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  • Help with a gear?

    Can anyone give me the specs of this gear?



    16 tooth, 3/4" thick, 5/8" bore, 1-1/2" OD. I need a replacement in steel, but I have no idea how to figure pitch or DP or whatever.

    It's off an old Wellsaw bandsaw, so it's imperial, not metric.

    Thanks.
    Doc.
    Doc's Machine. (Probably not what you expect.)

  • #2
    16+2/1.5, would seem to be a 12dp gear.
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942

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    • #3
      Mcmaster Carr part number 6325k24 should get you there if you machine the face off of it.

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      • #4
        On the cheap-

        https://www.ebay.com/itm/Martin-S121...0AAOSwnTxZbTmd

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        • #5
          Put this in your favourites: https://www.technobotsonline.com/gea...alculator.html

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          • #6
            Originally posted by oxford View Post
            Mcmaster Carr part number 6325k24 should get you there if you machine the face off of it.
            -Thanks, Ox. I was hoping to be able to find one on McMaster, I just wanted to make sure I had the details right.

            And the extra hub is perfect- the original gear was held on by a simple cross-drilled roll pin, which, judging by the marks on the ring gear, went on walkabout more than a few times.

            Some previous owner replaced the roll pin with a soft dowel, and peened the beejeebers out of it to hold it in place. I was forced to drill it out to get it loose, and now it's right in between two sizes of roll pin. (Which I didn't really want to use anyway.)

            With that gear, I can make the shaft slightly longer, key it, and use the setscrew to lock it on- the extra hub thickness can extend away from the gearbox, there's nothing for it to hit out there.

            Thank you, gentlemen, much appreciated.

            Doc.
            Doc's Machine. (Probably not what you expect.)

            Comment


            • #7
              Check your pressure angle...perhaps faulty memory says they used 14.5PA
              McMaster only stocks 20 degree pressure angle.

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              • #8
                Originally posted by 1200rpm View Post
                Check your pressure angle...perhaps faulty memory says they used 14.5PA
                McMaster only stocks 20 degree pressure angle.
                The part number I have from McMaster is a 14.5PA but 1200rpm brings up a good point. Doc you should do some checking before you order that part. I don’t want to see you get the wrong one on my account.

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                • #9
                  Originally posted by 1200rpm View Post
                  Check your pressure angle...perhaps faulty memory says they used 14.5PA
                  McMaster only stocks 20 degree pressure angle.
                  -How would I tell?

                  Doc.
                  Doc's Machine. (Probably not what you expect.)

                  Comment


                  • #10
                    It can be hard to tell visually one such low tooth counts, looking at the gear it mates to should help, the difference becomes more obvious as the tooth count gets larger.

                    BTW- my bad McMaster does stock 14.5, I just didn't scroll far enough....apologies.
                    Last edited by 1200rpm; 03-16-2019, 10:22 PM.

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                    • #11
                      Gear tooth profile chart might be of some help: https://dspace.mit.edu/bitstream/han...artheorybg.pdf Boston Gear brochure, see page 141

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                      • #12
                        It does look like a 14.5؛ PA gear, but the lower number of teeth makes it difficult to know for sure. Perhaps if you took photos (CLOSE UP) of the teeth of a more numerous tooth gear, it would be easier to tell.

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                        • #13
                          Originally posted by Doc Nickel View Post
                          -How would I tell?
                          Doc.
                          Your sample is worn, so no guarantees, but ....
                          If it is 20°PA, the Span over 2T will be approximately 0.3877", 3T will be approximately 0.6337", & 4T will be approximately 0.8797".
                          If it is 14-1/2°PA, the Span over 2T will be approximately 0.3873", 3T will be approximately 0.6408", & 4T will be approximately 0.8943".

                          I'm going to wager it is 14-1/2°.

                          Comment


                          • #14
                            Originally posted by Zahnrad Kopf View Post
                            Your sample is worn, so no guarantees, but ....
                            If it is 20°PA, the Span over 2T will be approximately 0.3877", 3T will be approximately 0.6337", & 4T will be approximately 0.8797".
                            If it is 14-1/2°PA, the Span over 2T will be approximately 0.3873", 3T will be approximately 0.6408", & 4T will be approximately 0.8943".

                            I'm going to wager it is 14-1/2°.
                            -Both gears are pretty badly worn. I can't easily replace the ring gear (internal teeth, about 10" in diameter) but I figured that besides the pin issue, a new spur gere here would help take up some of the "slack". ('Course, it's a bandsaw, not like a lathe or something. )

                            Anyway, what exactly am I measuring here? Just point-to-point on the tips of the teeth? Flank-to-flank?

                            Doc.
                            Doc's Machine. (Probably not what you expect.)

                            Comment


                            • #15
                              Originally posted by Doc Nickel View Post
                              -Both gears are pretty badly worn. I can't easily replace the ring gear (internal teeth, about 10" in diameter) but I figured that besides the pin issue, a new spur gere here would help take up some of the "slack". ('Course, it's a bandsaw, not like a lathe or something. )

                              Anyway, what exactly am I measuring here? Just point-to-point on the tips of the teeth? Flank-to-flank?

                              Doc.
                              Ideally, the Tooth Flanks at Pitch Diameter. Practically, you are looking for relative numbers and their relation to the ones I posted. Normally, a Disc Micrometer is used for these measurements, typically. It’s a modern day replacement for Gear Tooth Calipers and commonly how it’s done these days. It just so also happens to be good at exposing and illustrating the difference between the Pressure Angles. In pinch, you can use a caliper for this exercise, here.

                              If you end up wanting the replace the Ring, we can help. Get me some basic dimensions when you’ve chance.

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