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Thread: Blue collar sinebar

  1. #1
    mklotz mklotz's Avatar
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    Blue collar sinebar

    Sinebars are usually thought of as measurement tools only, not to be used in actual machining operations. Before I got a set of good angle blocks, I decided that it would be a good idea to make a sinebar I could use to support work in the milling vise without having a massive guilt attack.


    The design is simple. Two rollers bolted to the bottom of a 1" wide steel plate and a stop with chip undercut bolted to the top. I'm not going to cry if an errant endmill takes a bite out of it.

    Is it as accurate as the high-priced version? Of course not, but it's very rare in our world of shade-tree machining that one needs to cut a super precise angle.

    Assuming you use the same diameter stock for the rolls and take care to mount them parallel, the biggest accuracy issue is the distance between the rolls. It doesn't really matter what this distance is as long as you know it with some precision. Here's how to determine it...

    Borrow an angle master plate (30 deg is a good size to use) and mount it on the sinebar. Build a stack under the sinebar until a DTI traced across the master shows no slope, ie, the sinebar angle is the same as the master angle (we'll call it A). Then L, the roll-to-roll distance is given by:

    L = H/sin(A)

    where H is the height of your stack.


    For a full discussion of sine bar errors, see my thread...

    Sine bar errors
    Last edited by mklotz; 07-08-2017 at 10:23 AM.
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    Regards, Marv


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  2. The Following 5 Users Say Thank You to mklotz For This Useful Post:

    Jon (10-05-2015), kbalch (10-06-2015), Paul Jones (10-07-2015), PJs (10-06-2015), Toolmaker51 (11-23-2018)

  3. #2
    Content Editor DIYer's Avatar
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    I appreciate this post in that it gives an example of making a measurement tool that can be done at home. Unless one is shooting for high precision tolerances, which Marv admits is not the purpose of this build.

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    Content Editor DIYer's Avatar
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    Thanks mklotz! We've added your Sine Bar to our Measuring and Marking category, as well as to your builder page: mklotz's Homemade Tools. Your receipt:


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    Ed ke6bnl's Avatar
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    I do like the added calculations you give to determine the center to center of the base, I want to make this but want it very thing as a angle guide and to be able to also clamp down in vice.

  6. #5
    mklotz mklotz's Avatar
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    Quote Originally Posted by Ed ke6bnl View Post
    I do like the added calculations you give to determine the center to center of the base, I want to make this but want it very thing as a angle guide and to be able to also clamp down in vice.
    Note that, if you use a 30 deg reference angle, ie A=30, then sin(A) = 1/2 and L = 2*H. This way you won't have to dig out the calculator. :-)


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