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  • shaper bit geometry

    If I have an Armstrong tool holder that looks like it has rake built into it, do I still put the same end relief and back rake into the bits? All the illustrations show similar angle, but none tell me if I should use a tool holder or mount it directly to the tool post ring.


    thanks in advance
    bedwards

  • #2
    That holder is meant for lathes. You can make a proper tool holder from scrap. Look carefully at the cutter on this shaper. That's all you need.

    http://www.youtube.com/watch?v=adRlGffXM5k

    The other artful bodger has some excellent pages on shaper cutters here:

    http://www.artfulbodger.net/docs/shaper/index.html

    Edit:

    If you haven't seen Kay's shaper site you're missing a treasure trove of shaper information. Here's a couple pages that show shop made tool holders and some shaper-specific Armstrong holders:

    Main page - http://www.neme-s.org/shapers/

    http://www.neme-s.org/shapers/column...column_33.html

    http://www.neme-s.org/shapers/column...column_42.html (scroll down)
    Last edited by dp; 11-24-2013, 11:23 PM.

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    • #3
      Thanks, I've got a lot of studying to do still.

      bedwards

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      • #4
        A problem of using the lathe style holders is the cutter is tipped into the cut, and any bending is going to force the cutter deeper into the cut which is a positive feedback function. Shapers don't have the the lathe's half-moon spacer below the cutter to adjust the rake - you get the full effect.

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        • #5
          There is a great book out there with a wealth of knowledge written for the apprentices of "Shop Theory" from The Henry Ford Company", every new machinist should look for one. I see one on Amazon for $32.00. http://www.amazon.com/Shop-Theory-Re...rentice+manual

          There is a great chapter on shapers and tool bit sharpening. Rich
          Last edited by Richard King; 11-25-2013, 12:48 AM.

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          • #6
            I suspect that's why I've had a problem with mine digging in or hogging. It would cut just fine for a while and then just dig in. I've got it where its cutting well after messing with the tool bit geometry. I'm going to grind some larger bits and try it without the tool holder.


            thanks
            bedwards

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            • #7
              On my own shaper in this video you can see a straight Armstrong tool holder in the clapper tool post. The cutter is perfectly perpendicular to the work, and parallel to the clapper face. Those holders work fine and show up on Ebay frequently. I'm still looking for a gooseneck holder and they're less common.

              http://www.youtube.com/watch?v=oZFFYIvTLiE

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              • #8
                That toolholder looks like the one I have only a different brand.


                bedwards

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                • #9
                  I had a problem with digging and hogging, chatter, when cutting a long keyway in O-1 steel. The solution was twofold. First, I found that the work was more rigidly mounted when clamped directly to the table, second, I put the cutting tool directly in the tool post and omitted the tool holder. The holder seems to give the tool more of a leverage advantage and allow more flex in the setup.

                  Although I generally get a good finish when cutting a flat surface, putting the tool bit directly in the tool post seems to keep things more rigid there too. Now the only time I use a holder is if I need the reach.

                  Although I haven't yet experimented with it, I have often wondered about using a tool bit with a "V" shape toward the center of the bit to curl the chips inward while cutting a keyway. Something like this:
                  My drawing does not depict the exact shape, obviously with the one shown there would be a small hump left in the center of the keyway. I'm certainly no artist, but I think the idea comes across.

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                  • #10
                    Originally posted by bewards View Post
                    That toolholder looks like the one I have only a different brand.
                    bedwards
                    The cutter on your tool holder is angled toward the vise. Mine is vertical.

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                    • #11
                      Originally posted by dp View Post
                      The cutter on your tool holder is angled toward the vise. Mine is vertical.
                      I think your right.

                      bedwards

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                      • #12
                        Armstrong tool holder for a small shaper... It has slots for every 45-degrees - in between angles can be set by the clapper on the shaper.





                        Tool shapes from How To Run A Metal Working Shaper South Bend Lathe Works ...


                        Last edited by Mike Burdick; 11-25-2013, 02:01 PM.

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                        • #13
                          You might also have to change the direction of the toolholder to place the HSS bit to the rear (closer too the hinge).
                          I seem to get more chatter when the tool bit sticks out too far from the clapper hinge.
                          By turning teh toolholder around you place the HSS but under the hinge.
                          Another thing is to have an approximate 45 degree angle on your HSS bit to 'shear' off the metal.
                          Makes teh cut smoother and peels off shavings. They are directional so you would have to make one for right and then for left cuts.
                          Make a final set with a large round radius (and the 45 degree angle).
                          This is a finishing bit and puts a smooth surface on the part.
                          http://www.youtube.com/watch?v=5hY6UGMUG3k
                          (pardon the sound near the beginning as I had a bad belt shaking the pulleys)

                          I made my toolholder and it is similar to the Armstrong pictures above.

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                          • #14
                            Here's a NO. 46 Williams Shaper-Tool Holder for internal work ...

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                            • #15
                              Originally posted by Mike Burdick View Post
                              Armstrong tool holder for a small shaper... It has slots for every 45-degrees - in between angles can be set by the clapper on the shaper.



                              http://img.photobucket.com/albums/v1...psc4be7980.jpg

                              Tool shapes from How To Run A Metal Working Shaper South Bend Lathe Works ...

                              http://img.photobucket.com/albums/v1...aper_bit_0.jpg
                              http://img.photobucket.com/albums/v1...aper_bit_0.jpg
                              This is the tool holder and tool geometry you want to use on a shaper.

                              One more point, "Digging in" was mentioned. Tool deflection in a shaper is a problem because the tool, following its elasticity increases its depth of cut. If the tool is placed behind the face of the clapper box the tool tends to "self relieve". However shapers have no tool lifter mechanism. It drags back over the work on the return stroke. A tool placed behind etc drags harder and in some geometries this drag can damage the work or the cutting edge or both unless manually or mechanically lifted.

                              The Armstrong holder illustrated can simply be reversted in the tool post and short tools used to reduce the overhang. Reversing the tool holder is not a cure-all. Mounting the tool holder with the tool forward is probably most convenient for all but form cuts and broad nosing.

                              These Armstrong holder are not cheap

                              http://www.ebay.com/itm/METAL-SHAPER...2#ht_284wt_610

                              The Armstrong, OK, or Williams "turret style" (Bill Charbinau's name for the general design) tool holders are easy to reverse engineer, scale down, and make for the home shop machinist.

                              The traditional forged Armstrong or Williams tool holders best suited for the shaper are made without built-in rake). Look for the prefix "T" before the number. "T1S," for example identifies a zero-rake tool holder for 1/4" square tool steel, straight (tool alighed on the shank axis). The "T" series were often called "carbide" holders because they allowed use of the brazed-on carbide tools used from before WW II through the 60's.
                              Last edited by Forrest Addy; 11-25-2013, 03:06 PM.

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