Biax set up and use
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  1. #1
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    Default Biax set up and use

    I am new to scraping and just got a biax 7 ELM. My scrap marks are not looking as smooth as I feel they should and I need some help diagnosing the problem. I'm running a 6" insert type blade with a sandvik scraping insert ground at 60mm radius with a 5° negative take. Are the blades not polished to a high enough grit? Too slow a speed? Not enough force? Any help would be appreciated. I'd love to take the Richard king course however not sure when the next one close to Oklahoma will be.

    This was just a strip I ran across the table to show what I'm seeing in my cast iron parts



    Last edited by Lucaselef; 03-24-2021 at 06:35 PM.

  2. #2
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    Speed will have more to do with your scrape spacing and ability to aim. That chatter looks to me like you either aren't holding the scraper solid and level, or the blade is dull/angle is off. With the blade ground correctly, the angle the scraper holds it at is all set so you only need to worry about keeping it level. It helps to cradle it in your lower arm and work with your head over the action. Given the weight of the Biax, you don't necessarily need to bear down on it unless you're really hogging metal off, but you also don't want to hold it loose and let it just bounce and skip across the surface.

    Also, if your part has room to shimmy and vibrate, that can translate into the scrape.

  3. #3
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    What do you mean by ground at 60deg? Can you take a pic of blade from side?

    L7

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    Sorry, It has a 60mm radius on all 4 sides. And then each side has a 5° negative rake ground on each side of the cutting face. I added some more pictures. The cutting face I'm using to cut looks just like the radius on the left/right you can see.

    Edited. They're 60mm radii

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    If you are running the Biax too slow, it tends to hog into the metal, also causing chatter.

    The insert-holding blade is terribly stiff. I have milled the shank of mine to less than 1/3 of the original thickness and got a pleasant tool to operate.

    Paolo

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    I agree with Paolo on the insert holder blade being stiff.

    I assume you have the rubber bushing where the blade mounts to the tool. If its old and hard get a new one. A lack of flex will make the scraper hard to control and lead to chatter.

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    what material are you testing on?
    looks like steel, you should test on cast iron.

    Franz

  8. Likes ballen, Richard King liked this post
  9. #8
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    One more tip:- To see if the blade is sharp enough push it gently across the back of your thumb nail. If it is correctly sharp, it will cut off a layer of nail/fluff. If it just slides across the nail, the cutting edge is rounded and it won't cut the metal.

    When the blade is properly sharp, you need almost no force on the Biax to remove metal. When it gets blunt, you need to press more firmly and the blade chatters.

  10. #9
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    I was seeing the chatter In a cast iron table. I ran the part across my steel table just to get a picture.


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