Cutting tool steel.

Discussion in 'Clock Construction' started by bytes2doc, Jul 16, 2016.

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  1. bytes2doc

    bytes2doc Registered User
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    Aug 31, 2009
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    I'm in the midst of making the click and click spring from unhardend steel. I can't find unhardened steel at online metals. Do you buy hardened metal and aneal it? Or use mild steel?

    The anchor is from tool steel.

    The tool steel I got was a plate of 3/16th O1 and having a difficut time cutting it. I tried heating it to a dull red with a propane tourch and air cooled so that a file bites into it. I have used three metal cutting saw blades to get through this. Obviously I'm doing something wrong.

    Any and all help is greatly appreciated.

    barry
     
  2. glenhead

    glenhead Registered User
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    Nov 15, 2009
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    The steel you buy isn't hardenED, it's hardenABLE. O1 steel is a bleep to cut. For 3/16 inch, you can use a 14 tooth-per-inch blade to remove more metal per stroke. Lower is better in your case. If you use a jeweler's saw or something with a really high tooth count you're going to go through them at a horrifying rate. If you use a bimetallic blade it lasts a bit longer, too. Once the piece is cut and formed, you harden and temper it to the desired color, probably a nice dark blue for a click and click spring.

    Glen
     
  3. jhe.1973

    jhe.1973 Registered User
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    Hello barry,

    While O1 is somewhat harder on tools it is cut all the time in machine shops.

    You don't say if you are cutting by hand or with some type of power saw.

    If you are using a power saw, the blade is likely traveling too fast. If by hand, you must maintain a fairly high pressure on the blade so that you don't work harden the cut.

    It is also possible that by trying to anneal the steel you hardened the area to be cut. It all depends on how completely the steel was heated and how slowly it was cooled. For example, if the part was held in a vise or pliers while heating, the area near where it was held would likely harden because the vise or pliers would draw the heat away too quickly.

    The hardening takes place as a result of how quickly the steel is cooled after heating. The quenching method is secondary - oil cools more slowly than water so the shock to the metal is less. Oil/water/air hardening steels are designed for the rate of cooling that the cooling medium will give.

    To completely anneal your steel, it should be heated as uniformly as possible to red heat, preferably on a firebrick and IMMEDIATELY placed in something that will allow it to cool very slowly. I use a pail of dry sand and it must be covered with the sand also, not just tossed on top. It will take hours - possibly overnight - to cool to room temperature. You can also use dry ashes, but they might etch the surface from the alkali content.

    I believe I have heard of using plaster of paris or cement powder also - I just don't know of the results with these powders.

    Hope this is of some help!
     
  4. shimmystep

    shimmystep Registered User
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    Are you using any cutting lube? If not, it'll help, and your blade will last a bit longer.
     
  5. bytes2doc

    bytes2doc Registered User
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    I finished the click by using a bench grinder and a belt sander to bring it into shape. Interestingly is was not difficult to file and draw file the piece.

    i was using a jigsaw with highspeed steel blades, trying both a low tooth count and a high tooth count.

    However the speed was high and I was not using lube. I'll lower the speed on the other end of the raw stock that was not affected by my miserable heating attempt. Maybe I'll try it on the anchor.

    thanks all

    barry
     
  6. jhe.1973

    jhe.1973 Registered User
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    Hi Barry,

    If you, or anyone watching, are interested, the recommended cutting speed for various materials and cutting tools is usually expressed in surface feet per minute - SFM. Just to help visualize this, it is the same as miles per hour but on a smaller scale.

    High speed steel for cutting soft carbon steel is 80 - 120 SFM. Most annealed tool steel is 70 - 90 SFM.

    These speeds jump to 400 - 600 SFM and 300 - 450 SFM respectively if you are using carbide cutters.

    To calculate the SFM for a jig saw you would have to know the distance of the stroke and how many per minute. My jig saw runs pretty fast even on its slowest speed, but I never bothered calculating the SFM.

    I did a quick search and found lots of SFM calculators:

    https://www.google.com/search?q=surface+feet+per+minute+calculator&ie=utf-8&oe=utf-8

    This just one:

    http://www.carbidedepot.com/formulas-turning.htm

    The above are for simple turning or milling.

    Because it is possible that clock/watch people might have live tailstocks that rotate a cutting tool against a revolving part, it should be noted that both rotating speeds/diameters have to considered to get an accurate figure for how much material is moving past the cutting edge.

    Regarding your annealing attempt (which might have been just fine) consider this quote from Einstein:

    "If we knew what it was we were doing, it would not be called research, would it?"

    :thumb:
     
  7. bytes2doc

    bytes2doc Registered User
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    That was it!

    Slowing down the speed of the blade, adding oil, and a constant pressure, cut right through without any problems.

    Thanks all for your advice.

    barry
     
  8. jhe.1973

    jhe.1973 Registered User
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    Hi Barry,

    Glad to hear that it worked out well for you!

    :coolsign:
     
  9. Vernon

    Vernon Registered User
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    Jim,
    Thanks for the great explanation on annealing. I need to practice and have struggled with the at others have explained.
     
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