Thread: Sloped Gullets

Originally Posted by Bushmiller

I agree that there seems little point in sloping the gullet on a rip tooth as you loose the chisel effect.

Woah, I wasn't saying that !

... but I think the subject is extremely interesting.
Paul

Originally Posted by Bushmiller

There was a comparison test of a rip saw with sloped gullets. I have to say I am not sure there is an application there unless you have extremely curly grained timber.

Not in respect to this thread ... but it's precisely ripsaws that I would first like to know about, before crosscuts.
Some day.
Thanks for mentioning those videos from Isaac at Blackburn.

I think there was a proposal that the Acme 120 no-set saw in crosscut profile should be a beveled tooth-front with a vertical rear wall, via sloped gullets.

Cheers,
Paul

Paul

I was not agreeing with you on the "no application" aspect for rip teeth. It was somebody in the links.

The ACME 120 saw does my head in. It is unlike any of the other no-set saws including the other offerings from Disston. Firstly it had a tooth that was filed with a special saw like a cant saw file, but in addition it had a safe back (no teeth) so I am not really sure how it functioned. It had a taller tooth than you can achieve with a triangular file.

Other manufacturers did not follow this with their no set saws.

Regards
Paul

I did check on the saws and I have 5 Disston D-23 saws all 8ppi and 26" long. I also have three D-95s at 8ppi. I am thinking that the D-23s could be the initial test and depending on the outcome a further refinement could be done with the D-95s.

My proposal in measuring the cutting efficiency is not to use a time basis, but to count the number of strokes using primarily the weight of the saw. Some qualification can be added to allow for smoothness of cutting action and the quality of finish.

Regards
Paul

Watching with interest here; I recently picked up a few old-but-not-worth-anything-old saws to try my hand at sharpening and setting. Two rips and two x-cuts; the rips will be filed straight across as per tradition but I'll have a play with the x-cuts.

Thanks Chief

If you get your saws done before me feel free to post the results here if you wish. The problem with a test of this nature is that there has to be a "control" saw so everything else can be compared to that. Two saws does not provide a great deal of flexibility, but is still worth a "play."

Regards
Paul

Great idea Paul, watching with interest.

No worries Paul but I doubt I'll beat you to it as I don't get home until the 17th and before I tackle this I've got to de-rust them and either build or buy a saw vise.

Go for it, Paul, but keep the goals simple and the variables to a minimum, as you first proposed. As I said in the other thread, 'performance' is a rather nebulous thing to measure and in this type of experiment it's very difficult to eliminate 'observer bias'. I did some comparisons of (backsaw) rip-saws with different rake angles, different set and different plate thicknesses quite a while back. I posted on one 'test' (different plate thickness) but couldn't find it on a quick search (probably buried in a thread on another topic ). My 'finding' on that particular, rather brief comparison was that all else being equal, plate thickness didn't alter the rate of cut (or not over the range I tried), contrary to popular belief and the ads of some saw-manufacturers at the time. However, that was a very limited trial, with freshly-sharpened saws in one type of wood and so my 'findings' are definitely open to question and 'what-ifs' on a number of grounds.

What I have found in doing comparisons of saws is that even though I concentrate hard on letting the saw cut & not adding pressure, I can get quite a range in the length travelled for a given number of strokes - more than I would have expected, so I'm obviously applying some (variable) pressure despite my efforts to not do so. When I measured and averaged the cuts for each saw, the differences in the lengths cut by each were much greater than the differences in the averages - I didn't need to do a fancy statistical analysis to know that meant there was almost certainly no difference. However, my simple 'experiment' is open to question on the grounds that I may have had an agenda, and since I was the one doing the cutting, I may have consciously or unconsciously biased my efforts to get the 'result' I wanted....

But don't let the potential pitfalls kill the spirit of enquiry!

Hello Paul,

this sounds like a worth while exercise, as a suggestion to help with all the saws do the same number and length of strokes,
and remove any human variance.

Once you have the saws all filled and set the way you want for the comparison, if you could have them held (without harming
the saws) in some sort of reciprocal mechanical devise, similar to a drag saw.

You could get them all individually started into the wood (being the same piece) at the correct and same angle,
then stop the devise at a pre marked starting line.

Then run the devise, and maybe put a mark at every 5th stoke, depending on how big the board is, you could go to 50 strokes,
or figure out a different way to measure, that you would be happy with.

As to where you would get such a devise, think of a treadle sewing machine, as an old fashioned way or there are more modern
devises that one may find in ones local sex shop (which we will not go any further with), but with this type of devise you could
vary and regulate its speed. Or you could look at a mechanised hack saw for inspiration.

Regards

Graham

Ian

What are you trying to say? Do you mean it's not a perfect world?

You have mentioned one aspect in particular that I neglected and that is the gauge of the saw. They are the same model and same length, but there might be a range of eras so I will check the gauge and note that when the testing takes place.

The very fact that the human element is present means that any test is subject to some physical variance whether we rely on distance sawn, number of stokes to complete a cut or time taken to execute a cut. At this stage without any other alternative I will just adopt a relaxed style. The way I try to saw is that if I couldn't keep sawing for fifteen minutes continously without pausing ( there was a time when I would have said thirty or even sixty minutes) I am exerting far too much pressure. I think that is about the best I can do.

I also take on board the "agenda" and you are so right with this. I look at other threads and realise the lengths people are encouraged to go to achieve the desired result. In fact that last statement we see so often in public life!

I am hereby declaring my interest in sloped gullets, from the theoretical side, and I will take the attitude that I wish to disprove it. That will hopefully negate any bias I might have.

Regards
Paul

Graham

You have, in a slightly different way, echoed Ian's concerns.

Under other circumstances the power hacksaw approach would be I think a perfect way of evaluating, but it would mean butchering the saws to fit and I am not prepared to do that, plus I would need to source a power hacksaw. I do have a broken one, but I need to complete this little experiment before they cart me out in a box or burn me so I don't really think that is an option.

The local Historical Society had an open day recently and there was a display of the old "hit n' miss" motors and at least one of them was connected to a drag saw, but alas they have gone and I'm also thinking that size matters so 26" is not going to hack it.

The closest I could get to a drag saw is if I borrowed some of my wife's clothes, but then I might have some difficulty with the scrutineers .

We don't want this thread shut down even before the experts wade in so we might just leave any other mechanical suggestions where they were.

The truth is that the result will be an impression. What might be interesting is if I could persuade a couple of other people to conduct the test with me. I could undertake not to wear any clothes worn ordinarily by women! That might reassure the fearful amongst you.

Regards
Paul

Don't worry Paul, your secret's safe with me.

Originally Posted by rob streeper

Don't worry Paul, you're secret's safe with me.

Regards
Paul