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  • Thread Dial : Lantern Gear

    I am thinking about constructing a threading dial. The other post on this has started me thinking about several aspects of this project and the necessary gear is one of them.

    A proper match for the leadscrew is a very nonstandard worm wheel so it must be made with special tooling. Therefore $s or time. On the other hand, this gear does not carry any significant load, runs at a dead slow speed, and does not have to have a 100% uniform rotational speed as a proper involute shape would provide. It must simply stay in mesh with the lead screw and indicate it's position for engagement points. Another important consideration is that it not cause any damage to the lead screw.

    A lantern gear would be fairly easy to make. A body that is a simple turning and then drill a series of holes at the helix angle. Cut and install some short lengths or drill rod in the holes and you are done. Since the loads are really small, this should work very well.

    Am I missing something? Does anyone see any problems with this idea? Will a gear of this design harm the lead screw over time?

    Paul A.
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

  • #2
    For that matter, why not a gear made up of rounded-end pins on the circumference of a disc? Or one cut like a clock wheel? My threading dial is a homemade one with a gear made by hobbing (not very well) with a 8 pitch tap. It works OK. I have a second gear that I intended to turn down to a thin disc about 1/8" thickness just to try it. So long as it is on the midpoint of the worm, I can't see why it wouldn't work.

    Ian

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    • #3
      That will work. Another simple method is to make a gear using a coarse tap as a gear cutting hob. The main concern is to get the proper number of teeth. This is determined by the diameter of the blank, and may be helped by gashing slits in the blank to get the gear started.
      You could probably make a very simple thing that looks like a gear with a spindex and a tapered milling cutter. Angle it so it approximates the angle of the leadscrew thread. There is not a great deal of accuracy required, as you say, it is not driving anything.
      Jim H.

      Comment


      • #4
        For anyone interested in making this kind of gear (or any other) I would recommend No. 17 of the Workshop Practice Series, Gears and Gear Cutting by Ivan Law. The thread dial in the photo below is one that I made for my old Standard-Modern lathe. I used a spin index and a fly cutter on my homebuilt vertical milling machine to produce this gear. Sorry that it's not the best photo but it is the only one that I have. (sold the lathe)

        To invent, you need a good imagination - and a pile of junk. Thomas A. Edison

        Comment


        • #5
          <font face="Verdana, Arial" size="2">Originally posted by Paul Alciatore:
          I am thinking about constructing a threading dial. The other post on this has started me thinking about several aspects of this project and the necessary gear is one of them.

          A proper match for the leadscrew is a very nonstandard worm wheel so it must be made with special tooling. Therefore $s or time. On the other hand, this gear does not carry any significant load, runs at a dead slow speed, and does not have to have a 100% uniform rotational speed as a proper involute shape would provide. It must simply stay in mesh with the lead screw and indicate it's position for engagement points. Another important consideration is that it not cause any damage to the lead screw.

          A lantern gear would be fairly easy to make. A body that is a simple turning and then drill a series of holes at the helix angle. Cut and install some short lengths or drill rod in the holes and you are done. Since the loads are really small, this should work very well.

          Am I missing something? Does anyone see any problems with this idea? Will a gear of this design harm the lead screw over time?

          Paul A.
          </font>
          Paul, if you don't want to go to the trouble of drilling the pin holes at the helix angle, you could drill them straight and tilt the entire indicator to match the helix angle.

          THAT OLD GANG 'O MINE

          Comment


          • #6
            At the end of the month I'm setting my gear hobber up to do some worm wheels to fit an 8 tpi acme thread.
            If there is enough demand and the general design is similar I could do a batch of wheels to fit the most popular lathe or lathes [ South Bend & Atlas ?? ]and ship them to one person Stateside to ship to others who want them.
            If we can come up with a couple of standard sizes I can work out the rest. Just need to know leadscrew diameter [ for the helix angle ]and how many teeth, goto be 8 tpi.
            If we keep them thin enought, 1/2" ? then shipping won't be too bad UK to Stateside for a batch to one person.
            UK to Stateside for each gear would be too much.

            Anybody want to stand up for this?
            Cost will be minimal as machine time is already written off, material, brass, is likewise so it comes down to paying marginally above the shipping costs to me and internal shipping in the US to be paid to whoever stands up.

            John S.

            [This message has been edited by John Stevenson (edited 02-22-2004).]
            .

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



            Comment


            • #7
              I ship regularly, I would be willing to reship via Priority Mail. Shipping will be $4.30 in the US up to one pound, whatever anywhere else.
              Most of the smaller leadscrews are 5/8" or 3/4", with 3/4" probably most common, so one setup might be close to universal.
              Jim H.

              Comment


              • #8
                Actually thinking about this because they will be 8 tpi they will fit all 8tpi screws, only the helix angle will change.
                If we split the difference between 5/8" and 3/4" then they would still mesh well enought to suit both.
                Biggest fly in the ointment is hand.
                Do any have left hand leadscrews?
                May have to do two patterns ?

                Someone has nicked my Parcel Farce booklet off my desk so I can't state prices to the US until tomorrow, not normally too expensive for small stuff.

                John S
                .

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



                Comment


                • #9
                  To the best of my knowledge, they are all right hand. If anyone has any different information, speak now etc.
                  Jim H.

                  Comment


                  • #10
                    .........Just an FYI, the gear I bought for my new threading dial came either straight tooth or helix. Cost was the same: $42. Has a .250" hole for the shaft, is .700" wide, and .600" tall. Uh, didn't count the teeth.

                    Rick
                    Son of the silver stream ..... Bullet caster.

                    Comment


                    • #11
                      <font face="Verdana, Arial" size="2">Originally posted by Buckshot:
                      .........Just an FYI, the gear I bought for my new threading dial came either straight tooth or helix. Cost was the same: $42. Rick</font>
                      Not bad, That works out to about $1680.00 per hour

                      John S.

                      .

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



                      Comment


                      • #12
                        A while back one or the other of the mags had an article on hobbing thread dial gears with a v-thread tap. Because it is not a power gear, it works fine, and does all it needs to.

                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #13
                          Thanks to all for the many replys! I am trying to design an improved thread dial and I want it to be as easy and cheap to make as possible. All the original ones and most of the home mades are standard style gears and I wonder how some "off the wall" style gears would be recieved by others.

                          ian-g,

                          The pins and thin gears will work OK as long as the lead screw is not grooved. Mine is and I suspect many others are also. So this is not a universal solution but is good in some cases.

                          Carl,

                          Yes, I thought of that. But if I make a special jig, it will be just as easy to do the angled holes.

                          John S,

                          Sounds like a generous idea. Very nice of you to offer. But in my case, I'm not looking for a single gear but rather an easy way of making them.

                          Another thing I have thought about is making or buying one and then using molding techniques to make plastic copies. But I'm not sure how well they will hold up.

                          Paul A.
                          Paul A.

                          Make it fit.
                          You can't win and there is a penalty for trying!

                          Comment

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