Shaarpness-Geometry or honing?

Re: chipping or rolling

Warren in Lancaster, PA

>I am wondering if plane irons bedded at higher angles are more vulnerable to chipping and rolling.

I'm late to this party but...

Steve Kubien

>...in my more-limited-than-most experience, on a bevel-down plane, a few degrees isn't going to make a difference (now don't go getting extreme on me. Let me explain). My Knight smoother and jointer both came with irons with a 30 degree bevel and they take shavings as nice as you could want. My Bailey style planes are all bevelled at 25 degrees (primary bevel) and they take shavings as nice as you could want.

I don't think it makes a huge difference.

Steve Kubien

Higher Bed Angles

Steve Elliott

>You're right. The higher the bed angle of the plane, the more stress is put on the blade edge during cutting. My tests have been done at a bed angle of 47.5 degrees.

Re: Shaarpness-Geometry or honing?

chichi

>Thanks to all for their comments. Moses confirmed my belief. There are two factors. A perfectly honed 90 deg. edge may be defined as sharp, but wont be very useful. A more acute angle is needed and there is a trade off between edge holding and ease of use. Somewhere between 25 and 30 deg. is the practical range for most steel.

Thanks,

Bob

Re: cutting...

paul womack

>... depends on more than just the edge.

The presentation of the edge matters (e.g. bevel up or down), blade relief matters, and the bevel also control access to the cut.

This is why paring chisels, carving chisels and plane blades are sharpened differently.

BugBear

Re: Shaarpness-Geometry or honing?

paul womack

>A line has width.

Not according to my Greek uncle Euclid. I was always taught at school that the things I made with a pencil indicated the position of a line, but weren't (themselves) lines, common parlance not withstanding.

BugBear

Re: Shaarpness-Geometry or honing?

William Duffield, on the Cohansey

>A 90� edge is certainly useful for beading tools (e.g. #66) and as a starting point burnishing a hook on a card scrapers. Starting with a sharp edge when preparing these tools is just as important as a sharp edge on a plane or chisel.

So what are those things made with pencils?

Pam Niedermayer - Austin, TX

>

Re: Serrated Edges

Vic Parisian

>Yes, but you will never feel bad about putting them through the dishwasher...:>)

Re: Serrated Edges

Pam Niedermayer - Austin, TX

>Oh, yeah, the dishwasher, I knew there was something I forgot, :)

Pam

Re: So what are those things made with pencils?

paul womack

>In common parlance - "lines".

To a mathematician, most of the time - "lines".

When you're answering an exam question - "marks indicating the position of lines"

But I suspect you knew that.

BugBear

#66 question

paul womack

>A 90� edge is certainly useful for beading tools (e.g. #66)

Data point, and tangential thread; the #66 is the exception. All the beading/reeding/scratch tools I know of EXCEPT the #66 run the blade vertical when in use.

This has the property of allowing these tool to cut both on the push stroke and the pull stroke. This can be very useful in some circumstances. To exploit this, it is CRITICAL that the blade be sharpened "square across".

The #66 leans the blade forward; giving a trailing cut. This makes it easier to use, but also means it can only cut in one direction.

Given this, I do not know if the blades for #66 must be/are sharpened straight across. Does anyone know what Stanley and/or LN say about this?

BugBear

Re: #66 question

William Duffield, on the Cohansey

>An interesting observation, Paul. I'm looking forward to more observations and opinions.

IIRC, L-N recommends sharpening them by polishing the flats. The profiles of all the scratch stocks that L-N provides with their #66 are cut at 90� to the flats. Also, they are all conveniently bilaterally symetrical, so 90� makes them work just as well if you reverse them in the tool (maybe if they get dull part way through a job). The L-N scratch stocks are much thicker than the original Stanleys. In addition to less chatter (initially) they can be resharpened more times before becoming too thin to use without chatter. The tool holding arrangement of the #66 is very adaptable to different thickness of the tools, but precision is necessary in the width of the cutters.

Re. burnishing a hook: I note that it would be very difficult to apply a hook to the edges of these, especially to the fluting cutters. The steel used is also much harder (about Rc 58, IIRC) than saw steel, so finding a tool capable of burnishing a hook would be difficult even for the simpler profiles.

Re: #66 question

paul womack

>Also, they are all conveniently bilaterally symetrical, so 90� makes them work just as well if you reverse them in the tool (maybe if they get dull part way through a job).

It is very difficult to START a scratch tool at an end; it's dramatically easier to start in the middle and run off the end.

Of course, any real workpiece has 2 ends, which means if your tool won't work both push AND pull, you're in trouble.

I suppose (in theory) you could reverse the cutter, and move the fence to the other side, to reverse the tool's direction, but I suspect it would be tricky to do this accurate, and tedious at best.

BugBear

Re: #66 question

paul womack

>maybe if they get dull part way through a job

Forgot to say - I've never blunted a scratch stock cutter. I will admit to not doing much woodwork, and normally working on small pieces, but those 90 degree bevels sure are sturdy!

BugBear

Re: #66 question

William Duffield, on the Cohansey

>I've not had problems with blunting or dulling of mine either. The only ones I would expect you might have to rehone are the unhardened blanks that you cut your own profiles into. Of course, being unhardened, they are also relatively quick to rehone.

Re: #66 question

William Duffield, on the Cohansey

>I guess I was not clear. I only mentioned the symetry w.r.t. having two useful edges from the same tool, instead of just one, as with a molding plane. Of course, starting a cut with a scraper is more difficult than with a molding plane, but even with molding planes, I use the method you suggest: starting near the far end, and back up my starting point with each pass to lengthen the profile. Sometimes, you can just cut the first inch or so (25 to 30 mm) off the front end of the board, where the profile is imperfect.

Re: #66 question

paul womack

> Sometimes, you can just cut the first inch or so (25 to 30 mm) off the front end of the board, where the profile is imperfect.

Yes - a good technique for applied mouldings, less good for "worked" table edges ;-)

BugBear