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  1. #1
    bobnolathe is offline Plastic
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    Default cutting tapers with a lathe

    This is another item about cutting tapers on the lathe. (taper 002.jpg(65.8KB) ATT 00003.htm(477bytes)) It is different in having a couple of ideas that I had not seen before. This set-up can be removed from the lathe and replaced without changing the settings,it does not require changing tailstock settings, only one measurment is required, and it works.

    When the tailstock is set over to cut a taper the center of the work rotates around the lathe center point, digging a circle out of the countersink hole and the edges of the work ride on the sides of the point, often damaging it. In place of a 60 degree center use a single ball from a ball bearing set. Make a socket for the ball in the tailstock holder by drilling a countersink and then opening this with a ball nose milling cutter. This forms a hemispheric pocket with a small dimple in its base that help hold lubricant. Place the ball in this socket. The ball should be the same size or smaller than the socket. Small diameter turnings work best with a smaller ball. The work at the headstock can be held by a 60 degree point as there is no rotary movement, only angular displacement. If the work has a large a ball joint may be used here also. The ball holder for the tailstock is bored into an insert fitted into boring head . (taper001.jpg(61.3KB) ATT00003.htm (477bytes)) Or a tool holder can be made with a dovetail slide that adjust by a threaded shaft. Both methods provide sensitive adjustment and can be removed and replaced without changing settings. Duplicating a taper from an existing part is done by mounting the pattern between center s as the work to will be held when the taper is cut. Using a dial indicator adjust the left side of the pattern taper to be parallel with the lathe bed. The pattern needs to be reversed, end for end, from the direction the taper is be cut, (taper004.jpg(59,3KB) Att00035.htm477 bytes)). Cutting is done by traversing the apron, not be moving the compound. Making a taper to specs rather than a pattern requires knowing the amount of set-over and lenght of the taper. Note that making duplicate parts, using the same settings, will only work if the parts are all the same length This system allows lathe speeds high enough to make carbide inserts happy and give a nice finish. (Taper0005.jpg(63.7KB ATT0043.htm(477bytes))

  2. #2
    4GSR's Avatar
    4GSR is offline Titanium
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    Where's your pictures?

  3. #3
    johnoder's Avatar
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    Maybe he needs some help with making live links that you can actually open. See brown text here:

    Images and Links

    John Oder

  4. #4
    L Vanice is online now Diamond
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    This idea, including the ball center, has been covered here before. It is possible to find it with a search. Among other replies, you will see a picture of my English-made Royal taper attachment, which is the Rolls Royce version of the idea.

    Amazing price on tailstock accessory?

    lathe TS adjustment for machining a taper

    Larry
    Last edited by L Vanice; 10-13-2008 at 04:32 PM.

  5. #5
    Carl Darnell is offline Titanium
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    As best I can tell it's been done since the early 1900's, like WW1 or before. Most the time a ball is used on both ends.

    What your trying to do with the ball is get a solid fit so the work don't move around. The old machinists that told me about it didn't use a round pocket in the headstock or tailstock ends, they cut the pocket in the work and tapers with a center drill and ran the ball in lead paste.

  6. #6
    bobnolathe is offline Plastic
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    Default cutting tapers with a lathe

    Quote Originally Posted by 4GSR View Post
    Where's your pictures?
    I put pictues addresses in the piece, but dont know how to maake them stand out and blue like pros do. try googling the address ,, Appreciate your interest. Ihad seen the boring head idea before but not the ball bearing idea with it. this thing runs great at speed and does not tear up the center or the work.. Bob

  7. #7
    bobnolathe is offline Plastic
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    Quote Originally Posted by 4GSR View Post
    Where's your pictures?
    I now have Noder instructions re pictures, many thanks for that. Bob

  8. #8
    David Utidjian's Avatar
    David Utidjian is offline Titanium
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    Bob,

    I did (almost) the exact thing you are describing a while back.

    I posted pics here and here.

    I found it necessary to harden the countersunk center that mounts in the boring head otherwise it would heat up and gall after a while. I made mine out of O1 and hardened it with no temper. I wanted it to be as close as possible to the hardness of the ball bearing. I did not find it necessary to harden the countersunk center for the spindle. Depending on the amount of taper it may be better to use a ball type center then a regular 60 deg pointed center in the spindle.

    With the few refinements mentioned above and once I got it all adjusted I was able to knock out a dozen #2 Morse taper blank arbors for my lathe and indexing head in short order. None of the centers or balls wore out in the process.

    I also made a "master gage" set for MT2 (shank and socket) which makes checking the work and setting it up another time MUCH quicker. With the "master gage" MT2 shank all mounted between the ball centers and a dial test indicator on the compound I can quickly dial in the taper on the boring head until the shank indicates 0 TIR for its length. With the "master" MT2 socket I can quickly check the work by blueing the blank with a Sharpie and give it a wipe with the socket. My "master" MT2 shank is six inches which gives me plenty of flexibility.

    I suggest you make a "master" for your setup and it will make subsequent setups a heckuvalot easier.

    -DU-

  9. #9
    Frank Ford's Avatar
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    For turning short tapers, I came up with a little fixture that helps me set my compound to reasonably precise angles with very little effort. It uses a sine bar, indexing against the tailstock ram, or a bar held between centers:



    Here's the full story:

    http://www.frets.com/HomeShopTech/To...nefixture.html


    Cheers,

    Frank Ford
    HomeShopTech

  10. #10
    David Utidjian's Avatar
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    That is a very elegant setup Frank. I would have to fly cut the sides of my compound (casting with paint) to assure it is parallel to the compound dovetails for it to work for me. Not all of us have a nice HLV

    I think I will do that when when I build my new cross slide. I am making one that is extended and has a set of T-slots for mount tooling on the back side of the work.

    -DU-

  11. #11
    Frank Ford's Avatar
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    David -

    I think you could make a similar fixture that would fit tightly in the T-slot of your compound and then true it up by mounting a big end mill in the headstock, and swinging your compound around to the back side so you could mill the ledge in situ by advancing the compound. Seems like it might work reasonably easily.

    My HLV is actually a Sharp (Taiwanese clone, but nice).

  12. #12
    David Utidjian's Avatar
    David Utidjian is offline Titanium
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    Quote Originally Posted by Frank Ford View Post
    I think you could make a similar fixture that would fit tightly in the T-slot of your compound and then true it up by mounting a big end mill in the headstock, and swinging your compound around to the back side so you could mill the ledge in situ by advancing the compound. Seems like it might work reasonably easily.
    Yeah I thought of that. Trick would be to get the blank to register repeatably in my compound T-slot. Then there is the problem of only about 2-1/2" travel in the compound (half of my sine-bar). I could make it up with the cross slide if I can get them exactly parallel. Doable but fiddly. I think I would use a fly cutter in the spindle with about a 6" diameter swing! (light cuts).

    In any case... however I get it done... the utility of your idea is so great that it will be worth doing it.

    I have a nice spacer set that stacks and screws together and could even be screwed to the fixture making the setting up of angles on the compound both quick and precise.

    My HLV is actually a Sharp (Taiwanese clone, but nice).
    I have seen those Sharp-HLVs at EASTEC. They look to be nice machines.

    -DU-

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