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  • Involute spline

    Looking for a CAD drawing or details of a 13 tooth 16/32 DP 30 degree PA Involute spline or a program that can generate these

    .
    .

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




  • #2
    Let me know when you find one John. As you know, I need to make a 6-tooth, 16/32 spline.
    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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    • #3
      I dunno if this is any help but....




      John do you have access to solidworks or solidedge? if so camnetics do a program called GearTrax for solidworks/solidedge and it does an excelent job of gears, splines and pullies, its not cheep tho:/

      if not then let me know what dimensions you need that arnt on the image above and i'll endevour to sort them for you.
      Last edited by sconisbee; 01-19-2008, 10:43 PM.

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      • #4
        Small son has Solid edge but not the trax program.
        I have a very good program that draws involute gears and it may be able to do splines.


        I have the specs for the spline from a demo version of a program called Quick Spline 1.5
        Fortunately the spline I want falls within the demo limitations of the program, sorry Lazlo 6 splines doesn't, so I'm going to draw this today and check it against the spline data I have.

        If so I'm sorted.

        Sconisbee,
        Any chance of a copy of this spline as a DXF ?

        What I an trying to do is find a cutter that fit the spline.
        I know the PA on these is 30 degrees and they are 16DP but cut at 32 DP setting but I'm sure I can find one way out the range that's very close.

        I normally have these cut by a local gear company but sometimes I may have to wait a week for them to pull a simple job like this in and being able to mill a shaft out quickly will help.

        In reality I just need to understand a bit more about these.

        .
        .

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



        Comment


        • #5
          Originally posted by John Stevenson
          Looking for a CAD drawing or details of a 13 tooth 16/32 DP 30 degree PA Involute spline or a program that can generate these

          .
          John I would think that any CAD software that can generate an involute gear should be able to do the splines too. Different fingers on the same hand. In a lot of ways a ASA Involute Spline can be considered an extreme form of the Fellows type of Stub Tooth Gear. A system inwhich different diametral pitches are used to determine the circular pitch of the tooth and the other is used to determine the height and OD

          This is from my Barber Coleman Gear handbook

          "Standardization of involute splines was first accomplished in 1939 when the original standards for involute splines were adpoted by the American Standards Association. They included specifications only for 6,10, 16, 24 and 36 teeth of odd pitches. They were found to be inadequate, and in 1946 ASA standards were adopted which included specifications for splines with six to fifty teeth and from ONE/TWO to 48/96 diameteraL pithch. In 1950, a new standard, ASA B5.15-1950, was established by the American Standards Association. The purpose of the new standard is to increase the number of applications of standard involute splines as well as to simplify engineering for both the hob manufacturer and the user.

          The new standards include complete specifications for splines from six to fifty teeth and from ONE/TWO to 48/96 diameteral pitch. Manufacturing tolerances and allowable errors for both external and internal members, for each individual spline,as well as the dimensions for all classes and tuypes of fits are listed. Basic formulas and their applications are discussed on page 190."

          If you are interested in doing gear work and can find a copy of this book buy it. Also if you ever see a book titled "14,000 Gear Ratios" buy that as well. Invaluable if doing work o purely mechanical gear hobbing and shaping machines

          Last edited by Spin Doctor; 01-20-2008, 09:14 AM.
          Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

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          • #6
            Why an involute spline? What advantage does it have over another tooth shape such as stub acme?
            Free software for calculating bolt circles and similar: Click Here

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            • #7
              Originally posted by Evan
              Why an involute spline? What advantage does it have over another tooth shape such as stub acme?
              The book in my above post list a number on manufacturing advantages primarily over papallel key spiles. One is that one hob will cut all numbers of teeth for a given diameteral pitch. Parallel key spines require special cutters for each particular size and number of teeth along with class of fit. Along some other advantages the most important is that the tooth has maximum strength through the minor diameter where it is needed. Any Acme Stub Tooth if it has a tooth that is staight onits side will havee the same manufacturing problems as a parallel key spline. One thing I could never figiure out is just why did they ever settle on 14 1/2 D for the pressure angle on the early gear systems along with using it for Acme Threads. Any advantages over a 30 D based system IMO would of been hugeley out weighed by the easier manufacturing of tooling for a 30D system. And Metric Acme are 30D
              Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

              Comment


              • #8
                The larger the pressure angle the more it tends to force the gears apart. 14 1/2 PA has much less such force than 20 PA. That results in less wear on the hub bearings. I would guess that better bearing materials has allowed the use of 20 PA gears more often.
                Free software for calculating bolt circles and similar: Click Here

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                • #9
                  Originally posted by Evan
                  Why an involute spline? What advantage does it have over another tooth shape such as stub acme?
                  Didn't you read the long thread I started last week, entitled "Why Involute Splines?"

                  The short answer is that an involute spline has a lot less backlash, and it can handle around 400% more torque than a straight-sided spline.
                  "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                  • #10
                    Originally posted by Evan
                    The larger the pressure angle the more it tends to force the gears apart. 14 1/2 PA has much less such force than 20 PA. That results in less wear on the hub bearings. I would guess that better bearing materials has allowed the use of 20 PA gears more often.
                    Evan, This doesn't really apply to splines as they are external and internal, not spaced apart.
                    In this case they are for coupling DC motors to hydraulic pumps, purely a splined drive.

                    SD,
                    I have the same Barber Coleman book and the 14,000 ratio's plus the book of Moulds ratio's
                    I probably have close to 100 book just on gears and gear cutting.
                    I could sit down and read all thru these to draw an accurate involute shape but I was trying to cut corners and get a CAD drawing already done so I could work on that.

                    It seems as if my involute drawing program will accept the various changes to actually draw an involute spline.
                    Only problem I have is the drawings says 0.9908 " over two pins and Quick Spline says 0.9859.

                    I still have the broken stub so I will take an actual measurement this afternoon to check which one it mates up to.

                    I can still tweak the Involute program to finish up with the needed 0.9859 but at this point it's very close to using two button cutters as per a normal form tool.

                    .
                    .

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



                    Comment


                    • #11
                      Sure John your more than welcome to have a copy pm you your email addy and ill send you the dxf for it

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                      • #12
                        Originally posted by Spin Doctor
                        John I would think that any CAD software that can generate an involute gear should be able to do the splines too.
                        The hard part is the stub form. Involute splines are spec'ed as 16/32 DP, 12/24 DP, ...

                        The numerator defines the diametral pitch, and the denominator is the stub pitch.

                        So John's 16/32 is a 16 DP spline, with the tooth depth of a 32 DP tooth.

                        By the way, most ANSI standard involute splines are 30° pressure angle. The ANSI spec also has 37.5 and 45° pressure angles, but MH implies that they're very rare.
                        Last edited by lazlo; 01-20-2008, 11:30 AM.
                        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                        Comment


                        • #13
                          Originally posted by John Stevenson
                          I have the specs for the spline from a demo version of a program called Quick Spline 1.5

                          Fortunately the spline I want falls within the demo limitations of the program, sorry Lazlo 6 splines doesn't, so I'm going to draw this today and check it against the spline data I have.
                          John, I just downloaded Quick Spline, and it just calculates the specs from page 2161 of Machinery's Handbook. I can write an Excel spreadsheet to do it in 20 minutes.

                          I was actually looking for something that would generate a .DXF file for a 6 tooth, 16/32 DP involute spline, which would have a 0.5" major diameter: the spline on the Clausing telescoping leadscrew.

                          Sconisbee: the Clausing leadscrew spline is a 6-tooth version of John's spline. If it's not too much of an imposition, could you send me a .DXF of the 6 tooth version?

                          Thanks!

                          Robert
                          Last edited by lazlo; 01-20-2008, 11:38 AM.
                          "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                          Comment


                          • #14
                            If you know the width of the tooth at the top, pitch line and root why not just draw an arc at those radii that are centered on the tooth center. Then draw a spline* line through the three end points. Isn't that an involute? When drawing gears in AutoCAD that's how I have had to do it.Then just do an array command around the center point for the number of teeth. and fill in the gullets.

                            *to bad in AutoCAD spilne doesn't mean spline

                            PS Editing this in. After you draw the spline drop two circles that match pin diameters yo have that have into the space between two teeth and one on the opposite tooth. The distance over the circles should be your theoritical true size. Class of fit will determine how much under for sliding fits,
                            Last edited by Spin Doctor; 01-20-2008, 01:02 PM.
                            Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

                            Comment


                            • #15
                              lazlo this is what geartrax spits out for 6 tooth 16/32, but it doesnt look quite right to me, but if its of any use i can generate a dxf of it and send it your way

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