Stanley no 50 with 3/16″ cutter not working

One thing to remember is that there is no such thing as “the number 50” there are at least 4 distinct models I know of, and probably more. It was made from 1884 to 1962 with many variations. Like the bench planes, there are different ones.

First, Sharpen the iron. That it is deflecting says it’s not sharp enough. ( or it’s not temped, but I doubt that). It’s a tiny iron. Take small cuts. Make sure it’s straddled on the skate. Not much room for error.

And for your test don’t use a scrap you wouldn’t put in your best work. Picknice, clear even grained stock .dont try to plane into rising grain. One of the “secrets “ of success with the tool is careful stock selection. That’s true for any plane with no defined mouth.

When you use the small retainer bolt for narrow irons you remove the arched sliding skate, . It just clogs things up, because there is no room for shavings.
try again, then post a picture of how you have the chip deflector and iron mounted. On some models the sliding section can’t be installed because the bolt is permanently mounted.
Post a picture and maybe I could get more specific.

On most ( all?) models the chip deflector is only used with the forked match ( tongueing ) cutter to deflect the shavings on the right side towards the right. So half the shavings go left, half go right. This was added because the original plane was just for beading, and there was no provision for chip deflection for a match cutter.

With all other irons you use the depth stop and don’t use the deflector. Shavings go to the left. The deflector is just for the one iron. It would never be mounted with the narrow irons. In the picture of the envelope, note it’s not just called a shaving deflector. It’s a “shaving deflector for matching cutter”.

The match cutter has (should have ) its own depth stop mounted right on the iron.

In the diagram attached, F And H aren’t used together. They fit the same hole H is used only with the match cutter.
Likewise, B and J aren’t used together. Pick one or the other, not both.

Also in the diagram, D and G aren’t used together. Some folks think G is an alternate depth stop. It’s not. It is used as a fence for putting a bead next to the tongue of T&G board. When it is used, you remove the regular fence D.
Stanley calls it a beading gauge . On some planes, it locks to the sliding skate.with a little rebate. You use the regular depth stop on the main body for all beads.

Directions are here: http://www.hansbrunnertools.com/Stanley%20by%20numbers/50inst.pdf
It has directions for which pieces to use for each operation.

Hope that helps.