Turning a precise taper on a manual lathe
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    Default Turning a precise taper on a manual lathe

    The drawing calls for a taper of 7 deg, 7 mins & 30 seconds.
    Length of taper 0.625". (in the sense of the "x" axis).
    I've calculated Y axis deflection of 0.078" with this taper over 0.625".

    I have a DRO, and taper turning attachment.
    So 0.625" in the X axis should give me 0.078" deflection on the tool post, or Y axis, when the angle is correctly set.

    It may take several "dry runs" to get the taper right, but does this make sense ?
    (I'll need to be careful any backlash is "taken-out")

    Thanks
    Bob

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    And you can get multiples of the "nearness" simply by going further - longer set up helps to" fine tune" the angle

    This set up allowed me to read directly on a large "tenth" indicator - not using T/A but compound

    Setting Lathe Compound For Tapers

    have fun

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    Excellent point, thanks.

    Follow up point, how do I measure the taper ?
    I'll be turning it "smaller diameter towards headstock".
    Seems to me if i calculate the smaller diameter, then turn a straight bore to this diameter. Once I start the taper, if I turn out all the parralell bore with the taper, that should be to size.
    That's not really measuring it though.
    How would I measure the taper, please ?
    Bob

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    Quote Originally Posted by Overland View Post
    Excellent point, thanks.
    Checked out your link - I forgot to halve the angle !!
    Two good reasons to seek input.
    Thanks.

    Follow up point, how do I measure the taper ?
    I'll be turning it "smaller diameter towards headstock".
    Seems to me if i calculate the smaller diameter, then turn a straight bore to this diameter. Once I start the taper, if I turn out all the parralell bore with the taper, that should be to size.
    That's not really measuring it though.
    How would I measure the taper, please ?
    Bob
    This is down in a bore, similar to an A-series or D1 series mount?

    Critical need?

    Make yourself a gage ... out in the open air - first. Get the ANGLE right off an UNDERSIZED bore. Then carry it outward. Don't expect to nail it, first-go with no material left for recovery.

    Fine work, use the diff between two precision edges, 1.2.3 blocks, gage block stack, uber-good DI... wotever your bestest goods that you actually HAVE, not just WISH you had.. can give you.

    Practice - out in a less restrictive area - can verify the setup.

    Extra care is usually cheaper than failure.

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    I forgot to halve the angle !!
    The 7.125 degrees (or 7 deg, 7 mins & 30 seconds) is half the included angle - for 3.0" taper per foot on dia - such as the D type spindle nose

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    Don’t know about your taper turning attachment for a precise “7 deg, 7 mins & 30 seconds” but Tubalcain’s vid on using a lightweight sine bar w blocks and magnets against the compound might be helpful to get it closer than the attachment?

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    Thanks Thermite,
    Not sure I fully understand your points.
    Yes, a chuck taper, about 5" OD, for scale.
    I could set up the taper turn attachment as discussed above.
    Then turn a plug gauge using a second chuck as a reference. Maybe so the gauge fits in to be flush with chuck, using dial gauge or straight edge.
    Then turn out taper, carefully, until gauge fits flush.
    Am I understanding ?
    Bob

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    I've set tapers on the taper attachment by using a sine bar. A couple #8 tapped in the side of the T/A lets me mount a small aluminum shelf to hold the sine bar. With the right gauge blocks under one end of the sine bar and the mag base on the bed of the lathe, I just run the carriage back and forth and adjust the taper to zero runout on the indicator.

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    Just doing some more reading....
    Read one article that said on D1 mounts, the taper and face must both touch.
    I'm thinking that requires an absolute size, with "0" tolerance.
    Surely this can't be correct.
    Should there be a small clearance on the face when the taper is snug ?
    What should this clearance be ?
    Thanks
    Bob

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    If the best you can do makes a clearance dimension, it should be the diameter, not the face. The face is the larger mounting diameter, therefore it will give you more rigidity. Yes, there is a slight tolerance on the diameter, from a very very slight to a slight press fit in the taper. The cam pins will pull it home.

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    Quote Originally Posted by Overland View Post
    Thanks Thermite,
    Not sure I fully understand your points.
    Yes, a chuck taper, about 5" OD, for scale.
    I could set up the taper turn attachment as discussed above.
    Then turn a plug gauge using a second chuck as a reference. Maybe so the gauge fits in to be flush with chuck, using dial gauge or straight edge.
    Then turn out taper, carefully, until gauge fits flush.
    Am I understanding ?
    Bob
    The number in D1-"n" is the diameter in inches of the mounting taper, so I presume D1-5"?

    For A series, D1 series, (identical geometry, just different attach fasteners), or the squirrelier by far Cazeneuve proprietary (TWO fastener schemes, same weird taper)?

    No, not exactly, you are not.

    The reference/safety flat isn't meant to touch at all. Not even under the tension of the draw-up fasteners at their full engagement.

    So checking without pull-up force applied is only a guess, wants over a thou of air-gap. How MUCH over a thou depends on the materials and the plate "beef".

    The key to all of those is that they are drawn-up interference fits. The mating parts are required to distort within their elastic limit.

    For the A & D1, the flat is meant to NOT QUITE come to bear.

    If it DOES fully bear, the taper wedging action is worn, no longer a tight enough interference, and needs re-cut (better-yet, re-ground - it is just that touchy).

    This isn't TOO hard to assess, as the flat is at the rear and can be accessed.

    The Cazeneuve, OTOH, may be either wedged up the cone off the draw-in force of a trio of thick conical tipped fasteners arranged radially in a thick overlapping rim, ELSE drawn-up by four A-style face bolts arranged longitudinally. One may pick either one, but never use both on the same installation.

    Sort of a 4-way crossbreed between and among a D1 with clamping force @ 90 degrees, a facebolted A series, genius-level patent holder Henri Rene Bruet's usual clever economy..... and the Devil.

    "The Devil" because the taper is longer and shallower, must move FURTHER for full (but stronger) engagement, and the indicator/safety flat that insures the mount is where it is meant to be, engagement-wise, and cannot be tipped by assymetrical force or a crash, is not at the top.

    Mssr Bruet put it down-bore at the closed end where it is the very Devil to assess!



    PM has several threads on the D1 geometry.

    Making sure the "interference fit" taper draw-up works according to plan is crucial.

    As I only have the smaller of the D1 sizes, (3 and 4) buying backplates at $55 (CI) to $125 (forged steel) and checking them carefully for fit is far less costly in time as well as money than trying to DIY my own. Same again with camlock studs. Mac-it for the stronger US threads, Shars for the weaker metric threads.

    I also import my Cazeneuve's backplates. From France.
    They get a stiff price for them. VERY!

    But they have the CNC coded and the QC & QA gauging, so they fit perfectly, too.

    You can DO this. Others have.

    But a trivial exercise it was never. Especially not when backplates are so cheap and so consistently accurately made.

    First, one has to understand what it is meant to do.

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    Thanks Thermite.
    I found this from a few years back.

    I could make a gauge off a spare chuck and use that to turn the taper.
    Some very precise work required.
    I did my apprenticeship back in the early seventies, then got "promoted". Spent my career in the Supply Chain and Application Engineering in the tire industry. Now I'm retired I'm building up a shop for interest, doing repair work and one-offs.
    So much to learn, but it's fun !

    D1 Camlock Taper - Dual Contact?

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    Quote Originally Posted by Overland View Post
    The drawing calls for a taper of 7 deg, 7 mins & 30 seconds.
    Length of taper 0.625". (in the sense of the "x" axis).
    I've calculated Y axis deflection of 0.078" with this taper over 0.625".

    I have a DRO, and taper turning attachment.
    So 0.625" in the X axis should give me 0.078" deflection on the tool post, or Y axis, when the angle is correctly set.

    It may take several "dry runs" to get the taper right, but does this make sense ?
    (I'll need to be careful any backlash is "taken-out")

    Thanks
    Bob
    I'm not sure if someone here is pulling someone's leg here ;-) or not ?


    Ok.

    My math can sometimes get a bit 'Wobbly" but there's no stated accuracy or precision or tolerance band or + this or - that.

    ________________________


    As a kid I was sent to school where by the age of nine you had to be able to tell military-time and was taught 'math" by a retired RAF Major - "Major Gick's" and his "bendy friend" in the closet if we didn't behave - said "Bendy friend" being a small thin cane that would be revealed from time to time for the express purpose of being shown the instrument with which one would be beaten with if one did not behave. ~ This was at a time when teachers could still smoke in the classroom, cigarettes or pipe either or and there was no actual limit on how much or how loud you could scream at a child (regardless of age). But honestly no-one ever f*cked around and the "Bendy friend" was never used. Pure fear of the imagined consequences seemed to suffice ... But he had incredibly detailed models of steam engines (that he built himself) and displayed in the classroom in a glass case as well as amazing origami-like models of super complex three dimensional shapes hanging from the ceiling ~ which may explain how or why I got into 3d computer graphics and VR systems. + things engineering related / "Machining" related.

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    7 degrees , 7 mins, 30 arc seconds ---> 7° 7' 30"

    7 degrees ---> 7.0000 degrees.

    7 arc minutes ---> [60 mins in a degree of arc ∴ 7/60 = 0.11666666 or 0.1166(reoccurring)*

    30 arc seconds ---> [3600 arc seconds in a degree of arc or 60 seconds in an arc minute ] ∴ 30/3600 = 0.008333333 or

    0.0083(reoccurring)*


    so,


    0.16666667(rounded up for calculator people) + 0.0083333 = 0.125 (when taking into account recursion ).

    0.125 is an 1/8th of a degree.

    So the taper being asked for here is.

    7.125 degrees,

    7.125°

    or 7 and one 1/8th of a degree.


    Still wondering about included and non included angles etc. so is it really 14.25° (full included angle) ? 1/2 angle 7.125° - which rings a bell.

    Will re-read thread and re-check "Math".

    Depending on type of taper attachment - taper per foot ?

    Maybe using log tables or your tan function (in deg mode not "rad" mode) on your calculator, or "Machinery's Handbook"

    That's

    1.5" over a foot.

    1.5" over 12".



    1.5 inches over a foot,

    one and half inches over a foot just so inches and arc seconds do not get mixed up.

    1.5000 inches per foot (for example) is not a reliable indication of the actual tolerances required. Actual tolerances are required or even statements of "tapericity " - but in this case sounds like 1 1/2" over a foot taper = 7 degrees, 7 arc minutes , "And" 30 arc seconds.

    1.5" over a foot (taper) = 7°, 7', 30" (exactly).

    (I haven't checked to see where or IF any divergence occurs at a much higher number of decimal places (obviously not really practical or actionable to 25 decimal places anyway or achievable in a practical fashion especially in this context of tools used. but hey... whatever. ).


    1 arc second is 1 degree divided by 3600 = 0.00027°(reoccurring).

    The intent of 30 arc seconds (in the context of ( 7° 7' 30") is unknown or unknowable as an indicator of precision in this case with the information thus far provided.



    Maybe @DrCielo is right... Machinists CAD Tool - Looking for ideas


    __________________________________________________ _______________________________________________


    * For some reason I can't use any of the superscript notations for reoccurring decimals on this site / forum ?

    Repeating decimal - Wikipedia

    ^^^ Such as these ... to use "R" or brackets would be confusing - (sorry !)
    Last edited by cameraman; 09-14-2021 at 12:19 AM.

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    Camerman,
    Thanks for your input.
    I used Exel (Excell or whatever)

    It likes radians, so
    7 deg = 0.122173
    7 min = 0.002036
    30 sec = 0.000145
    Total = 0.124355
    Work the trig from there using Excel imbedded functions, I got:
    0.625" in X axis gives 0.078125" in Y.

    By the way, that's half included angle, as pointed out earlier.
    I think I'm correct... but when I try to make the gauge I guess I'll find out.

    But the really interesting part is the accuracy required, and understanding of the principles, to make this work. A very interesting challenge for an old guy on an old lathe...
    Bob

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    Quote Originally Posted by Overland View Post
    Thanks Thermite.
    I found this from a few years back.

    I could make a gauge off a spare chuck and use that to turn the taper.
    Far better to use a new and virgin backplate than a(ny)chuck as had seen use.

    And you can just use your own SPINDLE, too.

    The lovely thing ABOUT a D1 is that you can be turning a female D1 in a 4-J. Dismount it, turn it 180. Try the fit on the spindle. Mount it back to that spindle, same camlock stud in same numbered hole, and have essentially zero error. Try that first. If it isn't so, your existing D1 is worn or damaged.

    Brand-new backplates are dirt-cheap, and will have no wear or damage. When I take-in a new one or a decent-looking used one, it gets test-fitted at once. New studs if need be. I stash spares as those DO wear. Sometimes very badly.

    The female taper, surprisingly doesn't seem to wear much at all. The spindle may - it has to mount ALL the nose-art, not just work now and then as a magnetic chuck that loafs for years might. Even then, the male spindle taper is more likely to get a ding - easily stoned away - than suffer overall wear.

    Only then are the backplates put aside to await the next "bargain" on a new/NOS flat-back chuck, collet gadget, or wotever turns-up...

    I have the two 10EE spindles IN each of the two 10EE lathes, third spindle loose as a spare, so there be my "plug" gage side, even were I to have one of those in-use.

    As cheap as D1 mounts are, there is NFW I'd divert to DIY.

    FAR too many other things not getting done that I have NO easy way to "just buy".

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    Quote Originally Posted by Overland View Post
    Camerman,
    Thanks for your input.
    I used Exel (Excell or whatever)

    It likes radians, so
    7 deg = 0.122173
    7 min = 0.002036
    30 sec = 0.000145
    Total = 0.124355
    Work the trig from there using Excel imbedded functions, I got:
    0.625" in X axis gives 0.078125" in Y.

    By the way, that's half included angle, as pointed out earlier.
    I think I'm correct... but when I try to make the gauge I guess I'll find out.

    But the really interesting part is the accuracy required, and understanding of the principles, to make this work. A very interesting challenge for an old guy on an old lathe...
    Bob
    You didn't read the rest of what I wrote, (as I was still "adding" stuff).

    That's 1.5" over a foot.
    "taper"


    - it's OK to set your "computational device" to degrees and use the tan function on a calculator. Slide rule would work, log tables, machinery's handbook, those little tables and books that machinists carry around or have stuffed into their tool boxes variously. There's a scientific calculator on your i-phone and android phone. if you turn the calculator on your i-phone sideways it turns into a scientific calculator. Not as fancy as a Texas instruments graphing calculator but with pencil/pen & paper you can get pretty far

    @Overland you're funny

    That should be compatible with some of the most ancient taper attachments on the planet, no fine mic adjustments or straining eyes to figure out Vernier scales.

    Taper and tracer attachments can do some incredible things.

    Unfortunately I'm packing stuff up so all my old books on older taper standards and methods where-in are in said boxes + a bunch of much older "Machinist theory" books that go back to the early 1960s, 1950s and 1930s.

    Good luck

    Where's @littlerob1 when you need him ?

    If I say littlerob1 backwards three times in a mirror - " 1borelttil, 1borelttil ..." does that work ? Does he appear ? Bettlejuice, bettlejuice

    Bye

    __________________________________________________ ___________________________________

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    Beetlejuice | Even More Top Beetlejuice Scenes | Warner Bros. Entertainment - YouTube


    ____

    Again: Turn your i-phone calculator that comes with the phone - sideways. Don't worry about the fact that the "calculator" is running on what is essentially a 'Super computer" literally in your pocket. ~ and by "Magic" a pretty powerful and numerically rigorous scientific calculator "Appears" .

    maybe I got my math wrong and you could double check it.




    ^^^ Tech Jungle - shows what to press to go into scientific calculator mode from normal calculator mode. so "Tan" function and 2nd for inverse Tan (depending on calculator) . Good argument for clean on line advertising free standard "calculating" interface. - Perhaps like what @drcielo maybe thinking about. Aimed at machinists but also explains how to do these calculations by hand if one wants or needs a deeper dive.

    Mainly thinking for education purposes for kids that's can't afford Excel etc. I'm thinking a kid in a local library or community center that's trying to learn this stuff or figure this stuff out and maybe does not have access to a computer at home.(for many reasons)

    Not every kid has a "smart" phone or a computer or 'Excel" .
    Last edited by cameraman; 09-14-2021 at 12:15 AM.

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    Web 2.0 scientific calculator

    Ohhh look an online scientific calculator ^^^ (except it's jamm packed full of distracting advertising all around the edges ... how distracting especially if one is ADD (like me) ) - reminds me of another wedbsite / message board can't quite place it... Ahhh it will come back to me

    @drcielo lol...

    Free Online Math Calculator and Converter

    ^^^ you can get into a lot of trouble here ... I don't think their 'taper" calculator was made by or for machinists (cough cough).

    I dunno man I'm wondering where the sticks / monkey / banana guy is ?

    Later,

    Peace

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    Thermite,
    All this started when I was thinking about converting a solid casting L1 chuck to D1-8.
    I've not seen an adapter available, and not sure if I could convert one, to screw onto the existing thread.
    Just "chasing this rabbit" a little. No decisions made yet.
    Thanks, to all, for input.
    Bob

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    Although the taper has a short lenght I would set the tool death center
    Also if you use a indicator on a taper
    The bore will be convex otherwise

    Peter

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    Quote Originally Posted by Overland View Post
    Thermite,
    All this started when I was thinking about converting a solid casting L1 chuck to D1-8.
    I've not seen an adapter available, and not sure if I could convert one, to screw onto the existing thread.
    Just "chasing this rabbit" a little. No decisions made yet.
    Thanks, to all, for input.
    Bob
    That isn't how you do it. If even you do it at all.

    What you do is machine the L-Series chuck to a flat-back, first. You have the L-series retention system to get out of the way. You can ignore the L series female taper & keyway.

    Once you have a flat back with some form of registration, such as a shallow cavity, a shallow boss, ELSE ability to pick-up on the remains of the L series female taper dead-nuts accurately?

    Then you machine a store-bought D1 backplate that already fits your spindle to fit the newly created flat-back register.

    That way, you get to choose where you bolt the backplate, and whether through-bolted from the front.. or blind bolted from the back.

    I'd suggest from the back, and with a higher count of modest fasteners rather that just a few larger ones.

    Then again, I wouldn't do it at all if the L-series mount is not trashed.

    L is a damned good system, actually. I'd trade it, as-is, for:

    - a flat back,

    - a D1 that already fits.

    - ELSE for an easier to modify A series mount, also one that already fits a D1 and needs only the camlock studs added.

    Size for size, A & D1 use the identical American Standard short taper for their interference-fit taper and flat, just different retention means;

    - face-bolt for "production" spindles, CNC and powered-closer these days, mostly, that will "usually" wear the same workholding system for years on-end until it needs a rebuild.

    - camlock for R&D, toolroom, or job shop where change is frequent.

    L series is actually faster to swap than any D1- even the original Pratt & Whitney TWO pin version.

    By the time you hit a six-stud D1, change is rather slow!



    PS: Is it possible to fab a D1 plate that carries an L-series taper, key, and spanner-operated retention collar?

    Yes. Just stack and dowel-pin and/or TiG a thickener plate to a stock D1 to get the depth you need for the L series snout.

    It could even be easier to do than to try to convert an integral-back L series to an integral back D1. Once fabbed, it could mount ANY same-size L-series, too.

    Even so.. that does not make it as good an idea as a flat-back spigot that is as strong as it needs to be with but 50 thou - or even less - of interlocking depth, pressed or thermally shrink together, then bolted.

    Y'see.. what REALLY puts all this adaptor shite on the back burner is dirt-simple.


    More than one chuck exists in the world. A LOT more!


    Just that basic.



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