1. #1
    After having made a program to write the Gcode for milling timing pulleys (see another thread) I decided to make a form tool and cut them with that.

    It's all in the video here:



    I used the vertex 6" rotary table holding a 5" chuck with the 2" aluminium bar. I first machined the bar to the correct diameter for 30T on the lathe - 48.00mm, then put in on the rotary table using the DTI to get it on centre.

    Some pictures:

    Attachment 3901
    Attachment 3902
    Attachment 3903
    Attachment 3904
    Attachment 3905
    Attachment 3907

    Towards the end of the video I put the pulley in my new toy:

    Attachment 3906

    I thought the bandsaw cut it quite quickly, however over the 50mm distance it was off square by about 5mm which I don't think is very good. I will check the blade tracking and guide to see if that's what caused it. Either way it's a lot quicker than cutting it by hand, though on this occasion I should have just parted it!
    Last edited by Lee Roberts; 03-04-2012 at 09:04 PM. Reason: added vid

  2. #2
    Quote Originally Posted by Jonathan View Post
    I thought the bandsaw cut it quite quickly, however over the 50mm distance it was off square by about 5mm which I don't think is very good. I will check the blade tracking and guide to see if that's what caused it. Either way it's a lot quicker than cutting it by hand, though on this occasion I should have just parted it!
    I think the reason you have the taper cut is due to the way you held the bar in the vice, and being to aggressive with the force of the cut.

    You should have a piece the same diameter at the other end of the vice to stop the vice jaws pivoting "See Picture" and a piece of flat bar under the piece to stop it tilting.

    Where has the router gone or is that in another department ?

    Well done on the video.

    Phil
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  3. #3
    Quote Originally Posted by M250cnc View Post
    I think the reason you have the taper cut is due to the way you held the bar in the vice, and being to aggressive with the force of the cut.

    You should have a piece the same diameter at the other end of the vice to stop the vice jaws pivoting "See Picture" and a piece of flat bar under the piece to stop it tilting.
    Ok, I'll run it more slowly and put another bit in the other end next time. I've just checked and the bar did not move in the vice at all, it was the blade that wandered.
    I think I should have moved the guard/bearings closer together...it didn't want to budge though.

    Quote Originally Posted by M250cnc View Post
    Where has the router gone or is that in another department ?
    It's still in the same place - yes the workshop is getting a bit cramped now!

  4. #4
    You may have the blade tension too slack.

    Try cutting a small piece off a longer bar, you may have had it at an angle without realizing it.

    The blade should break before it wanders that much.

    Get a bigger shed. Lol

    Phil

    Sent from my HTC Desire using Tapatalk

  5. #5
    Quote Originally Posted by M250cnc View Post
    You may have the blade tension too slack.
    How slack is too slack? I know that's a difficult one to answer, but is seems fairly stiff at the moment. Would you say it needs to be under more tension than a wood bandsaw?

    Try cutting a small piece off a longer bar, you may have had it at an angle without realizing it.

    Quote Originally Posted by M250cnc View Post
    The blade should break before it wanders that much.
    I must have it too slack then since with it switched off if I lift the saw up and down you can see the blade is pushed to the side significantly.

    Quote Originally Posted by M250cnc View Post
    Get a bigger shed. Lol
    I'm with you on that one! I think my mum would move out though...

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