Hardening a tool rest

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  • #48762
    randy
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    • Topics Started: 39
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    The T-rest that came with my W-J lathe is pretty soft.
    I cleaned, filed, finished it to a nice condition when I got it, but after some light use, the flat is getting some gouge marks.
    I know that I can harden it, but not sure of the proper method to heat/quench it ?

    Any ideas ?

    Thanks

    Randy

    #54772
    arutha
    Participant
    • Topics Started: 85
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    Hi Randy,
    I have exactly the same problem, I polished all the dinks out of mine when I got it and it is looking quite rough again. I dont know if they were designed that way for a reason but as for hardening I dont know.
    Paul.

    #54773
    randy
    Participant
    • Topics Started: 39
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    I’m sure that somewhere I read where you can harden them….probably in my own library somewhere, but I can’t find it !!!!
    I’ll let you know Paul !…thanks for the support.

    #54774
    Bob Tascione
    Moderator
    • Topics Started: 38
    • Total Posts: 1559

    Hi Randy and Paul,

    I have both soft and hardened T-Rests with my personal preference being the softer metal. In most cases I like when the graver can ‘bite’ into the rest when needed. Otherwise the graver seems to slide too easily when I want it least. I’ve never hardened a T-Rest but if it’s made of high carbon steel it can be hardened. There are a couple of ways to test the carbon content of the steel in a home shop with normal tools. One is by doing a spark test with a grinder. This works real well and is a good, valuable and fun process to learn. Should be lots of info online if you have an interest. The other is to just try heat treating the part and see what happens. :)
    To do this you would bring it to a dark orange to bright cherry red color which is at the upper end of the critical temp. range of about 1325 to 1600 F. This is a perfect temp. for quenching. After quenching clean the part up with some steel wool so you’ll be able to see the color changes while tempering. You can now temper the the piece by bringing it to a dark blue color and then slowly removing it from the flame. Let it cool slowly and you should be good to go. This tempering will take the brittleness out of the part but will also reduce the hardness about 30% to 35% when taken to the dark blue shade. Still should be much harder than if it was at it’s normal non-hardened pearlite state. If you want it harder then when tempering just stop at a shade before reaching the dark blue color. Something like dark red to purple rather than dark blue.

    Hope this helps guys!
    Bob

    #54775
    randy
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    • Topics Started: 39
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    Thanks Bob,
    I know the grinder test, so I’ll give that a whirl if I now decide to harden this.
    You’re comments about it being able to bite into the rest at times gave me pause for thought.
    I’m thinking now, that maybe I need one of each, depending on what task I’m applying it to.
    For reducing shaft diameters I can see me wanting it hard, so that the graver can glide easier, but softer when I need to focus on a particular spot, and can’t risk it moving on me.

    Take care

    Randy

    #54776
    arutha
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    • Topics Started: 85
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    If you manage to harden the rest you have it wouldn’t take too much to make a soft tool rest out of brass. Something I might try myself!

    #54777
    randy
    Participant
    • Topics Started: 39
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    I’ll have to ponder that….might be the ticket

    #54778
    cazclocker
    Participant
    • Topics Started: 9
    • Total Posts: 85

    Hi, I just found this thread. I find that like Bob, when the tee-rest is left soft, my graver kind of “bites” into it and tends to stay put without sliding back and forth. As to excessive nicking into the tee-rest, I try to at least partially solve that with how I prepare my gravers. Before I even grind the lozenge tip, I start prepping my graver on a fine India stone. I just round off one of the corners, along the full length of the graver blank. I don’t round it off very much, just enough to get rid of the sharp 90-degree angle. Then once I have one of the corners rounded, I then take the blank to the grinder to start making the lozenge shape. The rounded corner becomes the bottom of the lozenge shape. After stoning the lozenge to mirror brightness, the rounded corner becomes the corner that I seat onto the tee-rest. I have one graver where I rounded two opposite corner edges – one became the base of the lozenge and the other became the tip of the lozenge. The only thing I don’t like about that graver is I can’t cut super-sharp cuts because of the slightly rounded tips. My gravers, when prepped this way, stay put on my soft tee-rest even though it’s rounded a little bit.
    …Doug

    PS….I don’t know, but I suspect tee-rests were made soft intentionally. Most of our lathes were made nearly a century ago by the old-time industrialists who really knew how to make stuff the right way. I love old technology!

    #54779
    arutha
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    • Topics Started: 85
    • Total Posts: 1536

    Hey Doug, what a great idea! Why didn’t I think of that?
    I have since made a couple of t-rests and don’t mind them being soft, infact I am quite used to them now so I don’t seem to have that problem. It seems the more experience I get under my belt the more I use the machinery, the better I get at using the machinery. I remeber back when I started I was almost too frightened to turn it on and tried doing everything by hand. When you are trying to make a living from this you soon learn that certain machines can speed things up quite a bit yet there are still certain jobs better done by hand.
    Paul.

    #54780
    randy
    Participant
    • Topics Started: 39
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    Thanks for your experience on this Doug…gives us ( and me ), more options !

    #54781
    cazclocker
    Participant
    • Topics Started: 9
    • Total Posts: 85

    @Randy wrote:

    Thanks for your experience on this Doug…gives us ( and me ), more options !

    No problem – the main issue is that with the graver blanks we use on our lathes, the 90-degree corners along the lengthway edges are very sharp and are essentially the same as the corners on our cutting broaches. We use our cutting broaches all the time to remove metal, when we want to enlarge a pivot hole. Similarly, the sharp corners of our gravers can’t be blamed too harshly for making nicks in our tee-rests. So dulling one or more of the longitudinal edges only makes sense.

    I basically learned how to make gravers by reading the article by W.R. Smith on Sherline’s website. You can see the article here: http://www.sherline.com/gravers.htm The article is old, so the prices are outdated but the product numbers are still good.

    For my HSS graver blanks, I order product #71093082 from MSC. They’re $6.71 each. I ordered a dozen of them a long time ago and I still haven’t used them all!
    …Doug

    #54782
    randy
    Participant
    • Topics Started: 39
    • Total Posts: 594

    Thanks Doug,
    I’m familiar with the Sherline article. I have some very nice ( new ) gravers that I just finished shaping awhile ago. I hadn’t thought of dulling the edges as you suggest..so I’m going to do that next.
    Sorry for the late reply…been crazy busy with family health issues lately.

    Best regards,

    Randy

    #54783
    cazclocker
    Participant
    • Topics Started: 9
    • Total Posts: 85

    @Randy wrote:

    …Sorry for the late reply…been crazy busy with family health issues lately.

    Best regards,

    Randy

    I sure know how that aspect of family life goes. Hang in there Randy!
    …Doug

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randyHardening a tool rest