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Telescoping Jack Screw - FINAL PROJECT

Discussion in 'A BEGINNER'S FORUM (Learn How To Machine Here!)' started by jlsmithseven, Apr 9, 2017.

  1. Wreck™Wreck

    Wreck™Wreck United States Active User H-M Supporter-Premium

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    I may give you some insight as to what you might expect in the real world, if you do not go directly from school to working for an aerospace/automotive/pharma contractor.
    If your first employer is a job shop then you will be required to do exactly that, whatever is needed.
    You may have to deburr 1000's of parts or just run a saw for days at a time, degunk the coolant sumps and so on.

    It will take a bit of time before they just give you a drawing and work order because they know that you can make the parts without supervision. At that point you will become entirely to valuable running parts and will no longer have to do the second operations and other simple tasks.

    Good Luck
     
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  2. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    I understand that every place is different. My internship is this summer.
     
    Last edited: May 4, 2017
  3. Wreck™Wreck

    Wreck™Wreck United States Active User H-M Supporter-Premium

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    Excellent, do what you already know and go from there.
     
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  4. T Bredehoft

    T Bredehoft Active User H-M Supporter-Premium

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    Make an excellent impression, you may be able to get a job there based upon their experience with you.
    You can always hope.
     
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  5. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    The purpose of these internships is to get familiar with the place. We picked these from a list for jobs we would hope to have. I've heard good things about this company, so I believe it's a good fit. Then when I graduate, I'll already have experience with what they need me to do and we can go from there.
     
  6. TakeDeadAim

    TakeDeadAim H-M Supporter - Premium Content H-M Supporter-Premium

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    I've been in both roles in that I started as an apprentice and was given machining and repair tasks that slowly increased in difficulty based off my success in doing what I was given. I was also given many "duties various as assigned" jobs from going to pick up parts, cleaning, washing the shop truck and emptying the trash. Ive also been in the spot where I dealt with new employees and gave them tasks much in the same way I describe above. Mind you I was never and am never a guy who will walk past a full trash can or dirty bathroom and then go get someone who is working to take care of it.

    I did however send people who were standing around to do things that were "theirs to do"; kind of a reminder that hey you need to take care of these things when you see they need doing. By them seeing me do it I always felt it was a good demonstration of just that, do what needs doing when you see it.

    Best advise I can give you is just that; don't walk in the door with the attitude "I'm here to make parts and only that", The fastest way to make yourself recognized as a good worker is to do the following.

    Show up to work on time and ready to work
    Consider your appearance despite the fact you work in a shop
    Do what you are asked to do when and how you are told to do it
    Do the extra things you see need to be done; If the paper towels at the wash sink are out, replace them, if the sink is dirty, clean it. If you use a machine, clean it, if you use company tools, or borrow tools, return them. De-bur everything you do, even the cut off's. Label stock before returning it to the rack. I hope you get the idea here and believe me they will notice if you do and if you don't. There are many people here who have run shops and I am sure they can confirm that if you want to stand out these, and many others, will make that happen.

    I wish you great success in your pursuits, it is great to see young people getting into what is and always has been a great career.
     
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  7. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    Much appreciated TA. Very well said.
     
  8. brino

    brino Active User H-M Supporter-Premium

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    Absolutely agreed!
    If I needed to sum it up in one word it would be "attitude".

    ......and from what I have seen on this site, Justin (the OP) is on the right track. He is always trying and pushing himself to do the best he can.

    I think he will do very well........on this site, in whatever shop he frequents and in life!

    -brino
     
  9. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    Thanks for the kind words everyone! It means a lot.

    So anyways back to my project, I got done threading both ends of what will be my SM Jack Screws with the rounded nose on them. My next step my professor said was to put this piece in the collet holder and mill the edges to the hexagon nut. So I will do that a little later on. I got most of the lathe work out of the way on these, so I want to go ahead and start another section. Only reason is, people are still on other machines and we have a few weeks left. By that final week, it's going to be hard to get on a decent lathe. So I want to do all the lathe work I can as soon as possible. Would the LG Jack Screw be a good next section? Do it the same way I've been doing this section, with one on each end? Thanks and enjoy the photos and video!


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    Last edited: Apr 18, 2017
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  10. mikey

    mikey Active User H-M Supporter-Premium

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    Threads look good, Justin. It might be a good idea to chamfer the ends before threading for smoother engagement of the threading tool. You can also do it afterwards but do it so the thread start easily and it looks better.
     
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  11. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    Did chamfer after these were taken, I originally forgot. Enjoy the threading video :)
     
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  12. kvt

    kvt Active User Active Member

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    Mikey yes the chamfer would be nice, but looking at the drawing, unless the instructor given them authorization to modify, Does not show any chamfer on that end, It just shows flat, Which I would say is an oversight by the person drawing it. OK my bad, I see he did chamfer them now.
     
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  13. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    So you guys who'd like to do this project will get to learn a few things today. At the expense of my mistakes lol.

    I went in today at 9am. I turned down and knurled a section for the LG Jack Screw. Came back after a test at 1230pm and it dawned on me. I knurled before ever turning down my 1.375" sized stock to the 1.310 callout on the print. This was after I center drilled, faced, and cut sections out for the external thread. So, the key thing to learn here is that turn down your stock before knurling. Also note that knurling adds approx. 010" to your final dimension, depending on how much knurling you're doing.

    Anyways, I started a new piece and got almost to tapping the inside. Was taking .125 thousandth passes here and a feed rate of about .006 and it worked out nicely. Lots of smoke, but I got to rip through the part and get a lot done!!

    I drilled entirely through it so all I have to do is tap the inside, then do more external threads and done! Enjoy.

    [​IMG]
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  14. brino

    brino Active User H-M Supporter-Premium

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    Could you not just take a skim cut to remove the knurling?

    -brino
     
  15. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    Yeah I thought about it, but the piece was cut into like 3 different diameters so gripping it on the chuck wasn't going to be fun. I had another piece already cut so it didn't take me much longer to get back to where I was...
     
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  16. jlsmithseven

    jlsmithseven United States Active Member Active Member

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  17. Rustrp

    Rustrp United States Active Member Active Member

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    You say; "whenever I get on the mill," but link to a 5C collet setup, which would be used on the lathe? Which piece of the jack screw are you planning on doing on the mill? In the mean time I will go back and read the details on your project.
     
  18. mikey

    mikey Active User H-M Supporter-Premium

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    Pretty simple. You find a 5C collet that fits your work piece diameter and slip it in the block, then put the work piece into the collet and tighten the black ring on the back of the collet to lock the work in solidly. Then you can turn the collet block in the vise to cut 3, 4 or 6 sided flats or features.
     
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  19. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    So basically the same size as I've been holding it on the lathe chuck right? Like in the middle? Then keep turning it for the 6 sides I need in the vise jaw? I think I'm talking about the left picture in the link on Amazon...
     
  20. mikey

    mikey Active User H-M Supporter-Premium

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    The diameter of your work piece has to be able to fit into a 5C collet but basically yes, you would put the collet in the hex-shaped block and lock it in place in the vise. Then you cut one flat, turn the block and cut another flat and so on until all six flats are cut.
     
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  21. Rustrp

    Rustrp United States Active Member Active Member

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    I like show and tell. When I'm in the shop I see it happening.

    Edit: When I asked about the 5C collett it was because I got the distinct impression there would be a milling task to complete on the lathe and if it's in the description I missed it.
     
    Last edited: Apr 19, 2017
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  22. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    hey guys, I'm not starting internal threading yet, but I want to keep it in the back of my mind. my teacher said drill bit 1/16 smaller and bore it .005 bigger than the minor dia. is this the minor diameter of the thread pitch (using 1-10 threads). Thanks!

    [​IMG]
     
  23. Rustrp

    Rustrp United States Active Member Active Member

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    With my limited knowledge of single point thread cutting I'll say yes.

    Edit; Was this a trick question? The print shows 1-8 UNC.
     
    Last edited: Apr 20, 2017
  24. mikey

    mikey Active User H-M Supporter-Premium

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  25. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    It has been changed to 1-10 UNS, sorrY!! I mentioned it in my last question. So Mikey it is minor pitch diameter then...or just the actual Minor diameter of the thread itself?
     
  26. mikey

    mikey Active User H-M Supporter-Premium

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    Okay, so 1-10 UNS. The process is the same. Go here and find the 1-10 UNS specs. Look at the tolerance range for a 2b (class 2 internal) thread and note that the larger end of the minor diameter range is 0.913". Adding 0.005" to that gives you a bore of 0.918". That hole should allow a 1-10 2a external thread to fit if the thread is within the tolerance range for that thread. So yes, the ID of that bore will be your minor diameter.

    http://www.diecasting-mould.com/dat...t-Screw-Socket-Thread-Specification-Sheet.pdf

    Pitch diameter is the mid-point between the major and minor diameters so no, we aren't talking about that.

    Hmm, let me see if I can simplify this. When you turn your external thread it will have crest dimensions that have to fit into the female root dimensions with adequate clearance, while also allowing adequate engagement on the flanks of the thread, right? Your instructor is giving you a method that allows you to provide a little clearance at the interface between the root and crest of these threads so the two threads will fit without contact at those points. Did that clarify or muddy things up for you?

    [​IMG]
     
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  27. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    It helps thank you
     
  28. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    THIS IS WHAT I GOT DONE TODAY.
    Drilled with the .500 drill about 1 inch in. Then drilled with the 57/64 drill. Worked pretty well and cut pretty good. Don't have updated pics, this was taken before lunchtime but I got both sides done! They look awesome, I hope I can internal thread. My plan is to cut each piece off and grip on the knurled end. Then just run the internal thread tool completely through the part. Others have internal threaded to a shoulder, but I want to avoid that when this is my first internal threading exercise. Sound like a plan? Thanks guys!

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  29. T Bredehoft

    T Bredehoft Active User H-M Supporter-Premium

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    Threading internally more than about twice the thread diameter is chancy. You'll get spring on a long enough tool to reach that far through the double piece.
    You might try internal threading to a shoulder on a piece of scrap before you start the final pieces.
     
  30. jlsmithseven

    jlsmithseven United States Active Member Active Member

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    Unfortunately made a simple error today and cost me 10% of my grade on this project. Granted, I could do another one in a day based on my experience now, but it was a lot of work to mess up on the cutoff part of the procedure. My little end knurled is off by .010 and my total length is off by about the same. The sad thing is the knurled length had a tolerance of .010 and the length itself overall had a tolerance of .030. I believe my error was indicating the length on my lathe, then going back to the grinder and making sure the tip of my cutoff tool was sharp. Either way I messed up and it's 10% of my grade, but I have to worry about getting the other parts done because the Very Top Cap and the Top Ball part are due this Friday! I need some assistance.

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