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  1. #11
    Removing the bulk of material could be done with a TCT wood cutting router bit shaft sizes go up to 12mm, could the transition be finished on a lathe.

    Phill

  2. #12
    I had a go at machineing the keyway yesterday with my less than perfect cnc designed for cutting polystyrene and although I had to go very slow and I only took 1mm cuts it did get the job done quite well, it would have been even better if I had a long enuff bit too.

    Now I just need to find some one with a machine that can do the radius a bit better.
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  3. Quote Originally Posted by phill05 View Post
    could the transition be finished on a lathe.
    Only if the design is such that the corner radius is >= half the part width.

    -Nick
    You think that's too expensive? You're not a Model Engineer are you? :D

  4. #14
    Quote Originally Posted by magicniner View Post
    Only if the design is such that the corner radius is >= half the part width.

    -Nick
    Which makes it a piece of round bar if its square or not doable if it isnt.

  5. #15
    Update: I took the part to a proper machinist and its taken 4 weeks for the guy to put the radius on the corners, I get it back today and my attempt on my x2 mini mill was better! I think 1 out of the 4 sides is ok the rest he has not got the full radius on and one of them is a mile out its hardly touched it! so frustrated I wasted so much time waiting for the guy to do it let alone the 20 I still got charged.
    so back to square one! looks like im going to have to try and do it on my cnc but just use a very small step down and then Finnish it by hand.

    so the question is whats the best way to machine it like this? running down the length or short vertical passes?
    Last edited by charlieuk; 1 Week Ago at 11:51 AM.

  6. The answer depends on your machining strategy, are you using a corner rounding cutter?
    If using an End Mill then I'd go with linear cuts with a square endmill to rough it out to fine steps quickest then vertical passes with a ball end mill to best smooth the corners.

    At the size transition step can you get away with a groove around the part? Thus allowing it to fit flush to the step edge but eliminating the machined transition from the rounded corners at the step size transition?

    - Nick
    You think that's too expensive? You're not a Model Engineer are you? :D

  7. Quote Originally Posted by charlieuk View Post
    Update: I took the part to a proper machinist and its taken 4 weeks for the guy to put the radius on the corners, I get it back today and my attempt on my x2 mini mill was better! I think 1 out of the 4 sides is ok the rest he has not got the full radius on and one of them is a mile out its hardly touched it! so frustrated I wasted so much time waiting for the guy to do it let alone the 20 I still got charged.
    He might have been a Professional Machinist but that just means "does it for money", not that he's any good at it :D
    On the bright side he didn't charge enough to spend the time to set it up on a machine, with a down side that it sounds like he didn't :-(
    You think that's too expensive? You're not a Model Engineer are you? :D

  8. #18
    it was a 25x25mm bar and he said he just clamped it in the center so it obviously just defected, and he rotated it around to do each side rather than just clamping it properly and getting it lined up and do one side then just jog it over and do the other. Oh well im hoping I can re use the bit of stock he messed up as at least its not under sized I don't think. All the more reason to build a better machine myself.

    I cant use the corner cutter I got as it will not fit in er20 collets so going to have to use a straight and a ball nose.
    I don't quite understand the last bit your saying but the part has to fit down a tube with a fairly tight tolerance.

    many thanks

  9. Do you actually need the round profile?
    Would just cutting the corner off with a square endmill to create clearance work?
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  10. Quote Originally Posted by charlieuk View Post
    I don't quite understand the last bit your saying but the part has to fit down a tube with a fairly tight tolerance.
    What's the step for?
    Does the smaller section fit into something?
    Does the step provide location?
    You think that's too expensive? You're not a Model Engineer are you? :D

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