Jack Plane Flattness. How flat should it be?

[Lobby Dosser]

Heel, Toe, and Mouth should be flat and co-planer. And flat enough that you are satisfied with the output - no flatter.

[George]

Get a piece of glass. It's flat within the size of the finest grit you'll be using to lap the sole. If you're using paper, which has no thickness standard for either the backing or the thickness of the abrasive, MDF on your TS will be fine.

Essence of lapping, after all is getting to an _average_ by keeping things moving.

[David]

ah, buy a LV plane? I don't know any simple method of accomplishing at home, what LV does to the sole of their planes.

Dave

[bent]

yes, plates are supposed to conform to a standard and pass its tests. Which standards? With an item like this it wouldn't be worth your money without it. Most everything in the mechanical trades are. These are useful, interesting pages you could look up: (the information is endless). Knowing the code after the standard name is a code itself, date of inception or mod.

AGMA ANSI ASA ASME BS JAP DIN GGG ISO NEMA SAE ROCKWELL, Rc, Rb... ABEC

just one standard by one org encompases all the codes for all the steels. They team up. Buy copies. check their wwws.

Surface plates are sold by colour, The product should say what it is good for. They get incredibly accurate. They are several feet thick and dozens of feet wide and acuurate to a minimum of 1/10 000". Theres a million analyses and surface finish symbols. You literally have to be able to put a forklift on top of them and maintain this accuracy. Same with CNC machine tools. Parts are loaded on to them with forklifts and machined to 1/10 000" tolerances. You can get a dial caliper, inherent accuracy 1/1000" for $20 that is accurate to 1/1000". A dial is great. When you rock it you can see the dial go cw or ccw, tell you the exact hi/low spot. A micrometer is inherently accurate to 1/10 000" Screws are standardized for spiral runout, and absolutely everything from the angle of the head to the length of the unthreaded point, and the thickness of the plating, which is absolutely check, in conjunction with the thread profile check: two checks, three actually. Would ford buy unstandardized machine screws? Having markings is a givaway. ASME/ASTM is an example. Good/high standards(several levels) dictate what markings on the product are req'd to meet the standards. Size printed on drill bits, with rules about minimum printing relief. At the bureau of measurementds they actually keep a refernce of the size, say gage blocks, got a million bucks?. In temp, humidity, dust, light, air, etc. controlled . When you gotta check ya, you can base it on the speed of light, but what do you do, set up two speed of light machines side by side and do a comparison run? In some fields the entire science is driven by the standards. People say they get in the way. You can't find your hand in front of your face without them. All engineering in all tools are calculated based on preferred sizes. Anything you can't buy is wasted money. Machinerys Handbook, the bible.

sorry don't know the surface plate info.

[Mike Berger]

[bent]

N.I.S.T is another big one

the "Federal Specification" as opposed to Federal Standard, or anything else for granite surface plates is GGG-P-463c. Federal Specification coverage for master, calibration, inspection, and workshop gage block tolerance grades are under GGG-G-15C, March 20, 1975, which supercedes GGG-G-15B, Nvember 6,

1970.. Can't find or can't get in the www

[Tom Banes]

I suspect (tho' can't prove) that the deflection of an 18" long hunk of 1/2 (or 3/4) MDF under any reasonable hand pressure is so minimal that it's not in the equation. Is MDF flat - well it sure seems to be. My 1/1000 DI doesn't wiggle when I pass it across a clean piece (actually passing the piece under the DI). You're not going to put a heck of a lot of weight on it when sanding, at least not if you want the paper to survive.

As I said in my original response, the twisting that causes the rocking is far more of a problem than the absolute flatness of the sole. And, as other posters have noted, good enough is good enough.

You can read Jeff's notes at

's kinda considered an authority on "fetting" a plane.

Anyone know the origin of "fetting"? I've assumed it was a translation from the Scots brogue, but maybe there's another reason for the term.

Regards.

[bent]

not neccesary to be under standard to sell product in US unless say certain items -food. Some products are just lucky and can stamp std. approved. Some cheaper without. Some may but don't say it. Some may appear to be, but not in details. but for this you could prob find a std. And if it isn't, it would state something, and that may be in the class of a similar stdized product now to ask what good a surface plate is. i.e what other purchases it eliminates.

[bent]

thats JIS, I think

[Fly-by-Night CC]

snip

Yep I'd agree with you - use it as is for all your planing needs.

Fer criminey's sake, those people who flatten to 1 or even 5 thousanths have more time than sense. Are they trying to achieve an end result in the finished wood in the single digit thousanths? Just what's going to happen when the panel is sanded or scraped? Do they use 14" lapped sanding blocks to ensure the flatness left by the plane is retained?

Answer this: how many of the extraordinary pieces in museums and private collections were made with tools having any where near this precision? Those masters were using wooden planes that moved, to some extent, with the seasons. They were sawing by hand. They were flattening by hand to a reasonable degree of flatness - not measuring with surface plates and feeler gauges.

Learn how to establish reference faces and work off of those. Once that is understood all error and variance will become moot. You can spend hours upon hours flattening something that isn't going to transform your work into masterful art - or you can spend the time learning to use the tools at your disposal along with proper joinery techniques and come out far ahead.

[Lobby Dosser]

It is 'fettling'. Here's a good explanation:

[Dave W]

Just because the masters of old did not have access to surface plates etc. does not mean that the soles of their planes were not flat. Looking at a light with a straight edge, one can detect gaps smaller that one thousandth. IMHO the plane needs flattening!

[Fly-by-Night CC]

Have fun - I'll be out woodworking.

[Enoch Root]

"N. English make or repair. -- Origin ME (in the general sense 'to prepare'): from dial. fettle 'strip of material', from OE fetel, of Germanic origin.

I assumed it was divergent from 'fiddle' but that's a different word altogether, with its own origins.

er

[Enoch Root]

Listen, I got the 12x18 and wish I'd gotten the 18x24, and I'm sure I'd have still made wishes had I gotten that. :)

When I got them from enco (they have both grade B and A plates and the A plates are only a few dollars more) and enough other stuff to bring my total to $200 the shipping was free. BFG! Hey, is that a gloat?

er

[Mike Berger]

[CW]

Plonk