trouble with dovetails

[pam niedermayer]

...
This is my attempt at an illustration....

Don't know, Steve, but this is about as close to square as a mountain is flat. What's wrong with this picture?

The interesting thing is that with the ridged kerf bottom, the offset side of the saw may come closer to touching the line than one would have thought.

Pam

 

[promhandicam]

...
This is my attempt at an illustration....

Don't know, Steve, but this is about as close to square as a mountain is flat. What's wrong with this picture?

The interesting thing is that with the ridged kerf bottom, the offset side of the saw may come closer to touching the line than one would have thought.

Pam

I'm not quite sure I understand your question. Perhaps you are making a reference to table mountain which is more or less flat on top!

Having thought a little more about this (and I may be barking up the wrong tree completely), but if the saw is set after it is sharpened then if there was no fleam / bevel, as would be the case in a rip saw, then when the teeth are bent out, the bottom of the tooth would no longer be level. In actual fact, in this instance (sharpening then setting) the following illustration would perhaps be more accurate

If so, then in theory this would be ideal for cutting dovetails because when the saw cut is at an angle the base of the cut would theoretically be more or less horizontal. As I said above, it would all depend on how the saw is sharpened and set and in what order.

Steve

(who freely admits that he is making it up as he goes along :wink: )

 

[bugbear]

Having thought a little more about this (and I may be barking up the wrong tree completely), but if the saw is set after it is sharpened then if there was no fleam / bevel, as would be the case in a rip saw, then when the teeth are bent out, the bottom of the tooth would no longer be level. In actual fact, in this instance (sharpening then setting) the following illustration would perhaps be more accurate

Since Diston's diagrams show nice neat "chisels" for a saw I always set before (final) sharpening. If I didn't (as you point out, and illustrate) I would get my little chisels.

In any case, since filing is a more frequent operation than setting, the "horizontal chisel" model is the one that usually pertains.

BugBear

 

[MikeW]

Neat theoretical problems and practical diagrams one and all.

As I stop a hairs width away from the bottom, cut the waste with the handy dandy coping saw hanging at the back of my bench and pare the baseline, the corners aren't a bother and are crisp--regardless if they are crisply wrong :lol:

I have used a smallish knife for the corners as well. Works wonderful in softwood and softer hardwoods. A pita in harder woods, though.

The diagrams of the saw teeth do illustrate why dragging a file across the teeth post setting is a good thing. But the "problem" actually extends further than this head-on view. Looking down on the teeth one would see the faces are bent as well. I.e., they do not bend over and have the faces remain perpendicular to the sides of the saw. This effects not only rip filed saws, but lessens the fleam angle on a cross cut as the tooth slightly pivots/rotates as it is set.

More slightly useless info from me!

Take care, Mike
who's back to plan B...

 

[bugbear]

The diagrams of the saw teeth do illustrate why dragging a file across the teeth post setting is a good thing. But the "problem" actually extends further than this head-on view. Looking down on the teeth one would see the faces are bent as well. I.e., they do not bend over and have the faces remain perpendicular to the sides of the saw. This effects not only rip filed saws, but lessens the fleam angle on a cross cut as the tooth slightly pivots/rotates as it is set.

More slightly useless info from me!

And in anycase, I don't like applying high forces (e.g. Eclipse 77 saw set) to delicate, "finished" teeth, so I'm definitely in the set then sharpen camp.

BugBear

 

[Alf]

Practical people should look away now.

Dammit, I wasn't quick enough. #-o This is enough to scare people off both cutting dovetails and sharpening their saws - just hope it doesn't... :roll:

Cheers, Alf

 

[promhandicam]

snip - This is enough to scare people off both cutting dovetails and sharpening their saws - snip

For me at least it has done the opposite. I'd never seriously considered sharpening my own saws and for that reason have only drooled over MikeW's offerings. This thread took my interest and made me do some research and I now think that it is within my capability and that it would be worth getting the necessary files etc to have a try at sharpening an old tenon saw for starters.

Steve

 

[bugbear]

snip - This is enough to scare people off both cutting dovetails and sharpening their saws - snip

For me at least it has done the opposite. I'd never seriously considered sharpening my own saws and for that reason have only drooled over MikeW's offerings. This thread took my interest and made me do some research and I now think that it is within my capability and that it would be worth getting the necessary files etc to have a try at sharpening an old tenon saw for starters.

Steve

IMHO (and I've sharpened several saws) a tenon saw is the HARDEST saw to sharpen. The teeth are fairly small (which increases the difficulty) and have "fleam" which further increases the difficulty.

DT saws are not too bad, since although they have fairly small teeth, they're filed straight across, like a rip saw.

The easiest (therefore) is a large toothed rip saw, although in this modern age, few woodworkers actually own or use these.

Therefore I would suggest (essentially) practising your sharpening on any non-valuable saw with large teeth.

I have collated a few random links and tips here:

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

And here's some words from an earlier incarnation of me:

http://people.iarc.uaf.edu/~cswingle/ar ... _id=113401

BugBear

 

[Anonymous]

Tombo

Try marking the pins from the tails using a scalpel blade or a fine craft knife blade as here

https://www.ukworkshop.co.uk/content/view/70/45/

Of course, the saw is the most important part of the whole process and I ran a stone along the sides of the teeth on my LN DT saw when it arrived which made the cuts even easier.

Ohh, and cut 3000 like Cosman to be as good as he is :wink: :lol: Practice, practice, practice.......

 

[tombo]

thanks all, i am going to have to engage my brain and re-read BB's post :shock:
Although is was disheartened its always worth finishing a project, my new motto is "get it finished". If it still looks rubbish when complete i can scrap it then.
In the end i fettled the joints best i could then smacked it together with my big mallet. if in doubt give it a clout

the box didn't turn out too bad after all, unless you look really close.
I'm going to attack my DT saw with the diamond stone when it arrives but if thats no better i can see lie neilsen getting a bit richer very soon

Tom

 

[Chris Knight]

Tom,
It looks really very good indeed - nice and crisp.

 

[Philly]

Very nice Tom!
Philly

 

[David C]

Getting work finished, even when one knows where the small errors are is very important for confidence building.

The good news is that all dovetail joints tend to look much better after gluing and cleaning up with a sharp plane.

David C

 

[DaveL]

Tom,

Nice looking box.

If your going to scrap it pass it this way. :twisted: :wink:

 

[bugbear]

The good news is that all dovetail joints tend to look much better after gluing and cleaning up with a sharp plane.

David C

You've given away the secret!!

BugBear

 

[David C]

BB,

That I guess is how I see a great part of my role in life.

best wishes,
David

 

[engineer one]

ah and we thought it was to obfuscate and cloud the issues to make us all want to come on your courses, or buy your books :lol: :twisted:

must thank you as usual david for being so honest about things which drive newcomers mad with frustration because they do not feel brave enough to finish the job.

paul :wink: