saw sharpening - reshaping

[bugbear]

Following the recent thread on saw sharpening, I thought I'd make a diagram to clarify my thoughts (thank you Inkscape http://www.inkscape.org/).

I haven't done a full write up, but I think some people might find careful consideration of the pictures thought provoking...

http://www.geocities.com/plybench/saw_sharpen.html

(bottom of the page)

BugBear

 

[MikeW]

Thanks BB,

As it is oft said, pictures are worth a thousand words.

There are, of course, many decisions a person needs to make when sharpening a saw--both before and during.

I would propose the following to a person starting out. It is more important that the tooth tops are as even as possible as it is the having the general tooth shape even.

Spacing, while important, is less so (withing "reason"). It can even be argued (it has) that slight variations in both tooth spacing and shape result in less vibration during a cut.

I guess the point is that if when one sharpens their saw, if it looks a bit off when you are done, and it is not the tops, use it. You may find it cuts well.

If the tops are a little uneven, lightly joint it and reshape those teeth. The result may be a little unevenly spaced teeth but if it cuts fine, it is a more or less cosmetic issue.

Take care, Mike

 

[engineer one]

ok bugbear looks good, but having trouble printing it all off,
so the next question for mike w. may seem a bit dumb

mike, since few of us are initially going to sharpen many saws frequently
how long does the saw vise need to be. i can see when you are flattening
the top it makes sense to have the longest possible thing,
but when you are fling across the teeth, do you really need much
more support than the length of the vice ?

also with a backed saw, what support do you need near the teeth.
reading what you say, one is rarely using heavy filing motions, therefore
i cannot see what kind of damaging harmonics could be caused, but am of course happy to learn.

what i was hoping for was to make a couple of pieces of say oak
that were about 12 inches long, supported in the vice, and with angled tops. am i thinking along the right lines or ](*,)

if a 4inch deep cross saw is used, what happens?

more help would be appreciated
paul :wink:

 

[bugbear]

paul - have you read the instructional texts linked to on my page; they're pretty detailed, and illustrated.

BugBear

 

[bugbear]

Thanks BB,


Spacing, while important, is less so (withing "reason"). It can even be argued (it has) that slight variations in both tooth spacing and shape result in less vibration during a cut.

I'd heard something like that

http://nika.frontier.iarc.uaf.edu/~cswi ... =1#message

BugBear (who acted on what he heard)

 

[engineer one]

you'll want me to think next!!!!!!

finally got the printing done, just asking for extra info since i don't
know how much saw sharpening i want to invest in. might find time for
a life outside you never know :lol: : :lol: :lol:

paul :wink:

 

[MikeW]

Thanks BB,
Spacing, while important, is less so (withing "reason"). It can even be argued (it has) that slight variations in both tooth spacing and shape result in less vibration during a cut.

I'd heard something like that

http://nika.frontier.iarc.uaf.edu/~cswi ... =1#message

BugBear (who acted on what he heard)

Cool thread! thanks again BB.

One of these days I would like to sit down with the thread originator :wink: and buy him a pint (or two). Lots of things to discuss. Would be a good time!

Take care, Mike

 

[Pete W]

More thanks here.

Saw sharpening is very high on my list of tool-related tuits - my most-used saws are a pair of modern, plastic-handled, hardened-tooth, ugly beggars, just because they work. I have some lovely old models salvaged from the *bay, but they desperately need attention before they'll cut wood (yes, I've tried!).

At the risk of appearing bone-idle (which isn't far from the truth), and given that I've read BB's other thread on saw files, what is the current recommendation for buying files in the UK. Just point me at 'em, please

 

[engineer one]

peter since you are in london, you might find that shesto in NW10
might well be the place to try, sorry don't have their number to hand
but sure directory can help.

paul :wink:

 

[MikeW]

ok bugbear looks good, but having trouble printing it all off, so the next question for mike w. may seem a bit dumb

mike, since few of us are initially going to sharpen many saws frequently
how long does the saw vise need to be. i can see when you are flattening
the top it makes sense to have the longest possible thing,
but when you are fling across the teeth, do you really need much
more support than the length of the vice ?

I have a cast iron saw vice with 11 inch or so jaws. Not very big indeed. I usually clamp the saw roughly centered in the vice and hold onto the end of the toe (underneath) to stiffen the blade when jointing.

With such short jaws in relation to a full size hand saw, I need to move the saw twice while sharpening--a matter of seconds in a vice which uses a lever to opn/close the jaws.

also with a backed saw, what support do you need near the teeth.

All filing is done with the tooth gullets about an 1/8 above the jaws. This provide a lot of stiffening and avoids most/all of any vibration while filing.

reading what you say, one is rarely using heavy filing motions, therefore i cannot see what kind of damaging harmonics could be caused, but am of course happy to learn.

The vibration I was refering to is while sawing--not filing. Sorry for the confusion. It is possible that extremely even teeth engaging in the cut at their prefect spacing may actually cause the saw to vibrate. The theory says that even slightly uneven spacing mitigates this. Possible. Certainly is true in other circumstances.

what i was hoping for was to make a couple of pieces of say oak that were about 12 inches long, supported in the vice, and with angled tops. am i thinking along the right lines or ](*,)
if a 4inch deep cross saw is used, what happens?
more help would be appreciated
paul :wink:

There are many drawings on the web for making one's own wooden saw vice. I think there's one on Alf's site, and the link for Leif Hanson's web site has more. The wood jaws just need to be able to allow your biggest saw to "sit down" in the vice to have only the teeth showing (a wee bit more really). I have a Sorby 3 1/2 ppi rip saw (and I just found another <g>) that will not fit in either of my saw vices. I use two 10" x 18 mm flat pieces of Baltic Birch to which I fastened a strips of 1" x 5 mm thick BB along one long edge of each one. I clamp that in my bench vice. The small strips grip the edge of the saw at the teeth. Crude, but effective.

Well, tis time to go to sleep...take care y'all. Mike

 

[engineer one]

mike w.

thanks that is really informative, and both confirms my thoughts,
and secondly i think helps all of us who are thinking about taking the
ride down another slippery slope, ie saw sharpening alongside
plane and chisels, and spokeshaves etc..

talk about the "madness of king george" :lol:

anyway as an interesting aside, i finally got round to sharpening a blade
from one of the new wooden planes i had bought in a job lot,
the dutch ones "nooitgedagt".

its a smoother without a chip breaker but a run through the tormek, with
the back flattened on water stones, and then i loaded it on a flat surface,
pushed in the wedge, and then used a rubber mallet to fit the wedge.

i got really nice thin shavings with a smooth finish to both soft and hard
woods.

so i have at least learnt something else new working through the forum.

thanks again guys

paul :lol: :wink: ccasion5:

 

[bugbear]

hold onto the end of the toe (underneath) to stiffen the blade when jointing.

When working on saws that can't be held where I want them in my saw vise (old Woden) I simply attach "mass", and attempt to use inertia to damp filing vibration.

Suitable, easily attached, "mass" includes metal 'G' clamps, and toolmaker's clamps - I've also used long jawed mole grips.

I also used a toolmakers clamp (long parallel jaws) held in a large 'G' clamp (high mass)

It all helps, but is not ideal.

BugBear