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Don't run the boring bar into the chuck jaws on the end of the hole

Discussion in 'GOOFS & BLUNDERS YOU SHOULD AVOID!' started by Hukshawn, Feb 11, 2017.

  1. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    Glad to say I have yet to smash the chuck on the carriage.
    But, I have, however, dropped the 6" 4 jaw on my hand unscrewing it from the spindle... I suppose better bruise my hand than damage the ways.....
     
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  2. bobshobby

    bobshobby Australia H-M Supporter - Premium Content H-M Supporter-Premium

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    That reminds me of why I don't have a DRO. I always thought "Hobby Machining" was all about doing it manually, the original way, you know hands on. But I guess there will always be those who want explore new territories, like DRO's, CNC and all sorts of other tricks. One should always have, and use a carriage stop I'm thinking of designing one that will trip the feed. But too many other things to do at the moment.

    BTW. I haven't had a chuck or cutter crash since I was an apprentice, but I did have a few back then. Fortunately our Toolroom Foreman was a very wise and kind person, after a crash he would discuss the reasons for the crash with us, bringing all the apprentices together for a show and tell. while the poor victim was very embarrassed he was kind and helped us to understand all the inherent dangers of all the machines we had in our shop, and they were many. I have often felt since those days that I and my fellow apprentices (all 8 of us) were very lucky in that we had a very diversified training under the eye of a great foreman and his 3 leading hands plus all the toolmakers in the shop, usually 12 to 15 of them
     
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  3. Bob Korves

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

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    My lathe has a foot brake, and it is pretty useless like the other controls when something unexpected happens. By the time you get it stopped it has probably already bashed something pretty good. However, the foot brake is perfect when you are anticipating needing to use it. I have used it for metric internal threading tight up to a shoulder, leaving the half nuts engaged. No problem. My foot brake stops the spindle instantly if I have my foot resting on it and am mentally geared up to use it, even at higher speeds. I occasionally find it really useful.
     
    Last edited: Feb 19, 2017
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  4. darkzero

    darkzero Global Moderator Staff Member H-M Supporter-Premium

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    Speaking of foot brakes, I've seen some lathes (imports) that have a foot pedal connected only to a cut off switch, all it does it cut power to the spindle & does not actually have a physical brake on the spindle. I've always wonder what's the point in that setup?

    My lathe does have a real foot brake, cuts spindle power & has a physical drum brake inside the spindle pulley. I love having a foot brake. But I use it only for convenience, I've never had to use it to try & prevent a crash.
     
  5. utterstan

    utterstan Canada Active Member Active Member

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    I missed it by that much LOL to funny
     
  6. The Liberal Arts Garage

    The Liberal Arts Garage United States Active User H-M Supporter-Premium

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    Make a simple box , bandsaw or whatever the top, suitable for lathe and
    Chuck so that the chuck only drops 3/8" or
    so. Install or remove chuck safely with twenty minutes invested. ......BLJHB.
     
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  7. petertha

    petertha Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    What I try to do beforehand to protect myself is set my boring tool max depth & then use my homebrew stop which limits any further carriage travel. Actually I have 2 of these so I can put one on the other side of the carriage like when you have to bore a recess groove within 2 limits. You don't want to drive into them under power & they don't shut anything off. I just power feed until close & then traverse in my hand until the carriage kisses the stop, then repeat.
     

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  8. Fozzy Bear

    Fozzy Bear United Kingdom Swarf Registered Member

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    Yeah... It's one I've done too a long time ago. Once you've done it for the first time you never do it again.

    Best Regards,
    Fozz
     
  9. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    Nice carriage stops. I need to make one for sure. I'd like to save the pictures to make some myself, but it won't let me save. Huh...
     
  10. intjonmiller

    intjonmiller United States H-M Supporter - Premium Content H-M Supporter-Premium

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    How are you viewing the photos? It's very easy in Tapatalk. Should be just as easy in a web browser. Tapatalk even lets me upload them directly to my Google drive where I store projects and stuff, to then be viewed later on a tablet.
     
  11. petertha

    petertha Canada H-M Supporter - Premium Content H-M Supporter-Premium

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  12. bobshobby

    bobshobby Australia H-M Supporter - Premium Content H-M Supporter-Premium

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    I would love to have a foot brake, but unfortunately I would have had to go up a size to get one and that machine would not fit in the space I have, however as I said I'm thinking about making a carriage stop that will trip the feed, not a total solution, but a move in the right direction. I'm even thinking of how to fit a clutch/brake to the lathe, any ideas would be welcome. I'm thinking in terms of an automotive electric A/C clutch fitted to the motor. They can usually handle quite a few HP. and a second one fitted to the pulley at the lathe end of the belt, set up as a brake. Could be set up with a button connected to a foot bar to simultaneously disengage the motor and apply the brake, a separate lever could be used just as a clutch. I like the idea of a clutch very useful when doing a lot of stop/start work.
     
  13. bobshobby

    bobshobby Australia H-M Supporter - Premium Content H-M Supporter-Premium

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    It's always a good idea to place a wooden board on the bed under the chuck when removing, also useful when putting large heavy items in or out of the chuck.
     
  14. TORQUIN

    TORQUIN United States Active Member Active Member

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    One thought on emergency braking that comes to mind is the braking power of a VFD. I have mine set for gentle braking, but could ramp it up. I suppose it depends on the VFD, but they might be able to stop that motor very quickly. Rig up your emergency switches/stops to go through the VFD and it may work well.

    Chris
     
  15. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    This is my carriage stop, but I do not recommend it.
    It is very noisy!
     

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  16. petertha

    petertha Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    That's the metric clone. Each of the inscribed rings is mm of interference, so just divide by 25.4 to get inches of crash :)
     
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  17. TRX

    TRX United States Active User Active Member

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    Bah!

    At least you didn't bore your MT3 headstock spindle straight for half an inch...

    [oh, a squirrel!]
     
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  18. Groundhog

    Groundhog United States H-M Supporter - Premium Content H-M Supporter-Premium

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    In my experience it is easier/better to use a solenoid (or hydraulic or air cylinder) to hold a brake OFF. Use spring pressure to apply the brake. You can adjust the clamping force by the spring size (belville washer stack) and adjust the application rate by using a flow control valve when using a hydraulic or air cylinder.
     
  19. 4gsr

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

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    Oh, I have better than that! I know you guys get tired of my stories, but we got to keep this trade going.

    Dad told me of a man, wasn't him, working on night shift, was running a old lathe. He was spade drilling a hole in a piece of iron, I'm guessing somewhere around 3" in diameter. He doze off, next thing he wakes up and the chuck and piece of iron is just sitting there not turning on drill bar. The lathe was still running. He had bored thru the piece of iron, thru the chuck into the spindle until the part holding the chuck on parted off! What a mess he created!

    Well, being a oilfield machine shop, they were always fixing someone's mess up. The man bored a box tool joint connection in the spindle. Then on another lathe, made a pin connection to fit the freshly made one in the spindle. Made it up in the spindle, finished the outside to fit the chuck. (I assume the original spindle was threaded as most older machines were made that way) And threaded the chuck on and went about his business like nothing happen. Don't know if the boss ever found out either!

    Much for my story telling for the day.

    Ken
     
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  20. benmychree

    benmychree United States Active User H-M Supporter-Premium

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    In an extreme case, I remember the story about a guy at Mare Island Navy Yard who had a job boring a long hole, when suddenly the chuck fell off; he had continued his cuts until he bored all of the spindle away; I think the story went that when this happened, he put his tools away, picked up the tool box and left the premises (permanently).
     
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  21. coolidge

    coolidge United States Active User Active Member

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    When your brand new end mill starts smoking just let the CNC mill continue while cussing it loudly...later switch the mill spindle from reverse to forward.
     
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  22. bobshobby

    bobshobby Australia H-M Supporter - Premium Content H-M Supporter-Premium

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    I don't suppose you've got any pics or notes on the install..
     
  23. 4gsr

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

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    No. I never thought to take pictures of the conversion back then. I did this back around 1978 and the lathe was sold in 1996.

    If your familiar with the old Warner clutch brake setup that was shaft mounted, that is basically what I used. I don't even remember what size clutch-brake that I used. I remember doing a layout drawing on paper to get the mounting dimensions correct along with making a stub shaft to extend the input shaft length coming out of the headstock. Sorry I was not able to come up with anymore than that.

    Ken
     
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  24. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    I felt vulnerable only having a red mushroom panic button for emergencies that I might not be able to reach quickly enough so I installed a foot operated trip wire early in my adventure into turning. The system is cobbled to act on a power switch and triggers a homemade braking mechanism. It works but it does not give me any more comfort. It made me realize that there is no substitute for vigilance and awareness. The wisdom in the above quote is that if you are not on your game in machining you should be somewhere else.

    The few 'surprises' I have had operating the lathe prove that things happen so fast, chances are slim the panic stops will prevent serious injury or damage to the lathe, even if you manage to operate them. So they are there but I do not depend on them at all. I have never found out (yet) for myself how useful brakes might be in panic situations so if you have any personal experience to share I am all ears.
     
    Last edited: May 17, 2017
  25. bobshobby

    bobshobby Australia H-M Supporter - Premium Content H-M Supporter-Premium

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    Thanks Ken, no I'm not familiar with them. Although it sounds something like what I had in mind. At this stage a lot of guys are saying I should forget it and convert to 3Ph with VFD, and I guess I could I already have 3Ph on the property I would only need to bring it around to the other side of the garage a run of about 20m. Buy and fit a suitable 3Ph motor, and VFD, sounds all very simple but I've got no idea where to start.

    I'm a bit confused about this VFD stuff, because I've always believed that if you run a motor on a higher phase yes it will run faster but will probably over heat, And if you run it on a lower frequency it will run slower but also lose torque and overheat, so i'm still in the dark.
     
  26. Bob Korves

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

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    Overheating has more to do with load vs. cooling capacity than speed. A motor can be turning over very slowly, with the fan moving very little air, without problems if the load is small enough for the motor do dissipate the heat through radiation and natural convection, or short run duration. At high speeds, the typical cooling fan also puts out more air, to a point, and the heat load is also highly dependent on output load. A motor idling at very high speed, without a load, is pretty easy to keep cool. I do not experiment with over speeds of more than 10% on my old surface grinder, with light loads, and only apply very light loads at low speeds, for short duration. It does not pay to push a motor too hard, or to let it overheat. Inverter rated motors and others designed for that kind of work can take wide ranges of speeds and loads without problems.
     
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  27. benmychree

    benmychree United States Active User H-M Supporter-Premium

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    I had the Warner electric brake setup on one of my 19" swing Regal Leblonds, and it worked quite well, both in forward and reverse rotations when the lever is moved to the center position, but keep in mind that these would never do on a lathe with threaded spindle; the sights and sounds of a chuck unthreading and falling down between the ways is never a good thing. It has nearly happened on my present 19" with threaded spindle, I use reverse via a drum switch sometimes to slow the spindle down to a stop, and have had it thread off partially, but have caught it with a shot of forward rotation and avoided having the chuck fall off.
     
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  28. Silverbullet

    Silverbullet Active Member Active Member

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    Nope as soon as YA here the screaming of the lathe. Ouch
     
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