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  • how small end mills

    I can't blame Murphy for this, but it seems whenever I come up with a shop project, it requires a tool or special cutter that I don't have. My stock of custom cutters is growing. Now I'm wondering what's the best way to create a slot, roughly 1/16 wide, 1/6 deep, starting from a hole. The slot needs to be full depth from the side of the hole, which is .160 dia., to the edge of the workpiece. (no room for a slotting or slitting cutter to run out) I thought I could use (make) a milling cutter to do it, but there's too much flex at this small dia. Any ideas?
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    If a jewelers saw of 1"diameter won't do it than I might suggest a carbide circut board router they can be had down to about .035"and can be used in machines as large as a b-port mill you just have to feed them at about.001"per second at about 4000 rpm!This requires nerves of steel I admit but I have done it just be sure and lay off the coffee and use your favorite stress relieving medication first!
    I just need one more tool,just one!

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    • #3
      1/16" isn't a problem either with HSS or carbide endmill. Just make multiple passes so that you're cutting about 1/32" deep at a time. Clean the chips out between passes and use lubrication especially as you mill deeper.

      Feedrate of 0.001" per second is definitely too slow and you'll wear the endmill prematurely. Check the chart for the appropriate feedrate based on the material, endmill type, and depth of cut.

      Albert



      [This message has been edited by Rotate (edited 02-20-2003).]

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      • #4
        darryl:
        Smallest carbide endmill commercially avaiable is .oo5" - smallest drill is .oo40"

        http://www.kyoceratycom.com/

        As noted before, your feed rates are miniscule and rpms should be maxed out (they can handle 100k+ rpm).

        They do a beautiful job if you let them work and don't push them feed-wise - they cannot stand much lateral pressure - they shatter like glass when you do over stress them (trust me).

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        • #5
          Maybe make a mount for a die grinder or even a dremel to at least spin them at a more appropriate speed?

          Something that can go in a collet or clamp over the quill?

          Has anyone done this on the mill?

          Iv'e mounted a die grinder on the lathe in the past. It worked OK for what I was doing.
          (making dozens of scriber points from broken bits)

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          • #6
            .005 endmill? Ok, I'm going to check the one I made from a drill bit to see if I failed to get a cutting edge on it, since it should have done the job, being much larger at .063. I suppose carbide being stiffer would tend to get a better bite. My mistake also was too slow rpm. No stress reducing medication either, and I don't think I was holding my mouth right! I learn something new everyday. (serious on this part) I like the idea of a high speed attachment to the quill, is there a quality flexshaft with good radial and axial load capabilities? I wonder if a right angle air die grinder would make sense to retrofit, either with air, or modified to take a flex shaft- or, I'm thinking out loud now, can I pass a flexshaft through the spindle to drive an on-axis high speed secondary spindle, maybe built into a morse taper arbor- hmm


            [This message has been edited by darryl (edited 02-21-2003).]
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

            Comment


            • #7
              I'd probably use a 1/16" end mill, run fast, with a jet of air to keep the chips out of the way. In those small diameters, I find coolant can tend to make the chips clog up. As per Rotate, not too deep per pass. Of course with that size end mill you can't feel a thing as to how it's cutting, so keep your eye on what's going on and feed just fast enough so it's definitely cutting; again as per Rotate, look up "reasonable" speeds/feeds for what your'e doing and use that as a guide.

              If you need to finish to a precise width, make an initial cut with a 3/64" end mill and finish up with the 1/16". You say "roughly 1/16" wide" so maybe that refinement is unnecessary.....

              I'm not sure I'd dare try a carbide end mill in that small a diameter (maybe I'm a coward). Carbide is so brittle I'm afraid I'd snap it for sure. HSS is bad enough!
              ----------
              Try to make a living, not a killing. -- Utah Phillips
              Don't believe everything you know. -- Bumper sticker
              Everybody is ignorant, only on different subjects. -- Will Rogers
              There are lots of people who mistake their imagination for their memory. - Josh Billings
              Law of Logical Argument - Anything is possible if you don't know what you are talking about.
              Don't own anything you have to feed or paint. - Hood River Blackie

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              • #8
                You can use a endmill just fine but keep the feed rate slow as the small ones can walk off center if they are pushed to fast.
                I just need one more tool,just one!

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                • #9
                  In reading your post I noticed that the material that you are cutting is not mentioned. This would certainly have an impact on the type of cutter, speeds, feeds etc. All of the suggestions are good ones and I have used them in cutting small channels in both steel and plastic. I have primarily used HSS tools and most importantly kept the chips out. The best to you on your project.

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                  • #10
                    How about using a Woodruf Keyseat cutter. They come in quite small diameters and widths. probably more forgiving than a 1/16 inch dia end mill. Wayne

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                    • #11
                      Darryl,
                      What kind of material? Steel, Aluminum, brass? I like to run around 1500 rpm's with a very slow feed. Use a lubricant. Either a few drops of oil or a mist coolant. For going 1/16" deep I would probably make 6 passes if using a 1/16" end mill at .010/pass. It takes a little longer but will leave a cleaner slot. One thing to remember that if you are using an endmill the same width as the slot, you are cutting both conventional and climb at the same time so one side of the slot will look a little worse than the other. By taking smaller depth cuts you will minimize this.

                      Kevin
                      If it's not good enough for you, it's sure not good enough for anyone else.

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                      • #12
                        It's 6061, flat bar. I played with the endmill I made, got a better result. Then I changed my philosophy and ground a suitable cutting tool from another, larger diameter drill bit, mounted it in the mill, turned the spindle to align this cutter with the long axis, then used the x axis handwheel to shove the workpiece through the cutter. The mill became a hand powered shaper for a couple of hours. If I had to make this cutter over, I'd silver solder a strip of .o5o hss bandsaw blade into a slot cut in a shaft, and grind a cutting point on it. I think that would be stiffer and would take many more sharpenings before the strength and material was gone. I didn't bother locking the spindle against rotation, since it didn't seem to be rotating at all, but I noted that my mentally modified cutter would have been easier to align. I did pull the ac plug, though, after I caught myself reaching for the on-off switch at the end of one stroke. My arm was a little sore after cranking the table back and forth till the jog was done. And my mind was hurting a bit thinking about wear on the leadscrew and nut. Overall, this process gave me by far the best results, very clean grooves. My guitar project is coming along nicely!
                        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                        Comment


                        • #13
                          I got a box of 50, count 'em 50, carbide endmills not too long ago from Micromart for $24.95! that go from .010" to .125". So far I haven't had the, uh, mmmarbles to spin one up and see what it can do. Anyway, keep an eye out for this type of bargain! Never know when you'll need to mill a slot to hold a whisker or two.
                          I'm here hoping to advancify my smartitude.

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                          • #14
                            Gizmos2,

                            Just a word of warning. Those carbide bit with plastic collar were meant primarily for PCB drilling/milling and engraving. They are meant to work with fibre glass and soft metal so the rake angle is relative high. In other words, just because they are carbide don't expect them to machine hardened steel very well. They are ok with mild steel, as long as you're feedrate is low.

                            I don't mean to dampen your enthusiasm, but the price that you quote is actually quite common. I suspect that they are either over stocked items or they have been factory reconditioned, since you have no choice over the size.

                            You are definitely right about their usefulness. I've machined very small brass parts using these endmills with excellent results.

                            Albert


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                            • #15
                              I've told myself many times that I wouldn't buy carbon steel drill bits, taps, or any other type of cutter if hss or better was available, except for wood or some plastics. Hss just seems to perform better overall, in any kind of material that it's capable of cutting. I wonder if my homemade endmill would have done the job for me if I started with a hss drill bit? By the way, I'm using a diamond coated disc to do the sharpening, it leaves a mirror finish on edges, so I don't think there's an excess friction problem. Carbon steel just doesn't cut it (pun). It's too flexible.
                              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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