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  • Youtube cnc milling throws sparks

    http://www.youtube.com/watch?v=Wk2VYwCIcZE

    This endmill is throwing sparks.. My endmills throw sparks they die.. SO I guess this is a carbide in action? I got some never loaded them into the tool holders.

    Cutting about five times faster than I ever have.. As I learn I learn the envelope of destruction of cutters. And that funky laser I put on my mill? Looking at the red on the end of a drill as it sinks kinda brings back memories of drilling holes and talking on the phone, as I turned around, the end of the drill was red and getting shorter as it dissapeared into the metal..

    I can't drain the coolant as fast as I am applying it? I see the chopper guys on tele (usually how NOT TO DO SOMETHING) spraying full bore from five or six nozzles and washing away the aluminum shreds before they mar the surface.. WHERE does it all go? DO I need to build a retaining pond behind the shop?
    Excuse me, I farted.

  • #2
    After I watched that one I watched this one. It was also pretty interestng.http://www.youtube.com/watch?v=Gwrk0SwDJhI&NR
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    • #3
      That was an interesting video.

      I think the glowing red we saw wasn't so much sparks as it was very thin chips that were hot enough to oxidize right bfore our eyes. I've made this happen before - in fact I just did it again yesterday. I was shortening and resplining a Dana axle shaft, full hard. I could make it happen with the carbide inserted cut off tool if the chips got too thin. I believe the size of the chips was small enough that the combination of the heat in them and the surface area exposed to air got to a the point where they'd burn - just like very fine steel wool burns. The finishing cut on the seal surface also made this happen - 1 long stringy very very fine chip that was exactl like fine steel wool. It came off blue and curled around right on the carbide insert and eventually got hot enough to start the oxidation reaction. It burned for about 10 seconds.

      I made the same thing happen when I was cutting the splines. This a a forming cut with a TPG321 and about a 1.5" cutter running at 500rpm. The chips always come off blue hot, but if I backed the feed down some of the chips would light up in mid air like you saw in the video. If I turned up the feed to make a heavier chip, they went back to blue. I continued cutting 20 more splines and saw no more sparks.

      Of course I was cutting with no coolant both times. I need to get a small compressor and start using a mister for this job. Then I might get more than 1 or two sets of splines (.0625" deep, 2" long, 30 to a set) out of a set of points

      When I have a HSS end mill die and throw sparks, it looks different - at least to me. The sparks come right out of the cut, rather than lighting in mid air like I saw in the video.

      Gotta go watch the video from YOD now...

      That spinning looks pretty cool. I've never seen it done before. It's really disturbing to see someone touching the spinning work piece and then at the end pull it off the mandrel while it is still spinning...
      Last edited by Nutter; 11-25-2006, 11:32 AM.

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      • #4
        I think this one shows some sparks on a lathe: http://www.youtube.com/watch?v=vvKTkaTZfz0

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        • #5
          I have to agree with David here - on my little Bridgeport, sparks usually signal the death of an endmill. I get that if the tool is spinning too fast for the material.

          I like the spinning video. Is that really just a normal lathe with a special tool guide on the carriage? I also wonder what it would have sounded like if they hadn't over-dubbed that cute little acoustic guitar ditty. I'll bet it sounds pretty weird.

          Very cool - thanks for posting it.

          -Mark
          The curse of having precise measuring tools is being able to actually see how imperfect everything is.

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          • #6
            The thin chips fling a few sparks thats normal when running dry. It looks like they are milling 4140.

            I hope when they get to cutting for real and get some coolent blasting they change the program so the tool is not cutting air all the time. Thats WAY too much time cutting air. Stuff like that drives me nuts.

            CNC Mill or lathe I hate to see a machine cut air or rapid traverse way too far to index tools. Its dead time and makes the programmer look like he does not know what he is doing.

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            • #7
              If you guys want to see sparks, go to a machine tool show where Ingersol is demo'ing their cutters.

              They setup with a 50 taper mill and blocks of mild steel. For visibility they do the demo runs dry. Sparks and fire all over the place, quite a show.

              When the part is done the operator (with gloves) tries to hand it to the best looking babe in the audience. It's just barely warm.


              On edit: Of course we all want to do that on our machines, so some of us buy their cutters. Unfortunately they don't work quite as well for us. Unless we have a rigid 50 taper Mori like they use for the demos, that is.
              Last edited by DR; 11-25-2006, 04:03 PM.

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              • #8
                Originally posted by tattoomike68
                The thin chips fling a few sparks thats normal when running dry. It looks like they are milling 4140.
                Agreed, and that second video was most likely using ceramic inserts, I have never used them personally but I have seen them in action and it is scary for someone who grew up on manual machines, sparks and a loud nasty sound are the norm and expected when you are running them right.

                Originally posted by tattoomike68
                I hope when they get to cutting for real and get some coolent blasting they change the program so the tool is not cutting air all the time. Thats WAY too much time cutting air. Stuff like that drives me nuts.

                CNC Mill or lathe I hate to see a machine cut air or rapid traverse way too far to index tools. Its dead time and makes the programmer look like he does not know what he is doing.
                I run a small job shop and we use the cnc mills alot for small runs, 1,2, and 5 parts are the norm, I agree with you on the cutting dead air to a point but I had to break the other machinist of spending too much time optimizing the code to shave of a minute or two, it is counter productive if he spends another 15 minutes programming to save a total of five minutes of time on the part run. We use a cad/cam program also, if that code was done by hand then yeah there really is no excuse.

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                • #9
                  There was a video about a year back by Ingersoll with a VMC with 100+HP
                  spindle driving a cutting head about 30cm in diameter taking a 2cm deep full width cut on a big block of steel. Red hot chips were flying all around and two guys in the back ground were using pushbrooms to cleanup the chips. Toward the end of the video it was obvious one of the pushbrooms had caught on fire and flames were leaping up behind the cutter head. Lost the web site and cursory searches haven't turned it up. Formidable machine.
                  Steve

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                  • #10
                    That is exactly how I make TiN stumps and metal dust. My guess is they don't buy their cutters at HF. What really got my attention was this one: http://www.youtube.com/watch?v=1781k5rsJRY

                    If I tried that with anything softer than a stick of margarine I'd be pulling tool chunks out of the drywall - and maybe my chest. And I've never seen rotary faceting done before. How cool is that? I'd bet there's not a lot of HSM's that have this capability

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                    • #11
                      Seeing machinery like that one.. damn, my 1976 bridgeport is old.. she used to run on punch tape. Seeing things like that remind me I am in a hobby class now.

                      I had a powered indexer on my machine for a while.. it died while working on a harley fatboy rim.. I was running gecko drives back then.

                      I have had one failure since, a larken lost one of the regulators onboard. I have it here on the bench to fix. Simple fix.

                      I may put a air motor/encoder on that indexer this week.. I got some opto22 stuff left over and use the pulse input to index it. I am working on a rolling pattern design for the bead roller. I may redo the whole beadroller first thou, it is junk. Old saying, don't hop up junk.. your results will show. I got two weeks work just repairing what a mouse caused me to do to my robotics in the shop. *I jerked it all out and throwed it in a box. Heck Butch started it. It took me more than two days to rewire the damage he done to my bridgeport. And it still ain't right.. the plugs that slip on the drives to make pin header connections are screwed.
                      Excuse me, I farted.

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                      • #12
                        It's important to note thesound of that endmill, reminds me of the endmills I posted about awhile back. The ones I got aren't 90 degrees, more like 80 and 100 degrees, they make for a much quieter cut at higher speeds. I did a test run, 32IPM, 3800RPM, 1/2" endmill. I had a spark here and there but mostly a steady stream of blue chips flying everywhere. Chip removal was so good that even when cutting a pocket few chips got in the way. I was told by the sales person that the speeds actually keep the tool cooler as the chips carry away the heat and the EM is always in fresh cool metal. I would never have believed it until I tried it. I wish my Boss 5 had the spindle speed and table feed to take full advantage of those cutters, I've got a job where a 5/16" would be perfect. Salesman says too slow is bad for them and I believe him.

                        David, since I got those EMs I only use coolant on aluminum to keep from packing the EMs. I use two small diameter nozzles for higher pressure with less volume, table draining is never an issue. My sump is a 25 gallon drum and the table drains are plumbed independently with 3/4 copper into 3/4 ID vinyl tubing. I always vacuum out the table screens between parts.

                        My big lathe is the same way, 316 stainless with negative carbide inserts, it wants to see .400-.500" off the radius with a heavy feedrate. If the chips aren't blue the tooling dulls quickly. I get little "C" shaped curls that are too heavy to fly, they just drop. I call them clinky chips for the sound they make piling up. 15 HP on the lathe, the tools would love to use every bit of it.

                        I've been toying with a 5HP and inverter on the CNC, run a jackshaft where the current motor is and convert the vari drive to cog belts. I'd love 7-8000 (or more) RPM but the table still won't feed fast enough. Gonna sell this one eventually for something faster I think.

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                        • #13
                          Often machining dry with carbide cutters will actually extend the life of the cutters. Carbide has a tremendous ability to handle heat, and a horrendous ability to resist hot/cold cycling. Using coolant can cause microcracking that will shorten the life of the cutter tremendously.

                          The idea is to keep the heat in the chip, which a properly applied cutter will do a very good job of. You can make sparks all day long and nary get the cutter or the part far above room temperature.

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                          • #14
                            Originally posted by dp
                            That is exactly how I make TiN stumps and metal dust. My guess is they don't buy their cutters at HF. What really got my attention was this one: http://www.youtube.com/watch?v=1781k5rsJRY

                            If I tried that with anything softer than a stick of margarine I'd be pulling tool chunks out of the drywall - and maybe my chest. And I've never seen rotary faceting done before. How cool is that? I'd bet there's not a lot of HSM's that have this capability


                            Ok, it made me drool. Made me wish for zillions of dollars for such a machine, and the training to run it.

                            I watched it several times. I have a question. In the video, from times 1:21 to 1:31, there's an operation I didn't quite get. The tool changes to what appears to be a fly cutter. The part being cut appears to be rotated at speed, as does the cutter. The (very fast) operation results in hex flats cut into the part in two locations, like the perimeter of a bolt.

                            Did I see that right? I could swear that both the part and the fly-cutter looking thing were spinning, and fast. That's got to be an amazingly coordinated operation to achieve what they did the way they did it. Anyone else notice - care to shed some light?

                            -Mark
                            The curse of having precise measuring tools is being able to actually see how imperfect everything is.

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                            • #15
                              Wirecutter, they're doing polygon turning there. It isn't exactly a fly cutter, but it is very cool stuff. Take a special controller option to do it that costs more, but I agree, the result is amazing.

                              I've written a little about it in my blog if you search down for "polygon turning" you can learn more:

                              http://www.thewarfields.com/MT/CCBlog.htm

                              Best,

                              BW
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