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Parting Woes Solution?

Discussion in 'A BEGINNER'S FORUM (Learn How To Machine Here!)' started by savarin, Nov 21, 2016.

  1. savarin

    savarin Active User H-M Supporter-Premium

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    I just saw this (pun intended) and thought it may be of use to those who have problems parting.
    I rather liked it.

    I couldnt think where to post this so please move if necessary.
     
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  2. Christian Poulsen

    Christian Poulsen United States Active Member Active Member

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    ...just when I start thinking I've seen it all!...
     
  3. wawoodman

    wawoodman himself, himself H-M Supporter-Premium

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    I think it's pretty damn ingenious, considering how much trouble beginners (like me) have with parting off!
     
  4. chips&more

    chips&more United States Active User Active Member

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    What the heck!:confused 3: That's one for the books!!!
     
  5. Christian Poulsen

    Christian Poulsen United States Active Member Active Member

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    well yes, from what I see it looks pretty safe and it even has adjustable cutting pressure! (smiley face here)...so ifn' one doesn't have a good parting/cuttoff tool and holder and/or doesn't have the speeds and feeds down for cutin' off...why not this!
     
  6. 12bolts

    12bolts Global Moderator Staff Member Active Member

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    All it needs now is a small crank running of the leadscrew to provide some reciprocating action and spread the wear

    Cheers Phil
     
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  7. ndnchf

    ndnchf United States Active Member Active Member

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    My success with a parting too greatly increased when I switched from the old lantern toolpost to a QCTP and parting tool holder. But there are still time when I just need to saw something off and use a hand held hack saw. For small pieces, this is pretty clever, simple and effective little tool. I like it.
     
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  8. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    Sometimes when parting off in the lathe using carbide tooling, I'll stop the part off so it leaves a nub about 3/16" in diameter. Next I'll take my hacksaw, part it the rest of the way off with the lathe running. Haven't tried it at full diameter.
     
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  9. chips&more

    chips&more United States Active User Active Member

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    My 14” lathe is big enough, ridged enough and powerful enough to part without the typical problems. It’s those Murphy ones that I worry about. I will usually take my project out of the lathe and over to the power bandsaw cut-off instead of risking a blade catching or compound breaking or soiling my underwear or some other bad thing…Dave.
     
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  10. ndnchf

    ndnchf United States Active Member Active Member

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    Intrigued with the idea, I went out to the shop after dinner and cobbled one together from scrap I had laying around. Pretty easy to make. It seems to work pretty well, but needs a stronger spring than I have to replicate the downward pressure sawing by hand gives.

    Saw2_zpsbftzfcea.jpg


    Saw1_zps36azgfc0.jpg
     

    Attached Files:

  11. Christian Poulsen

    Christian Poulsen United States Active Member Active Member

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    ...looks like this op/set up is catching on!...I wonder if the original got a patent? (We better lawyer up!)...smiley face here
     
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  12. Bill Gruby

    Bill Gruby United States Global Moderator Staff Member H-M Supporter-Premium

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    If your spindle has the chuck screwed on I would suggest you do NOT try this. The original has the spindle running in reverse. The teeth on the blade set to cut that way. One snag of the blade and you could wear the chuck.

    "Billy G"
     
    Last edited: Nov 23, 2016
  13. ndnchf

    ndnchf United States Active Member Active Member

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    My set up has the spindle turning normally and the saw is arranged so the teeth cut properly. But good point about a chuck unscrewing if going the other way.
     
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  14. Bill Gruby

    Bill Gruby United States Global Moderator Staff Member H-M Supporter-Premium

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    I saw that the second was correct and only the original was going the wrong way. Kudos for the build on yours.

    "Billy G"
     
    Last edited: Nov 22, 2016
  15. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    ndnchf,
    may I ask which way the saw teeth were facing?
    how often did you have to lift the blade to clear chips? or do you just crank the slide back and forth a bit while it is sawing to clear them?
     
  16. ndnchf

    ndnchf United States Active Member Active Member

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    The teeth are facing away from the toolpost so they cut against the rotation. I just cranked it back and forth a bit. It is slow. I used a 32 tooth blade. An 18 tooth would be better and a stronger spring. I mounted the blade to a piece of 1/2" square stock with an 8x32 screw and lock nut.
     
  17. Wreck™Wreck

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

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    If you can release a threaded spindle with a hacksaw blade you are a better man then I am. I once owned a threaded spindle machine and unscrewing the chuck took considerable effort if it had been in use for several months or years.
     
  18. Bill Gruby

    Bill Gruby United States Global Moderator Staff Member H-M Supporter-Premium

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    With all due respect Wreck, read on please.If that blade jams or bends the teeth will jam or bind. If they jam the spindle could come loose.

    FWIW, I have a spacer washer on my spindle between it and the chuck. This makes for easy removal of the chuck after long periods of use. A set up like the first one with the spindle running in reverse will have the chuck loosen and come off if that blade jams.

    I leave you with this phrase, "Just because you haven't seen something happen, does not mean it can't happen.

    "Billy G"
     
    Last edited: Nov 23, 2016
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  19. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    And there is always the wisdom of using a locking mechanism on a screw on chuck probably conceived for guys like me.
     
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  20. Wreck™Wreck

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

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    I have actually spun a 20" 4 jaw chuck off of a threaded spindle, I fully understand the outcome of such a thing happening.


    However in my initial post I was wondering if one may actually unseat a threaded spindle with a hacksaw blade and a spring.
     
  21. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    I vote yes, given enough time and vibration, some will. Some won't, maybe, but which ones?
     
    Last edited: Nov 25, 2016
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  22. Bill Gruby

    Bill Gruby United States Global Moderator Staff Member H-M Supporter-Premium

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    Without mixing words any further than this post, the answer is, I don't know either but I damn sure don't want to find out. I posted the warning as a precaution.

    "Billy G"
     
    Last edited: Nov 25, 2016
  23. Christian Poulsen

    Christian Poulsen United States Active Member Active Member

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    I could see it happening if that hacksaw blade set up jams and crams ifn'n the chuck is turning in the "unscrew" direction without a "lock" (just like anything)...By the way, good catch to whoever caught that (somewhere above)
     
  24. Bill Gruby

    Bill Gruby United States Global Moderator Staff Member H-M Supporter-Premium

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    Safety is our primary concern on this Forum along with helping in any way we can. It wasn't hard to see in the first video that there was an accident waiting to happen. That is why it was brought to the attention of all. My sole purpose was to show what was going on and what could happen. I would not feel right if something happened to one of you and I had not said something. I would hope the rest of the membership felt the same.

    "Billy G"
     
  25. Wreck™Wreck

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

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    I appreciate your lessons about safety, carry on all.
     
  26. Garththomas

    Garththomas Canada Active Member Active Member

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    I imagine an operation like this would be a pretty low rpm operation
     
  27. Ozwelder

    Ozwelder Australia Active User Active Member

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    For goodness sake. o_O:confused::eek::eek:

    Take the time to learn and do it properly or line up a good eye doctor.
    Theres a good reason you haven't seen it elsewhere. Its just plain dangerous and an accident just waiting to happen.
    I am saying whats on my mind rather than remain silent and hear of someone getting hurt.

    Guys,as they say it ain't rocket science. I regularly part off with HSS through stainless 303 and on occasion 316.

    Ok these comments do apply to non production amatuers . I am not a jobber, so time is not a factor for me.

    Observe the basics.

    * Part off at center height
    * Part off square to the axis of the work -check set up AND that compound setting is on zero.
    * Set up for the minimum of PO tool overhang - half diameter of work + a smidgin
    * Ensure the rigidity of your tool holder and tool post
    * Use a constant (cross) feed
    * Where necessary use a lube - on stainless mine is a sulphur base lube
    * Sharpen the HSS tool as per info available -its there on the net
    * Watch for the curl shape of the swarf that comes off the steel - the shape, size and texture tell you so much .Most times with a lot of steels comes off like a cursive writing "C" and usually is very shiny at the cut face.

    I am certainly no machinist, merely an amatuer of some 8 or nine years experience but decided very early in my machining hobby to learn about using HSS. It has paid off in terms of economy versatility and not needing a wide selection of carbide cutters and tool holders.
    It took a bit of time , effort and study plus chatting to an old timer and I was parting off trouble free with HSS within 6 months.
    I hope this can help someone. Experienced machinists feel free to jump in and add something I may have missed.

    Regards
    Ozwelder
     
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  28. Mariah

    Mariah United States Iron Registered Member

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    My QCTP puts the parting blade off to the side and that results in things tipping and the blade digging in, mini lathes do this to keep your adrenaline drained...been there done that more times than I care to remember! My way of ending this problem was to turn the holder and parting blade upside down and use reverse for parting. If the tool digs in the blade tips away from the cut, this saves my parting blades and my adrenaline is back to normal! This worked so nice I drilled and tapped a hole on the blind side of the holder to set the tool height quickly.
     
  29. Catcam

    Catcam Australia Iron Registered Member

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    Novel and it uses up the broken blades you have laying around. May well work
     
  30. Catcam

    Catcam Australia Iron Registered Member

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    The original set up spun the chuck ( clockwise) so the hacksaw blade was in tension . this is a stable and preferred mode of operation. Your set up, with the chuck spinning anticlockwise puts the blade in compression which can cause the blade to buckle/ break. But if it works , it works.
     
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