I was in a pawn shop recently and I saw a Stanley no. 4 plane. I do not have one of those and I probably could have talked him down to 15$.
That being said I am not sure how to know if a hand plane is still in good function. Would hate to buy it to only find out later if I looked at _____ that I would have known to stay away. I saw some pitting on the sole but there was no rust.
When looking at hand planes what can I do to assess the tool to see if it would have a place in my collection?
Ideally you want a plane with the following:
Critical:
Highly preferable:
Rust and the sole can be remedied but would be nicer not to have to deal with. I personally would consider cracks or heavy wear around the mouth a deal-breaker if you want to use the #4 plane as-is, as a #4 plane.
If it's missing parts, you can easily find a replacement blade and can probably find the other parts, but that will increase your cost, of course, and you won't be able to use it until you do find replacement parts.
If the plane is badly damaged, you could use parts from the plane to fix another plan or you could make an infill plane. If you were looking at a wooden or transitional plane you could just replace the worn wood.
Unless there's enough rust to weld parts together or leave a surface pitted and uneven beyond repair, I've never had it be the reason for walking away from a hand plane.
The first thing I check is the quality of the plane iron. Flip the lever on the cap and pull off the blade and chip breaker. Learn to do this quickly so that you can get it apart faster than the pawn shop owner can protest. Watch out for junk blades or backs so messed up they aren't worth trying to flatten.
With the blade assembly off, check the condition of the the frog. Make sure the iron will bed solidly. Verify both bolts connecting the frog to the body are present and not rusted over. Play with the adjusters to make sure they move properly.
Bring a ruler and check the sole for flatness. You can also use the glass top of a display case to check for rock. Flattening a sole isn't hard, but why do it if you don't have to?
Lastly, look for signs of wear on the plane. If the totes are well worn, you may have found a keeper. This is a tool that has survived a long time and seen lots of use. If it looks pristine, be wary. It's possible there's something wrong and it never got used. (I have a Harbor Freight spokeshave just like this).
Every thing that has been said is bang-on. I would also look at the blade, generally one with a bit of life left has material left to grind, not too much pitting and is relatively thick. Take a look at the frog, generally frogs which have more surface area in contact with the blade are higher quality. Pre-war Stanley planes are a good bet.
Your question's answer depends on whether you are looking for a user plane, i.e. something you intend to use, or a collectible plane that you want to show off or resell for a higher price. The latter is very complex, but the former is straightforward. The easiest answer is to purchase a premium, new plane and call it a day.
If you purchase an old plane, you will have to expect to put some work into it such as derusting and cleaning. A number 4, a smoother, requires a bit more work than other planes. The sole should be as flat as possible to ensure very thin shavings. Don't expect it to be flat when you buy one. It can take anywhere from an hour or more to flatten the sole using cheap and easily obtained materials. There are tons of online resources that explain the process.
Under no circumstances should you buy one that has any size cracks, large chips or deep pitting. If you see any, kindly refuse. Such defects can compromise its function or its structural integrity. I would only buy such planes with the intent of salvaging it's parts that are in good condition.
The price of the plane depends on a variety of factors, including type, model and overall condition. It is hard to say without looking at it. There are some #4 that are very rare, fetching hundreds of dollars, but it requires a good eye and experience. $15 is a reasonable price for a number 4, even for a less desirable newer post war type.
