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Shop made all-thread

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  • Shop made all-thread

    I will be lathe threading 6" long 7/8 Acetal or Nylon rod at 14 tpi. I need only 5+ inches for the items I'll be making from this. I will need, later in the production line some <.5" pieces of that same rod, threaded the same.

    I have a thought to thread the 1 inch of "waste" material at the same time as I thread the 5 inches of the 6" rod by reversing the stock in the chuck, and indexing the cutting tool into the existing thread. I think I have the longitudinal indexing figured out, but I don't know if I might have to take rotational indexing into acount.

    I have thought about threading between centers, but I think the set up time each for several hundred of these would be counter productive.

    Am I on the right track or headed over the cliff?

    Pops

  • #2
    Threaded Rod

    Consider buying threaded rod stock?

    Comment


    • #3
      Why not run the material thru the headstock, and then only extend 6" at a time and tailstock them?
      Thread the 5" piece, and part it off.
      Like wise for the 1/2" pieces.
      Thread 6" at a time, and part-off 1/2" pieces.
      Or am I missing something?
      A 7/8 rod should fit thru most headstocks.

      Comment


      • #4
        When picking up an existing thread, I would do the following:

        Engage lead screw, tool well away from work.
        Start lathe. Stop lathe after all backlash is taken out of gear train and lead screw and tool is over thread to pick up.
        Put bright light under tool
        Use the compound feed to adjust the tool sideways, and cross feed to compensate for the inward movement that adjusting the compound results in assuming your compound is at 29.5 degrees.
        Adjust until no light is seen around the threading bit
        You have now dialed in the thread. Record dial positions and/or reset dials to 0

        Retract tool from thread, reverse lathe until tool clear of work, Stop lathe.
        Reset tool to recorded position if re-cutting existing thread. Reset tool to OD if cutting new thread, and finish at recorded position.

        BTW: Next time, Buy a <insert longest straight distance in car or trunk> lengths from local plastics shop. Then pass it through your lathe spindle and machine off the marks the chuck jaws left. 0 waste (Except for the kerf of your cutoff blade)
        Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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        • #5
          Another way would be to put a groove in the rod to the depth of the minor diameter, at the 5 inch mark. That gives a place for the cutter to run out into, then it won't matter if the threads pick up in phase or not.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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          • #6
            Spindle won't pass 7/8" unfortunately. HF Lathe 93212. Through chuck capacity 5/8”.

            Black Moons, that is basically what I was thinking of doing. The concept for trying this is to avoid the loss/waste of the end in the chuck. I'll give that a try when my material comes in.

            Thank you.

            Pops

            Comment


            • #7
              Originally posted by darryl
              Another way would be to put a groove in the rod to the depth of the minor diameter, at the 5 inch mark. That gives a place for the cutter to run out into, then it won't matter if the threads pick up in phase or not.
              I had thought of this, as well and will keep that in mind. I usually do run a groove at the inner end and at the middle when threading plastic, to give me a starting point for my cut off.

              Pops

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              • #8
                If you're really going to be doing hundreds of these, just have them made by someone with a screw machine, CNC with bar feeder, or cast them (which after mold cost would likely be cheapest option).

                If that's out, I'd seriously look into running them with a threading die instead of single pointing: I'd go so far as to do that on my lathe even though I can pass it through my spindle. Single pointing threads is not a sound production method - far too labor intensive for something so common as the pitch you're after, especially in plastic.

                Comment


                • #9
                  Delrin

                  First of all, I would use Delrin or Acetal rather than Nylon. The reason is that it machines very clean and easy. If you use Nylon you will have no end of strings to deal with when turning and strings hanging off all over the part. Trying to deburr Nylon creates more strings. That has been my experience anyway. YMMV.
                  When picking up an existing thread, set the levers to the proper settings, turn on the lathe and engage the half nuts with the cutting tool retracted from the part. When the cutting tool is over the threads on the part, turn off the lathe, leaving the half nuts engaged. Wind the cutting tool up close to the part, set dials at desired settings. Then loosen the toolpost and slide the cutter into one of the threads, making sure the threading tool is at a right angle to the part. Tighten the toolpost. Wind the cross slide back and you're set. No measuring, no eyeballing, the part sets the tool. Easy, fast, accurate.
                  For making the parts, you could cut 12" pieces, make an ending groove in the middle at 6" and center drill each end. Put one end in the chuck and one end on the live center. Thread that part, turn around and repeat. Part off in the middle groove, now you have 2 6" parts. Part off 1/2" from each of those and you have 4 parts. The only waste is the parting tool.

                  Comment


                  • #10
                    Originally posted by Toolguy
                    First of all, I would use Delrin or Acetal rather than Nylon. The reason is that it machines very clean and easy. If you use Nylon you will have no end of strings to deal with when turning and strings hanging off all over the part. Trying to deburr Nylon creates more strings. That has been my experience anyway. YMMV.
                    I'm machining Delrin white now and am seeing exactly what you are mentioning above concerning stringing. Probably I'm using the wrong toolspeed/feed or such. I have a couple of sticks of Nylon coming in this week and wanted to try it because of the cost. We'll see, as this is a design change and I don't have to use these experimental pieces in production. Prethreaded Delrin or hard Nylon is just as expensive as steel all thread.

                    When picking up an existing thread, set the levers to the proper settings, turn on the lathe and engage the half nuts with the cutting tool retracted from the part. When the cutting tool is over the threads on the part, turn off the lathe, leaving the half nuts engaged. Wind the cutting tool up close to the part, set dials at desired settings. Then loosen the toolpost and slide the cutter into one of the threads, making sure the threading tool is at a right angle to the part. Tighten the toolpost. Wind the cross slide back and you're set. No measuring, no eyeballing, the part sets the tool. Easy, fast, accurate.
                    I like that. I'll try that, too.

                    For making the parts, you could cut 12" pieces, make an ending groove in the middle at 6" and center drill each end. Put one end in the chuck and one end on the live center. Thread that part, turn around and repeat. Part off in the middle groove, now you have 2 6" parts. Part off 1/2" from each of those and you have 4 parts. The only waste is the parting tool.
                    Lathe reach is only 10" without the tail stock. I'm pushing it using 6" stock. I do like the idea of using the groove to indicate two separate parts to be theraded, though. That is almost toooo simple.

                    I'm using machines I can afford. I'm starting this business on my Social Security, so there is not much breathing room. Later, I hope to be in a larger shop and have some better tools for manufacture, but I'm stuck with using hobby stuff for now. HF mini lathe and Sieg X1. Band saw is down and I haven't found tires for it yet. Grinder is on the shelf below the lathe, so I'm on my knees for it. Green wheel sharpener hangs from the ceiling and is pulled down for sharpening carbide bits. Chop saw and bit sharpener are on a shelf and go outside to a table when needed. Raw stock is under the overhang outside, tarped. Drill press is shoved back on "bench" and dragged forward (after clearing tool bins out of the way) when needed.

                    Have I mentioned my machine shop is a grounded pickup camper?

                    Again, thank you all for the great help. Don't stop now.

                    Pops

                    Comment


                    • #11
                      Set the compound parallel with the bed.
                      Makes it easier to adjust when picking up a thread.
                      Forget the 29.5555555 degree thing.
                      It is only plastic.
                      Hell, I cut threads in steel with the coompound parallel,
                      and my threads look great.
                      Don't tell anyone.
                      Someone is sure to say I don't know HTRAL.

                      --Dooer
                      Last edited by Doozer; 03-22-2012, 08:12 AM.
                      DZER

                      Comment


                      • #12
                        Originally posted by armedandsafe
                        Prethreaded Delrin or hard Nylon is just as expensive as steel all thread.

                        Pops
                        Ah, So its really cheap then.
                        Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

                        Comment


                        • #13
                          Originally posted by Black_Moons
                          Ah, So its really cheap then.
                          I don't consider $8 a foot plus tax to be cheap when I just bought 6 feet of Nylon for less than $8 total, delivered. Delrin will run about twice that, but is still much less than steel all thread.

                          Pops

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                          • #14
                            Use a driving center.

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                            • #15
                              Originally posted by armedandsafe
                              I don't consider $8 a foot plus tax to be cheap when I just bought 6 feet of Nylon for less than $8 total, delivered. Delrin will run about twice that, but is still much less than steel all thread.

                              Pops
                              Then its not 'just as expensive as steel all thread' is it?

                              Personally, I would suggest trying to use a die. You might not even have to turn it to size first... I think after trying some small chunks with a die, Maybe make a sizing die if needed first (its only plastic, any old steel should cut a good length easily) and seeing if it worked well..

                              I would make some a nice die wrench and try and thread 6' lengths being held in my lathe chuck while I hold the die wrench, with the material being supported just by the die and headstock, no tail stock (Start a few threads manually before turning on the lathe..). Then part them with a band saw or chop saw or something.

                              Note: I don't think I would be so quick to try this with steel. 7/8" nylon rod sounds like it would snap before I do and that the cutting forces would be minimal
                              Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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