need to "drill" a 10mm hole, hard steel

  1. Matchless

    Matchless Member

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    Essex UK
    Right, bit of a problem, re-assembling my 1921 JAP engine with new cast iron pistons from a WD Bedford, I have added as much lightness as I can but they are still quite a bit heavier than the originals, nothing I can do about that,

    but the new made pins are also a lot heavier, originals had a 10mm ish hole through, new ones have a 10mm hole at the ends but 4mm through the center part, stronger but a lot heavier, I have found one good old one but need to "drill" through the center of the pin, so far I have blunted a drill and a milling cutter, removed a bit of metal but getting nowhere! is there a drill or cutter I can buy for less than a kings ransom to drill through the middle or can someone do it for me? the pins are around 3" long and 16mm OD, and obviously hardened,
     
  2. pressbrake1

    pressbrake1 Forum Supporter

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    2,415
    essex england
    Msc industrial do sensible priced carbides drills or Ive got a carbide slot drill you could have , just take it easy
     
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  3. northwest

    northwest Member

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    Blimey, that has just brought back a memory. I ground the gudgeon pins on one of my motors once to get the weight down. I had forgotten all about that.
     
    ronan likes this.
  4. Woody.v8

    Woody.v8 Blue gluer

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    you might be surprised about the hardness of the pin once you brake through the though skin, i drilled some hardened and ground gearbox shafts a while back, i just pecked through the hard case with a carbide end mill then went trough with a decent twist drill in the lathe.
     
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  5. tom2207 Member

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    1,604
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    uk northern ireland
    try a masonry bit , no hammer action , and see how it goes , not too fast and a fair bit of pressure ,,, often gets me out of a hole ,, no pun intended.
     
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  6. brightspark

    brightspark Member

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    the masonary drill should have proper cutting edges on it not an impact type bosch do a multidrill but I don't know if if they
    go up to that size. I put em on a green stone and sharpen them up same as a steel twist drill
     
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  7. tom2207 Member

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    1,604
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    i use them exactly as they are with the masonary grind on them , no problems ,, seriously hard to believe , but give it a try.
     
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  8. Matchless

    Matchless Member

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    I do have a set of those everlasting metal drills with tips like a masonary drill, first time I used one it shattered, lifetime warranty though, if I ever get to a car show again! so slow speed, what about lube? should I speed up near the end?
     
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  9. Matchless

    Matchless Member

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    I would have thought the same, the drill bit cut a taper, the mill flattened it off but still hard, will give a masonary type drill a go,
     
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  10. Onoff Member

    Messages:
    1,248
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    Sevenoaks, UK
    You can get them in 10mm yes. Called Bosch Multi Construction bits. Stunned me when I drilled a hard concrete block wall THEN a lump of steel straight after. Drilling wood was oddly no issue after that! Edge was/is still good. I keep a couple of the 4 piece sets, one in the leccy bag, one in the plumbing back. Got longer ones too bought individually.

    They also do an impact fitting set. Link found at random:

    https://www.toolmanyardley.co.uk/sh...9-multi-construction-drill-bits-set-14-shank/
     
    brightspark likes this.
  11. Brad93

    Brad93 M J B Engineering

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    Are you doing it in the lathe Pat?
     
  12. brightspark

    brightspark Member

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    If they go blunt sharpen them before they get to bad :)can generally touch them up twice before they burn out :laughing:
     
  13. Matchless

    Matchless Member

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    1,052
    Location:
    Essex UK
    yup, went down to 54 rpm lubbed up with that green paste, and went firmly in with a 9.5mm bit from the warranted for life car show set, it did cut through but I did feel bits breaking off the tip, crunch, tailstock feed jumped forwards but it kept going up to about half way, used my 10mm HSS drill to finish off, got a bit hard again towards the end but job done, just need to take back the broken drill for exchange! engine will go back together tomorrow!
     
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  14. Brad93

    Brad93 M J B Engineering

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    If you can wait till the weekend come over and we will try a carbide drill. I don’t have any carbide milking cutters though
     
  15. Matchless

    Matchless Member

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    Thanks for the offer Brad, all ok now, just need to sharpen up a few drills and a cutter!
     
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  16. timgunn1962 Member

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    Matchless likes this.
  17. Matchless

    Matchless Member

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    Essex UK
    ok, work in progress, took it off the road about 8 years ago for a rebore, the end pads had been left off the pins at some time and both bores were badly scored, tried brazing them up but did not do much good, did not want to sleeve them as these early JAP cylinders are thin and sleeve adds to overheating, so we went for a rebore & Bedford pistons, should be running by Wednesday,

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  18. Matchless

    Matchless Member

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    should be riding it tomorrow, resealed the petrol tank as the old petseal was destroyed by the ethanol a good few years ago, the stripper is very good but even the vapor will remove paint, hate doing it on a tank with good paint! mask it up with thick poly sheet and gaffer tape, timed it all up today, had to remove the valves to take about 20 thou off the stems as we had no valve clearance, less than none! and I have raised the rear of the footboards as they scraped the road on the slightest bend, roundabouts were a nightmare, was sold as a sidecar bike but I an riding it solo, no date code on the Dunlops, strange, they must be around 1955-60, plenty of tread! last picture is it going into the back of my old sprinter getting ready to come home from a rally in Poland 2008.
    Thinking about it I finished restoring it from a box of bits just before that rally, like a day before, sent pictures of it to the guy who sold it to me in 2007, he had been trying to restore it for 20 odd years, he was in tears when he got the pictures, he thought I was going to break it for spares and did not believe that I could or would restore it!

    20200803_194415_resized.jpg 20200803_194401_resized_1.jpg 20200803_194353_resized.jpg matchless 891.jpg
     
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  19. brightspark

    brightspark Member

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    nearly 1000 cc 8 hp :laughing:get well over 100 hp now for size engine
     
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  20. daleyd

    daleyd Member

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    Over 200 now
     
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