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Really basic taper attachment question...

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  • Really basic taper attachment question...

    I don't have one, but I want one... It was not offered with my lathe so I'll have to make one. I know close to nothing about them.

    To move the crosslide, does the feed screw get disconnected or does the taper attachment force rotation of the screw? or....

    Any example of home built attachments (not tailstock)?

  • #2
    Some types of TA's use the method of disconnecting the lead screw. Many South Bends do this. It is the cheapest way to make one. There is a slot in the casting that does you coarse adjustment and use the compound to do the fine.

    Others use a telescoping cross slide lead screw. The screw is two pieces but locked together with a spline or keyway. The back end of the screw is attached to the plate from the TA with thrust bearings. This allows you to adjust infeed with the cross slide.

    But it comes down to want or need. Do you want one or do you need one. I have one on my 10EE and have yet to use it.

    A very good start for a taper attachment would be a linear slide like THK, NSK, and others make. You could make a real long one for cheap. but the longer you make it the less angle you can get out of it without it hanging further off the saddle.

    bad thing about taper attachments is they are really limited to how steep a taper they can be cut. There is a variator attacment that was invented and made by Monarch that allowed a much larger range of taper from a standard TA.


    • #3
      That sure is nice work!

      Need? Want? I never like to dwell too long on the difference

      Current projects... I'd like to be able to cut (then grind with a TP grinder) tapers of say 3 inches per foot (B&S spindles) or steeper (flywheel and crank tapers for small engines). The usual MT pop up now and then. These are all relatively short. I also need to thread on tapers.

      Setting the tali stock over is limited on my lathe and incurs the time penalty of getting it back on center after use, or worse if I forget.

      Use the compound? Sure... but I always seem to run out of travel and I'd not sure about threading on tapers with a compound...

      This is about the time in my deliberations where my friend tells me (again) to just get a Hass TL-1 lathe... lol .. yes, he's right but...


      • #4
        Lakeside -

        There was a great series of articles about adding a taper attachment to a Sheldon lathe in HSM back in about 1982-1983, as I recall. If you can locate copies of these magazines, it will probably help your design. They cover all the "fitting" necessary to get the TA to operate correctly.



        • #5
          I made one for the 12" A/C a few years ago. Works great but if I had time to do it over, I'd actually make the taper swing a little smaller.


          • #6

            Here's a simple taper attachment that is easy to make. It uses a taut wire wrapped around a specified wheel which is attached to the cross-slide lead screw. The wire is attached to the lathe bed by means of two stand-offs. This, of course, works for inside, outside, long, or short taper turning.

            Plans for this taper attachment were published by the Home shop Machinist:

            Title: An Accurate Taper Attachment for Under $5.00.
            Author: J.O. Barbour, Jr.
            Issue: March-April 1986 Page 20

            How it works: A wheel is machined to an exact diameter needed for a certain taper. This wheel is attached to the cross slide lead screw. Then a taut wire is wrapped once around this wheel and fastened parallel to the lathe bed by stand-offs (see photo below).

            When the carriage moves it will automatically turn the cross slide in proportion to the machined wheel...thereby giving the correct taper. The wire doesn't have to be very strong since most of the stresses are on the cross slide lead screw or carriage. The main thing is that the wire wrapped around the wheel must not slip...which one wrap should accomplish when wire is drawn taut.

            I think this works great, especially for tapers that need to be made over and over again. Set up time would only involve the time necessary to attach the wheel and pull the wire taut.

            All parts don't need to be made with any particular accuracy with the exception of the wheel. This wheel needs to machined very accurately (minus one wire diameter less than calculated diameter). This is very easily accomplished using the lathe and micrometer. Of course, the stand-offs need to be strong - but that's not a problem!

            Here's an example: Lets say a 1/8" taper per foot is desired and the wire being used is 0.020" music wire. Since the taper is being cut on both sides, the cross slide only needs go 1/16" per foot of carriage travel. If the lathe has a 10 TPI lead screw then the wheel needs to turn 62.5 percent of a revolution in 12". This means that the circumference needs to be 0.625 X 12 = 7.500" then divide by pi to get a diameter of 2.387". So the final diameter of the wheel will need to be 2.387 - 0.020 = 2.367".

            As one can see, this is very handy as it doesn't depend on the length of material the taper is to be cut on, as it would be on a tailstock offset, just the taper per foot.

            One additional note:

            For the wire "clamp" on the stand-offs (which is not part of the article) a small drill chuck was used. This chuck sells for about $8.00 and can be obtained at most hardware stores. The chuck comes threaded for a standard size and the bolt used is threaded for about three inches. Flats were also machined on each side of the bolt so one can use a wrench to hold the chuck from turning when tightening the wire. In addition, the bolt has a small hole drilled thru its entire length for excess wire to pass. This setup works great to achieve the proper tautness of the wire so it will not slip on the precision machined wheel.

            Last edited by Mike Burdick; 05-20-2009, 01:50 AM.


            • #7
              That's a neat approach! it would be possble to make an extended lead screw and put that stuff on the back side of the cross slide. Might even be possible to make a set of pulleys that correspond to "standard" tapers.


              • #8
                Originally posted by lakeside53
                That's a neat approach! it would be possible to make an extended lead screw and put that stuff on the back side of the cross slide. Might even be possible to make a set of pulleys that correspond to "standard" tapers.
                That's a good idea to extend the lead screw so the discs can be on the back! I have this attachment made for a South Bend 9-inch so that wasn't a possibility. As for a set of discs for standard tapers? That's exactly what I did!


                • #9
                  Wait..... if I did the math correctly, with a 10tpi screw and a 3 inch taper per foot, I'd need a 57 inch (roughly) wheel? Looks like steep tapers are out with this design... A 10 inch wheel is all I can turn so that's a little more than a 1/2 inch per foot. Still interesting though.
                  Last edited by lakeside53; 05-20-2009, 01:57 AM.


                  • #10
                    Originally posted by lakeside53
                    Wait..... if I did the math correctly, with a 10tpi screw and a 3 inch taper per foot, I'd need a 57 inch (roughly) wheel?...
                    No! For a 3-inch per foot taper you'll need to remove 1.5-inches per side. On a 10 tpi cross-feed leadscrew you'll need to have 15 revolutions of cross-feed travel for every 12 inches of carriage travel. Therefore 12 in/15 rev equals 0.800 in/rev (meaning for every 0.8 inches of carriage travel there will be 1 revolution of the cross-feed leadscrew). Now divide by PI and the diameter of the disc will need to be 0.2546 - wire diameter.
                    Last edited by Mike Burdick; 05-20-2009, 03:23 AM.


                    • #11
                      LOLOL and math was (a very long time ago) my strong suite... My numbers were right, but not my "formula".

                      O.K., it was late, and I'd had a few

                      I can now see that the steep pitches would present more issues with wire coiling around a small pulley. I wonder if some of the no-stretch kevlar might not be the ticket. hmmm... need to play. It also occurs to me that the easiest way to extend my lead screw to the back is just to cut a slot in the end of the screw, and use a smaller coupling rod with a male flat to match.
                      Last edited by lakeside53; 05-20-2009, 10:46 AM.


                      • #12

                        My discs are made with a hub that has a brass tipped setscrew in it. That way, once I get my wire taut I can release the disc from the cross-feed leadscrew and move the cross-feed table in so I can set the depth of cut per pass and/or the final dimension of the part.


                        • #13
                          I know that I am resurrecting a very old thread but why start a new thread to discuss the same subject.
                          I will need to taper the axle half shafts on my 1966 MG Midget in the near future when I rebuild the rear axle. The tapers are not critical in their dimensions like a morse taper. Just need a nice smooth taper. And I don't have a taper attachment. Searched for DIY taper attachments and came across this thread. Everything made sense except calculating the diameter of the wheel. My Craftsman 12x36 has a 10 tpi lead screw on the cross slide. Also the back of the cross slide is open. I bought a coupler nut from McMaster Carr and will use it to attach a shaft to the lead screw. Everything will be on the back side of the lathe.
                          Back to the calculations for the diameter of the lead screw. Here are my thoughts.

                          10 tpi makes 10 revolutions for every inch of travel. 1 revolution equals .1" of travel. 1/16" of travel equals .0625" or 62.5% of one revolution. 1/8" of travel equals .125" or 125% of one revolution. If the circumference of the wheel is 12 inches (3.82" diameter) the wheel would make one complete revolution for every 12 inches of carriage travel and the cross slide would move .1" If the movement of the cross slide is less than .1" then the wheel needs to be bigger than 12 inches in circumference and if the movement is greater than .1 inches the circumference of the wheel needs to be smaller than 12 inches. For 1/16" movement per foot 12" would have to be equal to 62.5% of one revolution. 12/.625 equals 19.2" circumference and a 6.112 diameter wheel. For 1/8" movement per foot 12" would have to be equal to 125% of one revolution 12/1.25 equals 9.6" circumference and a 3.056 diameter. I posted this on another forum and one of the members there came up with same numbers as I did using higher mathematics.
                          This is radically different from what Mike calculated. Where did we go wrong?


                          • #14
                            Smart & Brown lathes have a cross slide quick disconnect system used before the taper turning attachment is connected. The taper turning attachment can only manage + - 10 degrees. It is important to have the tool tip exactly on the centreline for both internal and external tapers.
                            I have only tried it once using a 12" length bar and trigonometry for accuracy and the R8 taper test piece fitted the mill so well that only a gentle push left it hanging from the quill.