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Attn Starrett No. 199 Owners!

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  • Attn Starrett No. 199 Owners!

    There was a discussion here a few weeks ago about the Starrett no. 199 master precision level.

    (http://bbs.homeshopmachinist.net/showthread.php?t=39090)


    YOD suggested that the levels are built with a degree of concavity on purpose and that they should NOT be scraped flat.

    Well I contacted Starrett yesterday and got the following response:

    Originally posted by Paul Nault (Starrett Tech Support)
    Yes they are made concave. If you scrap it flat, the heat of your hand could cause it to rock as the metal expanded. If the scrape marks look good, I would suggest leaving it alone.

  • #2
    interesting, did not know that, I guess it makes sense. whenever i've used mine, for scraping or for setting up a machine, its a comparative tool; in words being dead on level doesn't matter, is the relative position of the bubble when readings from two places are compared.

    if you want to scrape a concave surface, I have a surface plate you could use
    .

    Comment


    • #3
      I didn't know that either Tom! (One of the Starrett 199 owners)
      "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

      Comment


      • #4
        Bowing out - or in?

        Originally posted by Fasttrack
        There was a discussion here a few weeks ago about the Starrett no. 199 master precision level.

        (http://bbs.homeshopmachinist.net/showthread.php?t=39090)


        YOD suggested that the levels are built with a degree of concavity on purpose and that they should NOT be scraped flat.

        Well I contacted Starrett yesterday and got the following response:
        Originally Posted by Paul Nault (Starrett Tech Support)
        Yes they are made concave. If you scrap it flat, the heat of your hand could cause it to rock as the metal expanded. If the scrape marks look good, I would suggest leaving it alone.
        I missed seeing this post earlier.

        That's fine - I can see the logic.

        What I can't see is just how bowed it is and from that how far it needs to "bow" under hand heat until it is dead flat - and what the operating temperature range is.

        Next of course is if the level needs to be "re-done", just how "bowed" do you scrape it - and how do you actually and accurately verify it?

        Send it back to Starrett? At what cost?

        Comment


        • #5
          That is fine if you always have the whole thing on a surface, but sometimes you use it on parallels as checking twist on a lathe. Then concavity is a potential problem.

          I strongly doubt that the concavity is much... about as much as you would see by a lightening of the "marking" towards the center.

          personally, I'd make it flat, and pick it up with a cloth in your hand...... more versatile. better an error when I might expect it (when heated by hand) than perfect in bad conditions and bad in perfect conditions.
          1601

          Keep eye on ball.
          Hashim Khan

          Comment


          • #6
            Chewin' it over

            Well JT,

            you may have opened a can of worms here - again.

            If the level is only supported at the ends and is in affect a "bridge" between its ends and if it is able to twist, then it seems that there is a good case to have adjustable screws as a tri-pod with one screw on one end and the two other screws the other end. A tripod once settled will not rock.

            With that unknown "hump" it makes it a bit suspect as regards using the base of the level as a straight edge too.

            Which, given that a "Camel-back" bridge straight edge is machined and/or scraped flat and given too that the basic structure is similar, why is the same caution that is applied to the level not applied to the Camel-backed straight edge that people use as a reference for scraping other flat surfaces?

            And lets not forget the possibility (probability) of uneven lighting and uneven heating on the surface plate too.

            So, while others cogitate and obfuscate about that lot, I will get back to my machine-top faces and my float-glass "flats".

            Comment


            • #7
              Its a goodie

              Just as a matter of interest, I chased up the details of the Starrett 199 and similar level details at the Starrett web site.

              Very interesting.

              Their level castings are "seasoned", the base is scraped and there is no mention of any "curve" or "hump" either.

              The accuracy is about 1:24,000 (inch) or 1:25,000 (metric).

              The metric 1:25,000 is 0.0004:1 which is 0.0004"/" or 4 "tenths" of an inch per inch which re-stated is 4.8 tenths per foot which re-stated again is 1:25,000 is the Atan of 0.00292 degrees x 60 = 0.1375 minutes x 60 = 8.25 seconds which is pretty close to an 8" "Phase 11" or "Vertex" rotary table which is indexed (via the vernier) to 10 seconds.

              So.

              Let's not get sucked in by all the hype.

              It IS a VERY good level - it just is not all that some who "beat" or "hype" it up before having a look at - or understanding - what the figures really mean.

              I have no good reason to doubt its performance - or those made in other areas - such as Asia and Europe - either.

              The link to the *.PDF file on the Starrett web site is:
              http://www.starrett.com/download/338_p439_444.pdf

              Comment


              • #8
                I think it boils down to scrape it how you like it.

                I've gone for generations thinking Starrett levels were scraped flat. Starrett sales info and specs make a big deal out of their scraping job but they say nothing about a calculated concave sole intended to counter the heat absorbed from the user's hand. Given absense of information to the contrary, I've taken for granted the level's sole was flat. I've even used it as a scraping reference a few times when I needed something that size.

                I attributed the concavity I found to small changes in the level's frame casting over time. So now I hear from a trusted source supported with a quote from Starrett that the Starrett #199 level soles are deliberately scraped concave.

                I feel Starrett kept imporant information from me. I don't care if something is deliberately one way or another. I just want to know precisely what has been monkeyed with and why so when I use the tool to its maximum potential I can make the appropiate compensations.

                I don't know how many Starrett levels I've re-scraped flat thinking the frames warped over time. I even remarked on it in recent posts. Shame on me. Now I feel like an idiot and think of Starrett as patronizing the knowledgeable users of its products. It's as though a skilled user couldn't be cautioned about heat input from casual handling of a precision tool.

                I present myself as an arbiter of such things and to be ignorant of Starrett's scraping practice on their level soles after 50+ years in the trade is embarassing to say the least. I apologise to my justifiably shrinking cadre.

                All that said, the concavity is small (I estimate about 0.0005" over the length) and not enough to count unless you bridge the level inconsistantly across 1-2-3 blocks or something similar.

                Still the Starrett #199 level is a superb tool and should be used and trusted to the limits of its calibration - or better if reversal technique is used. I have several and their bases will remain flat as I scraped them. I will continue to handle them with cotton gloves when the degree of accuracy warrants; the heat of my hands will not unequally warm the frame and so distort the sole. Concavity/convexity is not an issue.

                If stuff is scraped with a deliberate bias as in the production Starrett#199 level it should be placarded on the tool, noted in its calibration cert, and on the storage box label.
                Last edited by Forrest Addy; 01-29-2010, 09:03 AM.

                Comment


                • #9
                  Originally posted by J Tiers
                  That is fine if you always have the whole thing on a surface, but sometimes you use it on parallels as checking twist on a lathe. Then concavity is a potential problem.............
                  That's likely why they come in so many sizes, that would be my guess.

                  If we are leveling a surface plate the level being concave is a moot point. If we are measuring machinery that has been scrapped dead flat it's still a moot point. But, it's not a moot point if we are measuring anything with a slightly convex surface. A flat level would simply teeter back and forth like a rocking horse on a slightly convex surface. How accurate could that be?

                  Don't they make dedicated straight edges for that use?
                  Last edited by Your Old Dog; 01-29-2010, 09:04 AM.
                  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                  Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

                  It is true, there is nothing free about freedom, don't be so quick to give it away.

                  Comment


                  • #10
                    Originally posted by Forrest Addy


                    I don't know how many Starrett levels I've re-scraped flat thinking the frames warped over time. I even remarked on it in recent posts. Shame on me. Now I feel like an idiot and think of Starrett as patronizing the knowledgeable users of its products. It's as though a skilled user couldn't be cautioned about heat input from casual handling of a precision tool.

                    I present myself as an arbiter of such things and to be ignorant of Starrett's scraping practice on their level soles after 50+ years in the trade is embarassing to say the least. I apologise to my justifiably shrinking cadre.


                    .
                    Forrest, you're as good a writer as you are metal worker, that was funny...I don't think you have to fret any cadre shrinkage.

                    when i read Tom's account, i thought of applications where I've used it, (none being as a spotting referece) and i can't see how the work would suffer for the concavity....Provided the level was in close to the same fore & aft position when checking a lathe, i don't think such small concavity would affect the reading......then again i wonder about all those bowed things you scraped
                    .

                    Comment


                    • #11
                      You cannot "level" a non-flat surface, but you CAN level between any two POINTS or LINES, and frankly, I don't want some "decision maker" at Starrett deciding that my level must be "pre-distorted" to compensate for something which may not occur if a person with some sense uses it. See below for disclaimer.

                      NOT ONLY THAT

                      It sounds like total bull$hit to me, even if some idiot at Starrett said it. And I use the term "idiot" advisedly.

                      If you "pick something up", you are probably holding it BY THE TOP PART.

                      So the TOP will be "heated" more than the bottom, which will EXPAND THE TOP, and BOW THE ENDS DOWN. Until it equalizes, of course.

                      In other words, that will make the concave scraping worse, i.e. the level will be MORE CONCAVE.

                      if you DO "equalize it" at a HIGHER temperature than teh machine, then when you set it down, the bottom will CONTRACT, BOWING THE CENTER UP and MAKING THE CONCAVITY WORSE.

                      Apparently the claim is that they are trying to compensate for people who pick it up, and set the contact surface of the level on their bare hand as they carry it around.

                      or for people who set a cold level on a hot machine surface.

                      ONLY THOSE actions (or similar) could heat the BOTTOM, expanding it and causing the ENDS TO BOW UP. ONLY THOSE could be compensated by concave scraping.

                      I ain't buying it. Someone is not quite telling the truth here. They probably ARE concave, BUT NOT FOR THAT REASON. Eitehr the concavity is totally ineffective, as suggested by some who say it doesn't matter, or it can matter.

                      I tend to think it is fairly inconsequential as far as measurement, and it brings up the point of why Starrett saw fit to bother.

                      My conclusion is that IT HAS NOTHING WHATEVER TO DO WITH HEATING, THAT IS ALL SMOKE AND MIRRORS. The TRUE REASON is that if you scrape it concave, very slightly, you will be sure it will sit flat. END OF STORY.

                      I have done that with vise bases, and other things which I wanted to have sit flat and not rock. It works, provided you KNOW about it, and there is no good reason why that is a problem for the device in use. Starrett most likely scrapes them that way for that reason, if in fact they DO put in a concavity. At a half tenth concavity, you may not even notice a slight lesser marking in the center. Might be a bit more than that, but probably not much.

                      Nothing like the "banana" I had to send back to Grizzly.

                      Originally posted by Your Old Dog

                      If we are leveling a surface plate the level being concave is a moot point. If we are measuring machinery that has been scrapped dead flat it's still a moot point. But, it's not a moot point if we are measuring anything with a slightly convex surface. A flat level would simply teeter back and forth like a rocking horse on a slightly convex surface. How accurate could that be?
                      Nonsense...........

                      How "level" CAN a non-flat surface EVER be? IT CAN'T BE LEVEL, of course......

                      So there is no point in discussing leveling a cylinder in the round direction..... and every convex part is essentially a portion of a large cylinder, albeit possibly not a perfectly round one.
                      Last edited by J Tiers; 01-29-2010, 10:13 AM.
                      1601

                      Keep eye on ball.
                      Hashim Khan

                      Comment


                      • #12
                        Forrest, no worries about your "shrinking cadre"! In regards to the level, I posit the following:

                        Starrett scrapes the sole slightly concave in order to keep the level from "rocking" on a flat surface. It is probably done as a "safety factor". If slight uneven heating/sunlight etc causes the sole to move, it will either become more concave (acceptable if you are measuring at the ends of the level) or it will become flat. I seem to recall reading that the levels should only be used at the ends - i.e. it should be supported at either end and no where else.

                        So it is a combination of what Starrett says and what JT says. I suspect it is done mostly to "cover their own a**es" but it does compensate for expansion due to uneven heating.


                        Anyhow, I didn't post this to criticize anyone or their practices. Just passing on an interesting tidbit of information I found

                        Comment


                        • #13
                          My mint 199 is also hollow. I never liked it,especially when I have to set the level on 2 parallels across my lathe's bed. What I've always done is just set the 199 with exactly the same amount of overhang at each end of the lathe,so that it doesn't give a false reading due to the concavity.

                          I also have always worn gloves when handling it. I agree with the above post that says that heating the TOP of the level would only make it MORE concave. Makes perfect sense.

                          I haven't tried to measure the concavity of my 199,but it sure seems like it is more hollow than they say it is.

                          The whole thing doesn't make any sense to me at all. What idiot would carry their 199 in their bare hands while resting the base of the level in those warm hands?

                          I suppose I should carry the level around for a while,and then test it with blue in the surface plate?

                          I just find it irritating that the level is concave at all. If I used it more often,I think I would do like Forrest and scrape the damned thing flat. I'd like it better that way!!

                          Comment


                          • #14
                            My 2 cents worth

                            I also am a Starrett 199 owner and find a couple of inconsistencies. I don't handle the level by the sole, but rather from the frame. If the frame heats, the sole gets more concave, not less.

                            Second, Starrett didn't say how much it is concave. It may be only a tenth, but it will still stop rocking of the tool.

                            I heard much the same discussion about large bandsaw wheels. Some said the wheels should be crowned across the tire, some say the wheels should be flat. However, both agree that the wheels must not be hollow.

                            I would say that flat or slightly hollow on the level should both work as long as you know what the condition is and accommodate the geometry in your work method.

                            Comment


                            • #15
                              With the exception of my surface plate and my lathe bed I don't think anything I have tried to level has been flat as pi$$ in a pan. Therefore, the ever so slight arch serves me instead of working against me. I don't use it as a straight edge like I don't don't use a phillips screwdriver for a straight bladed screwdriver. I wouldn't expect my digital caliper spine to be straight enough to take the place of a machinist straight edge made for the purpose.

                              Forrest, what do you propose to do now? Now that you know the level is bowed do you plan on doing a recall on a life time of work? Your going to be busy grasshopper
                              - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                              Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

                              It is true, there is nothing free about freedom, don't be so quick to give it away.

                              Comment

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