Geared Taper Attachment(Variator)-My Version
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  1. #1
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    Last summer or fall I got casually interested in the Variator after I turned down a job because of travel limitations of the TA on my 16"CY. I was looking at a catalog cut sheet that happened to have a picture of the Variator, and said "there's the answer", and "this looks simple enough". At the time I posted about the Variator and Russ was kind enough to send me a link to the patent# 2,184,377. I made a print out, and in March designed my version.
    Before you ask, no I don't have a driving need for one, the refused job wasn't a big ticket item, and I hardly ever use the TA's on my lathes. It looks like a neat attachment and I want one, the only obstacles to get over was the cost of the gears and the lathe's 54" centers, a bit on the short side to really take advantage of the capabilities a Variator offers.
    As with all of my "homebrew" designs this is a weldment. I am approxiamately 60% finished.
    All the gears are 16 DP, 20 deg PA. There are 3 24T, 1 32T, 2 48T, 1 64T, 1 72T and 2 4' racks.
    The weldment is 5-1/2" wide, about 3-1/2" tall and about 11-1/2" long and currently weighs about 20 LBS, it started out at about 35 LBS. All the mill work, thus far, has been done on the K&T's.
    With a couple exceptions, I don't think that the pictures that follow need comments, they were taken in the order work progressed.














    Harry

  2. #2
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    One more picture;


    Harry

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    Looking good there, Harry. I want to see how it does on a steep taper.

  4. #4
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    So I am not familar with this type of setup. I have looked at the pics in other posts but can come with no NO idea as to how these work. Any easy explanations?

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    The geared taper attachment extends the range, dependant on the change gears used, of the TA. You can either cut tapers much steeper, but a lot shorter than the standard settings, or much longer than the ordinary travel.
    Look at the 4th picture. There are 3 slots in the bottom of the bracket. The 2 slots closest to the bed are alternate positions for a gear rack that attaches to the carriage. The 3rd slot is for another gear rack that attaches to the TA slide. The upper part of the bracket houses the change gears. The 2 rack gears are connected by gearing via the change gears. I have obtained 6 gears that will be used as change gears providing the following ratios; 1:1, 1:2, and 1:3, and if I understand the patent description correctly, and done my paper sketches correctly, the changes are a little different than the actual ratio. For example the 1:1 will actually have a change of 1:2 or 2:1 depending on which position the carriage gear rack is in.
    This may help, just type in the patent #2,184,377, you should get a top plan view;
    http://www.uspto.gov/patft/
    I hope this helps, but I will be posting more pictures as the project progresses.
    I feel that a ball bearing TA is a basic requirement, especially on the short, steep tapers, with this attachment.
    Harry

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    Wow, thats a pretty complex setup when you consider how easy it is to do with a servo motor and a little electronics. I look forward to seeing the finished product.

  7. #7
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    "Wow, thats a pretty complex setup when you consider how easy it is to do with a servo motor and a little electronics."

    It's not an accident that Monarchs, many of which were designed by C. Bickel (including the entire 10EE, except for the drive, which was C. Greene) are all mechanical, and most are still operating, some of these SEVENTY years after their construction.

    Likely, Slo-Syn, or the "servo du jur", won't be in business in seventy years from now, and its drives will be unrepairable in five.

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  9. #8
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    I'd be more tempted to get a CNC lathe, instead of going the servo motor and electronics route, besides that takes the challenge out it.

    Anyway, an update.
    This thing is going together very soon, all that needs to be done are the key ways in the gears, and a top cover, for which I've got to round up the material.
    I've spent considerable time taking care of alterations to the bowl and the gear shafts after I decided to interpose a bronze thrust bearing between the gear shafts and the bowl. The machine work took about an hour, but deciding which option was best and easiest took some time. I also had to conjure up the rack attachment brackets to the carriage and TA slide coupled with the proper alignments with the bed bracket, added a great of time. I'm not exactly pleased with the locator pin installations for the brackets, but they work. Decisions, decisions, with endless circular arguements with myself.
    Here are some more pictures;



    Rack bracket attached to carriage.


    Side view of both racks and their attachment points. Notice that there isn't a lot clearance, and there is definitely less inside the TA.


    Bottom view of racks in place in the bed bracket.


    The gear shafts and the rack brackets. Getting the racks and brackets properly aligned was not a walk in the park. Drill bits wander, even in center drilled holes, combined with awkward working positions made this difficult.


    Look at the gearshaft on the right. Having 2 mill axis going at the same time was not the intention. The 1/8" end mill went about .300" deep before I noticed the knee axis on the DRO doing strange things. It was one of those moments BTW, the cutter didn't break. I was truly impressed.


    Bracket ends of the racks. Each end is approx 1/16" shorter than the corresponding hole.
    Harry

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    Got it together today for some dry testing. I'm going to have to come up with some charts for the various combinations possible, with the change gears positions, carriage rack position, and swivel bar settings, especially + or - the zero setting. The thing to remember is that the carriage rack is the driver, and the slot in the bracket it's in makes a difference in what happens. I only tried one slot today, and reversed the positions of the 1:2 change gears(32 & 64 tooth gears), and changed the setting on the swivel bar to the max 9.5 degrees each side of zero.
    With 1 driving, 2 the taper was approx 9-1/3 degrees(last picture) and the length on the DRO shown on the Z scale is not the total travel available, there was still another 6" + to go in the swivel bar. All I have to do play with where the racks are at the start. If 2 drives 1 the taper doubled and was oppisite the swivel bar direction, this all got very confusing late on a hot muggy afternoon.


    1:2 change gears mounted.


    The other 2 sets of change gears 1:1(2 48 tooth gears), and 1:3(24 & 72 tooth gears). The holes in the 2 larger gears, may lighten them a bit, but they're there for a place to grab onto for removal.



    Bottom side of bed bracket assembled.


    The DRO reading. The 20"+ on the Z scale is already 2" past the maximum travel, 18", in standard configuration of the TA.
    Harry

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    Looks nice, but my head is hurting just thinking of the ratios of gears to angle of the TA. EEK!

    Im thinking of making a servo driven TA that would use the feedback from the DRO encoders to drive a servo motor on the compound based on the movement of the carriage. Shouldnt be terribly difficult. You could set in either rise/run or degrees.

    Then again I need to actually finish the projects I am working on first!

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  13. #11
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    I think its a pretty cool accessory- did Monarch or the other high end manufacturers supply them as options? I don't recall seeing them in any of my ATW documentation- old or new.

    Regards,

    Greg

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    From the catalog cut sheet, the Monarch "Variator" was a factory option, or could be added in the field, easily. I don't have other mfg's catalogs, so I don't know what they offered in this type of option. From some of the comments made by the late JimK, this was an option of Leblond. I do think, and from my experience this AM, this option should only be considered with a ball bearing TA, especially in the steep angle turning set-up.

    Had a clear head this AM, I decided to check the manual's the TA instructions, hoping to find an overhead layout that I could copy for use in the charts. Not only did I find the overhead layout, but the set-up positions for the two types of turning; long length turning and steep angle turning.
    The rack position, there are 2, of the carriage rack determines which type of angle will be turned. The position next to the bed is for long angle turning, with the lower tooth count of the change gear pairs being the driver. For example in the 1:3(24:72 teeth) the 24 tooth gear is the driver, look at the 1st and 3rd pictures above. The steep angle rack position is the middle slot(3rd picture) and the driver in the example above is the 72 tooth gear. The direction of the taper also matched the direction of the swivel bar.
    With this knowledge it was easy to test out all the combinations. I don't foresee in using this attachment, other than the normal difficulties in setting up the TA.
    Here are the results. DRO readings are for Z and X, and the included angle. The swivel was set at the max, 9*30'. All of the Z axis readings are the maximum travels, except for the 1:2 long angle where I ran out of room, actually the tailstock end of one of the racks was hitting a drill storage rack on that end of the lathe.
    Steep Taper:
    1:1 9.1632 Z, 6.2080 X, 34*6'+
    2:1 6.0566 Z, 6.1568 X 45*28'+
    3:1 4.4930 Z 6.0920 X, 53*35'+

    Long Angle Turning
    1:1 turns straight
    1:2 29.3698 Z, 4.9708 X, 9*37'+, there was still about 3-4" left on the swivel bar, I just ran out of room.
    1:3 28.2502 Z, 6.3536 X, 13*46'+

    The only set-up I expect may be problematic is the 3:1 steep angle, where the carriage was a bit more difficult to move.
    The actual max travels will be less, slack has to be taken out of TA before cutting begins.
    I'll try and do some actual turning tests next week. I got the cover material today, and will wrap this project up.
    Harry

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    Took 2 test cuts today, using the 24 and 72 tooth gears. The 1st picture , the bar is 2-1/2" D and the cut is about 23" long, the taper is 2*40'+ included angle, the small end is approx 1-1/2", the 2nd is a steep angle cut, the piece is 3-3/8" OD, the included angle 64*14'+. In both cases the finishes are quite smooth. The speed & feed were 563 RPM & .0044", matl is 1018.




    Harry

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  17. #14
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    Cool. How is the complexity of setup relative to a conventional TA- and is the feel & action of the backlash different?

    Tell you what though, seeing your finishes on 1018 sure is a lesson on how things ought to look... I seem to get good finishes more accidentally than not. Too bashful w/ the feed and less-than optimal tool edges I suppose.

    Thanks,

    Greg

  18. #15
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    It's going to take a little longer to set the geared version up than the regular version, mainly because I can't leave it set up. I have some adjusting to do to the TA itself. On the 3:1 steep taper set-up there seems to be more spring until all the backlash is out, and the carriage is definitely harder to move, which is not surprising. All the other ratios don't seem to affect the carriage too much. I was very impressed with the action of the long taper set-up, which is really the area I'm interested in.
    I'm going to have to shorten the rack gears though. I have a drill rack at the tailstock end of the lathe, and the racks are hitting the drill rack if I get the carriage to far to the right, and I'm going to need the room. I could have extended the bar another 4-5".

    I started out with a heavier feed, but the finish was terrible, so I dropped the feed from about .008 to .0044 and increased the RPM to 563 from 404. The DOC was .0625". With a smaller DOC and the negative rake insert, the finish most likely wouldn't have as nice.
    Harry

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    Thumbs up

    Nice setup,

    So what did you finally come up with for a taper chart ?

    This computer would not let me look at the US patent office images ...any ideas ?


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