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Pattern In A Sawed Off Round 1018

Discussion in 'QUESTIONS & ANSWERS (Get Help Fast Here!)' started by RVJimD, Mar 7, 2015.

  1. RVJimD

    RVJimD United States Active User Active Member

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    I am making a cross drill bushing to use in making my new T handle chuck wrench. I cut off this piece of 1" round 1018 steel and thought the pattern was interesting. Can anyone tell me what causes this? It looks like opposing half circles of the same radius as the part, but offset. There are three facing each other and they are ridges that can be felt. The direction of the saw was running right to left in the picture and from top to bottom. Is this from the part slightly flexing in the clamp, composition of the steel, the blade, the cheap saw? The small burr is the bottom/end of the cut.

    I looked at it again and I can also see a reproduction of the center hole. I think this is caused by the weld in the blade.

    Curious minds might be interested...

    Jim


    image.jpg
     
    Last edited: Mar 7, 2015
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  2. darkzero

    darkzero Global Moderator Staff Member H-M Supporter-Premium

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    That's a common pattern left by horizontal bandsaws especially when the blade bounces from improper feed & improper TPI. Hydraulic damper helps reduce that.
     
  3. rmsflorida

    rmsflorida United States Active User H-M Supporter-Premium

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    It's just harmonics of bandsaw blades.
    Reflecting in relationship to the pitch of the teeth of the blade.
    Regards
    Robbie
     
  4. John Hasler

    John Hasler United States Active User H-M Supporter-Premium

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    How tight is your blade?
     
  5. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    You might be running you saw blade a little too fast. Try to slow down the blade and see if the pattern changes or goes away. Might check to blade guides for proper running clearance, too.
     
  6. T Bredehoft

    T Bredehoft Active User H-M Supporter-Premium

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    If you compare the two sides of the cut you will find the same pattern, but half a space off. The teeth on the other side of the blade made the pattern on the other piece. When each tooth hit the bar, the teeth already in the bar jiggled a little.
     
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  7. scwhite

    scwhite United States Active Member Active Member

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    I think it is caused from the work ether moveing in the vice or the hole vice moving .
    But most likely the saw Guides are moving
    As the blade travels through the guides .
     
  8. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    I am having the exact problem today and was just about to post this. sae 660 bronze:

    DSCN5647.JPG
     
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  9. Rustrp

    Rustrp United States Active Member Active Member

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    There's always a bundle of reasons for the result of a cut and everything in metal has roots in speed-feed, tool and how sharp. When we move into the bandsaw arena we add a few more things but they are all related in some way. Speed, feed, blade tension, blade support (front and aft), along with guide to blade clearance. If the cut was straight and didn't wander then how sharp the blade was probably isn't a factor, because a dull blade results in a crooked cut. My first guess is speed-feed and the TPI, with or without coolant or lubricant.

    We could start a thread on Bandsaw Holograms, although light isn't a factor. BTW, looking at the photo it seems you have your shop set up in your kitchen. :D
     
  10. Rustrp

    Rustrp United States Active Member Active Member

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    http://www.starrett.com/docs/saw-resources/recommendations.pdf?sfvrsn=2

    Breaking in the saw blade is something that usually doesn't come with the saw instructions or is overlooked, but it does increase blade life. One of the first things to happen especially if TPI is to coarse are teeth ripped out which causes more teeth to be ripped out....and so on.
     
  11. expressline99

    expressline99 H-M Supporter - Premium Content H-M Supporter-Premium

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    I knew someone was going to see the kitchen. LOL!

    Mine is a small saw and new. I need to look at possible adjustments. Using a bandsaw is new to me.
     
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  12. Rustrp

    Rustrp United States Active Member Active Member

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    That's okay because even when we've been doing it for years there's still curve balls or just some things that we miss when we inspect after a blade change.

    I discovered the set screw was loose on the blade clearance guide that's set for the width/depth of the blade. The blades were getting dull quickly. I was cutting stainless steel bar so I use this as rationale. I was in the process of dulling blade #3 when the blade jambed between the guides and I discovered the loose set screw. The hardened guides were taking all the set out of the teeth.
     

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