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Re: [atlas_craftsman] 3996 crossfeed speeds, was 3996 crossfeed nuts class 4g

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  • wa5cab
    Tom, Actually, the instructions on pg 9 are telling you where to place the 40T sliding gear. I.e., whether to mesh it with the 16T (OUT) or 32T (IN) of the
    Message 1 of 69 , May 8, 2013
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      Actually, the instructions on pg 9 are telling you where to place the 40T sliding gear.  I.e., whether to mesh it with the 16T (OUT) or 32T (IN) of the compound gear.  You don't do anything to the compound gear.

      I don't know where this new compound gear Jon mentioned would go.  But I do know that it does not/can not go in place of the existing 16/32T compound gear.  The center to center distance between the compound gear and the tumbler gear above that drives it is fixed to match the 32T gear.  I haven't actually looked to see whether the larger gear would hit anything or not but if you replaced the 16/32T with a 64/32 you would speed up all of the feeds by 4X. 

      I would suggest getting the 3996 back up and running first.  If/when you come across the article you once saw, see what it actually says.  But in the meantime, the machine worked well as designed.

      Robert D.

      In a message dated 05/08/2013 07:01:29 AM Central Daylight Time, tmgsr@... writes:
      >>>I think that you must be referring to the Sliding Gear, which meshes with
      >>>the 16/32T compound gear on the reversing tumbler.  It doesn't slow down the
      >>>lead screw.  It speeds it up, to give you the top row of threads shown on
      >>>the chart on the QCGB.  The Sliding Gear is normally operated in the OUT
      >>>position.  With it in the IN position, and the selector handles set to E9
      >>>(.0042") feed, the feed would actually be .0084", not .0021".  It's explained on
      >>>Page 9 of the 3996 manual.  The earlier Atlas manual on the models up through
      >>>3991 does a better job of explaining, I think.  Although the photos in the
      >>>copy we have are rather poor.
      >Right, but you have to add an additional set of gears into the train. 
      >why the gear bracket on the QC has room for all those gears.  This can be
      >done for metric threads, as well.  So, if you inserted a 32/64 gear set,
      >with the driving gears turning the 64, and the 32-tooth gear driving the

      I'm going to have to look at this closer and see if I understand it
      correct this time, I am now to assume the sliding gear (h on pg 9) set
      16/32  will only increase above the .0042 and I will need to replace
      that set with a 32/64?

      confused a bit still on this, I just now realized that the directions
      on page 9 are telling me where to have the 16/32 gear placed for a
      particular feed or thread.
      At first I did not realize where the plate said in/out it was about
      that sliding gear, I thought it was for the in/out of the back gear-
      again the light bulb came on and I realize that really has nothing to
      do with the feed distance per spindle revolution



      Robert & Susan Downs - Houston
      wa5cab dot com (Web Store)
      MVPA 9480
    • wa5cab
      Pretty much any dog will work if it s the right size. :-) Armstrong made the same lathe dogs from at least the 30 s until at least the 80 s. If you ll send
      Message 69 of 69 , May 12, 2013
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        Pretty much any dog will work if it's the right size.  :-)

        Armstrong made the same lathe dogs from at least the 30's until at least the 80's.  If you'll send me the Item Number, I'll take a look at them.

        Robert Downs - Houston
        wa5cab dot com (Web Store)
        MVPA 9480

        In a message dated 05/12/2013 18:38:47 PM Central Daylight Time, tmgsr@... writes:
        >On Thu, 9 May 2013 11:28:17 -0400 (EDT), wa5cab@...:
        >>The original No. 142A set of four sold by Atlas had openings to handle
        >>1/2", 3/4", 1" and 1-1/2".  I would think maybe anything larger might be getting
        >>too heavy.  I bought the set and the face plate to drive it when I bought
        >>my 3996 in 1981.  And have to admit that I've only ever used any of them a
        >>few times.  The two operations where you would definitely need them would be
        >>turning a taper by the tailstock set-over method and checking or setting
        >>tail-stock set over to zero.  The latter being the only usage I can actually
        >ok thank you!

        how do I tell if I'm buoying the correct dogs, there is s et now I was
        looking at, but they said something about them being made in 52, I do
        not see sizes or  part number on them, or will any dogs work?


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