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To Harden ..or Not to Harden

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  • To Harden ..or Not to Harden

    The 1/4" pin that engages the ratchet wheel to drive the table feed on my Logan shaper broke the other day. The break was at the point where it's cross-drilled for a 1/8" pin that engages either of two V-notches, one of which is deeper, permitting feed. The shallower one suspends the ratcheting feed.

    The engagement end has a 60deg bevel with a flat milled on the opposite side to engage the ratchet teeth. I'm making a replacement out of oil hardening drill rod, which is a fairly simple matter, but I've started wondering if it might be better just to leave it unhardened. 'cause at that 1/8" cross-drill there's not much metal left.
    (The original was fully hardened all over BTW.)

    Or..., Can I successfully harden just the business end, leaving that cross-drill area soft?(about 1" from the beveled end)

    Or..., another option, since I recently got a can of Kasenit which I haven't tried using yet, is to make it of mild steel and try casehardening the beveled end.

    Any good (experienced) advice on this?

  • #2
    I can say that case hardening drill rod is a waste of time. It already has all the carbon it needs to harden.
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    • #3
      Mild steel and case harden the whole thing.
      To invent, you need a good imagination - and a pile of junk. Thomas A. Edison


      • #4
        As mentioned drill rod has enough carbon in it and the other option was mild steel that is case hardened. Why not make one out of each, you will have the machine(s) set up anyway and it will give you an excuse to try the Kasenit you have to in a real world scenario(instead of just trying it but not actually using the piece somewhere). I routinely make more than one spare while I have the machine(s) set up, that way if the piece doesn’t work well enough or breaks I have another one to use and don't have to stop what I’m doing to make another one. Use common sense with this and only make spares of small parts(not vises). I have a couple of spare draw bars for my mill-drill and other small spares that were made at the same time as the original. It is also a good habit so if a friend sees the item and likes it or you wish to sell one you don't have to set the machine up just for one item. I have three brothers that do upholstery work and any time one of them ask for a special tool I make four of them, one for each brother and one for me. Good luck.



        • #5
          Sorry, but I don't think this a forum for Viagra discussions!!!!


          • #6
            Thanks all.
            You make a good point Mike. That did occur to me early on, but then I didn't carry thru with making an extra. But I now have the drawings and dimensions, so making another will be no big issue. There wasn't any real fixturing needed. Hmmm, on second thought maybe I will make another of mild steel, just to try the Kasenit.

            Sorry Canonicalman, for the titillating topic title. Didn't really mean to "raise" that issue.


            • #7
              I made a new shaft and top knob with the arrow for the ratchet using drill rod and only hardened the business end. It works fine. In addition,I bored out the case and inserted an oilite bronze bushing. I extended the bushing to make the overall length about 3/8 inch longer. This provided more stability to the unit and makes it work ..

              Joe W


              • #8
                I was able to salvage the old top knob. I knew I'd never be able to make as neat a little arrow on a new one. But after drilling out the pin holding it on I still couldn't get the knob off the broken shaft, so had to drill out the shaft too. ...only after all that I was able to see the outline of the pin on the other side. It had looked like the pin was punched into a blind hole. Not so.

                I ended up doing the same, ..just hardening the contact end. I didn't try tempering it, but left it fully hardened, so a file just skates over it. Afterward I polished it up on a handstone, and put a sort of rounded bevel on it, thinking that'll work better on the 'gathering' stroke. Kinda like a cam lobe. Installed it this afternoon, and so far it seems to work at least as good as the original.

                I think this had taken some abuse in shipment last fall when I bought it (ebay). When it arrived that end of the table feed screw was bent, and was protruding from the packing and shrink wrap. So I'd had to remove it and do some straightening on that. But there's still some noticeable binding thru about 30 deg of the rotation of the screw. Which prompted the idea of rounding the bevel, because sometimes the ratcheting stops and the ratchet box just rocks the screw back and forth til I hold the screw for a couple of gathering strokes.
                Someone previously suggested tightening the nuts on the other end of the screw, and that helped a lot, but never completely eliminated the problem.

                I'll keep the idea of a longer, bronze bushing in mind. That might help too. Tho it seems to have a 'just right' sliding fit in the original steel bushing.

                One thing I really need to do is determine EXACTLY how to prevent the same event that happened the other day. And I'm not really sure why, but as I was manually reversing the table, with the pin in 'neutral' and machine operating, the ratchet box suddenly flipped forward toward the linkage arm and the knob contacted the arm. Of course it happened fast, and my eyes and concentration were on the table position, so I wasn't watching the ratchet box or link arm.
                But I could tell that the pin had an old crack in it because only a portion of the fracture showed new, shiny metal.