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Q on the rules redux - with some numbers

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Q on the rules redux - with some numbers

#1

Q on the rules redux - with some numbers

Denis Ch�nard, Orl�ans, Ont.

>Since it's already way down in the page...

PK wrote:

"But, you are making your own rule right there. I would certainly agree with "why not?", but that is a far cry from "should". You are arbitrarily saying that if a jack can't smooth it, then it is not flat enough. Says who? You? That makes it a rule? Why not say if a jointer can't do it, then it isn't flat enough? It all sounds very arbitrary to me. That is the point! We all have different ways of working. For you, it should be jack-flat. For me, smooth-flat is good enough, and using a jack is a waste of time in certain cases. Now you object to my smooth-flat 'rule', yet introduce your own rule that it "should" be flat by jack standards. "

First, I didn't say "should", but "shouldn't it?" Slight difference here...

I did spend some time running numbers, comparing a "generic" #4 vs. a #5. The #4 (Record) is 9" long, with the mouth set back 2 1/2" from the toe. I couldn't find info on the Stanley #5, so I used the Groz I have here (which seems to be the same in size to the Stanley). 14" long, with the mouth set back 4 1/8" from the toe.

My scenario is of a board that bowed upwards (i.e. the top is concave lengthwise) by 0.002" from the sole, measured at the center of the #4. That would give a warp of about 1/64" over a two foot length.

Because the blade is not centered, a #4 set for a 0.002" thick shaving will take a shaving about one-half of a thou. A jack set for the same shaving thickness wouldn't take anything except at the ends. The jack in this situation would require another 0.002" depth of cut in order to be able to take a shaving.

What this means is that a #4 used in this situation would smooth the board without removing the concavity, while a #5 wouldn't take anything in the middle of a board until the ends have been trimmed down. In the end, using a #4 would make a smooth, bowed board, while the #5 would both flatten and smooth it.

Now, if a 1/64" bow is acceptable to you, fine... I prefer to not be able to measure any "out-of-flatness"...

DC

Re: Q on the rules redux - with some numbers

#2

Re: Q on the rules redux - with some numbers

Dan Clermont in Burnaby

>Hi Denis,

Wood moves and we all have to live with that. I prefer to rough dimension wood on both sides and get it down to rough "proud dimensions" which is usually nmore then 16 thou or 1/64".

When I am close to glue up I put a day aside and try to do the joinery for the box or frame and panel in one go.

For example, before Christmas I started a computer storage unit which is done with han tools. I got the wood pretty close to final thickness. I then spent four hours sharpening plane blades and smoothing the panels. I then took the complete day to dovetail the box together(30" by 36")and took the time to miter the corners by hand.

The thing is you are best to final smooth the panels before assmebly and in some cases it is best to apply a finish beforehand. Who cares if a panel dips 1/64" after glue up over 2 feet? You are working wood not melamine. Who is going to notice a frame and panel door which is 16 thou concave and if it bothers you then when it comes to making the frame do so with a 1/64" smaller groove.

This is getting carried away.

Dan Clermont

Re: Q on the rules redux - with some numbers

#3

Re: Q on the rules redux - with some numbers

Greg Sloop, Portland Oregon

>HEY! Are you trying to confuse me with some reasoned evidence and clear thinking?!

I don't need no stinkin' evidence.

[Runs around screaming "Nayya, nayya, nayya! I can't hear you!]

*VBG*

Cheers,

Greg

Re: Q on the rules redux - with some numbers

#4

Um, yeah

Paul Kierstead

>1/64" is fantastic flatness for non-joinery of a surface, particularly panels. Since we don't even remotely agree on the goal, further discussion is pointless.

Re: Q on the rules redux - with some numbers

#5

Re: Q on the rules redux - with some numbers

Joel

>If you actually care about the 1/64" over 2' (and you may or may not depending on circumstance.)

and all you have is a #4 - plane the ends until the 1/64" is gone then plane the whole board. You have to pay attention to the board because the plane is short but it works fine. Much like planing a concavity out of a 6' board with a long plane. (same technique).

However if you have a nice wide 2' board, that is nice and flat, except for a little dip in one area - maybe because of a little tearout that needs to be removed, or different grain that moved. You could with a longer plane, be forced to plane the entire surface, just to level that area, or use a nice shorter #4 to make the job slightly easier and just plane locally.

It all depends on what you are trying to accomplish. (It's not rocket science).

Re: Q on the rules redux - with some numbers

#6

No argument

Denis Ch�nard, Orl�ans, Ont.

>

Re: Q on the rules redux - with some numbers

#7

Re: Q on the rules redux - with some numbers

paul womack

>If one wishes to smooth without flattening, one could adopt the principle of Japanese smoothing planes, which are useless for flattening (by design).

detailed thoughts

I have a cheap Stanley #4 converted to this principle, and using it is an interesting and disconcerting experience if one is used to flat soled planes.

BugBear

Re: Q on the rules redux - with some numbers

#8

Putting this in historical context

Bill Houghton, raining again...in Sebastopol, CA

>though I'm certainly not any kind of historical expert.

The rule is, do enough to achieve the effect you want/need to achieve. An ebeniste has different standards from a farmer, but both of them have standards, and neither one is wrong for the goal.

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