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An interesting machining problem

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  • An interesting machining problem

    Planing irons, or planing forms. When making a split bamboo(cane for our british friends) fly rod the piece of bamboo(culm) is split into small strips each strip is then planed to a 60 deg profile on the planing forms. A small block plane is normally used.
    The planing forms are usually made from .750 square CR, 60 inches long. A tapered 60 deg groove is milled along the length of the material. To do this the two pieces are are joined together with dowel pins and screws.
    The taper usuall goes from @.025 [email protected] .080 and then the two pieces are flipped and a wider taper, from @.080 [email protected] .125 on the other side.
    How would you accomplish making the tapered grove having only a BP? Assuming the material is straight and flat.

  • #2
    Hmm. I can see using a dovetail cutter in the mill. Between the flat bottom and the angled side of the cutter, you could get 60 degrees. It seems like it's more of a problem to clamp the piece to the table such that the groove produced is deeper at one end than the other. Getting the dovetail cutter to make a groove with both sides at the proper angle with respect to the workpiece would be another orienting and clamping problem, but shouldn't be too hard to do.

    Maybe more details on the project would help us give better ideas.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


    • #3
      Seems to me you could do it with a sine vice/table, rotated on the mill table to give a compound angle, just using an end/side mill.
      Caveat emptor, I haven't sat down and worked out the trig tho!
      Just got my head together
      now my body's falling apart


      • #4
        Do it by hand and file it

        Last edited by oldtiffie; 08-18-2007, 11:48 AM.


        • #5
          My apologies, I didn't notice the 60" length.
          In that case, I'd go along with tiffie.

          I'm a lazy bastard, so I'd start with the 9" angle grinder followed by 5" with flap disc, then draw file.
          Just got my head together
          now my body's falling apart


          • #6
            All that to drown a worm ????


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


            • #7
              make a compleat fool of yourself
              Just got my head together
              now my body's falling apart


              • #8
                I thought split cane rods were made using hand tools and planning boards.
                Once they are set up the angles and tapers are easy just produce dozens and pick the best which I think is why thet cost so much to buy!!
                I have tools I don't know how to use!!


                • #9
                  Go to How's it made from the discovery channel and look for the program they just had it on in the last couple of weeks. How some fancy rod company builds them and they went over that.Sorry I'm of the
                  John Stevenson All that to drown a worm ????
                  school of thought I didn't pay attention when they were showing putting the 60'angle on the pieces and how they ran it thru the machine. But I think it was a router type set up.
                  Been there, probably broke it, doing that!
                  I am not a lawyer, and never played one on TV!
                  All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or the suggested uses, Wear safety glasses, closed course, professionals only


                  • #10
                    All that to drown a worm ????
                    It's fly fishing, no worms. Regardless, while I like to eat fish catching them is best left to professionals with nets. I think of recreational fishing as in the same category as watching paint dry. Long periods of boredom followed by more long periods of boredom...
                    Free software for calculating bolt circles and similar: Click Here


                    • #11

                      Last edited by oldtiffie; 08-18-2007, 11:49 AM.


                      • #12
                        Fish (n): white flesh which comes shrouded in deep-fried golden, crispy batter;
                        Usu accompanied by chips and the heavenly aroma of salt and vinegar.
                        To be eaten directly from the paper.

                        Goes well with Emu Bitter or Strongbow original.
                        Just got my head together
                        now my body's falling apart


                        • #13
                          Cane Rod Making

                          To keep the block plane blade from digging into the metal planing form many rod builders mill a shallow groove down the centre of the planes sole. This allows the blade to engage the cane but not the metal form.

                          John, only a worm would suggest that flyfishers use - well - worms! Now we're not beyond using fluff to imitate a worm...

                          We flyfishers are a duplicitous lot.


                          • #14
                            You could cut this groove on a BP but only 20" at a time depending on the available table travel. You have to set up for it. First make a long tapered fixture keyed to the table with a shoulder to stop the work against. then start cutting with a ground to form end mill. Cut and slide. pick up and cut again then slide again. PITA but it can be done. There will have to be some handwork but it's not a difficult problem.

                            As it happens I've made a few of these on a planer where I clamped the work to the proper slope and using the side head cut the groove detail.


                            • #15
                              The chief advantage of flyfishing is that there's more to do when you're not catching fish. For the record, everyone I've ever fished with put their waders on one leg at a time, and had days when they got skunked. Real life lacks all the editing done on those TV shows.

                              Back to the planing forms: it's been a few years since I've seen any, and that was before I discovered the machinist approach to metalworking, but I do remember enough to be helpful.

                              The forms I've seen were considerably wider than .75", probably 1.5" - 2" on average. The length of the form depends on the desired length of the rod sections. 5' long sections would probably be used only for 2-handed spey rods or salmon rods. Most forms are therefore shorter.

                              I think the V-groove had little or _no_ built-in taper in any of the forms I've seen. The ideal rod taper is a subject of disagreement on a par with religion & politics combined, and varies with rod length and intended use. I know of one repairer/restorer who uses a roll of adding machine tape to record tapers full size, miking the rod every inch or so.

                              The taper is accomplished by setting the differential screws which join the 2 pieces of the form. This is the part I'm fuzzy on, since I haven't handled a planing form since long before I first cut a screw thread. IIRC differential screws have 2 different threads along the length of the screw (i.e. a different one toward each end) allowing precise fine adjustment of the taper. As far as diameter, tpi, thread class, etc. goes, I don't have a clue.

                              To build a cane rod, 6 precisely tapered identical pieces are planed for each rod section (generally 2 or 3), after pressing out the joints in the bamboo. The bamboo in question, Tonkin Cane, comes only from an area of about 40 square miles in China. The 6 pieces are then glued together, sometimes heat-treated, varnished, and grip, reel seat, and guides are added. Think of the last fishing rod of any sort you saw, and imagine planing and gluing 6 pieces that end up as small as that rod tip. The amount of hand labor involved pretty much precludes getting rich on rod-building, even given 4 figure prices for the finished product.

                              One rod builder I met said that even with religious obsession with the tapers, he was never sure how the rod would feel until he put a line on the finished product and cast it. This probably shouldn't be a surprise when one combines precise machining methods with an organic raw material.

                              A good cane rod has a wonderfully "sweet" feel when casting, but they are delicate, expensive, and _heavy_, which is why the vast majority of fly rods (including all of mine) are made of graphite (carbon fiber).

                              Last edited by BillB; 06-26-2007, 12:36 PM.