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  1. #1
    Join Date
    Aug 2019
    Location
    Revesby - Sydney Australia
    Age
    56
    Posts
    1,183

    Default How NOT to make a T-nut

    So, I needed to make a T-nut to attach tooling on my Hercus lathe:
    IMG_0099.jpg



    Here are the steps I took, just so you don't repeat my mistakes

    1. Pick a piece of steel plate/strap which is pre-drilled and tapped, to "save time!" Make sure you don't check how hard the steel is
    2. Cut a bit off roughly the correct size: IMG_0098.jpg
    Five minutes in the cut-off saw? Wheel must be blunt )

    IMG_0100.jpg
    3. Realise that this steel is too hard to mill, file, cold-chisel, or generally do anything but grind.

    Decide that a narrow cut-off wheel in an angle grinder is the way to go, because it will remove a minimum of material - should allow me to cut two slits instead of grinding the whole keyway out.

    Clamp grinder to a surface plate with angle iron and packers as a guide
    IMG_0101.jpg
    Precision ground die press tooling under the job. Closest thing to parallel blocks I have
    4. When it is starting to get dark, jump right in and start grinding.

    What could go wrong?
    IMG_0102.jpgIMG_0103.jpgIMG_0104.jpg
    5. The cut isn't going well. Is the steel really that tough?

    No - the grinding disc isn't parallel to the surface plate.
    Didn't take a photo, but the slit is a different height on each side of the job. About 3mm across the 40mm.
    6. Start afresh the next day. Measure twice, cut once? IMG_0106.jpg
    7. Narrow cut-off wheels are surprisingly flexible.

    This means hundreds of passes to try and recut & correct the angled slits, because the angle pushes the disc down or up
    IMG_0107.jpgIMG_0108.jpgIMG_0109.jpg
    8. Find another spacer for the other cut.

    Measure its height on one side only, because you are basically lazy
    IMG_0110.jpg
    9. Jump right in and start cutting. Should be finished by lunch! IMG_0111.jpgIMG_0112.jpg
    10. This little block of steel is getting too hot. Screw a threaded handle in IMG_0113.jpgIMG_0114.jpg
    11. Inspect the cut. Height isn't quite right.

    It looks like my spacer isn't parallel. More angled cuts.

    Search for something else to use. Not going to finish before lunch
    IMG_0115.jpg
    12. Start again with different spacer. Near end of cut, feed in from wrong side of wheel. It actually clears the removed material better. IMG_0116.jpg
    13. After about 4 total hours, hold the hot job in my burning hands, and bolt it in before you can see the imperfections IMG_0118.jpgIMG_0119.jpg

  2. #2
    Join Date
    Dec 2013
    Age
    56
    Posts
    1,416

    Default

    I would have gave up long ago, drilled and tapped a new peice of steel I could mill.
    Saying that did carbide not want to touch it?
    Using Tapatalk

  3. #3
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    71
    Posts
    5,942

    Default

    Going by the sparks, I'd say that is a piece of tool steel or Bisalloy.
    So much for a "quick" job, that's how most of my 5 minute jobs turn out
    To grow old is mandatory, growing up is optional.

  4. #4
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default

    Nigel, remember there are other members scattered around the country (and for that matter the world) who in the main don't mind helping others out. I'm assuming you ground the T nut because you did not have a mill. While it's satisfying to be able to say that you did it all yourself, a little job like that would be no problem for someone with the right gear. Much less frustration...

    Michael

  5. #5
    Join Date
    Aug 2019
    Location
    Revesby - Sydney Australia
    Age
    56
    Posts
    1,183

    Default

    Dave: Only have some old screw-in HSS end mill cutters.
    (unless you count little Dremel style Carbide burrs and Diamond toys)
    I could risk my factory neighbour's Carbide cutters, but would that be socially responsible?


    KB: I'm guessing its Bisalloy. Probably the fixed block from a guillotine or shears.


    Michael: Indeed. I'm still building up contacts.
    Do have some people who could help, but wanted the satisfaction of doing it myself.
    Also,

    1. no suitable mild steel block was handy - still building up the scrap pile

    2. correct assumption! Sold Dad's RongFu mill to a friend about 4 years ago.
    (admittedly, it was a better drill press then mill)

    3. factory neighbour offered a rod of 4140 to turn a big new bolt out of,
    bit I wanted the satisfaction of doing it myself.
    And it was a bit of fun learning, pretending I was a tool or die maker.

    (who, from what I've seen, precision grind everything?)



    P.S. Just for fun, here is what the slight tapered edge of a cutoff wheel does. On the other side of the wheel, it did automatic feeding!
    Last edited by nigelpearson; 29th Sep 2019 at 04:16 PM. Reason: Add silly video clip

  6. #6
    Join Date
    Dec 2013
    Age
    56
    Posts
    1,416

    Default

    As Michael said, there are plenty of us out there that will help out, and you will probably get someone close by and willing to share info and ideas etc and learn more while you visit.
    We all started somewhere, I only wish pre internet I had a mentor, I would have loved it instead of learning on my own.

    On the other side, I can can see myself in my teens doing something like you have done, never say never has always been me, and nothing is too hard no matter how many hours it takes as long as it saves a few dollars and gets the job done, lol.

    Dave J
    Using Tapatalk

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