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  1. #11
    mekanik's Avatar
    Lives in Barrow in Furness, United Kingdom. Last Activity: 10 Hours Ago Has been a member for 7-8 years. Has a total post count of 552. Received thanks 63 times, giving thanks to others 68 times.
    Top marks M8 i have bookmarked that supplier just in case i need one @ some stage, love a guy that does the research PPPPPP
    Mike

  2. #12
    PS.
    Just discovered on the page of the DIN 874 straight edges, that there is another page. Its called: Straight Edges made from Steel, no DIN, Testing Accuracy in Item Description, Faces grounded, Length from 500 mm to 6000 mm. Here are the even cheaper " scrap like" :-) edges. Scrap for them, treasure to me.
    Example:

    enght 2000 mm, height 40 mm, width 8 mm


    Straight Edges Steel
    finely ground,
    Tolerance flatness: 112 m,
    Net- weigth: 4,8 kg

    Made in Germany

    Price without Tax: 114,50 EUR
    Price incl. Tax: 136,26 EUR

    So 112 micrometers =0.112 millimeters, and thats for 2 meters. Not bad for 136 euro. If i make a big build i will definitely buy one similar

  3. #13
    Greeny's Avatar
    Lives in North Yorkshire, United Kingdom. Last Activity: 15 Hours Ago Has been a member for 8-9 years. Has a total post count of 102. Received thanks 12 times, giving thanks to others 7 times.
    This one looks ok.
    MeasureShop.biz: Flat straightedge, steel

    Part no: 1689 104
    2000 x 60 x 12mm
    din 874/2. 58 micro meters
    111.80 + vat

  4. #14
    Quote Originally Posted by silyavski View Post
    You almost got me there :-) . But isn't it that a square straight edge has 4 edges that could be used for that against the ones that have only 1 sharp edge?
    I believe their purpose is a bit different and definitely i believe i need the square- to compare between rails in all directions / the twist i mean/ .
    If I'm reading you correctly you mean this;

    Click image for larger version. 

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    But if you angle the straight edge on the left it will bend and not be straight any more.

  5. #15
    Quote Originally Posted by EddyCurrent View Post
    If I'm reading you correctly you mean this;

    Click image for larger version. 

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    But if you angle the straight edge on the left it will bend and not be straight any more.
    Hi,
    maybe you misunderstood me because of my English. I meant there are 2 types, beveled/like a knife/ and ones that look like bar. So as far i understood, you said that the beveled is better, cause you can see easier the light, when touching some surface to be measured.
    So what i believe, the square could be more useful for me, constructing a cnc, because it has 4 edges versus one of the beveled.

    Click image for larger version. 

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    First it can serve as a master guide to straighten the first square shaft supported rail when mounting on the red axis, fig 1 , so its true straight

    Then check the straightness on blue axis, fig2 /hence proper tightening on hopefully straight surface or if not-if properly shimmed.

    Then check twist/ green axis/ fig 3 and 4.

    With a beveled edge i don't see how you can perform and alight twist, as many of the beveled edges i saw are straight only at the knife beveled blade. fig 2 is where the beveled edge shines, but if i simply flip and use one corner, its the same.

    Click image for larger version. 

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    PS: edited, axis not showing
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by Boyan Silyavski; 10-09-2013 at 08:24 PM.

  6. #16
    I've got both and the bevelled edge is far more versatile and the one used most.

    You cannot angle the straight edge like you show because your straight reference edge is lost because it's bending and will just follow the curvature of the surface. The reference edge is only meant to be used in one direction and must be 90deg to surface your checking any tilt/bend and error is introduced.

  7. #17
    Quote Originally Posted by JAZZCNC View Post
    I've got both and the bevelled edge is far more versatile and the one used most.

    You cannot angle the straight edge like you show because your straight reference edge is lost because it's bending and will just follow the curvature of the surface. The reference edge is only meant to be used in one direction and must be 90deg to surface your checking any tilt/bend and error is introduced.
    Thanks, i get it now. Ok, i will look for a beveled one.

    Now recapitulating everything it seems that the Maun even if not ultra accurate is made from carbon steel opposed to all other mentioned. And at theit web site i saw it was beveled.

    So i send a couple of emails.

    -To Maun, to ask them if its hardened carbon steel, cause at their web they don't say so, say steel. No carbon at any place. All sellers say carbon. We will see.
    -To Measuresop which Greeny suggested, cause here they have some beveled straight edges which look quite cheap , so i asked about the accuracy.
    -To Precison tools to see if they will ship to Spain this and if this can serve as a straight edge, cause it states tolerance 40micrometers
    - to ebay member who is selling the Igaging 36 inch to ask if he could check straightness before sending. yes, back here, as the brand ones a very expensive.

    Will see what happens.
    Last edited by Boyan Silyavski; 12-09-2013 at 02:32 PM.

  8. #18
    mekanik's Avatar
    Lives in Barrow in Furness, United Kingdom. Last Activity: 10 Hours Ago Has been a member for 7-8 years. Has a total post count of 552. Received thanks 63 times, giving thanks to others 68 times.
    Hi M8
    This is only my opinion and i am sure others may disagree but i would forget about the Maun straight edge, i couldn't see any thickness quoted so it's more than likely a bendy one,the other bevel edge rule is quoted as steel and galvanised and i didn't see any tolerance/flatness quoted, i would stick with the magic numbers DIN 874/2 a parallel straight edge of reasonable thickness should be fine you can see the smallest of gap by placing a light behind the straight edge.
    Take no notice of e-bay sellers the DIN 874/2 rules will be checked under controlled temperature conditions in a tool room using some rather expensive gear. a box for your precision straight edge is a must buy.
    Hope that helps, i am now awaiting the flack.
    Mike
    Last edited by mekanik; 12-09-2013 at 05:49 PM.

  9. #19
    Quote Originally Posted by mekanik View Post
    Hope that helps, i am now awaiting the flack.
    Mike
    No flack from me I'm 100% in agreement. My bevelled edge is 5/8" thick came from Vickers tank factory and would cost more than a small car today and weighs nearly has much. It also has stamped on it working temperature range it's accurate at and it's quite narrow, it will also be fair way from calibrated by now so I treat it with kid gloves and it's away in it's wooden case ASAP.

    You get what you pay for.!!

  10. #20
    Thanks a lot for the info!

    The Maun edge if happens to be from hardened steel/ still no info/ , could be good for drawing straight lines
    Here is the drawing from their web:
    Click image for larger version. 

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    I will stay with the magic number.
    Will fiddle until the end of the week and if nothing more interesting jumps, will buy from Germany. They answered me and told me that the scale also is a straight edge. Yes, i wanted beveled, scale and hardened and inox but ...$$$.

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