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  • Involute Gear Profile

    Hello,

    Since I am now in the process of making the gear blanks, I am either looking for involute gear cutters, on E-Bay, or trying to figure out how to grind a single-point cutter out of HSS. Since I need to cut anywhere from 30 to 64 teeth, on each gear, it looks like I am looking for a #2, #3, and a #4 18DP cutter. Unfortunately, it appears that only larger tooth cutters are available at the present time. Buying a new cutter is out of the question. So, that leaves me with the prospect of grinding my own single point cutter and making a tool holder for it.

    Though I have found many instructions, on this site and others, that detail how to draw involute gear teeth...and as a side-effect, the cutter profile. But, what I am wondering is: Is there a computer program that is specialized in making the profile? Specifically, is there a program where I would enter that I need the profile for a #2 18DP cutter and it draws it to scale? Do some CAD programs allow you to specify that you want a 30 tooth, 18 pitch, involute gear and draw them automatically?

    Brian
    Last edited by Rif; 10-18-2007, 03:13 PM.
    There are only 10 types of people in the world: Those who understand binary and those who don't.

  • #2
    This wont give you much data but is fun to play around with.

    http://woodgears.ca/gear_cutting/template.html

    Comment


    • #3
      Originally posted by tattoomike68
      This wont give you much data but is fun to play around with.

      http://woodgears.ca/gear_cutting/template.html
      Thanks! I just checked that out. Since I am only making low-speed change gears, that may be close enough.

      Brian
      There are only 10 types of people in the world: Those who understand binary and those who don't.

      Comment


      • #4
        Brian,

        There are many programs out there that can draw gears but very few that can draw them geometrically correct, many fudge the calculations especially the part below the pitch line.

        I use a small program called Involute that generates a correct profile but it's a paid for program and they don't do a demo copy.

        Before that I used a freeware program called GearGen which is an old DOS program and is out there on there internet.

        Do a search and download this GearGen and punch in your numbers and it will save the output as a dxf file.


        .
        .

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



        Comment


        • #5
          Hi Brian. I don't think you would want to single point that large of a pitch. The banging would be tremendous. Before that I would buy a piece of tool steel and make a circular cutter and have it hardened. Here's a link to a computer program for involute curves.
          http://www.hobbing.com/
          gbritnell

          Comment


          • #6
            Here's an article I wrote showing how to generate the profile in CAD:
            http://www.cartertools.com/involute.html
            Largest resource on the web for Taig lathes and milling machines, www.cartertools.com

            Comment


            • #7
              The freeware version of Allycad draws geometrically correct gears using Unwins construction.

              http://www.allycad.com/


              Free software for calculating bolt circles and similar: Click Here

              Comment


              • #8
                Hi Rif,

                Originally posted by Rif
                Since I need to cut anywhere from 30 to 64 teeth, on each gear, it looks like I am looking for a #2, #3, and a #4 18DP cutter. Unfortunately, it appears that only larger tooth cutters are available at the present time.
                I went through this process myself (of trying to cobble together a gear cutter). Ebay has 18 DP cutters all the time, and they're cheaper than most because lathe owners are looking for 16 DP cutters, and clock makers are looking for 24, 32, and 48 DP.

                I usually pay $8 - $16 for a 16 DP cutter, depending on how many times it's been resharpened (look at the flats between the cutter teeth). 7/8" arbor gear cutters also sell for a lot less than 1" cutters -- I'm not sure why.

                There doesn't seem to be any 18 DP gear cutters on Ebay right now (there usually are), but Lane turned me on to Wholesale Tool, which sells Chicom HSS cutters for really cheap, and they're surprisingly well-made:

                18 DP, #2 (14 1/2° PA) $19.08:
                http://www.wttool.com/product-exec/p...e_Gear_Cutters

                18 DP, #4 (14 1/2° PA) $19.08:
                http://www.wttool.com/product-exec/p...e_Gear_Cutters

                Cheers,

                Robert
                "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                Comment


                • #9
                  gbritnell has a good point about the "banging" with a single-point cutter. If you end up going that route, take out as much metal as you can with a slitting saw first -- gash the tooth spaces -- to lessen the amount the single-point tool has to contend with.
                  ----------
                  Try to make a living, not a killing. -- Utah Phillips
                  Don't believe everything you know. -- Bumper sticker
                  Everybody is ignorant, only on different subjects. -- Will Rogers
                  There are lots of people who mistake their imagination for their memory. - Josh Billings
                  Law of Logical Argument - Anything is possible if you don't know what you are talking about.
                  Don't own anything you have to feed or paint. - Hood River Blackie

                  Comment


                  • #10
                    I believe you have a shaper so, depending how enthusiastic you are about making tools, you might be able to make gears on that shaper.

                    Some time ago John Stevenson posted links to many files in his "Moving On" thread. He invited members to poke through and copy files of interest before they disappeared. I poked around and found he had many interesting files concerning gears. These files are still available so I assume John's offer continues. If you go here:
                    http://homepage.ntlworld.com/stevens...lsteve/hidden/

                    and look at the mysteriously named files P1.jpg, P2.jpg, P3.jpg and P4.jpg you'll find an interesting design for an involute gear cutter attachment to fit a shaper. The shaper bit is easy to grind because it has straight sides rather than the involute profile; this jig generates the involute profile on the gear teeth using first principles.

                    I copied these files because I'm pursuing a shaper locally and thought this might be an especially interesting way to cut gears. It would take some effort to build the jig but it doesn't look super difficult - always easy to say when suggesting someone else to do the work

                    A little farther on in John's directory you'll find a different gadget, used to automatically profile gear cutter teeth on the lathe; see Spage1.jpg, etc. This looks really nifty but unfortunately the first page of the article seems to be missing. Still a neat article to read even if there may not be quite enough info to build one.

                    And then there's John's info on how to make involute cutters: http://www.metalwebnews.com/howto/gear/gear1.html


                    John

                    Edit: added info on shaper bit shape, 2) link to metalwebnews
                    Last edited by GadgetBuilder; 10-18-2007, 09:33 PM.
                    Location: Newtown, CT USA

                    Comment


                    • #11
                      I DID notice the "cost prohibitive" comment...

                      But, how expensive do you THINK they are?

                      I don't know what they go for on ebay, I don't even have an ebay membership. But cutters can be had brand new for about $25 per from Victor Machinery. At least I have bought a number of them from Victor, and that is what I paid.

                      Therefore, it looks like you would pay $75 or so buying all new. You could make your gears, and still have the cutter.

                      I have made gears on the shaper. Can be done, surely, but it is not for the impatient.

                      The biggest hassle is the feed, which on bigger gears (I made 12 pitch) must be very small in order to avoid a big banging as the full profile is cut at once in the last few passes. Half-thou feeds were the order of the day in order not to destroy the fixture, or bang it out of position.
                      CNC machines only go through the motions

                      Comment


                      • #12
                        If you want to make you own gear cutters, there is always this gem, written by a famous author:

                        http://www.metalwebnews.com/howto/gear/gear1.html

                        Oops, this was already mentioned earlier in the thread.
                        Oh well, it IS a good one...
                        Last edited by alanganes; 10-18-2007, 10:13 PM.

                        Comment


                        • #13
                          Originally posted by J Tiers
                          I DID notice the "cost prohibitive" comment...

                          But, how expensive do you THINK they are?

                          I don't know what they go for on ebay, I don't even have an ebay membership. But cutters can be had brand new for about $25 per from Victor Machinery.
                          Read my post on the previous page Jerry:

                          Originally posted by Lazlo
                          Ebay has 18 DP cutters all the time, and they're cheaper than most because lathe owners are looking for 16 DP cutters, and clock makers are looking for 24, 32, and 48 DP.

                          I usually pay $8 - $16 for a 16 DP cutter, depending on how many times it's been resharpened (look at the flats between the cutter teeth). 7/8" arbor gear cutters also sell for a lot less than 1" cutters -- I'm not sure why.

                          There doesn't seem to be any 18 DP gear cutters on Ebay right now (there usually are), but Lane turned me on to Wholesale Tool, which sells Chicom HSS cutters for really cheap, and they're surprisingly well-made:

                          18 DP, #2 (14 1/2° PA) $19.08:
                          http://www.wttool.com/product-exec/p...e_Gear_Cutters
                          Last edited by lazlo; 10-18-2007, 10:53 PM.
                          "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
                            Involute gear cutters for around $25? Ok, I am buying them. I didn't look at WT. I think I checked Grizzly and Enco. Since I didn't find anything there, I used Google and searched for them and found places that sell them for over $100. I was thinking that 3 gear cutters would cost over $300!

                            I will check out WT.

                            Thanks!

                            Brian
                            There are only 10 types of people in the world: Those who understand binary and those who don't.

                            Comment


                            • #15
                              I just ordered the gear cutters from WT. The total cost was about $66, including shipping, for the 3 cutters I need.

                              Thanks again for all the info.

                              Brian
                              There are only 10 types of people in the world: Those who understand binary and those who don't.

                              Comment

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