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    Default geometry tooth profile Gates Polychain

    Hello

    Does anyone have or know where to get the geometry of tooth profile to make a cutter to make a pulley to fit a Gates Polychain Carbon synchronous belt that is 14 mm pitch .

    HTD profile won't work for me.

    I checked Toronto Gear in Ontario and to have an 80 tooth pulley make it is about $2000 can.

    Not saying its over priced but too much for a hobby project .

    I have a lathe and small mill so making a cutter from O1 is the plan.
    I have searched and there was a thread somewhere about a Gates engineer giving someone a drawing for a tooth profile ,,, those guys aren't suppose to do that its proprietary info,, I guess he didn't know .

    Thanks ED

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    Did you actually talk with someone from gates technical department ?

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    Making a special of anything is expensive
    . Does it have to b 80 tooth?
    *80 tooth for $425.

    80 tooth $425
    Gates 14MX-80S-20 Poly Chain GT2 Sprocket 14.036 Inch Diameter 7719-2080

    71 teeth $300
    GATES POLY CHAIN GT SPROCKET - 14M 71S 68 J -NEW | eBay

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    Take a look at patents.Google.Com, use Assignee=gates. You will see a lot of patents describing profiles in great detail.
    I made my own relieved 12 tooth cutter for T2. 5 along with the requisite Eureka Relieving device.
    The most critical dimension will be the overall diameter, a few thou is enough to screw up belt seating.

    This search will pull up what I think is the most relevant patents: Google Patents
    In their catalogue they specifically mention "tractix mathematics" as the basis for this tooth profile. Note that the belt tooth profile is not necessarily the same as the sprocket tooth profile, it certainly isn't for the T series metric tooth profiles.

    Gerrit

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    What Gerrity said.

    AFAIK, "Gilmer" is the Grand-Dad. Patents are out there because several outfits SINCE have produced an "improved" profile and they protect it. Pirelli has one of the more elegantly explained, for example.

    Does it really work better? Pass. With a shop full of ancient Gilmer goods, I can't afford to test it!

    The precision, OTOH, I DO know is for all realistic purposes every bit as demanding as any decent GEAR, PLUS a bit.

    Yes. PLUS.
    .
    Y' see.. an involute gear is only in contact at one tooth pair, "and a half" or so as it transfers the load to the next one.

    A synchronous belt, by contrast has "wrap".

    ALL of its "teeth" as happen to be in contact need to be nicely seated AND smoothly engage and dis-engage lest they wear-out MUCH too soon. Or jump. Really bad news, that can be.

    Yah cannot cheat on that with a bit of undercut, a skosh of change to shaft CL spacing, nor lapping-in a now no longer standard gear by spoon-feeding it Clover compound or such.

    Shorter answer? The shape and fits are more critical than first appears.
    So no, not cheap, If not in money, then in f**k-with TIME to "get it right".

    If, OTOH, you do not actually NEED the "synchronous" feature? PolyV or MicroV AKA "serpentine" belts with NON-synch longitudinal ribs are so forgiving they are often run without even any grooves in a former flat-belt pulley at all.

    Not that their grooves are all that hard to turn, either, rib-to-rib "pitch" widely published.

    WORKING "pitch line" is back to being a continuous diameter at give-a-damn "close enough" to the ratio sought, not a series of precise steps.

    Half-decent tensioning does the rest.

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    Yes I did contact someone from Gates and they politely said they can't provide a drawing . Have you actually talked to someone from Gates that would provide you with the info??????

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    thanks for looking I wanted aluminum a cast iron one and it weighed a ton . Its for an airboat.

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    Quote Originally Posted by ewaring View Post
    ...Its for an airboat.
    Good application. Plenty been done before you.

    Not one to cheap-out on, though.

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    thanks Gerrit ,, its starting to look like I'll go with the 70 tooth aluminum pulley I have .

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    One thing to keep in mind with these type of belt/pulleys: the tooth shape and size is the same for all diameters
    This is one way to make 4 tooth cutters, not requiring a diversion into the world of Eureka or other relieving devices: http://www.deansphotographica.com/ma...ultipoint.html

    Gerrit

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    Contact British Hovercraft as they use the same belt drive system on most of their hovercraft as well as being involved in hovercraft racing. I have dealt with them in the past and found them excellent to deal with.
    The British Hovercraft Company – British-built Hovercraft Excellence

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    Quote Originally Posted by ewaring View Post
    Yes I did contact someone from Gates and they politely said they can't provide a drawing . Have you actually talked to someone from Gates that would provide you with the info??????
    Yes, I did years ago, they sent me the tooth profile data points, our Wire EDM operator
    ran with them, making the replacement pulleys we needed.

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    Quote Originally Posted by ewaring View Post
    thanks for looking I wanted aluminum a cast iron one and it weighed a ton . Its for an airboat.
    BTW you didn't tell gates "it's for an airboat" did you ?

    Read the warning inside the front cover of any Gates catalog.

    Also, what's wrong with this ?:
    Century Drive Systems: Airboat Belted Reduction Drive Unit, Components

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    A while back I wanted to do a custom pulley for one of the less popular proprietary belt profiles. Seemed like an easy thing. Ended up being a f---ing rabbit hole and I eventually gave up and just paid way too much for a factory pulley. For future designs, I'll never again use that company.

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    Geartrax has the polychain profile - Camnetics

    You don't need to buy the software, they will sell you a single model at a reasonable price if that's all you'll need. At least they would at one time, I haven't asked recently. Round tooth belt pulleys are generated, every tooth count has a slightly different profile the same way gears of different counts have different shaped teeth, so you need a profile for an 80 tooth pulley.

    Gearotic also has round tooth belt pulley profiles, HTD for certain, I can't find whether or not they have polychain by lookiing at their site and I'm away from my shop ATM, an email might be productive. "Gearotic Motion Gear design Software"

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    Whats wrong with the century drive ????
    None fit the engine I have , I want a 80 tooth pulley , not entire drive costing major bucks and what makes you think I didn't read the front cover of Gates and last but not least this has nothing to do with the original question of tooth profile .

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    thanks good idea I sent them an email. Again thanks for the response

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    Thank you I will contact Camnetics .

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    Call Ash gear also, They might have a cutter or another solution. If they have a gear shaper cutter to rent, anyone with a big enough gear shaper can cut your pulley for you. there are several gear shop owners posting here that can help you for a lot less than what you were quoted. for example, when another shop comes to me to just cut one simple gear for a repair job, I quote a minimum charge of $150 (2hours) to cut one gear if it's a simple setup and what you are describing should be. Add the rent for the cutter and shipping both ways for the cutter and shipping for your blank and finished part and you have your pulley cost. the advantage of doing it in a gear shaper or hobber is that it's generated correctly. On the other hand lots of aftermarket Harley rear wheel pulleys are just milled with an endmill on a VMC. those are under 1.5" wide so you can get away with a small diameter/short endmill, cutting a 3' or so wide pulley that way might not work out so well.

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    Quote Originally Posted by ewaring View Post
    Whats wrong with the century drive ????
    None fit the engine I have , I want a 80 tooth pulley , not entire drive costing major bucks and what makes you think I didn't read the front cover of Gates and last but not least this has nothing to do with the original question of tooth profile .
    You told me gates said NO.....if you read the inside cover, you can see they are "lawyered up" and never mention the word "air" to them.

    As in "airplane...not even "airboat".

    No need to "go postal" on me..... Maybe you should just "go".

    Is this what you teach your shop students eh ?


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