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Thread: Precision Tools in Woodworking

  1. #61
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    Quote Originally Posted by Richard Shaefer View Post
    Well, if you want to play that game, I have degree in engineering too. I'm also a professional engineer every day of the week, I teach a masters class in bridge design, and I'm an expert in seismic retrofit design, and engineering materials science.

    As I said before, I'm happy that you have methods of work that suit your needs.
    But I think you take it too far by at least a full order of magnitude.
    Just a suggestion here, but you might be happier sharing your methods of work and how they have helped you and just leaving it at that rather than being offended by others who may disagree.
    Like I said, just a suggestion.
    Thank you for your suggestion.

    I have no problem with people that disagree with me. After all, this forum is a place for people to share their opinions, and those opinions are going to clash. And you will note that I did not respond to those that objected to things I actually wrote in my post.

    But I do not feel it useful to remain silent in cases of misunderstanding. You wrote that wood could not be measured to .0001" because it is so soft the micrometer would crush the wood. That may or may not be, but the fact remains that nowhere did I suggest using a micrometer to measure wood to the ten thousandth. Go back and check.

    If you are interested, I use a digital caliper to measure wood thickness when planing by hand or by machine. By pure coincidence, my Mitsutoyo measures to the ten thousandth of an inch, but it would be silly of me to suppose that measuring to .0001" would be useful outside of a CNC production situation, or that a dial caliper with its big jaws could actually measure wood to that level consistently. I ignore the last digit. And ignoring that last digit is irritating. The next caliper I buy will not measure beyond .001". Once again, I do not suggest using a micrometer to measure wood, nor do I suggest that readers of this forum should measure to the ten thousandth of an inch with any tool. Please do not accuse me of being an idiot, or for not paying attention in school, for something I did not write.

    One thing I learned while working in the industry is that, while there are similarities, steel and wood are not the same, as you correctly pointed out. They have very different engineering properties. Consequently, there are significant differences in how wood must be handled to achieve consistent tolerances. But that doesn't mean that it can't be done, just that most people don't know how to do it. The truth is that the people on this forum don't need to concern themselves with such tolerances, therefore, I apologize for even mentioning that CNC machines could cut/mill wood to high tolerances, and for the misunderstanding that factual statement has created.

    Another post ridiculed the specs that I recommended. What specs? What recommendation? I simply told of two of my experiences that actually mentioned tolerances, one about the accuracy of a particular steel tool, and the other about some CNC machinery. But I did not recommend a single spec, or tolerance, or numerical value to anyone, nor did I suggest that the readers of this forum should follow some specific specs or tolerances. Go back and check. If someone disagrees with me, that is their right, but if they post a criticism of what I wrote, I insist that criticism be about something I actually wrote, and not attribute nonsense to me. If left alone, incorrect attributions often come to be perceived as factual.

    Thank you again for your entirely correct suggestion.
    Last edited by Stanley Covington; 02-12-2013 at 8:12 PM.

  2. Quote Originally Posted by Stanley Covington View Post
    Thank you for your suggestion.

    I have no problem with people that disagree with me. After all, this forum is a place for people to share their opinions, and those opinions are going to clash. And you will note that I did not respond to those that objected to things I actually wrote in my post.

    But I do not feel it useful to remain silent in cases of misunderstanding. You wrote that wood could not be measured to .0001" because it is so soft the micrometer would crush the wood. That may or may not be, but the fact remains that nowhere did I suggest using a micrometer to measure wood to the ten thousandth. Go back and check.

    If you are interested, I use a digital caliper to measure wood thickness when planing by hand or by machine. By pure coincidence, my Mitsutoyo measures to the ten thousandth of an inch, but it would be silly of me to suppose that measuring to .0001" would be useful outside of a CNC production situation, or that a dial caliper with its big jaws could actually measure wood to that level consistently. I ignore the last digit. And ignoring that last digit is irritating. The next caliper I buy will not measure beyond .001". Once again, I do not suggest using a micrometer to measure wood, nor do I suggest that readers of this forum should measure to the ten thousandth of an inch with any tool. Please do not accuse me of being an idiot, or for not paying attention in school, for something I did not write.

    One thing I learned while working in the industry is that, while there are similarities, steel and wood are not the same, as you correctly pointed out. They have different very engineering properties. Consequently, there are significant differences in how wood must be handled to achieve consistent tolerances. But that doesn't mean that it can't be done, just that most people don't know how to do it. The truth is that the people on this forum don't need to concern themselves with such tolerances, therefore, I apologize for even mentioning that CNC machines could cut/mill wood to high tolerances, and for the misunderstanding that factual statement has created.

    Another post ridiculed the specs that I recommended. What specs? What recommendation? I simply told of two of my experiences that actually mentioned tolerances, one about the accuracy of a particular steel tool, and the other about some CNC machinery. But I did not recommend a single spec, or tolerance, or numerical value to anyone, nor did I suggest that the readers of this forum should follow some specific specs or tolerances. Go back and check. If someone disagrees with me, that is their right, but if they post a criticism of what I wrote, I insist that criticism be about something I actually wrote, and not attribute nonsense to me. If left alone, incorrect attributions often come to be perceived as factual.

    Thank you again for your entirely correct suggestion.
    Maybe you could try articulating exactly what we are supposed to do with these sensitive instruments in one paragraph. I assume if we're not supposed to measure wood then we're supposed to measure machines and other tools. Then what? What is it EXACTLY that you propose we do with this information besides wring our hands?

  3. #63
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    Ok, A little table i made awhile ago, just for example. I MIGHT have used a tape measure, once, maybe twice during the entire build. For some reason, i can not see worrying about .0001" in wood. It may vary from one day to the next, depending on weather conditions in the area. What fit perfectly one late afternoon, might not fit at all, or be too loose the next morning. The wood computer desk I am sitting at , has breadboard edges. They are now 3/8" too long, due to the dry winter weather. Next June or July, they will be just the right length, again. Does a "precision tool" account for such items??

    Steel will move as well. Remember that a steel bridge needs to be assembled from parts, and if the sun should heat them up enough, it will be hard to install the last bit of frame work. The rest has "swelled" enough to make the last opening too small. SDC14252.jpgSDC14230.jpgMy squares.

    Yes i use a square, or two, just for layout work. mainly as a guideline from my handsaw to follow. Layout a mortise, or a tenon. Just lines to guide the hand tool. Nothing more, nothing less. As for the tableSDC14280.jpgLooks good from here. Daughter loves it, and, it matches her Grandmother's old chair.
    Last edited by steven c newman; 02-12-2013 at 8:45 PM.

  4. #64
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    Maybe folks didn't make it this far down in the original post (it was rather long). Its worth pointing out that nowhere did Stanley say these were required to do good work or that we all needed to run out and buy them... in fact he stated up front what a lot of folks seem to be saying as rebuttals.

    Quote Originally Posted by Stanley Covington View Post
    If you have been working with tools for a long time and think this is all nonsense, then I wish you well. But there may be guys without your skills that might find these ideas useful so retain your flames. I am not saying this is the only way to get the job done. After all, folks were making excellent furniture millennia before mankind could even hope to measure a thousandth of an inch. And there are lots of tricks for magnifying errors in woodworking to make them obvious. What I am saying is that, long-term, three precision tools can make the job easier and more efficient and give you greater confidence in your other tools.
    I'm not going to run out and buy this stuff either, but I still appreciate learning what tools he finds beneficial, in what capacity and why. I wonder how many of the people who are so offended (as opposed to simply in disagreement) would be singing the same tune if they paid $400 for a new plane and learned that it was out of tolerance.

    Again, I have the same disagreements, and am in the camp of "a tool is as a tool does" and also "if it looks/acts square, flat, even, fair,,, whatever, than it is good enough" but I can still understand appreciate the other perspective...

    ( Of course, the fact that I have a bachelors degree in pyschology and an Ivey League masters degree in education makes me more qualified to understand multiple perspectives than the rest of you... I would insert a giant eye-rolling smiley con here but they don't make one big enough for me to thoroughly convey my level of sarcasm)

    Anyway, I'll say again. This has been an interesting thread... if nothing else good food for thought, and I appreciate Stanleys, detailed descriptions and clear explanations of his points despite the fact that they may not be my thang. This thread has also evoked some good discussion different sorts of measuring equipment and in what aspects of woodworking (if any) higher tolerances may be especially helpful.


    Last edited by Chris Griggs; 02-12-2013 at 9:19 PM.
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  5. #65
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    Ah, you want the executive summary. Here we go, step by step.

    1. Get three reliable measuring tools, a diemaker's square, a straightedge, and a micrometer. Do not use them for daily work, but set them aside, carefully protected. Let's call these tools "Standards."

    2. Using these Standards, test the accuracy of any layout and measuring tools you are considering buying before you buy them, if possible. If your tests reveal that a tool does not meet your personal expectations for accuracy, decline to buy that tool. Alternately, if it is not possible to test a tool before buying it (i.e. an Ebay, catalogue, or internet purchase), use these Standards to test the tool upon receipt. If it fails your test, either return it to the seller, or dispose of it otherwise, but do not rely on it. You may also want to test the precision of other tools, for instance, the flatness of a plane's sole or the angle between sole and side if you intend to use it for shooting.

    Note: The diemaker's square can be used to test for square, of course, and for flat/straight. The straightedge can be used to measure flat/straight over distances your diemaker's square can't. The micrometer can be used to test the precision of a vernier/dial/digital caliper. Keep in mind that you cannot reliably test the precision of one tool using another tool of equal or lesser precision. For example, if the caliper you are testing reads to .001", then the tool being used to check it must be able to accurately measure to at least .0001". The same principle applies to squares and straightedges. An example of how not to test would be to go to Home Depot and try to test the accuracy of one Empire brand framing square by using another Empire brand framing square taken down from the same wall. On the other hand, going to a Rockler store and testing a 6" Crown square against a 7" Incra guaranteed square, while not ideal, at least makes sense.

    3. Using these "Standards," periodically re-test your layout and measuring tools (and any other tools you deem necessary) to determine if they still meet your personal expectations for accuracy. The frequency of this periodic testing will vary from person to person, of course, but it makes sense to base it on how frequently, and how hard, you use your tools. If your tools meet your expectations, all is well. If they don't, then you have to make the decision to either ignore, repair, replace or do without.

    4. If, during the normal course of events, you suspect one of your layout or measuring tools (or other tool) is out of tolerance (i.e.a layout square shaved repeatedly by a marking knife), or has been damaged, perhaps due to a fall from your bench to a concrete floor, for instance, test it using these "Standards" to ascertain if it still meets your personal expectations for accuracy. If it does, all is well. If it doesn't, you have to make the decision to either ignore, repair, replace or do without.

    I hope that is concise enough. Please cease the wringing of hands.

    Stan
    Last edited by Stanley Covington; 02-12-2013 at 10:27 PM.

  6. #66
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    Of course, the fact that I have a bachelors degree in pyschology...
    That must be some rarified field. Looking it up gave me no clue as to what it is. Picture 2.png

    jtk
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  7. #67
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    I haven't seen any digital caliper that would measure closer than a half thousandth. That's why I prefer a dial caliper. Easy to interpolate to a quarter thou. by where the needle falls. Of course,over several inches,calipers are not accurate to .001" anyway,but for comparative measuring,when I want 2 pieces of metal to fit just to each other,they are fine. I also don't want to deal with battery failure,oct excessive battery failure found even (or especially) in Starrett digital calipers.

    By the way,working to a tenth of a thousandth even in steel is not the easiest thing to do. This was alluded to earlier. The machined surfaces are rougher than that small a measurement,and precision grinding is usually resorted to in order to even get surfaces that are smooth enough to warrant that measurement. Holding master precision levels in the hand will warp them some. I wear gloves when leveling my metal lathes with mine. How many here have actually worked to tenths?

    By the way,where can I find a digital caliper that measures to .0001"?
    Last edited by george wilson; 02-12-2013 at 10:40 PM.

  8. #68
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    Quote Originally Posted by george wilson View Post
    How many here have actually worked to tenths?
    By the way,where can I find a digital caliper that measures to .0001"?
    Sorry I'm not actually in this conversation, but I have to answer this. Me. +\-.0002 was real common when I was in the mold making business. And .00005 occasionally, but that's a whole different world. Temp control, vibration control, Moore jig bore mounted on 4 ft of concrete foundation, but not in my home shop. And defiantly not with a caliper! Splitting a thou is quite common but there are still a lot of machinists that don't have the knack. They can sometimes fit something close but as far a holding the numbers consistently they lack the focus.
    Ok I'm just bragging, back to the sideline for me.
    Alright on edit I'll weigh in on topic also. The only true precision tool I use for wood is my dial caliper. I like it for measuring board thickness when I use my thickness planner and occasionally when I rip a board to width on my table saw. But it is a bit of a crutch. I learned machining way before taking up this sport and I'll never be able to unlearn.
    Last edited by Leigh Betsch; 02-12-2013 at 11:25 PM.
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  9. #69
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    Quote Originally Posted by george wilson View Post
    I haven't seen any digital caliper that would measure closer than a half thousandth. That's why I prefer a dial caliper. Easy to interpolate to a quarter thou. by where the needle falls. Of course,over several inches,calipers are not accurate to .001" anyway,but for comparative measuring,when I want 2 pieces of metal to fit just to each other,they are fine. I also don't want to deal with battery failure,oct excessive battery failure found even (or especially) in Starrett digital calipers.

    By the way,working to a tenth of a thousandth even in steel is not the easiest thing to do. This was alluded to earlier. The machined surfaces are rougher than that small a measurement,and precision grinding is usually resorted to in order to even get surfaces that are smooth enough to warrant that measurement. Holding master precision levels in the hand will warp them some. I wear gloves when leveling my metal lathes with mine. How many here have actually worked to tenths?

    By the way,where can I find a digital caliper that measures to .0001"?
    George

    Thanks for the insight. The Mitsutoyo digital caliper is a 500mm unit I bought in Japan around 2004 for measuring glulams. They don't show it in their product line anymore. And you are right, it reads out to .0005" in inch mode, not .0001". And that extra digit makes it a pain to read.

    Since you are a professional machinist, what brands or even specific tools would you recommend nowadays?

    Thanks,

    Stan

  10. #70
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    If flat and square are not important; why do people flatten the backs of plane blades? Is it so we can make a flatter surface with our cambered blade? Why do we lap the soles of planes? If our square is off and we saw to that line do we fix it with our equally crooked shooting board? These are things I'm asking myself and learning as I go. I'm learning what good equipment is and what close enough is and how a lot of times its not. When I did metal fab work (30 years worth) some people's close enough was and some people's wasn't; but the tools never lied. They were consistent; weather accurate or not they did it the same every time. It was up to you to learn the tools and make them perform better than their condition. In my woodworking if the end result is not close enough; I ask my self was it my focus, my skill or my tools. As mentioned by someone earlier I disappoint my tools a lot. If I find its skill/focus I work on that. If its the tool I repair, replace or figure a way to make it work knowing its limitation. You have to be able to determine if its the tool or you though. If a more precise square or straight edge improves my end result and saves me time and material I might talk my penny pinching self into spending the money; after I wasted about five times that much time and material though. Precision; is it a tool that you start with or something you figure out on the way?
    Threads like this can be good food for thought. Hay lets get into marking tools because if your using a pencil instead of a marking knife and your knife is not single bevel well then; oh never mind.
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  11. #71
    [QUOTE=Mark Dorman;2062664
    Threads like this can be good food for thought. Hay lets get into marking tools because if your using a pencil instead of a marking knife and your knife is not single bevel well then; oh never mind.[/QUOTE]

    Funny enough, I find I'm more accurate with a pencil than a knife. For some reason, I find it very easy to split a pencil line, and very hard to nail a knife mark. When I'm marking things off, sometimes I'll intentionally make the line fatter than it needs to be, in fact. Let's say I want to mark off a measurement. I find it very difficult to put the pencil down EXACTLY where I want it and mark, so lately what I've been doing instead is making a mark as close as I can, and then I widen it a bit so that the measurement I want is dead center of the width of my mark. If I overshoot a touch, no problem...I just widen the other side a touch and I'm back in business Maybe that's difficult to visualize. I should make a video. Anyhow, that's so much easier than make a mark...woops...erase the mark...make another mark....grrrr....erase.....

    When I do it, it feels like this should be one of those tricks that we all learn about, but I've never seen it talked about anywhere. It probably even has a fancy name, like "fat marking" or something. Someone help me out here.

  12. #72
    Stanley, I did understand you were using the Standards to calibrate your other meassuring tools. Of course, in specifying a set of standards you implicitely define the specs you want to work with in woodworking. It all goes together. The precision you want in your woodwork is reflected in the Standards you keep in the closet. And the other way around.

    You really only need a good straightedge. You can make these yourself. Plane the edges of two battens and compare them to each other. Or put a sheet of sanding paper on a piece of thick floatglass and use that to straighten the batten. There are probably more tricks, but I just splurged and bought a steel straightedge with a DIN "certificate". A chinese one of course, because that is plenty good enough for me.

    When you have a reliable straightedge, you can use it to find or create a straight section on your workbench and use that to calibrate your squares.

    And I have still no idea why you want to meassure thickness of wood with a dial or vernier caliper. You can use a marking gauge to compare boards and see if the faces are parallel. And thing like tenons are fitted to size.

    So I still think you are going overboard with your precision tools. But if it makes you happy, I won't argue against that.

  13. #73
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    Quote Originally Posted by John Coloccia View Post
    Funny enough, I find I'm more accurate with a pencil than a knife. For some reason, I find it very easy to split a pencil line, and very hard to nail a knife mark. When I'm marking things off, sometimes I'll intentionally make the line fatter than it needs to be, in fact.
    Very interesting. For many years I have used a marking knife for anything I thought needed precision. I still do, for the most part. For layout requiring less precision, like a cut with a skillsaw, I tend to use an inkline or a carpenter's pencil sharpened to a chisel point.

    But I was in the Woodcraft store in Stanton CA one day and purchased Rob Cosman's dovetail DVD because a friend had praised his techniques, and because we share the same alma mater. I was shocked to see him using, not a knife, not a pencil, but a ballpen! I was scandalized.

    But one day a few years later I was laying out tight dovetails in 1-1/4" thick softwood and found my knife was wandering all over the place. On top of that, I couldn't see the knife marks when I was done. I guess my aging eyes were letting me down. So I tried a ball pen, just like Rob shows in his DVD, and found it worked very well indeed. Of course, I still lay out pins using a knife. I find myself using a ballpen more and more, and a pencil less and less.

    I have since bought most of Rob's DVD's.

    Thanks, Rob!

    Stan

  14. #74
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    Quote Originally Posted by Kees Heiden View Post
    Stanley, I did understand you were using the Standards to calibrate your other meassuring tools. Of course, in specifying a set of standards you implicitely define the specs you want to work with in woodworking. It all goes together. The precision you want in your woodwork is reflected in the Standards you keep in the closet. And the other way around.

    You really only need a good straightedge. You can make these yourself. Plane the edges of two battens and compare them to each other. Or put a sheet of sanding paper on a piece of thick floatglass and use that to straighten the batten. There are probably more tricks, but I just splurged and bought a steel straightedge with a DIN "certificate". A chinese one of course, because that is plenty good enough for me.

    When you have a reliable straightedge, you can use it to find or create a straight section on your workbench and use that to calibrate your squares.

    And I have still no idea why you want to meassure thickness of wood with a dial or vernier caliper. You can use a marking gauge to compare boards and see if the faces are parallel. And thing like tenons are fitted to size.

    So I still think you are going overboard with your precision tools. But if it makes you happy, I won't argue against that.
    I think we are talking about different types of woodworking, Kees, and there is nothing wrong with that. Whatever gets the job done for you is what you should use.

    You wrote "when you have a reliable straightedge." That is the whole point of my post, Kees. You and I just have different definitions of the word reliable.

    The matched batten tool you mentioned is very very ancient and pretty good. In fact, one of the first tools I was told to make as a young man was just that. I copied the one the old boy that taught me kept in his toolbox. I used a piece of fine-grain quartersawn hinoki (believe it or not the wood was once a piece of Ise Shrine). I cut the stick in half and then connected the two pieces together with two sliding dovetail pins. I also added a bamboo wear strip on the edge of each batten because hinoki is a bit soft. In Japan they call it an "awasejogi"合わせ定規 which translates to "opposing rulers." I still use it for truing the soles of my wooden-bodied planes. I love that little thing, but frankly speaking, its not nearly as reliable as my 24" Starrett straightedge, or even my much cheaper Shinwa straightedge, and its a lot harder for me to accurately judge the gap between the wear strip and the surface I am testing. But if matched battens work well for you, great.

    You wrote that you have no idea why I would want to use a dial caliper. Have you tried using a dial caliper for measuring wood thickness? A lot of people find them pretty handy, and decent Chinese made units can be bought very cheaply nowadays. Here is one example where a caliper can be handy. As you know, a good handplane is a very precision tool that can shave a thousandth of an inch reliably with every stroke. If you measure the thickness of your plane shavings at a particular setting, a caliper can help you determine how many strokes are necessary on one one side of the board to make it closely match the thickness of the opposite side. That can save a lot of trial and error and squinting at marking gauge lines when prepping material.

    Is a dial caliper essential? No. And I am not saying you must use a dial caliper to do good work, Kees, just that I, and many people, find them very useful. The micrometer I suggested just helps to make sure the caliper is measuring correctly.

    I agree with you totally about tenons.

    Best of luck.

    Stan

  15. #75
    Yes, we work differently with different perspectives. I did like the discussion a lot though and think it is good when both views are displayed in the same thread.

    BTW, I use my vernier calipers often because it is such a handy nifty little tool, but in woodwork I don't use it for its accuracy. In the little metal work I still do, I use all the tools you describe though.

    Nice story about that Japanese straightedge. I like that kind of stuff.

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