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  • to climb or not to climb

    Hi All
    Been doing a bit of milling using my x1 mill machining a tool holder for my new tool post. The holders will just not go low enough to get to centre line so I thought just mill a bit of the bottom edge.
    Sooo as the x1 is a bit small I thought just take small passes - so take the first pass a few thou a full 1/2" then just as it came to the end it sort of took hold and tried to pull the cutter into itself.
    So after change of underwear I tried to find any play in the ways tweeked them up and had another go - slightly better but I am convinced I can see the cutter deflect as it enters the holder.
    I then thought (bad move) lets try a carbide cutter may be sharper. All seemed to be going well when it seemed to grab in the middle of the cut and bits of the cutter were no more.
    So I tried another tack and moved to the full amount I wanted and took small passes down from the top - slow but sure.
    Holder now has tool on centre!!
    So question is what way does the cutter have to go to stop climb milling!
    Peter
    I have tools I don't know how to use!!

  • #2
    So question is what way does the cutter have to go to stop climb milling!

    ************************************************** ***********************
    If I understand your question correctly, here is the best answer I can offer: The cutting tool (we are talking about a side face mill here, or an end mill but using it as a side mill) should be rotating into the material and as it enters contact with the material. It will be pushing against the direction you are moving the material.
    As an example, let's look at using a vertical mill........
    The milling machine is rotating in a clockwise direction, as viewed from above.
    You want to have your material that you are cutting positioned on the right hand side of the cutter. This gives you the conventional cut you desire.

    If you have the material on the left side of the cutter and advance into the cutter, the result will be a climb cut and the cutter will most likely try to 'snatch' the material away from you.

    Now, let's assume you have another similar cutter except it is a left handed cutter. You switch it out and reverse the mill direction so the new cutter is rotating correctly to cut (CCW looking down). You must move your material to enter right of the cutter to avoid making a climb cut.

    Now, if the mill cutter is an end mill, then it makes little difference which side the material is positioned on relative to the cutter. The cutter is positioned over the stock and cuts easily without grabbing because it is doing what it is designed for.....end milling.

    If it is a lathe or milling operation, the rule is the same. Feed into the cutter from the proper side to avoid climb cutting. The proper side to have your material on is the side that the cutter touches first as it rotates......pg

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    • #3
      Think of the cutter like a tire on a surface. If the cutter wants to push the surface away in the direction of travel, you are "standard milling". But if it wants to pull the surface past the cutter, you are climb milling.

      To put it a different way, if you had no screw on the axis of travel, and just used your hand to push the table into the cutter, then would the cutter self feed and pull the work in, or just push the table back toward your hand and stop when you quit pushing? If it stops when you quit pushing, that is standard milling. Once started, if it want to pull the work on through even without you pushing, it is climb milling.
      Russ
      Master Floor Sweeper

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      • #4
        Oh, and particularly when going over half a cutter width of cut, always set the cross slide lock! At or near full width, I snug up, but do not lock, the axis of travel so that it doesn't try to back feed due to something happening on the exit side (like a tiny shift in cross slide, slight runout, chip weleded on a flute, etc).
        Russ
        Master Floor Sweeper

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        • #5
          Make a diagram on paper and stick it to the side of your mill. Eventually you will quit referring to it and you can take it down. Painless way to learn so you don't have to think too hard.

          Cheers,

          BW
          ---------------------------------------------------

          http://www.cnccookbook.com/index.htm
          Try G-Wizard Machinist's Calculator for free:
          http://www.cnccookbook.com/CCGWizard.html

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          • #6
            Right on

            Agree with the previous advice re. climb milling.

            I do climb mill at times but I am very careful!!! My mill is fairly substantial - but it has its imits with climb milling!


            I'd be less concerned and more inclined to use climb milling if I had good ball-screws fitted instead of the usual acme lead-screws on my "X" and "Y" feeds!!!

            As I see it, you were milling out the four bottom faces of a turret (normal) tool-post. They can be quite tough at times.

            If it were me, I'd have put it "right side up" in my vice or clamped it down on my mill table and used a fly-cutter on it.

            Conventional (ie "up" or "non-climb") milling can be a problem as well if the milling cutter (end mill or side cutter) is not sharp or is too flexible due to too deep or long a cut as it will "rub" (instead of cut) until it raises and gets under a burr.

            Result? - broken cutter - or a lot of disturbing noises.

            As an aside, but not totally unrelated to this thread, I've seen a lot on this forum on using milling cutters but very little on sharpening them.

            A casual reader could reasonably assume that all cutters were supplied sharp and stayed sharp without any sharpening being need.

            Not so - very much not so.

            Having said that, I'd like to know how others keep their milling cutters sharp - assuming of course that they don't use blunt or non-sharp cutters!!!

            Assuming too of course that tools DO get blunt and assuming too that not everybody either owns or has access to a Tool & Cutter grinder, how are they kept sharp?

            Or put another way, how do they sharpen those "pre-used" and "pre-loved" milling cutters that they buy so cheaply on e-Bay or "Yard Sales" etc?

            Comment


            • #7
              The descriptions of climb milling have been pretty decent.

              As a general rule, I don't bother with climb milling on a machine without either ballscrews (so just about every machine at work) or special provision to do so (big horizontal mills). The benefits are negligible except in the rarest of cases, and the chance of scrapping the part or damaging equipment is just not worth risking something unnecessary.

              Originally posted by oldtiffie
              Assuming too of course that tools DO get blunt and assuming too that not everybody either owns or has access to a Tool & Cutter grinder, how are they kept sharp?

              Or put another way, how do they sharpen those "pre-used" and "pre-loved" milling cutters that they buy so cheaply on e-Bay or "Yard Sales" etc?
              You can touch the face of an endmill against a pedestal grinder, like sharpening a drill, to remove burnt up corners. Just be careful not to knock off the edge of the other flutes.

              If the cutter is dull up the flutes, you need a tool and cutter grinder, or another grinder capable of the same action. You're not going to be able to sharpen endmill flutes without a grinder that possesses all the motions of a TC grinder.

              Comment


              • #8
                Bingo!!

                Originally posted by toastydeath
                ....................
                ...................
                ..................

                You can touch the face of an endmill against a pedestal grinder, like sharpening a drill, to remove burnt up corners. Just be careful not to knock off the edge of the other flutes.

                If the cutter is dull up the flutes, you need a tool and cutter grinder, or another grinder capable of the same action. You're not going to be able to sharpen endmill flutes without a grinder that possesses all the motions of a TC grinder.
                Thanks TD - good one - as usual.

                You've hit the nail right on the head.

                Now lets see who puts up with blunt cutters and who does what about them.

                Yep - as I think you are aware - I do have a T&C grinder.

                "Touching up" the base cutting edges of an end mill can be done with a "Spindexer" (with care) - but as you say, it is only emulating one function of many on a T&C grinder.

                You have quite correctly addressed the needs and methods for sharpening the "side" cutting edges as well. A hand-held slip stone or diamond honing (stick) can help in the initial stages if done well enough soon enough.

                This pre-supposes that the cutter is HSS as TC is a bit more difficult to do.

                I wouldn't consider giving the "full treatment" to any cutter less than 10mm (3/8") on my T&C grinder as the risks (quite "tight" working spaces too near the wheel etc.) are too high and the cost of new cutters are just not viable. I keep several sharp spares of the cutters I use most.

                As Lane and John Stevenson have pointed out on several occasions, there are plenty of uses for end-mills that are beyond using as end-mills. Some of those uses have been very creative - as are lots of stuff/posts from Lane and John S.

                Comment


                • #9
                  oldtiffie, ballscrews are the last thing you want on a manual mill. Ball screws are very efficient at changing rotational movement into lateral movement. But the inverse is true as well. Lateral movement will create rotational movement. So what this means is the cutter grabs on to the work and acts as a rack and pinion and all hell breaks loose.

                  With conventional acme screws they cannot be back fed at conventional thread pitches so there is no issue other than backlash in the nuts and the thrust bearings at the ends.

                  CNCs have servos or steppers that will hold their position and thats why they can be used with ball screws.

                  Check your nuts for any backlash setting to get as much backlash out as possible. Also set up an indicator with the probe resting against end of the lead screw to check for axial backlash in the screw itself. Ig there is a center drilled hole in the end of the screw use a but of grease to hold a little steel ball in place and indicated off that.

                  Remember also that tool holders are often hardened steel like 4140. I cut down 1/8" off a 3/4" tool holder for my lathe and that was quite interesting. I used an indexable insert cutter from Iscar with ADKT inserts. Quite a show until I found the correct feeds and speeds. Left a near mirror finish when I was done though.

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                  • #10
                    I know it's not necessary to say this for most of those posting in this thread, but for other readers, "climb milling" is possible (and beneficial) on most any significant machine for the final *light* finish cuts. I do it all the time even on my worn old Bridgeport. I just lightly set the x-axis lock, and make a light 5-10 thou (or even more depending) cut under moderately slow power feed. No problems at all, and the finish is much nicer...
                    Russ
                    Master Floor Sweeper

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                    • #11
                      Thanks for all the answers my problem was due to climb milling and flex in the cutter so as it exitted the cut it grabed the holder.

                      Now next question - when using a T slot cutter do you cut each side separately or both in one go as the cutter will be climb cutting on one side and not the other if you see what I mean?

                      Peter
                      I have tools I don't know how to use!!

                      Comment


                      • #12
                        Originally posted by BobWarfield
                        Make a diagram on paper and stick it to the side of your mill. Eventually you will quit referring to it and you can take it down. Painless way to learn so you don't have to think too hard.

                        Cheers,

                        BW
                        LOL! Bob that's comical! Umm...reminded me, I had a photocopy of a book page that had the pics of both types of milling on the wall beside my mill for a couple of years. It worked!
                        I have tools I don't even know I own...

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                        • #13
                          I haven't ever milled anything and I've been wondering about this climb milling stuff. Thanx to this thread I finally understand the difference.

                          SP

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                          • #14
                            Originally posted by ptjw7uk
                            Now next question - when using a T slot cutter do you cut each side separately or both in one go as the cutter will be climb cutting on one side and not the other if you see what I mean?

                            Peter
                            It is pretty unlikely that you will be able to cut one side then the other with a t-slot cutter. They are generally sized with a shank that just fits down the typical slot for that size.
                            Russ
                            Master Floor Sweeper

                            Comment


                            • #15
                              climb milling

                              Kennametal used to pound into our head to climb mill if we could. This of course depended on the rigidity and mass of the machine. Most home shop machines are too light for climb milling. That is to say, with a light table it is too easy for a cutter to pull the backlash out of the table. Everything is relative so with very light cuts it may be possible.

                              In climb milling the cutter tooth gets its biggest bite at the top of the cut and gets progressively less down to nothing as it rotates out of the bottom of the cut.

                              In conventional milling the cutter tooth starts at the bottom of the cut with nothing and is forced into taking and ever increasing bite as it exits the top of the cut.

                              Jim W.

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