# Oops.  Crashed it.



## ogberi (Nov 27, 2014)

Yup.  I'm not too proud to admit I crashed my Taig lathe last night.  

And I crashed it but good.  :/

First off, all safety gear was in place.  Eye protection, apron, fingers well away from any rotating or sharp objects.  

I was drilling stock in the 4 jaw chuck, and like an idiot, forgot a spacer behind the item.  The drill bit was a 1/2" silver and demming, and I was making the last of 6 passes with progressively bigger drill bits.  

Because I have a digital caliper mounted on the carriage, I usually run it up under the chuck and lock it down so it's safe, vs removing it from the lathe.  I always turn everything by hand before firing up the spindle to make sure it all clears.  

In this case, the drill bit punched through the back of the workpiece, and touched the taper in the spindle nose.   Being a razor sharp bit, it immediately dug in and the spindle came to a screeching halt. Literally. The belt from the treadmill motor slipped, as it's supposed to. Unfortunately, the chuck unscrewed itself when the spindle came to an abrupt halt.  The Taig 4 jaw chuck is a fairly substantial piece of steel for such a small lathe, and even at only a few hundred RPMs carries plenty of inertia.  

The good news is that because the drill bit was all the way through the workpiece, the chuck and workpiece were contained.  It didn't come flying off the lathe.  It did, however, shoot towards the tailstock end as the chuck unscrewed itself.  One of the chuck jaws slammed into the insert carbide tool I had in the toolpost, shattering the insert and bringing the chuck itself to an abrupt halt with a thoroughly pants-wetting bang and shower of sparks as the carbide insert decided this was way more of an interrupted DOC than it could handle.  The breaker on my DC speed controller tripped an instant later, even as I was reaching for the power switch.  

It all happened in the blink of an eye.  Everything had already stopped moving by the time I hit the power switch.  

As for the damages - none to me.  As I said above, I keep my fingers out of harm's way.  My safety glasses didn't have a mark on them, and they're always on when I'm working on a machine or with a tool.  

The internal spindle taper has a gouge in it, which is ugly and I'll have to dress with a toolpost mounted pencil grinder.  Thankfully, I don't use the Taig's spindle taper (the proprietary one) for anything.  

The carbide insert is toast.  The whole top chipped and broke, and I'll have to check the toolbit itself to see if it's bent.  It's only 1/4", but pretty stout.  

One of the lathe jaws has a ding in the side of it, but nothing that would affect how it grips a workpiece.  I'll stone down the ding so nothing protrudes.  

The rest of the 4 jaw is fine, thankfully.  Being that I'm down to only 1 4-jaw chuck, I'd have hated to mess this one up. 

The drill bit has a tiny chip in one cutting edge, where it grabbed the spindle.  That'll stone right out without an issue.  

I checked the headstock alignment and it's still where it was to begin with, so nothing moved there.   The tailstock I'll check after the holiday, and cut a test bar to make sure everything is okay.   


So there you have it.  One forgotten item, putting a spacer behind the workpiece before grabbing it in the 4 jaw chuck and drilling it, lead to this.   That the bit could pass through the workpiece and jam in the spindle taper never crossed my mind.   I got off lucky here.  Only minor damage to the lathe and some tooling, and none to myself.  Other than slightly damp boxers and my pride.  

So why admit to world + dog that I made an idiotic mistake?   'cause I'm human, I ain't perfect, and everybody screws up once in awhile.  With luck, maybe my serving as an example of what *not* to do will prevent others from making the same mistake.   

Have a great thanksgiving, and stay safe!


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## Terrywerm (Nov 27, 2014)

We all make mistakes from time to time, it is human nature and nothing to be ashamed of. Thank you for taking the time to tell us of your experience. Your crash has not occurred for nothing. You have learned from it, and so will every person that reads this thread.


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## David S (Nov 27, 2014)

Yes I think it is very appropriate to remind folks what can happen in situations like you had.  I used the MT2 taper on my 618 all the time and would hate to screw it up.

Thank you for posting.

David


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## Franko (Mar 19, 2015)

Everything I really know was learned by making a mistake. All the rest is just hypothetical theory.


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## coolidge (Mar 19, 2015)

That **** will buff out!


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## RVJimD (Mar 19, 2015)

I see the original post is pretty old, you are probably ready to move on?

After thinks about this for a moment I think I understand.  The drill bit was just large enough to catch the internal spindle which stopped and that allowed the chuck to unscrew?  At first I was thinking "wouldn't it get tighter and stay in place?"

Hope you got everything back in shape by now.

Jim


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## ogberi (Mar 19, 2015)

Yup, old post, but not embarassing.  I goofed and forgot one little thing and *crash!*

It happens, less frequently as you gain experience, and it can be scary as heck.  Even a 4" 4 jaw chuck at a few pounds can launch with serious energy. I considered a few ideas to prevent the chuck unscrewing in a similar situation, but I swap out chucks on the Taig frequently, and none of them lended themselves to quick chuck changes.  

Thankfully nothing was hurt other than the gouge in the spindle and the insert.  It also wrecked the insert screw, but I have spares.  Tiny darn things love to jump onto the shop floor....


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