Back Flattening

[David C]

If I am not mistaken, this thread was about rescuing old tools where the back was in a dreadful state.

David C

 

[Joel Moskowitz]

I am a bit mystified by the new Ray Iles OBM design with a rounded back. Can't be a good idea IMHO.

cheers
Jacob

Inless you are using the term "back" differently than i the backs of the Ray Iles Mortise chisels are flat. The front above the bevel are slightly rounded for comfort but they as they are above the bevel they do not interfere with cutting - and in fact are a historical detail you sometimes find on very old (18th century) mortise chisels.

 

[dunbarhamlin]

The primary bevels of one Ray Iles chisel I have is decidedly askew (lines drawn perpendicularly across the face and bevel would not be parallel) though the original secondary bevels were such that the cutting edges were true. Am nibbling away at one side of the primary each time I sharpen to try and remedy, as it does indeed seem to it them prone to consistently damage one side of the mortice when prying out. It doesn't seem to affect direction of cut much, though I am using soft stuff at the mo, and I don't believe it is a technique issue as another is not so afflicted and doesn't show the same tendency.

 

[Anonymous]

I am a bit mystified by the new Ray Iles OBM design with a rounded back. Can't be a good idea IMHO.

cheers
Jacob

Inless you are using the term "back" differently than i the backs of the Ray Iles Mortise chisels are flat. The front above the bevel are slightly rounded for comfort but they as they are above the bevel they do not interfere with cutting - and in fact are a historical detail you sometimes find on very old (18th century) mortise chisels.

I was taught to call them face/back rather than back/front. As it seems more logical I thought I'd stick with it.
Yes I suppose the rounded back won't affect the cut as all the wedging action is at the bevel end even when the chisel is buried in the mortice. Don't see what it has to do with comfort though, as you don't let go of the handle in use.

cheers
Jacob

 

[mudman]

"Tune" an OBM? :lol: :lol:
Just needs to be sharp. Doesn't matter about flat face, although needs to be geometrically regular in section as someone pointed out, otherwise it could twist I suppose.
I find all this tuning stuff a bit odd, it's as though every newly aquired tool should be re-machined as though it's just an unformed bit of steel.
In reality most things just need a quick sharpen and you are off. Rust and pitting disappear with use unless extreme.
PS

Boggs: The bottom and sides of the blade
must be flat and square (the top of the blade is irrelevant).

He's wrong, ideally the side are tapered, so not sqaure with the face, the back matters too i.e. has to be parallel to the face as the face/back wedging action is essential part of using an OBM, unlike most other chisels.
I am a bit mystified by the new Ray Iles OBM design with a rounded back. Can't be a good idea IMHO.

cheers
Jacob

Edited to remove original posting as I don't want to start any arguements.

Suffice to say.
Chisels = knackered = lots of work to put right = satisfaction at end of day.

 

[mudman]

If I am not mistaken, this thread was about rescuing old tools where the back was in a dreadful state.

David C

Thank you David, that is exactly what this thread is about.

 

[Anonymous]

snip
Chisels = knackered = lots of work to put right = satisfaction at end of day.

That's alright then if it keeps you happy :lol:
Wouldn't bother myself - if that knackered I'd bin them, they don't cost a lot.

cheers
Jacob

 

[Derek Cohen (Perth Oz)]

I would like to add a few nuggets to this discussion.

And, as David noted, this is about rehabbing old mortice chisels. I have done a bunch over the years and this is what I recommend.

The back of the chisel must be flat, not rounded. You cannot get a sharp edge otherwise. What you will instead find is a permanent wire edge (burr) identical to the effect of a wear bevel on a plane blade. The presence of this wire edge after you have done the usual tghings to remove it indicates that the back is not flat enough.

The problem is (1) getting the back flat with the least of effort, and (2) maintaining the "squareness", that is, bearing in mind that the sides of an OBMC are tapered.

Lapping the back is done using sandpaper, as per my article at
http://www.wkfinetools.com/contrib/dCohen/z_art/lappingBlade/lappBlade1.asp

I usually start with 80 or 120 grit, depending on how much needs to be removed. I would not use an Extra Coarse DMT (I do have one) as this is 220 grit, and you will find it too slow (and just wear out the DMT).

The more difficult/crucial aspect of the OBM variety is keeping the tapered sides centred. This translates to keeping the backs flat on the sandpaper - not tilting them one way or another.

In my article I only have to deal with square sided plane blades. I used a magnetic base to hold the blade. I do the same with chisels. The rectangle provides a decent reference to gauge whether I am level.

A variant to the is to add a cross bar to the top (or to the chisel back - especially the narrow 1/8" ones). I recall BB writing up this tip when sharpening saw blades.

Regards from Perth

Derek

 

[MikeW]

Wanna have some fun?

Quick--everyone here do a *short* non-argumentitive, non-wordy definition of:

Back = ******
Face = ******

On a chisel.

No fair looking in your favorite reference. Really: NO LOOKING.

In other words, state which side of a chisel is the face, which is the back.

Replace the asterisks above with two simple words:

Beveled side
Non-beveled side

I think some of the confusion/argument is due to these definitions.

Take care, Mike

 

[MarcW]

...
Back = ******
Face = ******
...
Beveled side
Non-beveled side
...
I think some of the confusion/argument is due to these definitions.
...
Take care, Mike

Hi Mike,

Thought that too... that's why I earlier gave a hint in this thread. We had that problem some time ago...

back-seat-driver mode out now

Face = non-beveled side, i.e. the side that has to be flattened

Cheers,

Marc

 

[Anonymous]

snip
Face = non-beveled side, i.e. the side that has to be flattened

Cheers,

Marc

Agree. Same with plane blade, similar with saw i.e. back is opposite the cutting edge.

cheers
Jacob

 

[David C]

Hampton & Clifford in "Planecraft" use face,

Garrett Hack uses back,

So far I can find nothing in Joyce!

David C

 

[MarcW]

Robert Sorby mentions in their catalogue 05/06:

...The face of each chisel has an indentation point...

The indentation is on the side that has to be flattened... at least on my RS chisels.

Cheers,

 

[Anonymous]

George Ellis uses back and face i.e. flat side for face, on plane irons. Doesn't seem to mention chisel sharpening, but that was in the days when sharpening wasn't really a problem.

cheers
Jacob

 

[Derek Cohen (Perth Oz)]

I always thought that the back-face distinction was thus:

Regards from Perth

Derek

 

[Anonymous]

Derek
What would you call the (side) opposite to your back? Front? Top?
Why call the bevel face as well?

cheers
Jacob

 

[Derek Cohen (Perth Oz)]

Hi Jacob

I think that the "face" and the "bevel" are not completely interchangeable. Almost but not completely.

We could talk of the "bevel face" to mean the entire area comprising the bevel. For example, the bevel face is hollow ground, or the bevel face is flat ground.

So why then not just use bevel or face? Because we could also talk of the "bevel edge" to mean the intersection between the bevel face and the back of the blade.

Is there a "front"? I think so (the opposing side to the "back").

Similarly, I often use "shoulders" to refer to the sides of a blade, particularly when describing the nature of the bevel here, such as dovetail verses firmer chisels. I think of "narrow shoulders" or "shallow shoulders" verses "full shoulders".

I emphasize that this is my terminological logic (if there is such a word/phrase ) - it is interesting that others see this differently.

Regards from Perth

Derek

 

[Sgian Dubh]

Far too much anal nit-picking going on in this thread.

Just flatten the bloody things on the back a bit if needed, the flat bit opposite the honed edge, then just sharp'n'go so to speak.

How is it possible to make such a common or garden task so blasted involved? If there's any more analysing and debating of minor details goes on I swear we'll be attempting to raise this straightforward maintenance task into one of the worlds most involved and mysterious arts; an art that requires groups of priests, incantations, zen like chanting and swinging incense holders to achieve.

It's all getting just plain silly. Slainte.

 

[Derek Cohen (Perth Oz)]

How is it possible to make such a common or garden task so blasted involved?

Actually I wasn't aware that defining sections of a blade was anything more than an attempt at simplifying communication. Or should we go back to grunts? :lol:

What we do with, or how we use, this information is another thing of course. That is where anality can enter the picture.

Regards from Perth

Derek

 

[dunbarhamlin]

Problem is when meanings are reversed it makes communication unreliable.

I'd rather my assets were decimated than halved, but misuse of 'decimate' (reduce by one tenth) has rendered this a foolish assertion in the eye of the majority. Which is right? Both - but common ground must be established before meaningful discourse can proceed.

Steve