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Thread: Grinding stones for air grinder - do the different colours mean anything?

  1. #11
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    Quote Originally Posted by workingonit View Post
    When I was 50'ish I asked the TAFE if I could do a machining trade course to better understand my machines and methods and was told only if I had an apprenticeship...
    I tried approaching TasTafe regarding a few courses I wanted to do out of interest for hobby. Sadly I had the same response as I don't have a trade certificate it was a no. It's sad and disappointing that there is little opportunity for adult education in skills.

  2. #12
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    Quote Originally Posted by workingonit View Post
    Afraid I'm only Wiki qualified. Green and yellow are the purist, being formed closest to the heat source. I can only guess that would mean sharper grains and better grinding characteristics for tougher tooling.

    I'm guessing you're retired - do you keep up your skills in any hobby way? When I was 50'ish I asked the TAFE if I could do a machining trade course to better understand my machines and methods and was told only if I had an apprenticeship...
    I most certainly am retired. I am 77. I still have a full complement of fitter's, repairer.s and restorer's tools, a lathe and drill press, three bench grinders, a tool post grinder, stick and mig welders.

    I can't speak for the NT TAFE system. Qld barely has one these days as far as trade skills go. TAFE's got closed down and shrunk willy nilly in the 1990's and the management were told to go commercial and offer courses people would pay well for. Before then most colleges offered hobby machining courses. Some guys had been doing these for 20+ years. Cheaper than owning your own machine tools and tooling. Also offered were courses in Foundry and in Blacksmithing. They also offered four level courses in Machining for people working or planning to work in the field and could get some training. Otherwise you did an apprenticeship. The four level course and a good bit of hands on experience might have got you a Tradesman's Rights Certificate. Most shops regarded these with a good degree of suspicion and thought of the holders as glorified TA's.
    URSUSMAJOR

  3. #13
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    Quote Originally Posted by twr7cx View Post
    I tried approaching TasTafe regarding a few courses I wanted to do out of interest for hobby. Sadly I had the same response as I don't have a trade certificate it was a no. It's sad and disappointing that there is little opportunity for adult education in skills.
    Interesting to hear someone else had the same response. I find it ironic that I'm a baby boomer educated by second hand old tech books that no one wants now, and by forums and youtube. Sympathy for Bigbjorn, as I've met a few fitters and turners, the common theme was that they could turn their hand to anything, whereas these days its certificates for one application only and otherwise hopeless outside the box.

  4. #14
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    Quote Originally Posted by Bigbjorn View Post
    glorified TA's.
    I used to go bush camping on weekends with a well paid TA at Jabiru mines. His job was to pass the tradesman the required tool, and put up with it being thrown back at him if it wasn't the right one Sort of like a golf caddie...

  5. #15
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    Quote Originally Posted by workingonit View Post
    I find pure aluminium tends to clog the grindstone face
    Yep, you were right about that:



    I found the white ball stone to be the most effective although the curve on the sides has been flattened out from use and it's started to take on more of a cylindrical shape now.

    Anyways, managed to achieve what I needed with them. I had had the kit for years sitting in a drawer unused so it was just a bonus.




    Previously the ID of the hole through the mounting flange was 3mm smaller than the pipe which meant there was a lip possibly disrupting/restricting airflow a bit. The inlet manifold opening hole was also bigger than 60mm, so no reason to be smaller. Now it's been opened up to match although from the photo looking into the inlet manifold it seems there's a lip on the left side of it's inlet (possibly the EGR replacement is not exactly built straight?), but I can live with that as it's better than it was.

  6. #16
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    Quote Originally Posted by twr7cx View Post
    Yep, you were right about that:



    I found the white ball stone to be the most effective although the curve on the sides has been flattened out from use and it's started to take on more of a cylindrical shape now.

    Anyways, managed to achieve what I needed with them. I had had the kit for years sitting in a drawer unused so it was just a bonus.




    Previously the ID of the hole through the mounting flange was 3mm smaller than the pipe which meant there was a lip possibly disrupting/restricting airflow a bit. The inlet manifold opening hole was also bigger than 60mm, so no reason to be smaller. Now it's been opened up to match although from the photo looking into the inlet manifold it seems there's a lip on the left side of it's inlet (possibly the EGR replacement is not exactly built straight?), but I can live with that as it's better than it was.
    Aluminium will clog normal double cut TC burrs. For ally work you need aluminium cut burrs which are much coarser with plenty of space for chips in the teeth. TC burrs need to be run flat out. I see hobbyists unfamiliar with their use seemingly afraid to open the throttle. For fine detail and fine finishing use diamond coated points. Slow but favoured by die makers for finishing.

    Those air die grinders need a high capacity compressor. They use lots of air to get the cutting speed up where it should be. Using them on the normal 240 v. home workshop compressor means spending a lot of time waiting for the tank to fill again.
    URSUSMAJOR

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