Who's kerf is it anyway...?

[Alf]

Mmm, Alf I will have to pick at that one and suggest that it is the amount of set together with the number of teeth that determines the cleanliness of the kerf, and not the type of tooth configuration, per se.

Just to put aside set and number of teeth, which I agree make a heap of difference, compare kerfs 5 and 6. Okay, so no two saws are identical, but those two are as near as I can get 'em and I would judge one of those kerfs as cleaner than the other. Am I deluding myself?

Incidentally, what made me choose #6 as the bowsaw was the memory of watching Tage Frid on his dovetail video trying to start the cut, and his bowsaw bouncing all over the show :shock: :shock: )

Really? Excellent. :lol:

Cheers, Alf

 

[Derek Cohen (Perth Oz)]

Am I deluding myself?

Is that a professional question?

Teasing aside, the answer is a definite maybe. :? This is what you said about the saws that cut kerfs 5 and 6:

The Governor and Wood saws both have rather too much set for dovetailling, but they make good small "tenon" saws.

When saws have too much set, they cut a wide kerf. This causes the blade to move around in the kerf, this will have two consequences: firstly, the saw will not have the benefit of a "fence" and be inclined to wander off line; and secondly, the blade (plus teeth) will bounce around and score the kerf wall, thus degrading the kerf finish.

So if you are using kerfs 5 and 6, the results cannot be evidence of the tooth configuration, only of the tooth set.

Regards from Perth

Derek

 

[Alf]

Am I deluding myself?

Is that a professional question?

:roll: :lol:

So if you are using kerfs 5 and 6, the results cannot be evidence of the tooth configuration, only of the tooth set.

Eh? But they both have the same number of teeth and the same set (set with the same saw set even), so you can eliminate those as factors. The only difference (within reason) between them is one is rip and one crosscut. Ergo, within reason, any difference between the kerfs could legitimately be ascribed to the tooth configuration. No? If they were both, say, crosscut with the same ppi but the set was different, only then would your statement make sense. I think. Maybe. Urgh, my head hurts... :roll:

Cheers, Alf

 

[Derek Cohen (Perth Oz)]

But they both have the same number of teeth and the same set (set with the same saw set even), so you can eliminate those as factors.

Alf, what I am saying is that if the sets leave too wide a kerf, then the movement of the blade will damage the kerf wall. Now if one blade is a x-cut (which, as I understand, is just a less vertical and less aggressive configuration), then if is going to be different from a formal rip cut, it will actually have the advantage. However in practice both can produce very similar quality cuts if the set is small and the kerf is tight. Conclusion - with the wide kerf it is still the saw set that is determining the quality of the cut.

My head hurts too (too late at night here), so I shall leave the reasoning to others for a while. But it has been a very enjoyable discussion. Thanks Alf

Regards from Perth

Derek

 

[Frank D.]

Just to throw in my .02, I think (it has been my experience) that of 2 saws with the same number of teeth and same set, for rip cuts, a rip saw will leave a considerably cleaner kerf than a crosscut because the crosscut spends more time (more strokes) in the kerf (to cut the same distance). This means that the crosscut saw, while cutting less quickly, will have more lateral movement and will wander more in the kerf (as it meets a greater resistance from the wood). The faster a cut, the cleaner the kerf, TPI and set being equal.
Frank

 

[Alf]

You can tell it's earlier in the day for Frank, can't you? :roll: :lol: I'm waving my hand in front of my face imagining I'm a saw blade in a wide kerf and getting precisely nowhere! S'no good, Derek, I thought I got it there for a minute, but nope. It's gone again. I'll have to stick with the bit I do get, viz:

what I am saying is that if the sets leave too wide a kerf, then the movement of the blade will damage the kerf wall.

Which says to me, if that's the case, then I'd expect both cuts to be equally damaged... Ah wait, I think I see. Firstly I agree totally that a finer kerf will give a cleaner cut. What I'm getting at is the fact that the two cuts with similar saws - one crosscut and one rip - have such marked differences in cleaness of cut, when the only obvious difference is the tooth configuration. What I think you're saying is you believe with a thinner kerf the differences would be unnoticeable and therefore irrelevant. Yes? (I hope so, or else I retire from the field defeated) In which case I really need to reduce the set on them and have another go, don't I...? :roll: <when I wrote that I thought I'd really got it, but reading it back again I'm not so sure!>

The faster a cut, the cleaner the kerf, TPI and set being equal.

Up until I counted the number of strokes I took, I would have said the same thing. Trouble is we have the variable of my technique thrown into the mix, which has messed everything up.

Cheers, Alf

 

[Derek Cohen (Perth Oz)]

Alf wrote:

In which case I really need to reduce the set on them and have another go, don't I...?

By George, she's got it!

Yes. I went to bed last night thinking, "Oh damn, I meant to say ...", which really tells more about my own tendency to obsess. :roll:

I think that's right. Reduce the set on the saws individually (that is, until each cuts smoothly and straight, and where the blade does not rock in the kerf). Then we can judge the quality of the kerf walls that they leave behind.

I look forward to the results.

Regards from Perth

Derek

 

[Alf]

I look forward to the results.

Chuckle. You're not familiar with the scarcity of Tuits around here yet are you? :lol: :lol: But I'll see what I can do. Unless anyone wants to come up with a convincing argument why I shouldn't...? (she asks in hope :wink: )

Cheers, Alf

 

[Anonymous]

On the subject of rip v crosscut. I have one of each. The rip cuts DTs much cleaner (both have almost zero clearance on the kerf) and faster buy about a third as many strokes - but the blade on the rip is 2" longer which gives longer strokes.

The crosscut is a much higher quality saw and I tend to use that one because it 'feels' nicer

 

[Aragorn]

Sorry to be so simple about this, but I'm really confused now. Could someone tell me which is going to give the better cut for dovetails: a rip or crosscut?? :? :?

 

[Alf]

Right, what's an interupted lunch break when saw theory is at stake? :roll:


Click piccy for a larger close up

I'm saying nothing. Vote for the one you consider the "best", Either "left", "right" or "both" - but avoid saying both if you possibly can. If you wish to state which you think is which tooth type as well, please feel free. Kerf length doesn't indicate anything; I simply forgot to gauge a stop line. I've done my best with their set, but I'm no saw doctor, so this is highly unscientific. Having cleared my yardarm, I go... :wink:

Aragorn, search me. I thought I knew, but now... :roll: I don't think you'd really be suffering with anything from Maine though, do you?

Cheers, Alf

 

[Gill]

Left.

 

[Anonymous]

Left

 

[Frank D.]

Left looks better, but the right kerf could be better than the left one with a few practice cuts . I'll go out on a limb and say it looks like the saw cut faster (rip?) but just didn't quite track as straight as it might have. The kerf is wider but this makes no differerence to the quality of the walls of the kerf, which look smoother than the left one. I could be wrong in which case I look like a total fool, but I contribute any way I can .
What the heck,
Frank

 

[Aragorn]

Left is best.
Hoping it's the crosscut??

 

[Alf]

the right kerf could be better than the left one with a few practice cuts

That was after a few practice cuts! :roll: I gave them both about half a dozen before I started, to be as fair as possible. And before anyone asks; no, I'm not building a machine to replicate a sawing action so we can eliminate the wayward element (i.e. me). :lol:

Cheers, Alf

 

[aldel]

yup, no doubt about it, left is best by a long way.

aldel

 

[Derek Cohen (Perth Oz)]

Alf

In the pursuit of the True Scientific Methodology, this study might be judged more objective if we could eliminate the bias of the tester, namely You. In other words, we should seek a Double Blind study where your right hand should not know what your left hand is up to. It strikes me that this experiment should be conducted in a dark room with the lights off. You should not be able to see the cut you make, nor should you be aware of the results beforehand. :lol:

Oh, the left hand one looks better.

Regards from Perth

Derek

 

[Alf]

In other words, we should seek a Double Blind study where your right hand should not know what your left hand is up to. It strikes me that this experiment should be conducted in a dark room with the lights off. You should not be able to see the cut you make, nor should you be aware of the results beforehand. :lol:

Are you sure my hands shouldn't be in seperate rooms too? :lol:

Actually a fresh theory is forming... I give you all due warning.

Cheers, Alf

 

[houtslager]

left