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My first spur gear

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  • #16
    Originally posted by michigan doug View Post
    " I don't think one should call it a "gear". "Roller with grooves" would be more accurate. No offense intended."

    I think you're a jerk. No offense intended.

    I see what looks like something approximating an involute tooth form. Not a roller with grooves.

    doug
    I understand why someone would post why its not exactly right. I also understand and completely, deeply, appreciate someone taking the tools at hand and making something that works (its the mode I like to think I work in)..

    But, I am sure Juergenwt posted his comment for a reason. Without taking anything away from the OP... I would like to know why Juergenwt thinks its more of a "roller with grooves" vs a "gear".

    I was thinking about making a "gear" myself just this AM, and would like a bit more education...

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    • #17
      "But, I am sure Juergenwt posted his comment for a reason"

      I would love to know it. I hope there is some interesting and complicated explanation. If there is, I would happily apologize for calling him a jerk.

      Finest regards,

      doug

      Comment


      • #18
        Originally posted by michigan doug View Post
        "But, I am sure Juergenwt posted his comment for a reason"

        I would love to know it. I hope there is some interesting and complicated explanation. If there is, I would happily apologize for calling him a jerk.

        Finest regards,

        doug
        I second that!
        John M...your (un)usual basement dweller

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        • #19
          Thanks to both of you cuemaker and even to you Doug.
          First let me give you a short look into my background. 3 1/2 years Apprenticeship as a Tool and Die Maker. After that from 1957 to 1997 employed as a Tool and Die Maker. The last twenty years as a Tool Room Foreman for a large Corporation. In between 3 years with the 28th Inf.Bat. 24th inf. Div..
          So now back to "Gears".
          I am not making fun over nor do I want to belittle in any way what herbet999 made. For someone with a limited amount of knowledge in the field of metal fabrication as well as having a limited amount of equipment - he did the best he could and you have to admire his resourcefulness. I do not know how and where his "gear" is being
          used and it may work OK. But for anything other than a slow moving hand operated operation - it is worthless.
          Now - for anyone wanting to make a "gear" to be used as a gear in some machinery or any other piece of equipment that is powered by electric or combustion motors -this method of gear fabrication is not an option. It would have a very short lifespan and would ruin any other gear coming in contact with it.
          A gear - let's say a very simple Spur Gear - is a very precise part and requires some very detailed know how to make. Much more than I could put down on this forum. But for starters let's look at a few basic requirements.
          Things you need to know before starting:
          How many teeth?
          What pitch?
          Metric (modul) or US standard diametrical pitch.
          Outer Dia.?
          Root Dia.?
          Pressure angle?
          So the very first thing you want to do is look into a Machinist Handbook.
          You will find many more things are involved before you even start.
          Now for Equipment:You need at minimum a Dividing Head. Depending on the number of teeth you may need a differential Dividing Head.
          You also need a horizontal mill and a gear cutter that represents the diametrical pitch or modul as well as the number of teeth you are cutting.
          You need to be able to measure the pitch dia. To get this you need the formula from the Handbook to get the right dim..
          In this case: Pitch dia = divide the product of number of teeth and outside dia. by the number of teeth + 2.
          You have to find out how to measure your gear.
          Many more things to consider before you even start. You will find all of it in your Machinist Handbook.
          The internet could be a good source. Making a gear that will work is not for someone with limited experience.
          Even if you should have the basic equipment - it would not be a gear to be used at higher speeds (Rpm). Those will have to be heat treated and ground and would require a very special steel.
          Hope this points you in the right direction.
          Here is a very short movie on how to make a gear: http://www.youtube.com/watch?v=VHTXaU7GZC0
          Last edited by Juergenwt; 11-24-2012, 07:47 PM.

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          • #20
            I think the OP did a good job all round as he used all that was availble to him by way of material and tools, he refined the gear cutter shape - and it worked to his satisfaction - can't get better than that.

            Comment


            • #21
              Originally posted by Juergenwt View Post
              Most likely good enough for whatever it is used for. You deserve credit for that. I don't think one should call it a "gear". "Roller with grooves" would be more accurate. No offense intended.
              As he said, "Most like good enough.....". That's the important part of the whole post. It won't pass NASA, but it will sure point many of us to a way to get something working when we have to. Nice work. I applaud the McGyver effort.
              Wayne

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              • #22
                I wonder if Juergenwt could tell us the rate of failure for a set of home made gears like these. This assumes that the cutter captured the tooth profile faithfully, and used at a reasonable speed.

                I was considering the idea of making a set of gears for a home made ring roller using a similar technique.

                Dan
                At the end of the project, there is a profound difference between spare parts and extra parts.

                Location: SF East Bay.

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                • #23
                  Gosh..... what a controversy...... when really there isn't one.

                  Yes, it is a reasonably effective use of available tools. Yes, it is a gear....... a fairly nasty one, full of geometric errors, frankly, as Juergenwt pointed out, although it may work for the application.

                  Visible problems include apparent uneven spacing, non-radial teeth, and imperfect tooth shapes.

                  Those problems come directly from the method of making it.

                  Replacing the vise with a very very simple basic indexing system with both parts (blank and gear) mounted on a common rotatable shaft that can be clamped in position would take care of many of those problems, if used with care. Measuring for centering would eliminate the non-radial teeth. A pin setup to index to each tooth would let the existing gear be the master.

                  Fitting the cutter to the existing gear (I have done that also) would then allow producing a creditable gear of proper tooth shape.

                  The setup would be very similar to that used, really, only the way of holding the gear blank changes.

                  I doubt the failure rate of gears properly cut is high..... the problems brought up are ones of improper cutting, shape, spacing, etc.

                  Form-cut gears may wear a bit differently to generated shape gears.... the form cutter is never perfect, but generation is usually rather close.
                  Last edited by J Tiers; 11-24-2012, 11:17 PM.
                  1601

                  Keep eye on ball.
                  Hashim Khan

                  Comment


                  • #24
                    One end (can't remember which) of a standard gear cutter set is very accurate - the others are less so but pretty good never the less.

                    At least the OP "gave it a go" and despite any errors it worked well enough to get him going again - which is a success by any measure. Its what suits the OP that matters - not the rest of us.

                    I wonder just how many would not given it a go if they didn't have the"right tools/cutters" and so the gear remained "unmade".

                    It might be a bit "shade tree mechanic" or "red neck" but as so many of the STM and RN stuff it worked - despite the "worry warts" and "purists" - and sceptics too?

                    Comment


                    • #25
                      Originally posted by Juergenwt View Post
                      Now for Equipment:You need at minimum a Dividing Head. Depending on the number of teeth you may need a differential Dividing Head.
                      You also need a horizontal mill and a gear cutter that represents the diametrical pitch or modul as well as the number of teeth you are cutting.
                      You need to be able to measure the pitch dia. To get this you need the formula from the Handbook to get the right dim..
                      In this case: Pitch dia = divide the product of number of teeth and outside dia. by the number of teeth + 2.
                      You have to find out how to measure your gear.
                      Many more things to consider before you even start. You will find all of it in your Machinist Handbook.
                      The internet could be a good source. Making a gear that will work is not for someone with limited experience.
                      Even if you should have the basic equipment - it would not be a gear to be used at higher speeds (Rpm). Those will have to be heat treated and ground and would require a very special steel.
                      Hope this points you in the right direction.
                      Here is a very short movie on how to make a gear: http://www.youtube.com/watch?v=VHTXaU7GZC0
                      Damn, no wonder I have been going wrong all these years, I obviously don't have the bare minimum, - damn.

                      Mind you the You tube video linked to is only using a crap Chinese round column mill drill instead of a horizontal mill and we know how crap they are.
                      .

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



                      Comment


                      • #26
                        This is what I needed the gear for. My inline sander. Works great. I'll see how long it lasts.



                        In the exploded view the gear is part #32. Just about the center of the page

                        Last edited by herbet999; 11-25-2012, 01:49 PM.

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                        • #27
                          You do not need anything super special to copy a gear which you have one of.

                          Here is an indexing system that I used several times to make bevel gears. Once with a hand ground cutter used in a shaper, otherwise with a horizontal mill, similar to the lathe method of the OP.

                          The screw you see at top of the fixture is to hold the master gear (a change gear from lathe) indexed to position. The whole thing was cobbled from scrap pieces that I had on hand.

                          The goodness of the form-cut gear is the goodness of the cutter, which may be commercial as in the picture, or hand ground fly cutter as the OP used (and I have made also). One correctly ground cutter is enough, should not need several, unless you try to do the undercut tooth form, in which case you may need an extra to do that cut.

                          The hand ground one was ground to fit the mating identical gear, and might as easily have been used as a fly cutter similar to the OP original method.

                          The cutter, no matter the type, must be set radial to the blank, so the cut teeth will be straight. That is same with any gear cutting.

                          A similar item to the one pictured might be made horizontal, not at a 45 deg angle, to make spur gears using one gear as a master.

                          Last edited by J Tiers; 11-25-2012, 07:21 PM.
                          1601

                          Keep eye on ball.
                          Hashim Khan

                          Comment


                          • #28
                            Herbet999 - you did a fine job to keep your sander going. What we have here is a "failure to communicate". Just like somebody may be able to help himself by replacing a bad tire one a bicycle with a water (garden) hose to keep going because he either could not get a new tire or he did not want to spend the money for it. It worked and that is what matters.
                            However - that does not make the replacement water hose a bicycle tire.
                            Just like nobody in his right mind would put this "Gear" in his Harley, having it produced in the way it was described.
                            So, for people having no knowledge of the geometry involved in making a gear - it looks like a gear - therefore it must be gear -
                            it all boils down to the question of whether it was made by someone doing the best he could just to help himself - and in many cases that's what it's all about- or was it made professional. I hope your sander works good for a long time.
                            For all who would like to know more please Google: Gear tooth geometry or gear tooth cutter geometry.
                            This has been an interesting little conversation and exchange - not really a big thing - but something applicable to a number of other posts on this Forum.
                            Last edited by Juergenwt; 11-26-2012, 01:40 AM.

                            Comment


                            • #29
                              Originally posted by Juergenwt View Post
                              Just like nobody in his right mind would put this "Gear" in his Harley, having it produced in the way it was described.
                              .

                              Bollocks, it's probably 3 times better than a Harley gear
                              Wish it was in the down feed of my POS Bridgy instead of the ones made by Timex.
                              .

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



                              Comment


                              • #30
                                Originally posted by Juergenwt View Post
                                Herbet999 - you did a fine job to keep your sander going. What we have here is a "failure to communicate". Just like somebody may be able to help himself by replacing a bad tire one a bicycle with a water (garden) hose to keep going because he either could not get a new tire or he did not want to spend the money for it. It worked and that is what matters.
                                However - that does not make the replacement water hose a bicycle tire.
                                Just like nobody in his right mind would put this "Gear" in his Harley, having it produced in the way it was described.
                                So, for people having no knowledge of the geometry involved in making a gear - it looks like a gear - therefore it must be gear -
                                it all boils down to the question of whether it was made by someone doing the best he could just to help himself - and in many cases that's what it's all about- or was it made professional. I hope your sander works good for a long time.
                                For all who would like to know more please Google: Gear tooth geometry or gear tooth cutter geometry.
                                This has been an interesting little conversation and exchange - not really a big thing - but something applicable to a number of other posts on this Forum.
                                I appreciate your input. As I stated in the original post, this gear was for an air sander. I have no intention of making one for my Harley even if I had a Harley. I think you are correct in pointing out that my method is not going to be sufficient for a lot of applications.

                                My interest in machining is more in support of my interest in cars and less a direct interest, although I enjoy machining as a hobby as well.

                                The reason for the post was three fold. First to gloat about my accomplishment. Second, to relay my experience in creating what I needed with minimal equipment (I include my lathe as minimal equipment only because it too was hobbled together from bits and pieces I've gotten on the cheap). Third, in hopes to elicit responses on how I could better my results within the confines of the level of equipment I'm using.

                                As for my experience, I found that indexing the blank using the old gear worked fairly well and I think is accurate enough for what I was trying to do. I also found that cutting at the slowest speed (125 rpm) worked the best and allowed the cutter to last through all eleven passes. I did use oil, applied from a squeeze bottle, for lubrication. I think the least accurate aspect to my process was the shape of the cutter(s) themselves. As I mentioned, I ground tool steel into a cutter by hand using a basic 6 inch bench grinder. To make matters worse, my setup meant that the tool steel had to be less than an inch long so holding the tool steel while grinding was an issue.
                                Last edited by herbet999; 11-26-2012, 10:38 AM.

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