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Cutting gears on a shaper...

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  • #16
    backwoods indexing

    Don't know if this is useful but I thought that I would pass it on. A friend of mine bought a taper attachment for his 13” SB and was faced with cutting the pinion gear on the crossfeed shaft.

    He ground a tooth profile on a HS bit, mounted it in his tool post and bolted a bicycle sprocket to the outboard end of the headstock.

    The indexing was accomplished by manually rotating the chuck and looping a chain over the sprocket. All the cutting was done manually with the carriage feed. It took about a hour or so to cut the pinion profile.

    Unless you are married to the complicated or automated methods this worked. That coming from someone who is fitting CNC controls to a 1927 11" SB, I still appreciate simple...

    paul
    Last edited by ironmonger; 06-23-2013, 09:22 AM.
    paul
    ARS W9PCS

    Esto Vigilans

    Remember, just because you can doesn't mean you should...
    but you may have to

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    • #17
      I've cut bevel gears with an Atlas Shaper.... For another shaper, they were the ones to drive the ram adjustment.

      No fancy drives, though, I used an indexing system, form tool cut, and did the "double shift". One pass down the middle on each toothspace to "gash" it, then a finish pass all around with it shifted to one side, and another with it shifted to the other side.

      I did find out how hard it is to advance the depth a half thou or so per stroke. At full depth, it gets a little scary cutting those U-shaped bits of swarf off the blank. You have a very long actual length of cutting edge in the work.

      I cut the form tool to fit the toothspace of what was left of the old gear.

      if you were to do a "generated" gear, you'd use a rack cutter, and I think you'd want to gash the blank first. It somewhat reduces the length of the cut, but also breaks up the swarf so it isn't one piece, and can fold up in a nicer way.

      You also would likely want to have fairly small advances, otherwise you have a coarser surface. But too small, and the cutter would have to be dead sharp to cut at all. The Boston bevel gears I have here have visible grooves in some places. but the working surfaces seem to be smoother, no doubt due to being cut by the side, and not the corner of the tool.

      Generating, you would not have as much length of cut as when form cutting, since one side at a time is progressively cut with the straight side of teh cutter, the other is roughed by the corner. And you are using a straight cutter, not a curved one that conforms to the surface.

      The blank has to be held very solidly.... a shaper, even a small one, has a lot of "shove". I used what seemed to be a rather flimsy setup, but it worked OK. I used the same setup later on the mill to make more bevel gears for different things. Accuracy is obviously better if you hold teh parts very solidly.
      CNC machines only go through the motions

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      • #18
        Hi Big Job, the system I am talking about is having a simple shaper tool that is ground to the PA and with straight sides like a rack tooth, this one tool will cut all gears in that PA family of gears.

        The shape of the gear teeth is generated by rolling the gear blank past the cutting tool. So you have the shaper ram moving, the table moving, and the blank slowly rotating on its axis.

        John

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        • #19
          OK, I have given up on the idea of gear trains! Thinking about Sir John's concept right now!

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          • #20
            Originally posted by The Artful Bodger View Post
            OK, I have given up on the idea of gear trains! Thinking about Sir John's concept right now!
            Don't give up on gearing if you can find a fairly complete set of change gears one consisting of 50 gear or more half of which includes prime numbered tooth counts..

            A rack mounted on the shaper saddle whose pitch plane is parallel to the block motion, a meshing pick-off gear and shaft with bearings mounted on the block, a change gear bracket with adjustable CD ider shafts, some calibration to determine the machine constant and the translation to rotary drive is complete. For every increment of linear block motion there is a proportional rotation of the pick-off gear. Determine that proportion, crank in the dividing head ratio and the needed change gear ratio is only a calculation away.

            But the critical factor is the change gear set. A simple thread cutting set will not do. You need a rich source of irrational ratios and for that you need prime numbered tooth counts among the change gears. IF an elaborate set of change gears is available that part of the problem is solved. If not (16Dp change gears run about $50 each) and you are not lavishly funded by deep pocketed third parties you better find an alternative.

            I'd think stepper drives on the translation and rotary axes controlled by a G code program as the electronic alternative. I'm attracted to the DivisionMaster indexing box. Feed the rotary stepper drive from a summing step/direction unit from US Digital. One leg of the sum input comes from the DivisionMaster and the other from the CNC corntol. This is only a push in what I thinkl to be the right direction. Much greater elaboration is needed before this concept can be deemed a plausible basis for a working prototype.
            Last edited by Forrest Addy; 06-23-2013, 05:38 PM.

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            • #21
              The shape of the gear teeth is generated by rolling the gear blank past the cutting tool. So you have the shaper ram moving, the table moving, and the blank slowly rotating on its axis.

              John, at first thats what I thought you were thinking. I built exactly that, forw / rev, varible speed I use it for roughing
              tapers then finish on a lathe. My reason is, by the time it makes a full revolution I sit down, come back more feed, sit
              down, then finish on a lathe. We all know do it on the mill, BUT Im not about to buy a certain or special cutter for a
              one time "walk in customer" so the shaper is a zillion times cheaper with a 2cent HSS blank. I grind the two sides little
              back rake and all is good one at a time. Going back, my attachment 1/2 welded steel rectangle using the tee slots.
              I turned & treaded a spindle for a 3 or 4 jaw chuck, adjustable dead center tailstock, powered by nice little dayton
              100:1 reduction. Forgot industrial fixed pillow block bearing off of the bearing two allen set screws (the brake). So with
              a 4 jaw eccentrics can be made and much more. Not at all hard to make, made it while snowed in. Next came my
              mill attachment air die grinder with an end mill (foot controled) slitting, cut off wheels & on& on. Picture a large collar
              turned on lathe for dimension then to the shaper down feed to make a bore change to drill bit drill right through then
              slitting blade make slit all left is to tap for a set screw all on a shaper. Then my lapper attachment cant explain that one
              but ill tell ya I can lap two pieces so so flat, when put together they are stuck like glue. cant think of the word, somthing
              like surface tensel adhesion? The powers of a shaper. Its just too bad we cant stick photos in here, dont know why like
              other sites , been said " no pics then it aint been done" and I got pics of all of this. sam

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              • #22
                http://www.homemodelenginemachinist....._9May1885.pdf
                Paul Compton
                www.morini-mania.co.uk
                http://www.youtube.com/user/EVguru

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                • #23
                  Originally posted by big job View Post
                  Its just too bad we cant stick photos in here, dont know why like
                  other sites , been said " no pics then it aint been done" and I got pics of all of this. sam
                  Read the second post down under general.
                  It tells you how to post pictures.



                  Just an example.
                  .

                  Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                  • #24
                    Sam, you can post pictures but first you must put your picture where the board can find it, that means you must first upload your picture to some picture hosting site of which there are several, I use flickr...

                    Here is my first attempt at cutting gears using a single point cutter on this little geared down drill press to cut a pinion. I stopped doing it this way as I did not like what it might be doing to the lathe bearings.


                    geared slotter by aardvark_akubra, on Flickr



                    OOPS, Sir John posted while I was typing..

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                    • #25
                      photos

                      Ok I got most pics in flicker then down the bottom it says enter url whats that? Its flicker aint it.?
                      I saved flicker to my desktop I think. Most other sites down the bottom of post it says manage att.
                      which goes into my pics or docs upload done that easy. Think I gotta ask some kid. sam

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                      • #26
                        Get your picture open on Flickr and look for something about 'share', that's where Flickr shows the URL of the picture.
                        John

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                        • #27
                          Thanks John any thing I click on I get a blank page saying "this page not found"I cant even find 13 pic I loaded I open and
                          just show one of my big lathes right click on lathe "page not found" try photo bucket cant register when I do it says
                          this email is already in use???? hellow what was I sleepwalkin I never been there before. Anyways the first time on flicker
                          all 13 thumnails I click on one it got bigger filled the screen clear as a crystal. click again on it goes back to thumbnails.
                          perfect I come back here, says I need url thing ok go back then anything i click on >page not found they dont like me
                          thanks John. Ill find some kid to do it.

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                          • #28
                            see it this works

                            here goes let see sam

                            NOPE!!
                            Last edited by big job; 06-26-2013, 06:53 AM. Reason: see if pictures loaded

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                            • #29
                              Basically, you're trying to make your horizontal shaper do what a vertical gear shaper was designed to do. Direct from your "favorite" other BBS: http://www.practicalmachinist.com/vb...shaper-113761/

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                              • #30
                                Originally posted by randm View Post
                                It wasn't brass, it was steel
                                Must be Lucas lighting

                                Every time I look at that vid it seems I notice something missed before. I like your tool holder - brilliant. Off to the shop to reproduce!

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