# G0602 tail stock quill repair



## WobblyHand (Jan 4, 2023)

My tail stock is marking up the male tapers that are inserted in the tail stock.  Thought I'd clean it up, but have run into a problem.  I borrowed an MT3 reamer from a fellow member @Aukai and received it recently.  This afternoon, I naively inserted it into the tail stock quill and it bottomed early.  Taking the reamer out, I see that the reamer cutting edges are about 110mm long.  However, this lathe has a short MT3 taper socket.  The MT3 dead center I have has a taper length of 75mm.  Furthermore, it seems that I re-assembled the tail stock incorrectly, and I can't even insert the short dead center with the quill set to 0.  The quill has to be set to 0.5" for the Grizzly MT3 short dead center to seat.

Looking at the tail stock exploded view only shows a plain screw going into the quill.  Mine seems to have some sort of extension that extends even further into the bottom of the taper.  It appears to be about 1/2" long, or roughly the amount of positive quill offset I need to insert the taper.  I don't like giving that up, as the usable quill stroke isn't all that long to begin with, about 2".  I had trouble with the reassembly last time, although I don't recall what the issue was.  It gave me a bit of trouble.  Maybe I threaded the tail stock lead screw in too far?  

The quill taper does indeed have issues and should be reamed.  I can see the problem and feel the problem with a finger.  Don't quite know how to fix the problem without altering the reamer.  Since it is borrowed, I don't want to do that!  Unless someone has a great idea, I will return the reamer, buy one for myself and alter it.  Or I could just buy a new quill, if that made more sense.  Seems the quills are $60.50 from Grizzly.  Any suggestions?

Part of me wants to repair it, because that's what we do.  Part of me wants to replace it, because something's wrong with it, and I'm not sure that it is just the taper.  I think the internal threads of the quill may need some attention, I'll check that in the tear down. ($31 for the tail stock lead screw).


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## jaek (Jan 4, 2023)

Can you extend the tailstock quill enough that the reamer fits into it?

That would at least let you clean up the taper and solve the problem of marking up male tapers.


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## WobblyHand (Jan 4, 2023)

jaek said:


> Can you extend the tailstock quill enough that the reamer fits into it?
> 
> That would at least let you clean up the taper and solve the problem of marking up male tapers.


Don't know, I'll give it a try.

Edit:  That helps.  Now the lead screw is out of the way.  What's a good way to actually ream this taper now?


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## WobblyHand (Jan 4, 2023)

Do I mount the reamer in a four jaw, indicate it to zero, then slide the tail stock up to it and slowly turn the chuck by hand or?  Although the quill is currently not good, doing this wrong is a good way to make it even worse...


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## RJSakowski (Jan 4, 2023)

It sounds like you have an obstruction in the socket.  My 602 will seat a standard MT3 taper with the tang which adds another 7/8" to the short end. You can pull the tailstock out once the lead screw is disengaged.  You may have to remove the set screw on top of the tailstock; I don't recall. ( I can't remove mine unless I remove the DRO scale).

edit: all my MT3 tapers are standard length and I have no problems with any.


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## keeena (Jan 4, 2023)

My G4003G has a similar issue with tools bottoming out "early"; the quill shows 1.3" when my drill chuck is installed. Granted - it does have a tang. But even tools w/o tangs bottom with ~0.75".

This is what I used for a reference when I did mine. I'm not sure if this guy mentions it, but make sure your TS is aligned with your HS before doing anything:


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## RJSakowski (Jan 4, 2023)

keeena said:


> My G4003G has a similar issue with tools bottoming out "early"; the quill shows 1.3" when my drill chuck is installed. Granted - it does have a tang. But even tools w/o tangs bottom with ~0.75".


I have cut the tangs or otherwise shortened the length on the small end on all but one of my MT3 tapers sdo they eject just before the end of travel of the tailstock quill.  The remaining one is used in an MR4 adapter so the tang is needed.  It ejects at just over 1" from full retraction.


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## WobblyHand (Jan 4, 2023)

Think something was added to the end, maybe because the short tangs weren't ejecting?  I've had to grind just about every MT3 thing so it would fit.  I'll take the tail stock apart tonight or tomorrow.

The reaming seemed to help some.  Certainly a bit smoother in, and it sort of pops out slightly more than before.  Didn't remove much, just to get a slight cut.


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## WobblyHand (Jan 4, 2023)

Still going to take everything apart.  I'd like to get that 0.5" of travel back.  Only have about 1.5".  Might have to replace stuff, I suspect the lead screw and quill threads might have been slightly damaged when the quill ran off the end a while back.

After that episode, I replaced the set screw with a larger one that was turned down to have a dog point.  Having screw threads bearing on the slot of the quill was a poor manufacturer's design choice.


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## pontiac428 (Jan 4, 2023)

This is how I did my tailstock.  The tailstock needed about .010 in my case, the spindle needed much less.  If I were modifying my ejector on the tailstock, I would make damn sure I can eject every tool that I have, tanged or not.  That is the minimum, unless you want to remove your tapered tailstock tools with a slide hammer.  Extending the ram well beyond interference with the ejector should be obvious before reaming.


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## WobblyHand (Jan 4, 2023)

pontiac428 said:


> This is how I did my tailstock.  The tailstock needed about .010 in my case, the spindle needed much less.  If I were modifying my ejector on the tailstock, I would make damn sure I can eject every tool that I have, tanged or not.  That is the minimum, unless you want to remove your tapered tailstock tools with a slide hammer.  Extending the ram well beyond interference with the ejector should be obvious before reaming.
> 
> View attachment 432147


Before today, it never entered my mind that the reamer would bottom.  And I feel a little embarrassed that I didn't think to extend the quill to avoid it.

Good idea on using a collet chuck for the reamer.  I hadn't thought of that or the dead center in the spindle.  The dead center only works if there's a corresponding spot on the tap.  I spent more time centering the silly tap in the four jaw, when I could have simply mounted my ER40 chuck...  Dope slap.

At least I did a couple things right, like locking the quill when reaming, using the four jaw, and only moving the chuck by hand.


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## rwm (Jan 4, 2023)

When I scored up my tailstock I realized I only had to take off the high spots and not re-machine the whole taper. I used the reamer by hand with cutting oil and got a great result.


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## RJSakowski (Jan 4, 2023)

I modified the MT3 tapers on my two chucks and my live center to a uniform length. This was about .20" shorter that the standard MT3.   In the case of my live center, it had a button head cap screw that provided access to the bearings inside.  I replaced the button head cap screw with a custom screw that recessed and gained about 5/8" of travel. On one, Igot tooo zealous and cut too much away so I drilled a hole in the end and pressed a button in the hole to correct.  

In the event that a taper is too short to be ejected by the lead screw, on the 602 at least, if I loosen the nut on the dial , I can tap the lead screw forward to pop the taper out.


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## WobblyHand (Jan 4, 2023)

Just by a visual, it appears to be a bit better.  Might blue a taper and see how much coverage I have.  I really can't go any further in, as the male tools are receding into the tail stock just a little bit.

Never had a problem with the tapers being too short, all of mine are way too long.  Have had to grind almost all of them.  In any case, the tapers sort of pop out now, like they are spring loaded.  Previously they were sort of pushed out slowly.  Don't know if that is significant or not.


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