Page 3 of 7 FirstFirst 12345 ... LastLast
Results 21 to 30 of 61

Thread: Reaming Hardened Steel

  1. #21
    Join Date
    Feb 2014
    Posts
    968

    Default

    Quote Originally Posted by epicfail48 View Post
    Strictly speaking yes, that would work, but adds way more complexity and work that im looking for. Im more asking if a carbide tool can reasonably be expected to cut through hardened steel
    If it were mine - I'd try drilling the hole after blade tempering with a straight flute solid carbide drill, no reaming needed. In hard steel those seem to leave a very precise hole size with reasonably good finish. I think it would be best to do this with either a very small pilot hole (drilled before hardening) or none at all; I'm not sure it would work well to fix a hole that's already drilled and warped.

    Your blade may be too hard for the type of drill I'm thinking of - I've seen them listed as only good for ~50 Rc - but I've drilled through fully hardened O1 tool steel with these so it might be worth a shot.

  2. #22
    Join Date
    Mar 2015
    Posts
    3,501

    Default

    Maybe get a D-bit grinder and start making your own carbide D-bits for this.

    Sent from my SM-G950U1 using Tapatalk

  3. #23
    Join Date
    Jan 2005
    Location
    Buffalo NY
    Posts
    4,435

    Default

    Quote Originally Posted by epicfail48 View Post
    ... If the holes are sloppy, the fit of the entire knife is...
    4 thou, right?
    For real, 4 thou??
    That is too loose???
    That is 4 thou radial location.
    I assume you can get the pivot
    bolt tight, so you can have almost
    zero axial play. If that is the case,
    then 4 thou radial play is nothing for
    a folding knife. If it is spring loaded locking
    then you will notice it even less. It seems to me
    that someone's OCD medication ran out of prescription.
    Design it with a countersunk hole and let the taper be your
    friend, and make a tapered bushing to suit the pin. Then achieve
    zero fit with the tapered bushing in the tapered hole. Split the busing
    if you want, and tighten to remove all play. That ought to get your man
    boobs out of a bunch, and cheaper than therapy any day of the week.

    -Doozer
    Last edited by Doozer; 07-01-2019 at 08:32 PM.
    DZER

  4. #24

    Default

    I made a part in O1 for a labeling company last week, the OD is 2.150" -.0007 -.0002 (ISO GD&T tolerancing) and the bore was .630" + .0000 -.0005, it is 8" long.
    I told my employer that I would leave .010" per side for finish grinding after hardening. He did not like that idea and told me to turn it to size so I did as told.
    After hardening he had me measure it and it grew .004" on the OD and .002" on the ID. I told him that it will be rejected but he shipped it anyway.

    Sure enough a day later it returns with a Notice Of Nonconformity.
    I told him that we can grind the OD smaller but we can not grind the ID smaller. I believe that it is scrap.

  5. #25
    Join Date
    Feb 2014
    Posts
    968

    Default

    Quote Originally Posted by Doozer View Post
    4 thou, right?
    For real, 4 thou??
    That is too loose???
    That is 4 thou radial location.
    I assume you can get the pivot
    bolt tight, so you can have almost
    zero axial play. If that is the case,
    then 4 thou radial play is nothing for
    a folding knife. If it is spring loaded locking
    then you will notice it even less. It seems to me
    that someone's OCD medication ran out of prescription.
    Design it with a countersunk hole and let the taper be your
    friend, and make a tapered bushing to suit the pin. Then achieve
    zero fit with the tapered bushing in the tapered hole. Split the busing
    if you want, and tighten to remove all play. That ought to get your man
    boobs out of a bunch, and cheaper than therapy any day of the week.

    -Doozer
    I'm getting the strong impression you've never built or even re-assembled a quality folding knife.

  6. #26
    Join Date
    Oct 2012
    Location
    San Antonio TX, USA
    Posts
    2,686

    Default

    I do like the formatting though

  7. #27
    Join Date
    Jul 2017
    Location
    Springfield Mo
    Posts
    592

    Default

    Quote Originally Posted by Yondering View Post
    I'm getting the strong impression you've never built or even re-assembled a quality folding knife.
    You beat me to the punch with that comment. I also get the impression that the "butterfly knife" part was missed. This aint a friction folder or a fixed blade, it requires precision. If i could get it done with a backyard hackjob, i wouldnt be asking the question.

    Ill see about ordering in a carbide tipped reamer before i do the next blade, the few useful responses have indicated thats where i should be looking, unless i want to completely redo the design (which i dont), or settle for crappy tolerances (ditto)

  8. #28
    Join Date
    Jul 2017
    Location
    Springfield Mo
    Posts
    592

    Default

    Also, Mr. Doozer, you missed the "pivot bushing" portion of things as well. Theres a bushing in the joint of this knife so you cant tighten the screws down so much they affect the action. May want to do some research on the style of knife before making insulting remarks about my medication status

  9. #29
    Join Date
    Jan 2004
    Location
    Missouri
    Posts
    31,542

    Default

    OK, you have a size problem, and a machining problem. Both are the result of heat treating that has to be done, so that part is a "known".

    DOES that part of the blade have to be RC61, or would it work as well if it was "only" RC45 or RC50? Something that would be more readily machinable to tolerance with good results.

    If you say "no, it has to be RC61", can you share why a still hardened but not "as" hard material in that portion of the part is not usable?

    If you agree that the somewhat less hard part is fine, then you have a choice of either not hardening that area so much, or of drawing that area back. I suspect drawing that area back is easier and more controllable.

    You said that it adds steps and time. OK. Now, how much time does it add to fiddle-fart around with trying to precisely size a hard as heck part without the proper equipment? Likely more than the drawback process.

    You would be money and time ahead if you just did a controlled draw-back of that area, probably by dipping it in a bath of molten material at a particular temperature to a specific distance for a specific time. The temp will give you the draw-back hardness result assuming you follow your process. The specific depth will allow you to avoid any drawing back of the cutting part of the blade.

    It sounds to me like a practical solution, that might actually have advantages to the user.
    1601

    Keep eye on ball.
    Hashim Khan

  10. #30
    Join Date
    Feb 2012
    Location
    Metcalfe, Ontario, Canada
    Posts
    1,359

    Default

    Just me and my crude methods, but if the blade was O2 or other simply treatable steel I would stand the blade upright in a container of water with enough of the shank exposed (we can debate "How much is enough" later , of course.) and play a small torch flame on the pivot area until the color looked right.

    Can't help but be just as good as or a little better than all hard when the owner puts a bit too much prying force on the knife.

    And of course you've added value to the product because now you can advertise the blades as "differentially hardened".
    Last edited by cameron; 07-02-2019 at 08:13 AM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •