Jack Plane Flattness. How flat should it be?

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Well, this make some sense, a flat surface around the entire edge of the sole, and hollowed out in the middle by about 0.001. Are you sure that the slightly hollow is 0.001 inch. How did you measure that? I am wondering how I might put such a feature on my plane.
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djs wrote:

accomplishing at home, what LV does to the sole of their planes.
Dave
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They don't need to be "entirely dead flat" at all. To be good enough for accurate flat planing, just enough flat areas where it doesn't rock at all. If the plane is to be used for chuting (or with a shooting board), the sides of the body need to be an exact 90 perpendicular to the sole... that's the hard one... as you had done.

You got the great deal! ... hhhmmmm ... I know a couple of machinists!

The method I used worked, it took too long, but no rocking.

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Wow, 6 planes flattened to 5 tenths, for only 50 bucks. I don't have that option. And I may not need it either. I was talking to my brother-in-law a little while ago, and he is a big hand plane guy, and he advised me that smoothing planes don't really need to be as flat as a jointing plane. This is just the opposite what you say the folks at oldtools.org tell you. Now I wonder who I should listen to. I'll have to visit oldtools.org to see what they are all about. Thanks for the reference.
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Using a straight edge, and holding 6 of my planes up against sunlight, the gaps were bad.
I sanded and sanded, going as low as 60 wt sandpaper. Then 120 wet dry. After two weeks of this, the soles still had hollow patches near the mouth and heel & toe dips. The guys on oldtools.org informed me that only my No. 3,4,4 1/2 and 5 plane need to be dead flat. I was getting nowhere, and had expended $25 on sandpaper.
So I asked my neighbor, a machinist by trade, if his workplace had a good surface grinder. He said they make MRI equipment for hospitals. I gave him about 50lbs of planes and he returned two days later with transformed tools.
The soles were within .0005" flat, with no hollows anywhere. And, the soles are at 90 square with the sides. I gave him $50 for his trouble and consider myself lucky. These are all Pre-WWII planes. Some are pre WW-1 planes.
I've heard of guys using a belt sander clamped in a vise to accomplish the same thing. By hand, you might be digging the proverbial tunnel to China.
Gary Curtis Los Angeles
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How do you know how flat your piece of glass is? How do you support it so that it maintains its flatness when you are working a plane on top of it? I would think that any pressure down on the glass while working the plane's sole would deform the glass plate to a non-flat surface.
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First, you need to determine how flat it is. Comparing to your tablesaw top won't do it. Do you know how flat it is?

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CW, No I don't know how flat my table saw is, but I did move the plane around in a quite a few positions on the table saw top and also on the extension table top and every place I put it the result was about the same. So I am pretty sure the plane isn't flat by approximately the amount stated.
I considered testing it on a flat piece of glass, but how flat is that? Especially if it is sitting on a non-flat table. Flat is a hard thing to be absolutely sure about.
DJS
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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.
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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.
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It doesn't ELIMINATE anything, it augments what you have.
bent wrote:

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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
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thats JIS, I think
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Plonk

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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.
--
Owen Lowe
The Fly-by-Night Copper Company
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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!
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Have fun - I'll be out woodworking.
--
Owen Lowe
The Fly-by-Night Copper Company
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