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Crooked draw bar threads in arbor

Discussion in 'A BEGINNER'S FORUM (Learn How To Machine Here!)' started by Tozguy, Aug 19, 2017.

  1. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    A brand new drill chuck arbor came in this week. When the draw bar would only engage for one thread before binding I figured that the internal threads need to be chased. But when the tap was run into the threads there was no resistance. Before removing the tap I noticed that it was cocked off to one side and not by just a bit.
    IMG_0245.JPG
    My first reaction was 'ahh $hit' but then I realized that a draw bar would not be necessary for most of my set ups. So it is kinda funny now.

    I might want to fix it eventually just for the challenge. Have you any suggestions on how to go about fixing it?
     
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  2. T Bredehoft

    T Bredehoft Active User H-M Supporter-Premium

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    I think I'd opt for the "Return to Vendor" choice. there's no good way to hold it to work on that end of it.
     
  3. woodchucker

    woodchucker United States Active Member Active Member

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    Yep, that's a POC return it. Wish Chinese stuff had more quality control. I don't know how that got drilled and tapped cocked like that. I would have thought it was an automated process that would naturally avoid that issue.
     
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  4. Bill Gruby

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

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    Absolutely send it back.

    "Billy G"
     
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  5. Ken from ontario

    Ken from ontario Canada Active Member Active Member

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    Tozguy, is that a Busy Bee arbor? If so, I have bought a couple of their arbors and they were okay but now that I see yours, I think I was lucky. never seen such crappy workmanship,.
     
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  6. kvt

    kvt Active User Active Member

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    Agree with the rest best choice is send it back. Unless you plug it you may forget about it and then try to use it one day where you really need the draw bar.
     
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  7. RJSakowski

    RJSakowski H-M Supporter - Premium Content H-M Supporter-Premium

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    I would think that a good photo that graphically demonstrates the crooked threading sent to the vendor would get you a new arbor without your having to send the defective on back.

    As to fix the defect, possibly using a Helicoil type solution would work if the thread is machinable. I would set the arbor up for boring and single point threading so that retapping doesn't follow the old hole. IMO though, unless I considered it a technical challenge, the job would be more trouble than it was worth. Arbors aren't expensive and it would be a lot of work to make it right.

    In the past, I have made my own inserts. If the thread was a 3/8-16, I would look at making a 1/2-16 insert. Since you are single point threading, you are free to choose whatever o.d. you want. I would mount the arbor and bore it for the new thread. Then, I would, make the insert, threading the O.D. Then I would remount the arbor and single point thread it for the insert. Do not disengage the lead screw gearing or remove the threading tool so that you retain the synchronization between the lead screw and the spindle.Using permanent LocTite, I would screw in the insert. After the LocTite sets, I would drill out the hole and thread the 3/8-16 threads.
     
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  8. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    Yes it is from BB. I get lots of good stuff from them but this is an exception. I bought it for $8 to make a ball center. For that it is fine.
    IMG_0246.JPG
    The tapers are very good so I may even put a drill chuck on it eventually.
    Its not worth the trouble to return it and I would rather take on the challenge of fixing it anyways, even if it is just for laughs. If I do get a good chuck for it then it could hold the arbor and make any drilling or boring of the draw bar end possible. (using a collet, 1/2'' stub, drill chuck, arbor, with a steady rest somewhere on the arbor). Then bore out and glue in an insert as suggested above.

    Thanks for your ideas gentlemen.
     
    Last edited: Aug 19, 2017
  9. woodchucker

    woodchucker United States Active Member Active Member

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    When you drilled that, out for the ball, was the shaft hardened?
    If not, that's interesting. I would have expected it to be case hardened.
     
  10. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    The arbor was first drilled with a HSS 8% Co center drill followed by a 3/8ths round carbide burr to finish.
    It felt like the center drill struggled some but it did the job. The carbide burr of course just breezed through it. Cute little puppy.
    7b579d7288ee4bf6e28fbdd4323210b2_large.jpg
    I'm not expecting the draw bar end to give me any trouble using carbide drills or boring bars.
     
    Last edited: Aug 19, 2017
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  11. Silverbullet

    Silverbullet Active Member Active Member

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    I'd send it back or ask for a refund. With proof at times they just refund rather then return. The cost to ship may be more the the cost of it new. So if you do keep it. I'd bore it out to the max at the base of the taper , then I'd make a plug and I'd braze or silver solder it in and drill and tap straight. If you don't think it's strong enough pin it before drilling and threading , soft pin of course. That way it couldn't pull out .
     
  12. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    I have never torqued an MT taper draw bar very tight. It just needs is to be snug. I would expect that for a 3/4'' deep plug glued in with strong Loctite would hold enough.
     
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  13. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    I have never seen a drill chuck arbor before that is threaded...
     
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  14. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    Hey Tozguy,
    i haven't used a ball center and have no idea of what you use a ball center on and how you would use it.
    pardon my ignorance, but can you shed some light?

    i like your spirit. in taking on the challenge, we'll all learn things we didn't know before!
     
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  15. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    Bob, as I wrote earlier there is very little need on a lathe for me to use a draw bar with it. Maybe for a drill press or other machine it would be necessary? I have no use for one with a tang either for that matter.

    Mike, my project is to taper a 24'' rifle barrel by offsetting the TS centre. There would be some slight rocking on both centres because of the off set. Some folks use a ball center for this so I'm giving it a try.

    I'm still working out the set up but this is the general idea. Will show pics next time.
     
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  16. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    I haven't seen a drill press with a draw bar, but they may exist. Some people, who want to use a drill press as a milling machine, would like that idea, which would still be a poor one. The tangs, while not intended for it, help to prevent the taper from spinning in the female taper, though they can and do twist if the torque is high enough. Their intended use is for pushing the taper out with a drift working sideways in a slot. The slots are common on MT adapter bushings and on some tail stocks, unfortunately not on mine. The tangs are usually softer than the rest of the tool, and can be filed on.
    [​IMG]
     
  17. Silverbullet

    Silverbullet Active Member Active Member

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    Bob on the m head there used and the atlas mill , and many of the foreign mills use them in mills many larger tapers . China makes lots of them for morse taper.
     
  18. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    Milling machine, yes. I have seen them with MT and draw bars. The original poster was talking about drill presses.
     
  19. Silverbullet

    Silverbullet Active Member Active Member

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    As a newbie he probably didn't know the difference in the arbors . In fact there's a post about making the flats up with threads to put on arbors for mills so they will work in tailstock and drill spindles.
     
  20. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    Fact is that my MT3 - JT6 arbor came with a draw bar thread. I know some about arbors but not so much about every machine that exists that such an arbor may be used in. Sorry if that led us off on a tangent.
     
  21. TakeDeadAim

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

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    I would agree a return to point of purchase is in order here and that one would think modern CNC process would preclude such errors. Where I would disagree is that Asian parts/machines have no QC. First off we don't know where this was made or by whom and second Ive had just as many need to return items from US makers lately. Recently a 1' drill that was so off center one would have expected it to not make it out the door of a very old US maker.
     
  22. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    The ball centres are working out very well. I made up two sizes 5/16'' and 3/8ths. Here is the set up being used to test tools, speeds, feed, etc. on some left over 416SS barrel. It has a very solid feel with no play in the hold.
    IMG_0262.JPG
     
  23. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    thanks for the clarification!
    looks like a sweet set up :)
     

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