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  1. #61
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    Dear Alan,

    When the "slow boat" arrives with your new DRO and scales, please post some photos and let us know if you are happy with it. IMO the critical point is the accuracy of the scales themselves. Once you have the system mounted, you can set up a tenths indicator and use some gauge blocks to check it at 25mm or 1 inch increments. If it's within a couple of tenths at every multiple of 1 inch, that's very reassuring.

    Cheers,
    Bruce

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    Quote Originally Posted by ballen View Post
    When the "slow boat" arrives with your new DRO and scales, please post some photos and let us know if you are happy with it. IMO the critical point is the accuracy of the scales themselves.
    I will do that Bruce. From what I have been able to gather it seems the 2 leading companies for the scales are Sino and Easson. The Sino is attractive in the sense that they provide a calibration certificate, and I don't think Easson does, but that I'm not certain of until I get them (I did order Easson). One of the nice things on the Sino DRO is they use a metal case on the DRO unit itself. Easson uses plastic for that. The Sino upgrades to the 1um scales is more, as the base price is more. Easson seems to make good quality glass scales, the quality looks nice, and that is exactly the glass scales that DRO Pros sells. Also, what Singer/K+C is using. That was some criteria I used when I decided on the Easson. For my lathe I might try the Sino if I am happy ordering on "slow boat". Supposedly it is shipping today or has shipped already, should take about 10 days, possibly less. The company I ordered from, Siton Tech, does sell Sino also. Less discount (only 5%), and scales a more to upgrade but they do carry the Sino product. They also carry HXX, SNS, Sinpo and Rational. Rational might be manufactured in Croatia, that I'm not clear on.

    I also agree with the magnetic scales having issues with temperature. Not sure how much it will effect things, but the glass scales seem to be proven over time and why I went with them.

    Quote Originally Posted by ballen View Post
    Once you have the system mounted, you can set up a tenths indicator and use some gauge blocks to check it at 25mm or 1 inch increments. If it's within a couple of tenths at every multiple of 1 inch, that's very reassuring.
    Are you f#@$ing serious ???? Use a tenth indicator on my FP1 ? I shouldn't need that type of accuracy! I mean, that type of accuracy is for the hypocrites using optical dividing heads and centering scopes to dial in the center of a nat's @$$, while others should be using .001" measurements.

    I think a friend has an old Harbor Freight DTI that says it's accurate to .001". I'll use that for you. Quality test equipment is way overrated...who needs Mitsutoyo...

    I should add one more thing about Sino product. Of all the DRO companies, Sino has been the biggest target for counterfeit product. I think it was wise of you to buy from a certified distributer in Germany. Even the vendor I bought from cautions against Sino products for counterfeits. They claim all of their product is genuine and that they're a Sino distributor in China...that I don't know...but that might be important for some who may be interested in a similar DRO.

    Cheers,
    Alan

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    HI Alan,

    Quote Originally Posted by traditional-tools View Post
    I also agree with the magnetic scales having issues with temperature.
    I am not sure who you are agreeing with. My issue is that one PM member who I trust has observed that they are not stable with time. He demonstrated that this has nothing to do with temperature, but might be due to long-term "creep" in the substrate material (stainless steel strip) of the scale.

    Are you f#@$ing serious ???? Use a tenth indicator on my FP1 ? I shouldn't need that type of accuracy!
    What I was suggesting was to check the accuracy of the scales after you have installed them, not for day-to-day work on the mill.

    Cheers,
    Bruce

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    Quote Originally Posted by ballen View Post
    I am not sure who you are agreeing with. My issue is that one PM member who I trust has observed that they are not stable with time. He demonstrated that this has nothing to do with temperature, but might be due to long-term "creep" in the substrate material (stainless steel strip) of the scale.
    Yes, I believe this is true and that they will change with the temp. I don't believe this will be a real problem for most people. Where it would effect the most is for people that use a lot of toolholders and adjust their tools to the DRO. In that case if you milled in cold and hot environments, I can see this being off. The reality is that most people don't do this, and it's more common to zero out the DRO when beginning to mill at any given time. Ultimately this is not good for measuring tools, which a DRO is. I don't think it would effect me, but I don't want to think about it, glass scales are proven as I've mentioned.

    Quote Originally Posted by ballen View Post
    What I was suggesting was to check the accuracy of the scales after you have installed them, not for day-to-day work on the mill.
    Why would you need to check for accuracy that you will never see or need ? Why would I want to check for accuracy that I will not be using ?

    It sounds like you're saying to check with accuracy I will not be using on the mill. This is confusing and honestly doesn't make sense.

    Now for a DRO Pros story. Everyone likes a story. I've exchanged PMs with a forum member. They bought and installed a DRO Pros magnetic system with an EL700. Those are both products from Electronica (I guess in India). The person also bought the probe that plugs in the DRO. They sell the probe at a discount for buyers of their products, but it still costs $295 if you buy a DRO from them.

    This person was getting random readings, changing from .001" to .006". DRO Pros told him this was normal and that the probe has a .003" resolution...in each direction, so that could be .006". He offered to sell it to me cheap if I wanted it, but said he wouldn't even want to do that to me. He ended up getting a Haimer 3D Taster, which is not electronic, but works perfectly and he merely needs to press the button on the DRO after using the Haimer probe. Haimer does make one that is electronic (not just digital, but with a cable) and it costs about $1200, so a pretty pricey tool. I was surprised that DRO Pros didn't replace that, but if .006" is the real number, that's embarrassing. FWIW, I discovered that the Tormach probe that they sell for their CNC machines is a dead ringer for the DRO Pros probe, with the exception of having a different plug connector on it. They sell the probe at $229 retail. Also they claaim that the positional for the probe is .0005", not .006". The person I mention couldn't get it to return to zero reliably either. Maybe the magnetic scales ? (j/k, it's a joke)

    For me, knowing that the product is made in India is worse than China. For people like me, India is eating my lunch in the same way the Chinese are eating the machining world's lunch. China is getting better at programming, but India is also...I just think it's unfair how the system works and provides so many H1-Bs to India. These people are making 6 digits a year.

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    Hi Alan,

    Quote Originally Posted by traditional-tools View Post
    Yes, I believe this is true and that they will change with the temp. I don't believe this will be a real problem for most people. Where it would effect the most is for people that use a lot of toolholders and adjust their tools to the DRO. In that case if you milled in cold and hot environments, I can see this being off. The reality is that most people don't do this, and it's more common to zero out the DRO when beginning to mill at any given time. Ultimately this is not good for measuring tools, which a DRO is. I don't think it would effect me, but I don't want to think about it, glass scales are proven as I've mentioned.
    What you have written here does not make sense to me, but perhaps someone else can follow it. In any case, temperature dependence of measurements affects both magnetic and optical measuring scales in similar ways, and can not be responsible for the 0.014" creep discussed earlier.

    Cheers,
    Bruce

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    Think i have a sense of the confusion on the magnetic scales and their accuracy....
    First off i don't have a dog in this fight as i an not in the market for any magnetic scale readouts and have no opinion as to whether the problem described by Bruce is real or an a one off occurrence...


    As i read the above posts, seems that Allen is of the belief that temperature is the factor and that the scale may expand of shrink due to temp...His point is that even so that change should not affect the
    positioning appreciably if the setup and tools are zeroed for the current temperature in the workshop....

    This is not the problem that Bruce is describing.....His point about the magnetic scales is that the stainless steel carrier that carries the impeded magnetic strip actually shrinks over time due to releasing
    latent stresses induced in the steel when its made....While temp may accelerate the change its not the real issue...the problem is basic to the scale's manufacture and how the SS backing changes over time.

    If this is true, it presents a larger problem...since the steel carries the magnetic code when it shrinks the code is also compressed and as a result the readings along the scale become inaccurate....
    Zeroing a tool to the scale will not help here as any move read by the scale will be misrepresented...Scaled as it were, as a factor of the steel overall change in length.

    Its like having a tape measure made from rubber....stretch the rubber and accurately print the measuring divisions on its surface....Inches, or meters, your choice....Now allow the rubber to relax and shorten in total length.
    The measurement marks are all still there, just not correctly spaced to conform to the actual distance....You can still mark off a one inch step using the tape, but in reality its not a true inch...and
    as you move along the scale (or tape) as the measured distance becomes greater the error will also become greater.....

    If the magnetic scales and their DRO had a correction register, one could compensate for the overall change that happens to the SS carrier over time...But i suspect that these boxes are not so fitted, or if fitted few users
    would be in a position to accurately correct the problem over the scale length.
    Here a poor correction likely gives as big a problem as the correction strives to fix....
    Better to invest in something of known and repeatable accuracy at the outset...

    Cheers Ross

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    I bought a Mitutoyo DRO second (or maybe third) hand a while back and just installed it on my 1955 FP1 this weekend. I had to shorten a scale for the x-axis. Still need to make a support for the readout box, but have to finish a customer project first.
    Anyway, i took some pictures to share, since i took a lot of info from this site.
    Y-axis, want to lengthen the clamp, so it won't hit the scale.
    img_20170603_111842.jpg
    This is a shot of the scale shortening. I cleared most of the alooy on the mill and then ground the glass with a diamond disc. I clamped the glass to minimize the risc of fracturing. It went surprisingly easy.
    img_20170603_115956.jpg
    This is the readning head that slides along the glass.
    img_20170603_111938.jpg
    Shortened scale on the x-axis.
    img_20170606_124732.jpg
    This is the bracket for the z-axis. This was the trickiest scale to mount. The older deckels don't have a flat base on this side.
    img_20170606_124747.jpg

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    Hi Ross,

    Quote Originally Posted by AlfaGTA View Post
    This is not the problem that Bruce is describing.....His point about the magnetic scales is that the stainless steel carrier that carries the impeded magnetic strip actually shrinks over time due to releasing latent stresses induced in the steel when its made.
    Thanks, that's exactly what I am trying to describe.

    The problem is basic to the scale's manufacture and how the SS backing changes over time. If this is true, it presents a larger problem...since the steel carries the magnetic code when it shrinks the code is also compressed and as a result the readings along the scale become inaccurate.
    Also right, but with one slight correction. The SS strip (about 1mm thick) does not carry the magnetic code itself. Glued to the SS strip is an even thinner (say 0.2mm) magnetised polymer strip, which carries the magnetic code. So when the stainless steel backing changes over time, it also stretches or shrinks the polymer strip and hence the magnetic coded markings.


    If the DRO had a correction register, one could compensate for the overall change that happens to the SS carrier over time.
    The Electronica DRO's do allow one to enter a compensation/correction factor. So the poster who described this problem "fixed" it by inserting the necessary correction factor. But he had lost confidence in the scales, because according to the manufacturer's specifications, this should not have been needed. So he wondered if the scale backing would continue to shrink or expand with time.

    Cheers,
    Bruce

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    Quote Originally Posted by AlfaGTA View Post
    His point about the magnetic scales is that the stainless steel carrier that carries the impeded magnetic strip actually shrinks over time due to releasing
    latent stresses induced in the steel when its made....While temp may accelerate the change its not the real issue...the problem is basic to the scale's manufacture and how the SS backing changes over time.
    I want to see this incredible shrinking stainless steel. Sorry, but it ain't happenin' to any degree relevant to milling machine scales. There might be residual ("latent") stresses in the stainless steel, but they have to be self-balancing through the thickness. So, while the skin might be under tension and theoretically subject to growing longer over time, the core has to be in compression to balance, and would be subject to growing shorter over time. Regardless, nothing is going to move at room temperature except somewhere beyond the 9th decimal point, so to speak. If you throw your stainless steel in a fire, you get bad results, but the stainless steel still won't change length in any appreciable amount. Certainly it might bend, curl, and warp, but the length measured along the strip will be very very close to the original length.

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    Quote Originally Posted by traditional-tools View Post

    This person was getting random readings, changing from .001" to .006". DRO Pros told him this was normal and that the probe has a .003" resolution...in each direction, so that could be .006". He offered to sell it to me cheap if I wanted it, but said he wouldn't even want to do that to me. He ended up getting a Haimer 3D Taster, which is not electronic, but works perfectly and he merely needs to press the button on the DRO after using the Haimer probe. Haimer does make one that is electronic (not just digital, but with a cable) and it costs about $1200, so a pretty pricey tool. I was surprised that DRO Pros didn't replace that, but if .006" is the real number, that's embarrassing. FWIW, I discovered that the Tormach probe that they sell for their CNC machines is a dead ringer for the DRO Pros probe, with the exception of having a different plug connector on it. They sell the probe at $229 retail. Also they claaim that the positional for the probe is .0005", not .006". The person I mention couldn't get it to return to zero reliably either. but India is also...I just think it's unfair how the system works and provides so many H1-Bs to .

    All mechanical probes have triggering lag...Now maybe the probe you refer to is a piece of junk...but be aware that one of the reasons probes work reliably and accurately on CNC machines is because
    the probe cycle gives repeatable feed every time to the probe trigger point...something you don't get working with a manual machine.
    Even the Haimer "Taster's" will give varying readings if the approach to the "Zero" is not consistent. Starting and stopping then moving again to the zero will give different results than just moving directly to
    the "Zero" in a smooth and consistent manner with even feed ....

    Cheers Ross

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    May I chime in here to give my first hand experience of the installation of a DRO system to my 1964 FP1 using magnetic strips purchased from a company in the UK 10 months ago. 3 axis digital readout package for lathes or mills magnetic encoders
    I have noted the various comments in this thread about "stretch" etc, and can say that after 10 months of use I have checked with guage blocks at inch intervals on all axis's and can verify that there is no discernible variation from when I did the installation.

    My previous mill had a Mitutoyo system on it and I can say that as far as I am concerned the magnetic scale system is every bit as good as the glass scale system of the Mitutoyo. Of course there is about a 30 year difference involved and probably the latest glass systems could be better, however as FP1's without a DRO installed are most likely to be found in the home workshop environment a top of the range glass scale system would probably exceed the value of the mill if installed today. Time will tell if the accuracy is maintained over the years but if not there is provision for the readout to be programmed for compensation.

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    Quote Originally Posted by rklopp View Post
    I want to see this incredible shrinking stainless steel. Sorry, but it ain't happenin' to any degree relevant to milling machine scales. There might be residual ("latent") stresses in the stainless steel, but they have to be self-balancing through the thickness. So, while the skin might be under tension and theoretically subject to growing longer over time, the core has to be in compression to balance, and would be subject to growing shorter over time. Regardless, nothing is going to move at room temperature except somewhere beyond the 9th decimal point, so to speak. If you throw your stainless steel in a fire, you get bad results, but the stainless steel still won't change length in any appreciable amount. Certainly it might bend, curl, and warp, but the length measured along the strip will be very very close to the original length.
    To be fair, I would like to see the actual change also, in the thread the Bruce linked to, they're talking about .006" difference, but I don't understand how exactly he was calculating as part it is is being done with the machine off. The thread is kind of confusing as opscimc is not a dumb guy, but his messages are complex to follow. Bruce doesn't follow mine all the time either.

    I honestly don't know $#!T from shinola but I would agree that they could change with temperature...If I understand you correctly, I think similar to you Rich, in that I would like to see that played out using the machine to produce a part in real world. Or at least use better test equipment.

    The substrate conspiracy also seems plausible, but I don't know how that really plays out in this discussion either, other than another theory conjured up by an engineer. I don't agree that it matters. Just another unknown about magnetic scales.

    In general, my conclusion is that magnetic is not as proven as glass...and that is what the Chinese seem to have mastered. Maybe I'll get some crap scales and a throw away DRO. I have bigger worries than loosing $450...I bought the package I did based purely on the scales. The DRO is just another computer to thrown out, or have let the electronic collectors take off to wherever they take 'em off to...I've been throwing old computer out for the past 30+ years...some of them I paid over $5k for...

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    Quote Originally Posted by AlfaGTA View Post
    All mechanical probes have triggering lag...Now maybe the probe you refer to is a piece of junk...but be aware that one of the reasons probes work reliably and accurately on CNC machines is because
    the probe cycle gives repeatable feed every time to the probe trigger point...something you don't get working with a manual machine.
    Even the Haimer "Taster's" will give varying readings if the approach to the "Zero" is not consistent. Starting and stopping then moving again to the zero will give different results than just moving directly to
    the "Zero" in a smooth and consistent manner with even feed ....

    Cheers Ross
    Ross,

    I don't know if that probe is good or bad, I watched a video where a guy used it to dial in a diameter of a large bearing and it got it without .0005 on one axis, and .0002 on the other. I thought that was pretty good.

    Also, it should be a given that you need to do this with circles by only using the X or Y between points, and even so it will only be as accurate as the square-ness of X and Y.

    Looking it it doesn't strike me as being a quality probe either. But then, it doesn't cost $1200. Deckel would never had shipped a probe like that...I don't think...

    Cheers,
    Alan

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    Quote Originally Posted by ballen View Post
    What you have written here does not make sense to me, but perhaps someone else can follow it. In any case, temperature dependence of measurements affects both magnetic and optical measuring scales in similar ways, and can not be responsible for the 0.014" creep discussed earlier.
    Since you didn't say which piece you don't understand, I don't know how to answer. In regard to DRO and toolholders, I was talking about people that use the tool settings to hold the distance of the tool from zero, so they can repeatably change tools on the lathe as an example. I see some confusion there as mills don't use tools in that way, but you certainly could set height like that on a mill using tool holders.

    The rest of that paragraph I was just saying I agree with the temp changing the scales, and how much that effects any of us I really don't know. As I said, I don't want to think about it and bought glass because it's proven.

    I like your substrate conspiracy...but show me the data.

    I will say the data which opscimc presents could be real, that I don't know. I don't care how accurate someone is with their vernier calipers, there are better ways to measure. You're asking me to measure with a tenths indicator, even though you contradict yourself telling me I shouldn't use that in the shop... ???? I don't understand that at all...

    I'd like to see this .014" creep you talk about. In a normal shop ? Or are we comparing machines in a walk in freezer vs a room full of heat lamps in a drying room ?

    Again, those kind of comments make me cautious about magnetic.

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    Quote Originally Posted by Peter F View Post
    May I chime in here to give my first hand experience of the installation of a DRO system to my 1964 FP1 using magnetic strips purchased from a company in the UK 10 months ago.
    You certainly can. Welcome. Is your FP1 a lever or dial version ?

    All of the Chinese units looks the same. The DRO looks like a SINO, the model number is similar to the newer SINO DROs. I don't think SINO makes magnetic scales though. You really need to open and look at the scales on the inside, IMO, to understand about the quality. If it works, they should be fine...

    Quote Originally Posted by Peter F View Post
    I have noted the various comments in this thread about "stretch" etc, and can say that after 10 months of use I have checked with guage blocks at inch intervals on all axis's and can verify that there is no discernible variation from when I did the installation.
    You're not the only one that speaks well of magnetic, I'm sure they work well. There seem to be some unknowns which is why I went with glass.

    Quote Originally Posted by Peter F View Post
    My previous mill had a Mitutoyo system on it and I can say that as far as I am concerned the magnetic scale system is every bit as good as the glass scale system of the Mitutoyo. Of course there is about a 30 year difference involved and probably the latest glass systems could be better, however as FP1's without a DRO installed are most likely to be found in the home workshop environment a top of the range glass scale system would probably exceed the value of the mill if installed today. Time will tell if the accuracy is maintained over the years but if not there is provision for the readout to be programmed for compensation.
    Certainly for me, buying a Newall would cost me almost as much as the machine. Hard to justify. Not too far behind and possibly a turnkey solution is what Singer offers (Easson scales). Even if you pay more, Singer packages it for specific machines, and knows most all of them. Then the DRO Pros in the U.S.A, who gets all of their glass scales from China (Easson scales). And then the option of ordering straight from China, getting Easson scales. I did opt for 1um scales as it was only $20/ea, I thought that was a no brainer.

    I don't know where you find Deckels, some could be in home shops, I know mine is. There seems to be a wide range of people that are attracted to them. I've seen them advertised in auto shops, machine shops, r&d shops...labs, etc...One I saw local was in a auto mechanic shop, doing brakes, engine repairs, stuff like that...some of it custom stuff that needed machining. I didn't end up buying it. They seem to be getting scarcer to find decent manual machines.

    When I bought my FP1, I had found a beautiful FP1 with dials that came out of the Ampex in Redwood City, not far from Oracle. There were a number of Deckels sold by a machine company in that area back in the 60s and 70s. It's a posh area. Another guy on this forum got it, and it was a smoking deal, IMO. It was a closed bid auction. It was a beautiful machine which I offered about $1400 for...it was in way better condition than the one I got a couple days later at a machine auction.

    I know a bit more about Deckels now and it was a nice machine. If I could just find an FP2 like that, I'd be a happy camper...I have to keep constraint of myself, new shop before the machine...new shop before the machine...new shop before the machine...new shop before the machine...

    I could justify a used 10 HP Phase Perfect...which will be going in the new shop...if anyone has one, ping me.

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    Hi Alan,

    Quote Originally Posted by traditional-tools View Post
    The rest of that paragraph I was just saying I agree with the temp changing the scales, and how much that effects any of us I really don't know.
    And I was just saying that whoever you were agreeing with, it wasn't me (unless you meant that the change in length could not be explained by temperature effects, in which case we ARE on the same wavelength.)

    The effects of temperature on length are easy to understand, and are quantified by the thermal expansion coefficient, http://hyperphysics.phy-astr.gsu.edu...les/thexp.html. The three materials which are relevant for this discussion are glass, steel, and aluminium. For steel the expansion coefficient is 13 parts per million per degree Celsius. So if you have a 16" steel scale, and you raise the temperature by 10 Celsius, it will increase in length by 10 x 13 x 16"/1000000=0.002".

    The temperature change needed to increase the length of Opscimc's scale by 0.014" is enough that he would not be able to enter the shop without protective clothing!

    I will say the data which Opscimc presents could be real, that I don't know. I don't care how accurate someone is with their vernier calipers, there are better ways to measure.
    If you read what he wrote, you will see that he used the SCALE from the calipers, which had recently been calibrated to 0.001", as a trusted length standard. This is a perfectly good method to verify a length change of 0.014".

    You're asking me to measure with a tenths indicator, even though you contradict yourself telling me I shouldn't use that in the shop... ????
    Alan, again, I never said that or wrote it!

    I'd like to see this .014" creep you talk about. In a normal shop ? Or are we comparing machines in a walk in freezer vs a room full of heat lamps in a drying room ?
    Opscimc described his measurement process in some detail. The temperature differences between his measuring standards and the objects that he was measuring was a most a few Celsius. This is far too small to explain the effects that he observed.

    Again, those kind of comments make me cautious about magnetic.
    In this point, we are completely in agreement. I would love to use magnetic strip scales on my machines, because they have tremendous advantages compared with glass scales, in their ease of mounting and resistance to dirt, coolant, and contamination. But I just don't trust their accuracy.

    Cheers,
    Bruce

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    Hi Peter,

    Quote Originally Posted by Peter F View Post
    May I chime in here to give my first hand experience of the installation of a DRO system to my 1964 FP1 using magnetic strips purchased from a company in the UK 10 months ago.
    That's very encouraging. Do you know who manufactured the magnetic scales? What's the specified accuracy?

    Cheers,
    Bruce

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    Everybodies getting their panties in a twist based on postings by somebody who's now a metrology expert but wasn't at the time, who probably made either incorrect measurements, then drew incorrect conclusions. If his scales were bad, why didn't he return them to DROPROS at the time? That's homeshop Harry for you I guess.

    Thinking that the stainless substrate changes length over time is not plausible.

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    Quote Originally Posted by ballen View Post
    And I was just saying that whoever you were agreeing with, it wasn't me (unless you meant that the change in length could not be explained by temperature effects, in which case we ARE on the same wavelength.)
    That much we are definitely in agreement about. The question is how much it will or should change. We're talking about 1/3rd of a millimeter. .014" is quite a bit. Even I can machine better than that! LOL

    Quote Originally Posted by ballen View Post
    The effects of temperature on length are easy to understand, and are quantified by the thermal expansion coefficient, http://hyperphysics.phy-astr.gsu.edu...les/thexp.html. The three materials which are relevant for this discussion are glass, steel, and aluminium. For steel the expansion coefficient is 13 parts per million per degree Celsius. So if you have a 16" steel scale, and you raise the temperature by 10 Celsius, it will increase in length by 10 x 13 x 16"/1000000=0.002".
    I will admit I don't understand temperature as well as you, but I understand it enough to know that it has an effect on metal, and a thin strip is very susceptible to change. However, the .014" is a lot of change. I just don't see that in any normal shop. As I mentioned, opscimc's messages are detailed and are sometimes difficult to follow, for me. Some measurements were months apart. Some were days...but even if he's the greatest machinist with a pair of verniers, digital calipers are much more repeatable. He states he can measure within .002" with them.

    Quote Originally Posted by ballen View Post
    The temperature change needed to increase the length of Opscimc's scale by 0.014" is enough that he would not be able to enter the shop without protective clothing!
    Ok, for some reason I thought you were backing that up.

    Quote Originally Posted by ballen View Post
    If you read what he wrote, you will see that he used the SCALE from the calipers, which had recently been calibrated to 0.001", as a trusted length standard. This is a perfectly good method to verify a length change of 0.014".
    I don't understand why he didn't use the scale/screws on his machine.

    Quote Originally Posted by ballen View Post
    Alan, again, I never said that or wrote it!
    You didn't say that exactly, but in so many words you wanted me to measure with a tenth DTI but that I wouldn't need that accuracy on my mill in use. You don't find that hypocritical ? Anyway, I'm not trying to put words in your typing. I found some of it to be similar hypocritical response that was being thrown at me above. Those are people that own comparators, optical rotary tables, and measuring tools that can, err...only measure to .001" evidently...LOL

    Quote Originally Posted by ballen View Post
    In this point, we are completely in agreement. I would love to use magnetic strip scales on my machines, because they have tremendous advantages compared with glass scales, in their ease of mounting and resistance to dirt, coolant, and contamination. But I just don't trust their accuracy.
    We are, I don't trust them until I understand them better. Glass is proven.

    I don't know when I'll get my order, but it could be here soon.

    My refi closed yesterday...I think I'll treat myself to a Harbor Freight DTI, that's all the accuracy I'll ever need...

    And I will tell you this, cause it's kind of funny in the sense of this thread. I have measured multiple times and different diameters on the lathe, and I will see times where a .001" Starrett plunger will show .002" TIR when centering, but a .0001" DTI will show .003". Obviously it's more sensitive, and it could be the gauge is off, but it has a calibration sticker from a couple years before I bought it...been a number of years since though...it's a decent gauge. I have to say I trust the DTI more.

    BTW, I bought a Starrett LastWord .0001 DTI from Danny here on PM, it was in one of those little red boxes with all the adapters and such...I think I paid him $120 plus shipping. Well, I learned I don't like those last word DTIs at all, and gave it away to a friend for free about a week ago...maybe it was too accurate for me ???

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    To answer a few questions- my mill is a lever model, the DRO is the latest Sino unit, from the markings on the scales they appear to be made in Germany. However, regardless of the country of manufacture they seem to conform in conjunction with the readers to the test certificates for each reader. I have the 5 micron ones which to me is quite sufficient. I have seen a 1 micron glass scale with the extra digit blanked off on the readout. The constant changing digit nearly drove the owner mad!, perhaps good on a cylindrical grinder but not on a mill.

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