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  • Slitting saw advice

    Will need to slit on my mill soon. Cut will be 1/4 wide not deep or long. Rifle barrel extractor grove. My mill is a Rockwell it’s not big or powerful. Might as well set up for slitting future jobs too.

    Looking at Arbors either R8 or run in a collet, what’s the best choice. If I go collet what about shank size. Other question is what size saw hole and should I set up for, keyed or no key.

    All comments apreceated

    Boats

  • #2
    Why do you need slitting saw for rifle barrel extractor groove? No tilting head or table in the mill?

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    • #3
      It tilts, guys that barrel this particular action (Stevens 44 1/2 ) all use slitting saws . Falling block the cut is at 6 o’clock on the face and goes all the way through the threads. Bolt action on the side set up is different . Say they get a better cut than end mills. Besides don’t have one want try it. Have a scrap barrel to pratice on.

      Boats

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      • #4
        I would consider a 1/4" a milling cutter and for sure go with an arbor--Keyed if your cutter has a keyway. Get the cutter then get the arbor to match. I just ordered a few sets of gear cutters and had to order 16 and 22mm arbors. I already had a 1" arbor for cutters. Tooling keeps stacking up.

        Also, is the large radius of the cutter a requirement for a blend? If a smaller radius would work, consider using a keyway cutter.

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        • #5
          Looking at Arbors either R8 or run in a collet, what’s the best choice. If I go collet what about shank size. Other question is what size saw hole and should I set up for, keyed or no key.
          I made my own arbor, 3/4" straight shank held in a 3/4" R8 collet. My preference is no key. If it jams, I'd rather it spins on the arbor than breaks or
          tears something else up. A straight shank also lets you pull it further out of the collet if you need more reach or push it further in if you need more
          table to blade headroom.

          Location: Long Island, N.Y.

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          • #6
            I have a Rockwell too and found it too fast for most larger dia. tools. What I did was take the aluminum motor mount casting off the top, make a square 1/2" steel plate to replace it and build a frame work on of the plate extending to the back where it is supported at the end of the round bar the head is mounted on. This frame work is basically a "longer" motor mount that allows mounting the motor at the back of the mill with the original motor on an idler shaft in the original motor position. Then I put a small cone pulley on the motor. I can now get down to about 90 rpm I think. Slow enough for larger dia. tools and I seldom need faster speeds than this setup allows but they are available by switching the belts positions from upper belt to lower belt etc. It has made the mill much nicer to use for most work.

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            • #7
              Stacking up unnessary tooling is what I want to avoid. Cut should be flat bottomed but it’s not critical. Saw ought to slice through leaving it flat same as if I cut it with a hacksaw. Hacksaw and file is how was done in home shops back in the day.

              Thanks all will digest & may have a few more questions.

              Boats

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              • #8
                Originally posted by boats View Post
                Stacking up unnessary tooling is what I want to avoid. Cut should be flat bottomed but it’s not critical. Saw ought to slice through leaving it flat same as if I cut it with a hacksaw. Hacksaw and file is how was done in home shops back in the day.

                Thanks all will digest & may have a few more questions.

                Boats
                I built a couple gatling guns and cut the extractor relief in the barrels (10 barrels) using a woodruff key cutter. Its very rigid and does a nice job.

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                • #9
                  One mistake I've seen many newbs make is running the slitter too fast or feeding too fast. Calculate correct speeds and feeds for the cutter before you start. When using a HSS slitter I never start faster than 60 RPM. Then I will move up to the correct speed judging by chatter and feel. Often you will have a slight variation in concentricity of the cutter teeth causing it to cycle during the cut. So feed in slowly until you get the hang of it. Hope this helps.

                  Best Regards,
                  Bob

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                  • #10
                    I just purchased an R8 stub arbor to use horizontal cutters on my Bridgeport. Shars currently has one on sale for $31.95 that will accommodate 1" ID cutters. The one I bought will take up to a 2" wide cutter. I would normally do slitting on the horizontal mill, but at 40+" long and 8" wide the part is to big for my horizontal mill.

                    https://www.shars.com/1-stub-milling-machine-arbor-1



                    They also have an R8 slotting saw arbor for $23.30 that will take multiple diameter saws. The slotting saw arbor isn't keyed like the one I purchased.

                    https://www.shars.com/slotting-saw-arbor-r8-shank
                    Last edited by projectnut; 03-14-2019, 01:18 PM.

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                    • #11
                      I have one of the 2nd ones you list, Projectnut, and find that it cuts fine if I am patient and get slow enough speeds and feeds for the material being cut.

                      I've wondered how the keyed versions hold up, i.e., which gives 1st the cutter or the cuttee. Don't think I've ever slipped the wheel on my cutter. (yet)

                      Dan L
                      Salem, Oregon

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                      • #12
                        If I'm reading this right the groove is 1/4" wide and shallow, which I take to be less than 1/4" deep. I'd agree this isn't really a slitting operation and it sounds like a keyseat cutter will do the job no problem, as has been mentioned. Maritool has them for $20. Cheaper than an arbor and way cheaper than a 1/4" side milling cutter.

                        As for arbors, both of the shars versions linked have their drawbacks, I built a DIY one (like many others) for a cheap carbide tipped trim saw blade I found on amazon. Home built arbor is a great lathe project and you can achieve better results than cheap imports.

                        http://bbs.homeshopmachinist.net/thr...straight-shank

                        Comment


                        • #13
                          ...and don't forget to CLIMB cut with whatever cutter you end up using.
                          Milton

                          "Accuracy is the sum total of your compensating mistakes."

                          "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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                          • #14
                            wdtom, not to hijack this thread but do you have a picture of the motor adapter that you made for your mill? (this is a model 21-100 correct?) Thanks, Jim

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                            • #15
                              Thanks all. Couple take aways.

                              My mill is about 250 RPM slowest, like to slow it down but won’t be able to before this job. That means small diamater cutter and very slow feed rate. This cut should be about 1/4 wide bit over 1/4 deep. Slow feed ought to work.

                              Think I will go several ways, primarily Woodruff key cutter run in a collet. Then a R8 Arbor with several slitting saws just to get the feel for how they work. No reason not to make up a Arbor for carbide small circular saws too. Not for this job but could be useful others. Aluminum for example.

                              Am a bit confused confused on climb vs no climb. I would think climb milling should be avoided. Run the cutter so it cuts down into the work no different than a table saws blade bitting into a board. Is there a reason to run the tool climb ? Any event will make a Few Cut’s on a junk barrel to work things out.

                              Would like to see a photo of the Rockwell slow arangement too.

                              Boats
                              Last edited by boats; 03-14-2019, 06:37 PM.

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