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Re: milling machines

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  • hughckelley
    I don t have a milling machine myself but I am vaguely familiar with my father s, which he uses for gun stocks. It s a very complex machine in comparison with
    Message 1 of 9 , Dec 5, 2012
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      I don't have a milling machine myself but I am vaguely familiar with my father's, which he uses for gun stocks. It's a very complex machine in comparison with my normal bike tooling needs and I'd think it's more time/cost-effective to farm those jobs out (not that I always bow at the altar of cost-effectiveness where bikes are concerned).

      Obviously it won't do you any good for metal fabrication, but I have been similarly tempted to get a 3D printer for small plastic parts (light brackets, shifter mounts, etc.).
    • Alex Wetmore
      I have two milling machines. One is a smaller CNC machine made by Taig and if I were making a sprocket I d use that one. The other is a small knee mill
      Message 2 of 9 , Dec 5, 2012
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        I have two milling machines. One is a smaller CNC machine made by Taig and if I were making a sprocket I'd use that one. The other is a small knee mill called a Grizzly G3102. Both live in my basement along with a South Bend 9A lathe and a Delta horizontal bandsaw.

        A Grizzly G0704 is another popular mill that fits in between the two in size and isn't too expensive. It is often CNC'd, although I think that the Taig is more capable as a CNC mill without major modifications.

        Do you have examples of what you'd like to make? Something like a 3sp 20t sprocket (just to pick something that we're probably all aware of) is not a trivial thing to machine. The 3 lobes would be hard to get right without access to CNC, and even with CNC there is a sharp corner at the edge of the lobe that would require hand filing or a very small endmill. You'd want a lathe as well to bevel the edges of the teeth on the sprocket.

        The Taig (and almost all hobbyist sized CNC mills) has travels too short to make a chainring of any decent size. It will move 12x5.5" on the X and Y axis, making the practical limit for chainrings just over 5" in diameter. That will make you a 30t cog or chainring, but not larger. With some clever programming and a rotary table you could make larger ones, but that type of programming is outside the realm of normal CAD/CAM packages. You'll also end up at the size where you need a large lathe to bevel the teeth.

        I use my milling machines primarily in frame building and in making tools for framebuilding. I've made my own frame, fork, and rack fixtures and small measuring tools (selling some of those paid for my Taig mill). I make the front dropouts for most of my bikes and use the manual tools to miter and slot tubing for framebuilding. I've gotten a lot of enjoyment out of having a small metal shop, but in owning it I've also gained a lot of appreciation for how metal is machined and understanding how complex or simple an item is to make.

        alex

        ________________________________________
        From: Geared_hub_bikes@yahoogroups.com [Geared_hub_bikes@yahoogroups.com] on behalf of bikealfa [mtwils@...]
        Sent: Tuesday, December 04, 2012 3:23 PM
        To: Geared_hub_bikes@yahoogroups.com
        Subject: [Geared_hub_bikes] milling machines

        I know some members of this list have milling machines.

        I am looking for a milling machine to do bicycle part stuff, like sprocket machining.

        What do people own and like?

        One idea is to get something small enough to live in the bicycle room. Another idea is to get a more conventional size machine and stick it in the garage near the frame repair stand.

        Or I could develop a relationship with someone who has a machine ...

        Comments desired.


        Michael Wilson



        ------------------------------------

        Yahoo! Groups Links
      • bikealfa
        What I want to make: 1) counterbore 24t 74bcd chainrings so the mounting bolts are flush with the teeth, not flush with the side that is 2 mm away from the
        Message 3 of 9 , Dec 6, 2012
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          What I want to make:
          1) counterbore 24t 74bcd chainrings so the mounting bolts are flush with the teeth, not flush with the side that is 2 mm away from the teeth.
          2) remachine the shimano cassette sprocket holder for narrower sprocket spacing and 3 mm inset, for 12 sprockets on my TT bike
          3) add a sideways pivot to Campy Ergopower brake levers, so they actuate the shift the way a Shimano shifter does
          4) shave the mounting surfaces of some chainrings so they will mount closer to the frame centerline
          5) make the adaptors and machine the 30t chainrings that allow me to put a 30t chainring on a 110bcd crank. I have one set, I want more. This allows a 30t chainring on a Clavicula crank, and also on a 110bcd powermeter crank like a Quark or an SRM.

          6) and when I REALLY get my act together - a front derailleur that does a triple where the inner sprocket is at about 30 mm chainline.

          I would not make sprockets or splines from scratch; that seems like too much work. I would buy sprockets and remachine them. I have had some success with hand files and hand grinders on tooth profiles and clearance for the chain. I have had some but less success with things like small screws added for prevention of chains falling between sprockets and for chain ramps. I can use files and dremels to make things fit. It is the precision to maintain flatness and roundness that I cannot do by hand.

          If I thought I had the design and manufacturing skills I would make a ratchet to replace the cable drum on a Rohloff hub, but I do not have those skills.

          I have not had a good reason to build my own frames. The frames that have appeared in front of me via trash, siblings, bike shops and ebay have been fine. The 1978ish Bob Jackson has been wonderful. That said - right chainstay clearance for 28 mm chainline 24 t or smaller inner sprockets would be interesting.

          All the sprocket stuff is in support of my gearing fetish, which is 70 inch for level road, close ratio around that level road, 110 inch for 50mph downhills, and only shifting the front when there is absolutely no other possible option. Because front shifting has never worked well for me. I use 46 t large rings and 11t small cassette cogs, and 15-19 corncob sections. I have no reason for 12 or 14 tooth cogs; 2 downhill gears is enough for me.

          The TT bike is the exception - it needs close ratio gears at the top end as well if I am to do 27mph average which is why I am doing 12 sprockets. It also needs low gears so I can get home afterwards.

          I would probably combine 2 sprockets if I wanted to do a custom 3-spline IGH cog, or buy a Miche or Marchisio shimano compatible sprocket and grind off the extra internal splines. I have welded sprockets together, but never had the need to use such.



          Michael Wilson

          --- In Geared_hub_bikes@yahoogroups.com, Alex Wetmore <alex@...> wrote:
          >
          > I have two milling machines. One is a smaller CNC machine made by Taig and if I were making a sprocket I'd use that one. The other is a small knee mill called a Grizzly G3102. Both live in my basement along with a South Bend 9A lathe and a Delta horizontal bandsaw.
          >
          > A Grizzly G0704 is another popular mill that fits in between the two in size and isn't too expensive. It is often CNC'd, although I think that the Taig is more capable as a CNC mill without major modifications.
          >
          > Do you have examples of what you'd like to make? Something like a 3sp 20t sprocket (just to pick something that we're probably all aware of) is not a trivial thing to machine. The 3 lobes would be hard to get right without access to CNC, and even with CNC there is a sharp corner at the edge of the lobe that would require hand filing or a very small endmill. You'd want a lathe as well to bevel the edges of the teeth on the sprocket.
          >
          > The Taig (and almost all hobbyist sized CNC mills) has travels too short to make a chainring of any decent size. It will move 12x5.5" on the X and Y axis, making the practical limit for chainrings just over 5" in diameter. That will make you a 30t cog or chainring, but not larger. With some clever programming and a rotary table you could make larger ones, but that type of programming is outside the realm of normal CAD/CAM packages. You'll also end up at the size where you need a large lathe to bevel the teeth.
          >
          > I use my milling machines primarily in frame building and in making tools for framebuilding. I've made my own frame, fork, and rack fixtures and small measuring tools (selling some of those paid for my Taig mill). I make the front dropouts for most of my bikes and use the manual tools to miter and slot tubing for framebuilding. I've gotten a lot of enjoyment out of having a small metal shop, but in owning it I've also gained a lot of appreciation for how metal is machined and understanding how complex or simple an item is to make.
          >
          > alex
          >
          > ________________________________________
          > From: Geared_hub_bikes@yahoogroups.com [Geared_hub_bikes@yahoogroups.com] on behalf of bikealfa [mtwils@...]
          > Sent: Tuesday, December 04, 2012 3:23 PM
          > To: Geared_hub_bikes@yahoogroups.com
          > Subject: [Geared_hub_bikes] milling machines
          >
          > I know some members of this list have milling machines.
          >
          > I am looking for a milling machine to do bicycle part stuff, like sprocket machining.
          >
          > What do people own and like?
          >
          > One idea is to get something small enough to live in the bicycle room. Another idea is to get a more conventional size machine and stick it in the garage near the frame repair stand.
          >
          > Or I could develop a relationship with someone who has a machine ...
          >
          > Comments desired.
          >
          >
          > Michael Wilson
          >
          >
          >
          > ------------------------------------
          >
          > Yahoo! Groups Links
          >
        • Alex Wetmore
          1) is easy and would probably be faster for me to do on a manual machine than CNC, although either would work. On a manual machine I d either use a DRO or
          Message 4 of 9 , Dec 6, 2012
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            1) is easy and would probably be faster for me to do on a manual machine than CNC, although either would work. On a manual machine I'd either use a DRO or rotary table to position the bolt circle diameter properly.

            2) I don't have a good vision of this. The spacing is controlled by the spacers between sprockets. If by inset you mean making a longer relief before the splines start then I'd do that on a lathe, not a mill. However it could be done on a mill with a rotary table.

            3) Sounds like one-off work that I'd do on a manual mill, but I haven't had an ErgoPower shifter in over a decade and don't have a good sense of how they fit together anymore.

            4) Is easy on a mill with a fly cutter or on a lathe.

            5) This must be a tripilizer? I'd like to see a photo of one of the adapters. They have to mount the 30t ring inside the inner ring, right?

            Watch for used ones on your local Craigslist. A "large" benchtop mill like the G0704 is probably about the right size and should fit most of your needs. A "small" knee mill like the G3102 is more capable in the long run but much harder to convert to CNC if that is a final goal (but based on the projects CNC doesn't sound like an advantage for your needs). If you have a way to move it you might find a large knee mill like a Bridgeport clone almost as cheaply as these smaller mills, mostly because most people don't have a way to move or store them.

            Buying used might not save you that much on the base machine, but it usually gets you a lot of tooling at rock bottom prices. Mill tooling is expensive, especially DROs ($400-$1000), rotary tables ($300-$600), vises ($100-$300), collet sets ($100-$400), quality drills and end mills. On a $1000 mill like the G0704 I'd ultimately expect to spend another $1500 on tooling, or to find a well tooled up used one for a lot less.

            On Craigslist you'll run into a lot of "mill drills". Round column ones like the Rong Fu RF-30 or the Grizzly G1007 are frustrating to use for projects with a lot of depth. When you move the head up and down the column it rotates around the column and so you need to re-locate the edges of everything. To compensate for this they have quills that extend a long way (5" vs 2 to 3" on most mills), but that isn't a great fix because the quill has more play when it is extended that far.

            However they are very stout for their size (much more so than the G0704), might meet your needs, and come up used a lot.

            There are square column mill drills like the Rong Fu RF-40 and RF-45 that are stout and fix the rotational issue, but they don't show up used nearly as often.

            I make my own frames because I enjoyed learning the process and get enjoyment out of making a bike where every detail is exactly right for my needs. At the same time I don't think that everyone needs a custom frame or that in the end there is a real end user benefit for having every detail exactly right... friends certainly do more impressive rides on their Surly Long Haul Truckers than I do on my custom touring bike. I just get pleasure in the making of them.

            This paperback is cheap and useful for your pursuits:
            http://www.amazon.com/Home-Machinists-Handbook-Doug-Briney/dp/0830615733/ref=sr_1_2?ie=UTF8&qid=1354812528&sr=8-2&keywords=home+shop+machinist

            It is written about much smaller machines (the author started the Sherline tool company) but covers all of the basics of machining in a very approachable and easy to read way.

            alex
            ________________________________________
            From: Geared_hub_bikes@yahoogroups.com [Geared_hub_bikes@yahoogroups.com] on behalf of bikealfa [mtwils@...]
            Sent: Thursday, December 06, 2012 8:24 AM
            To: Geared_hub_bikes@yahoogroups.com
            Subject: [Geared_hub_bikes] Re: milling machines

            What I want to make:
            1) counterbore 24t 74bcd chainrings so the mounting bolts are flush with the teeth, not flush with the side that is 2 mm away from the teeth.
            2) remachine the shimano cassette sprocket holder for narrower sprocket spacing and 3 mm inset, for 12 sprockets on my TT bike
            3) add a sideways pivot to Campy Ergopower brake levers, so they actuate the shift the way a Shimano shifter does
            4) shave the mounting surfaces of some chainrings so they will mount closer to the frame centerline
            5) make the adaptors and machine the 30t chainrings that allow me to put a 30t chainring on a 110bcd crank. I have one set, I want more. This allows a 30t chainring on a Clavicula crank, and also on a 110bcd powermeter crank like a Quark or an SRM.

            6) and when I REALLY get my act together - a front derailleur that does a triple where the inner sprocket is at about 30 mm chainline.

            I would not make sprockets or splines from scratch; that seems like too much work. I would buy sprockets and remachine them. I have had some success with hand files and hand grinders on tooth profiles and clearance for the chain. I have had some but less success with things like small screws added for prevention of chains falling between sprockets and for chain ramps. I can use files and dremels to make things fit. It is the precision to maintain flatness and roundness that I cannot do by hand.

            If I thought I had the design and manufacturing skills I would make a ratchet to replace the cable drum on a Rohloff hub, but I do not have those skills.

            I have not had a good reason to build my own frames. The frames that have appeared in front of me via trash, siblings, bike shops and ebay have been fine. The 1978ish Bob Jackson has been wonderful. That said - right chainstay clearance for 28 mm chainline 24 t or smaller inner sprockets would be interesting.

            All the sprocket stuff is in support of my gearing fetish, which is 70 inch for level road, close ratio around that level road, 110 inch for 50mph downhills, and only shifting the front when there is absolutely no other possible option. Because front shifting has never worked well for me. I use 46 t large rings and 11t small cassette cogs, and 15-19 corncob sections. I have no reason for 12 or 14 tooth cogs; 2 downhill gears is enough for me.

            The TT bike is the exception - it needs close ratio gears at the top end as well if I am to do 27mph average which is why I am doing 12 sprockets. It also needs low gears so I can get home afterwards.

            I would probably combine 2 sprockets if I wanted to do a custom 3-spline IGH cog, or buy a Miche or Marchisio shimano compatible sprocket and grind off the extra internal splines. I have welded sprockets together, but never had the need to use such.



            Michael Wilson

            --- In Geared_hub_bikes@yahoogroups.com, Alex Wetmore <alex@...> wrote:
            >
            > I have two milling machines. One is a smaller CNC machine made by Taig and if I were making a sprocket I'd use that one. The other is a small knee mill called a Grizzly G3102. Both live in my basement along with a South Bend 9A lathe and a Delta horizontal bandsaw.
            >
            > A Grizzly G0704 is another popular mill that fits in between the two in size and isn't too expensive. It is often CNC'd, although I think that the Taig is more capable as a CNC mill without major modifications.
            >
            > Do you have examples of what you'd like to make? Something like a 3sp 20t sprocket (just to pick something that we're probably all aware of) is not a trivial thing to machine. The 3 lobes would be hard to get right without access to CNC, and even with CNC there is a sharp corner at the edge of the lobe that would require hand filing or a very small endmill. You'd want a lathe as well to bevel the edges of the teeth on the sprocket.
            >
            > The Taig (and almost all hobbyist sized CNC mills) has travels too short to make a chainring of any decent size. It will move 12x5.5" on the X and Y axis, making the practical limit for chainrings just over 5" in diameter. That will make you a 30t cog or chainring, but not larger. With some clever programming and a rotary table you could make larger ones, but that type of programming is outside the realm of normal CAD/CAM packages. You'll also end up at the size where you need a large lathe to bevel the teeth.
            >
            > I use my milling machines primarily in frame building and in making tools for framebuilding. I've made my own frame, fork, and rack fixtures and small measuring tools (selling some of those paid for my Taig mill). I make the front dropouts for most of my bikes and use the manual tools to miter and slot tubing for framebuilding. I've gotten a lot of enjoyment out of having a small metal shop, but in owning it I've also gained a lot of appreciation for how metal is machined and understanding how complex or simple an item is to make.
            >
            > alex
            >
            > ________________________________________
            > From: Geared_hub_bikes@yahoogroups.com [Geared_hub_bikes@yahoogroups.com] on behalf of bikealfa [mtwils@...]
            > Sent: Tuesday, December 04, 2012 3:23 PM
            > To: Geared_hub_bikes@yahoogroups.com
            > Subject: [Geared_hub_bikes] milling machines
            >
            > I know some members of this list have milling machines.
            >
            > I am looking for a milling machine to do bicycle part stuff, like sprocket machining.
            >
            > What do people own and like?
            >
            > One idea is to get something small enough to live in the bicycle room. Another idea is to get a more conventional size machine and stick it in the garage near the frame repair stand.
            >
            > Or I could develop a relationship with someone who has a machine ...
            >
            > Comments desired.
            >
            >
            > Michael Wilson
            >
            >
            >
            > ------------------------------------
            >
            > Yahoo! Groups Links
            >




            ------------------------------------

            Yahoo! Groups Links
          • bikealfa
            I know the basic sprocket machining is easy; when I had machine shop access I used to do this sort of thing myself. Yes I know tooling is expensive. It is
            Message 5 of 9 , Dec 7, 2012
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              I know the basic sprocket machining is easy; when I had machine shop access I used to do this sort of thing myself.

              Yes I know tooling is expensive. It is also something you will not have when you want to use the machine, so you will have to order it and wait, or have spent a lot more to have tooling you will probably never use. Several reasons why I have not yet bought a milling machine.

              Project details:
              2) remachine the shimano cassette sprocket holder for narrower sprocket spacing and 3 mm inset, for 12 sprockets on my TT bike

              Cassettes have inidvidual sprockets and aluminum carriers. This is remachining the aluminum carrier so it sits 3 mm further onto the wheel - fits ZIPP disk wheels - and has narrower sprocket spacing.

              5) make the adaptors and machine the 30t chainrings that allow me to put a 30t chainring on a 110bcd crank. I have one set, I want more. This allows a 30t chainring on a Clavicula crank, and also on a 110bcd powermeter crank like a Quark or an SRM.

              No this is NOT a triplizer. This is a replacement bolt set, and a 30 t sprocket (we used a Sugino 74 bcd) remachined to fit over the steps of a 110bcd crank, and with 105 mm bcd and 4 mm countersunk bolts. The bolt set has the offset hole tapped for the 4 mm bolts, and the same shape for the large chainring as a traditional crank bolt - 10 mm base diameter and 12 mm shoulder to fit the counterbore. This also requires filing the crank arm spider so the chain can sit on the 30 sprocket correctly.

              Why the 30t on 110bcd?
              1) I like narrow crank spacing
              2) I like to put my large 46t chainring at the center of the cassette, so it works better with the large rear cassette cog.
              3) Superlight cranks (until the Lightning) were 110 bcd and I needed a 30-34 for Mt Washington hillclimb and did not want to change the cranks on my 13 pound road bike to something heavier
              4) Similarly power meter cranks are 110 bcd and this allows 30t rings on power meter cranks with good sprocket spacing
              5) The look is cleaner than the VO/TA 50.4 bcd and the 94 bcd cranks are hard to set up - they want a 100 or 98 mm length square taper BB spindle to put the cranks where I want them.

              Why not?
              You can buy for $200 a square taper crankset that has 30-46 sprockets, can take anything from 26-60 sprockets (24 if you drill it yourself), and has a stated width of 147 mm which means 140 mm when I set it up my way.
              You can buy TA cranks for $400 or so and set them up more-or-less exactly the way you want.
              You can buy Lightning cranks and a 94bcd spider and set it up with standard road sprocket positions.

              Michael Wilson
            • bikealfa
              I added 2 pictures of the 30 tooth sprocket installed on a 110 bcd crank to the mwilson photo album. No I did not disassemble it and show a picture of the
              Message 6 of 9 , Dec 7, 2012
              • 0 Attachment
                I added 2 pictures of the 30 tooth sprocket installed on a 110 bcd crank to the mwilson photo album. No I did not disassemble it and show a picture of the machined part in free air.

                Michael Wilson

                --- In Geared_hub_bikes@yahoogroups.com, "bikealfa" <mtwils@...> wrote:
                >
                > I know the basic sprocket machining is easy; when I had machine shop access I used to do this sort of thing myself.
                >
                > Yes I know tooling is expensive. It is also something you will not have when you want to use the machine, so you will have to order it and wait, or have spent a lot more to have tooling you will probably never use. Several reasons why I have not yet bought a milling machine.
                >
                > Project details:
                > 2) remachine the shimano cassette sprocket holder for narrower sprocket spacing and 3 mm inset, for 12 sprockets on my TT bike
                >
                > Cassettes have inidvidual sprockets and aluminum carriers. This is remachining the aluminum carrier so it sits 3 mm further onto the wheel - fits ZIPP disk wheels - and has narrower sprocket spacing.
                >
                > 5) make the adaptors and machine the 30t chainrings that allow me to put a 30t chainring on a 110bcd crank. I have one set, I want more. This allows a 30t chainring on a Clavicula crank, and also on a 110bcd powermeter crank like a Quark or an SRM.
                >
                > No this is NOT a triplizer. This is a replacement bolt set, and a 30 t sprocket (we used a Sugino 74 bcd) remachined to fit over the steps of a 110bcd crank, and with 105 mm bcd and 4 mm countersunk bolts. The bolt set has the offset hole tapped for the 4 mm bolts, and the same shape for the large chainring as a traditional crank bolt - 10 mm base diameter and 12 mm shoulder to fit the counterbore. This also requires filing the crank arm spider so the chain can sit on the 30 sprocket correctly.
                >
                > Why the 30t on 110bcd?
                > 1) I like narrow crank spacing
                > 2) I like to put my large 46t chainring at the center of the cassette, so it works better with the large rear cassette cog.
                > 3) Superlight cranks (until the Lightning) were 110 bcd and I needed a 30-34 for Mt Washington hillclimb and did not want to change the cranks on my 13 pound road bike to something heavier
                > 4) Similarly power meter cranks are 110 bcd and this allows 30t rings on power meter cranks with good sprocket spacing
                > 5) The look is cleaner than the VO/TA 50.4 bcd and the 94 bcd cranks are hard to set up - they want a 100 or 98 mm length square taper BB spindle to put the cranks where I want them.
                >
                > Why not?
                > You can buy for $200 a square taper crankset that has 30-46 sprockets, can take anything from 26-60 sprockets (24 if you drill it yourself), and has a stated width of 147 mm which means 140 mm when I set it up my way.
                > You can buy TA cranks for $400 or so and set them up more-or-less exactly the way you want.
                > You can buy Lightning cranks and a 94bcd spider and set it up with standard road sprocket positions.
                >
                > Michael Wilson
                >
              • Alex Wetmore
                Thanks for those photos. It would be great to see one more zoomed out to show the whole crank. I don t understand how the large ring is attached to the crank
                Message 7 of 9 , Dec 7, 2012
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                  Thanks for those photos. It would be great to see one more zoomed out to show the whole crank. I don't understand how the large ring is attached to the crank (I assume via the normal 110mm bolt circle) and how the small is attached to the large ring.

                  In trade I can share this photo of an adapter that a friend designed and that I cnc'd to fit 110/74 chainrings in a double configuration to a TA Cyclotouriste crank:
                  http://www.flickr.com/photos/88336152@N00/sets/72157628992155411/

                  I made one for myself too, but haven't used it yet. I have a fairly large collection of 94mm BCD cranks that I run as doubles when I want this type of gearing.

                  alex
                  ________________________________________
                  From: Geared_hub_bikes@yahoogroups.com [Geared_hub_bikes@yahoogroups.com] on behalf of bikealfa [mtwils@...]
                  Sent: Friday, December 07, 2012 6:16 AM
                  To: Geared_hub_bikes@yahoogroups.com
                  Subject: [Geared_hub_bikes] Re: milling machine projects

                  I added 2 pictures of the 30 tooth sprocket installed on a 110 bcd crank to the mwilson photo album. No I did not disassemble it and show a picture of the machined part in free air.

                  Michael Wilson

                  --- In Geared_hub_bikes@yahoogroups.com, "bikealfa" <mtwils@...> wrote:
                  >
                  > I know the basic sprocket machining is easy; when I had machine shop access I used to do this sort of thing myself.
                  >
                  > Yes I know tooling is expensive. It is also something you will not have when you want to use the machine, so you will have to order it and wait, or have spent a lot more to have tooling you will probably never use. Several reasons why I have not yet bought a milling machine.
                  >
                  > Project details:
                  > 2) remachine the shimano cassette sprocket holder for narrower sprocket spacing and 3 mm inset, for 12 sprockets on my TT bike
                  >
                  > Cassettes have inidvidual sprockets and aluminum carriers. This is remachining the aluminum carrier so it sits 3 mm further onto the wheel - fits ZIPP disk wheels - and has narrower sprocket spacing.
                  >
                  > 5) make the adaptors and machine the 30t chainrings that allow me to put a 30t chainring on a 110bcd crank. I have one set, I want more. This allows a 30t chainring on a Clavicula crank, and also on a 110bcd powermeter crank like a Quark or an SRM.
                  >
                  > No this is NOT a triplizer. This is a replacement bolt set, and a 30 t sprocket (we used a Sugino 74 bcd) remachined to fit over the steps of a 110bcd crank, and with 105 mm bcd and 4 mm countersunk bolts. The bolt set has the offset hole tapped for the 4 mm bolts, and the same shape for the large chainring as a traditional crank bolt - 10 mm base diameter and 12 mm shoulder to fit the counterbore. This also requires filing the crank arm spider so the chain can sit on the 30 sprocket correctly.
                  >
                  > Why the 30t on 110bcd?
                  > 1) I like narrow crank spacing
                  > 2) I like to put my large 46t chainring at the center of the cassette, so it works better with the large rear cassette cog.
                  > 3) Superlight cranks (until the Lightning) were 110 bcd and I needed a 30-34 for Mt Washington hillclimb and did not want to change the cranks on my 13 pound road bike to something heavier
                  > 4) Similarly power meter cranks are 110 bcd and this allows 30t rings on power meter cranks with good sprocket spacing
                  > 5) The look is cleaner than the VO/TA 50.4 bcd and the 94 bcd cranks are hard to set up - they want a 100 or 98 mm length square taper BB spindle to put the cranks where I want them.
                  >
                  > Why not?
                  > You can buy for $200 a square taper crankset that has 30-46 sprockets, can take anything from 26-60 sprockets (24 if you drill it yourself), and has a stated width of 147 mm which means 140 mm when I set it up my way.
                  > You can buy TA cranks for $400 or so and set them up more-or-less exactly the way you want.
                  > You can buy Lightning cranks and a 94bcd spider and set it up with standard road sprocket positions.
                  >
                  > Michael Wilson
                  >




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                  I added two more pictures, one of just the adaptors and one of the outer ring. I took it apart so I could make some tools to drill out aluminum chainring bolt
                  Message 8 of 9 , Dec 8, 2012
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                    I added two more pictures, one of just the adaptors and one of the outer ring.

                    I took it apart so I could make some tools to drill out aluminum chainring bolt sets and convert a few more cranks. Unfortunately one of the bolts stripped the allen, so I cannot use the 30t sprocket as a template yet. I am loathe to point the oxyacetylene torch at it because the cranks are aluminum. The only need for disassembly is to use the sprocket as a template.

                    I did this because the Bob Jackson bottom bracket threads were not clean enough to accept the Lighning aluminum cups, so some other solution was desired - the adaptors, or the TA or VO Grand Cru cranks, or a bottom bracket rethreading tool (100 pounds from UK is the least expensive I have seen). Nothing will work this weekend though.

                    If you do a small production run of the 110/74 adaptors I would buy 1.


                    Michael Wilson

                    --- In Geared_hub_bikes@yahoogroups.com, Alex Wetmore <alex@...> wrote:
                    >
                    > Thanks for those photos. It would be great to see one more zoomed out to show the whole crank. I don't understand how the large ring is attached to the crank (I assume via the normal 110mm bolt circle) and how the small is attached to the large ring.
                    >
                    > In trade I can share this photo of an adapter that a friend designed and that I cnc'd to fit 110/74 chainrings in a double configuration to a TA Cyclotouriste crank:
                    > http://www.flickr.com/photos/88336152@N00/sets/72157628992155411/
                    >
                    > I made one for myself too, but haven't used it yet. I have a fairly large collection of 94mm BCD cranks that I run as doubles when I want this type of gearing.
                    >
                    > alex
                    > ________________________________________
                    > From: Geared_hub_bikes@yahoogroups.com [Geared_hub_bikes@yahoogroups.com] on behalf of bikealfa [mtwils@...]
                    > Sent: Friday, December 07, 2012 6:16 AM
                    > To: Geared_hub_bikes@yahoogroups.com
                    > Subject: [Geared_hub_bikes] Re: milling machine projects
                    >
                    > I added 2 pictures of the 30 tooth sprocket installed on a 110 bcd crank to the mwilson photo album. No I did not disassemble it and show a picture of the machined part in free air.
                    >
                    > Michael Wilson
                    >
                    > --- In Geared_hub_bikes@yahoogroups.com, "bikealfa" <mtwils@> wrote:
                    > >
                    > > I know the basic sprocket machining is easy; when I had machine shop access I used to do this sort of thing myself.
                    > >
                    > > Yes I know tooling is expensive. It is also something you will not have when you want to use the machine, so you will have to order it and wait, or have spent a lot more to have tooling you will probably never use. Several reasons why I have not yet bought a milling machine.
                    > >
                    > > Project details:
                    > > 2) remachine the shimano cassette sprocket holder for narrower sprocket spacing and 3 mm inset, for 12 sprockets on my TT bike
                    > >
                    > > Cassettes have inidvidual sprockets and aluminum carriers. This is remachining the aluminum carrier so it sits 3 mm further onto the wheel - fits ZIPP disk wheels - and has narrower sprocket spacing.
                    > >
                    > > 5) make the adaptors and machine the 30t chainrings that allow me to put a 30t chainring on a 110bcd crank. I have one set, I want more. This allows a 30t chainring on a Clavicula crank, and also on a 110bcd powermeter crank like a Quark or an SRM.
                    > >
                    > > No this is NOT a triplizer. This is a replacement bolt set, and a 30 t sprocket (we used a Sugino 74 bcd) remachined to fit over the steps of a 110bcd crank, and with 105 mm bcd and 4 mm countersunk bolts. The bolt set has the offset hole tapped for the 4 mm bolts, and the same shape for the large chainring as a traditional crank bolt - 10 mm base diameter and 12 mm shoulder to fit the counterbore. This also requires filing the crank arm spider so the chain can sit on the 30 sprocket correctly.
                    > >
                    > > Why the 30t on 110bcd?
                    > > 1) I like narrow crank spacing
                    > > 2) I like to put my large 46t chainring at the center of the cassette, so it works better with the large rear cassette cog.
                    > > 3) Superlight cranks (until the Lightning) were 110 bcd and I needed a 30-34 for Mt Washington hillclimb and did not want to change the cranks on my 13 pound road bike to something heavier
                    > > 4) Similarly power meter cranks are 110 bcd and this allows 30t rings on power meter cranks with good sprocket spacing
                    > > 5) The look is cleaner than the VO/TA 50.4 bcd and the 94 bcd cranks are hard to set up - they want a 100 or 98 mm length square taper BB spindle to put the cranks where I want them.
                    > >
                    > > Why not?
                    > > You can buy for $200 a square taper crankset that has 30-46 sprockets, can take anything from 26-60 sprockets (24 if you drill it yourself), and has a stated width of 147 mm which means 140 mm when I set it up my way.
                    > > You can buy TA cranks for $400 or so and set them up more-or-less exactly the way you want.
                    > > You can buy Lightning cranks and a 94bcd spider and set it up with standard road sprocket positions.
                    > >
                    > > Michael Wilson
                    > >
                    >
                    >
                    >
                    >
                    > ------------------------------------
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