So I got things cleaned up, and the blade sharpened, which was a bit of a bear. The back is a bit crowned off on the corners, but I flattened as best as I could.

So tonight I put it back together and tried to get some shavings. First I tried cutting a hollow, i.e. a concavity. At first I had the chip breaker about 1/32nd from the edge, but I was getting nothing but jammed up in the mouth opening. Then I moved the chip breaker back to 3/64ths and was getting nice shavings.

Concavity on some scrap pine.
20230909_195211.jpg

I tried a convex curve next and it was getting jammed again with the blade where it was when I was doing the concave curve. So I moved the chip breaker back another 64th, and the results were better. It's still not as easy going as the concavity planing, but it was OK. It will take some experimenting on depth of cut and chip breaker placement.

Convexity on the other side of the scrap.
20230909_200808.jpg

Thanks again!

[Philip Glover]

The main thing to remember is always plane downhill and take light cuts.

Phil