Thread: Help: My 4TPI hand saw is against me

CK

I think you are on the right track with the set. Look closely and see if even a single tooth has more set than the rest. One way to correct this is to run a sharpening stone down the sides of the teeth. When the saw is still in the sharpening vice I use a very smooth file instead of a stone.

This assumes there is no kink or bend in the saw plate, which will also have a similar effect to that you describe. The Spear & Jackson No.88 was nearly at the top of the line.

Regards
Paul

Ps: It won't hurt to run a stone or smooth file lightly down the sides of the teeth even if you can't see a problem.

You could try a bit of lubrication. A very light wipe with oil or Scribble with candle wax down each side of the blade is worth a try. I am amazed at how much difference this makes and I keep a Paul Sellers can oiler (look it up) on my bench.
Bruce

Paul has pretty well covered what I'd have on my initial check list. A kink would be obvious, so we can rule that out, but rather than an over-set tooth, I would first look for a high tooth. Random over-set teeth can cause wobbly cutting and leave big score marks on the cut surface, but I haven't struck that as a cause of jamming (though all things are possible, of course). Under-setting will definitely cause binding & jamming, though the onset is usually a bit more progressive, not a sudden stop. That has me quite perplexed.

It's probably just camera distortion, but it looks like the teeth become uneven from about the 3.5" mark on the ruler. The rake angles seem to change from L to R, too, but that could also be an illusion caused by the lens not being perpendicular to the saw.

If you can't figure it out & have the time to drop by with it sometime, I'd like to take a look at it & see if we can solve the mystery together - two heads are better than one as they say (not true if they both have hang-overs! ), & I'm always keen to learn more about saw quirks.

Cheers,

It looks to me that where your saw stops suddenly, the teeth are misshaped and probably very blunt -- which would explain why the saw stops cutting as though it has hit a wall.


To fix, I suggest you:
1. run a flat file along the tooth line till the tooth line is straight and all the teeth have at a minimum a very small flat spot on their crests. The process is called "jointing".
2. resharpen the saw. After jointing, some teeth will need a lot more filing than others.
3. reset the teeth.
4. smooth the set so that the set is consistent along the tooth line.

Thanks a lot for the advise. I tried and checked all of them.

I thought I had sharpened the saw before but I went and did it again. Put the set on it and also smoothed over the sides again slightly. Still jammed.

Then I decided to try first a Disston D-8 first which had a higher TPI. After sharpening and setting same thing. Then I resharpened it with a bit of a higher rake to make it less aggressive and that did the trick on the D-8. Now she cuts well. At least that's what I think.

So I went back to the Spearior and also after putting some more rake on the teeth she goes much better.

I think now I just had her a bit too aggressive for me. I feel a bit embarrased that I did not figure that out earlier. There is a lot info out there, but I felt jamming is different to getting stuck.

At least now I also got around to sharpen the Disston too [emoji6]

I might still come back to your offer Ian W to see how I can further improve.

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Success, and more experience to draw from

Ck, you've got me a bit confused with your reference to rake angles. "Higher" rake angles generally mean the front of each tooth is closer to perpendicular to the tooth line (also called "more aggressive" rake). If it goes past 90*, that's 'positive' rake. Lower rake angles means the front of the tooth is sloped back more, i.e. away from the direction of cut (often referred to as "more relaxed" or negative rake). Hand saws are almost always sharpened with negative rake, as opposed to powered saw blades which usually have higher rake angles and some (like most bandsaw blades) even positive rake. I think I've figured out that your teeth had or were tending to, positive rake, which you've now eased. I've had a very similar experience.

I think it's a common problem that when we file teeth, we tend to put uneven pressure on the file. Keeping the file in the same spatial orientation & applying even pressure so it takes an equal amount off both sides of the gullet are the main 'tricks' to learn with saw sharpening. When I sharpened my first very large-toothed ripsaw the first few times, I didn't realise I was not holding the file so it cut evenly on both sides of the gullet. I was taking more off the top of the back of one tooth & more off the bottom of the other. Over three or four sharpenings, this rotated the rake angle forward by several degrees. Eventually, my saw was cutting very roughly and becoming almost impossible to start & I had to investigate.

I first thought I'd made a few high teeth, so I jointed it lightly, but didn't find any that were way out of whack. I can't remember what made the penny drop eventually, but I decided to check the rake angles, which is pretty easy with such big fangs. They'd crept up to a couple of degrees positive! I corrected that and it went back to being a much nicer saw to use.

Cheers & happy sawing....

Ian, I am still getting confused to which direction the rake angle is positive or negative. But from you explanation I cam confirm that I had to lean the teeth slightly backwards to fix the jamming. So that would have been a negative rake angle?

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Yep, you got it. Here's a diagram that I hope should remove all ambiguity: Saw tooth rake.jpg

Cheerss,

Edit: So much for removing ambiguity! Some folks viewed the teeth as pointing "up" instead of "down", which of course makes the diagram look wrong. The teeth are meant to be pointing down, not up. I hope no-one's gone & reversed he rake on any of their saws......

Originally Posted by IanW

Yep, you got it. Here's a diagram that I hope should remove all ambiguity: Saw tooth rake.jpg

Cheerss,

Ian; you've labelled the front rake side of the tooth facing the heel of the saw within your diagram.

Originally Posted by planemaker

Ian; you've labelled the front rake side of the tooth facing the heel of the saw within your diagram.

Are you reading the diagram with the saw plate at the top of the pic or the bottom? It makes a difference...

My mistake Skew. I was visualizing the teeth facing up.

Originally Posted by planemaker

My mistake Skew. I was visualizing the teeth facing up.

Stewie

I did exactly the same!



Regards
Paul

Apologies, looks like I just muddied the water!

Yes, the teeth are meant to point to the bottom of the diagram. I should've realised that many of you would look at the saw as if it was in the vise for sharpening, which is perfectly logical.

So much for my hubristic "..this should remove all ambiguities...."

Cheers,