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Poly-V Vs Micro-V belts

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  • Poly-V Vs Micro-V belts

    Is it true that both of these types of belts are the same profile, and the "Poly-V" and Micro-V" are just trademark names from different manufacturers?
    Is that correct?

    I am thinking of making a couple of pulleys using these belts. Micro-V are what the local NAPA parts store has so availability is easy. I see some profiles on line for Poly-V and just want to verify they are the essentially same thing.

    I know I can buy pulleys, making them is more fun.

  • #2
    I think they are called J profile belts, but there could be variances.

    -D
    DZER

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    • #3
      Yes, those are just trade names for the same items, take care... many profiles. Most Vehicle belts (Napa) are are K and L section. I use J for machine tools - easier to wrap the required amount on smaller pulleys, and 5 to 10 width can handle the required torque and hp.

      Napa may be local but there are literally hundreds of online suppliers, and almost any local bearing / transmission house will stock or have access to them.
      Last edited by lakeside53; 08-29-2020, 01:23 PM.

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      • #4
        I set up a feed screw on my lathe using 3/4-10 threaded rod. One turn of the wheel moves the carriage 100 thou, so the right spacing for the belt I used. I could have done that also by putting the compound parallel to the bed and using its dial, but this was a simple accessory to make and quite useful for moving the carriage a precise amount. Good for making the series of grooves for these belts.
        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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        • #5
          I think the cross section/ angle/ spacing is specific to each section (J, K, L etc) so double check before hand. I ground a HSS bit to the right profile and depth for a J section, so cutting the pulleys is pretty straight forward, especially if you have a DRO on your lathe.

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          • #6
            Thanks, that's what I guessed but wanted to confirm. The random 6 groove ones I looked at was a K section from what I saw.

            I know these are easily available on line and there are several places around here that deal in bearings & drives type stuff. I only default to the NAPA place when that works because I can walk there in under 10 minutes and the guy who owns the place is a long time friend. So if I'm spending money anyhow, may as well spend it with someone I know.

            I know how long the belt needs to be and I have a large amount of adjustment available. I'll probably just buy a belt and sort out the groove profile from there.

            Thanks guys, for taking the time to reply,

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            • #7
              One turn of the wheel moves the carriage 100 thou, so the right spacing for the belt
              I think the spec I read was more like 0.0925 pitch, but these things a flexible enough that it probably doesn't usually matter. In an ancient post by Sir John he said he used a piece of a 11-1/2 TPI pipe die to cut the pulley grooves (which is off in the other direction) and it worked fine in heavy use.
              "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

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              • #8
                The J profile pulley is .092 +-.001 lead. The K profile is .140 +- .002 lead. The H, J, K, L, M all have a 40 degree (+-.25 degree) groove angle. I have made many of the K profile pulleys.

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                • #9
                  Originally posted by Ridgerunner View Post
                  The J profile pulley is .092 +-.001 lead. The K profile is .140 +- .002 lead. The H, J, K, L, M all have a 40 degree (+-.25 degree) groove angle. I have made many of the K profile pulleys.
                  Thank you sir!, That is pretty much everything I need right there.
                  Much appreciated. Great looking parts there, nice work.
                  Thanks again.

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                  • #10
                    Thought I could add something. To get the depth of the poly vee grooves, instead of using wires or formulas, what I do is go in part way with a 40 degree tool. Move over the lead, and start to make the next groove. Doing this slowly going back and forth until I get a crest that is good, or good to touch with a file and/or Scotchbrite. On a DRO this now gives me the depth to make the rest of the grooves. Just move over the lead and make the next groove to this depth. Oh, using the cross slide to make these grooves takes a lot of lube etc because the grooves have a good bit of surface area in the cut.
                    Making a pulley with a shoulder and using insert tools, it is important to get right and left tools set to the same X and Z and height dimensions. Depending on where the grooves start, it takes a right or left tool to do the last groove. Otherwise the tool would hit the shoulder. If the tool set ups don't match the last groove or grooves will be wrong using a DRO. See the second picture of a commercial pulley wear pattern.

                    Picture of different hand insert tools and a multi groove tool. Need lots of HP to run the multi groove.

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                    Commercial pulley showing wear.

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                    • #11
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                      here are my efforts. Slightly screwed up one of the pulleys (spacing was off on a couple of grooves) but it doesn't seem to affect anything. LOTS of grip though, no more issues with the belt slipping and breaking the tip off my inserts. Took me several years to finish this project and Stepside's help with the delrin back gear, but it was worth the wait.

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                      • #12
                        Thanks to both of you guys, all good information and nice looking tools and parts there.

                        Did you make that mulit-groove tool or is that a commercial insert of some sort? I doubt my lathe has the oomph to use one of those anyhow, I'll end up just grinding tools as necessary. Probably only end up making a couple of these style pulleys anyhow and mostly just for the excercise of doing so.

                        Again, thank you for taking the time to reply.

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                        • #13
                          I have made many; just carefully ground a single point tool from HSS. Used my old optical comparator to get everything "just right". Dial indicator to step across to the next groove. Worked perfectly

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                          • #14
                            Originally posted by alanganes View Post
                            Thanks to both of you guys, all good information and nice looking tools and parts there.

                            Did you make that mulit-groove tool or is that a commercial insert of some sort? I doubt my lathe has the oomph to use one of those anyhow, I'll end up just grinding tools as necessary. Probably only end up making a couple of these style pulleys anyhow and mostly just for the excercise of doing so.

                            Again, thank you for taking the time to reply.
                            I'm afraid making a multi-groove tool like that is way beyond my capabilities. I had a company called Tool-Flo make them for me. I think they were from Houston, Texas. I had to do a minimum order with them which was expensive and more than what I wanted. If I remember, I had to buy the insert tool holder special too. The inserts were made for steel and I used them on aluminum. I had a good bit of chatter so there was a learning curve with them that I never did get quite right.

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