# Anyone ever fix the g0602 tailstock screw-out problem?



## dewbane (Sep 29, 2020)

On more than one occasion, I have accidentally screwed my tailstock quill out too far. One time, I did this with such enviable grace and aplomb that I had to either make or buy a new tailstock lead screw, and a new tailstock quill. Before you become too in awe of my awesome machining skills, I'll go ahead and admit that I bought the parts from Grizzly.

While working in the shop just now, even though I'm fully aware of the problem, and this issue has already cost me a lot of Abraham Lincolns for parts, I went and screwed the damn thing out too far* AGAIN*.

It's obvious that I'm not going to stop doing that, so I need to do something about this quill screwing out. Surely I am not the only moron with one of these lathes who keeps doing this. I'm writing in the hope that someone already fixed this, and their fix worked really well, and they are super proud of their ingenuity and stuff.




The heart of the issue is the way they milled this slot from the end. If they had plunged the endmill in and machined it like a keyway, this would be a non-issue. I know the world class machinists at Shang Dao Machine Making Corporate Company can doing make keyway, because my machine are have many keyway make in that honorable fashion. This quill no am make like keyway, and that creating is problem.

The bits drawn in red are how it should have been made. I just stood there and looked at the part for a few minutes, and I'm not really thrilled with any of the ideas I've had for putting some material there. I could tap and drill for a set screw. I could try hitting it with the wire welder to put a good blob or two at the end of this slot. Maybe I could build up something with brazing rod, and machine it into shape. I guess I could totally go cheap cheap and just stick a blob of JB Weld right there. I might do that, actually. JB Weld solves a lot of stupid problems, doesn't it?

Well, I'll drop this off for the Peanut Gallery while I go try not to butcher my third and final attempt at making a 29-tooth gear. I ain't wasting no more perfectly good alumniums on this demonstration practice project, so either way I go, I am done.


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## Aukai (Sep 29, 2020)

I have gotten carried away and popped the quill out more than once, and the keyway turns sideways, and getting it aligned again is not fun with an 14" MT3 drill bit hanging out of it. The channel has to be open to get past the key, unless it can be disassembled from the back.


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## dewbane (Sep 29, 2020)

Aukai said:


> The channel has to be open to get past the key, unless it can be disassembled from the back.


It's not a key though, it's just a set screw, and there is no problem screwing it all the way out. I figure it would be a little harder to get aligned blind with this mod, but there would be less need to align it blind, since it wouldn't be screwing out every time you turned around.

The other thing I thought about was making some kind of L bracket thing, and screwing it to the tailstock. Doable, but one would have to be cautious not to drill too far. I prefer the idea of putting back the metal that never should have been machined out in the first place.


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## Aukai (Sep 29, 2020)

Mine is a different brand, but it is irritating though


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## Lo-Fi (Sep 29, 2020)

Looks like there's enoug meat to drill and tap axially for a small machine screw securing a little plate to cap the end?


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## Mitch Alsup (Sep 29, 2020)

I might drill a small (0.0984 #40) and push in a 0.100 pin


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## hman (Sep 29, 2020)

Lo-Fi said:


> Looks like there's enoug meat to drill and tap axially for a small machine screw securing a little plate to cap the end?


Actually ... you could just drill & tap (radially) down inside the end of the slot and insert a setscrew (with blue Loctite to retain it), so its end is just below the level of the outer diameter of the barrel.  
-Or-
If you could find a socket head cap screw whose head was just slightly less than the width of the slot, you could D&T, then tighten the screw down, then file down the head as needed to match the curvature of the barrel.


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## Flyinfool (Sep 29, 2020)

Forgive me, I do not have this machine. But I am very curious as to what gets destroyed, and how, by screwing the quill out to far? 

I do that to my Jet lathe all the time and just have to put pressure on it and screw it back in. It is just a 2 minute irritation.


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## RJSakowski (Sep 29, 2020)

One of the modifications that I did was to add an iGaging DRO to the tailstock.  This prevents the quill from rotating even if the quill were to be extended past the keyway engagement.  If I extend the quill to far, I simply push it back while rotating the screw in reverse.  The process takes only a few seconds.  

As far as overextension goes, both the cross slide and the compound can be overextended in the same manner and the solution is the same.


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## dewbane (Oct 1, 2020)

RJSakowski said:


> One of the modifications that I did was to add an iGaging DRO to the tailstock.  This prevents the quill from rotating even if the quill were to be extended past the keyway engagement.


I can see that. That would be an excuse to start adding DRO.


> As far as overextension goes, both the cross slide and the compound can be overextended in the same manner and the solution is the same.


Overextension in those cases has never caused harm to the lathe though, so I haven't given it any thought.



Flyinfool said:


> Forgive me, I do not have this machine. But I am very curious as to what gets destroyed, and how, by screwing the quill out to far?


I was plunging a 37/64" drill bit into the stock to make a series of bushings that were on the order of 3/4" long. Drill out inside, turn outside, part off. I got greedy trying to go too deep in a single operation. I screwed the tailstock out too far, and that fat drill started spinning my entire quill. The threads on the lead screw and quill did not like that very much.


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## RJSakowski (Oct 1, 2020)

dewbane said:


> I can see that. That would be an excuse to start adding DRO.
> Overextension in those cases has never caused harm to the lathe though, so I haven't given it any thought.
> 
> I was plunging a 37/64" drill bit into the stock to make a series of bushings that were on the order of 3/4" long. Drill out inside, turn outside, part off. I got greedy trying to go too deep in a single operation. I screwed the tailstock out too far, and that fat drill started spinning my entire quill. The threads on the lead screw and quill did not like that very much.


That would be a problem.  Aside from that, it is not a good practice to run to the end of travel as the drilling torque could strip the threads of the lead screw or quill if only a single thread was engaged.  

You can limit the travel quite easily by drilling a hole for a small dowel pin at the end of the keyway.  Then end of the pin would be ground to slightly below the circumference of the quill.  Remove the set screw "key" and insert the quill. Then install the key.  This will of course reduce your total travel.


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## Flyinfool (Oct 1, 2020)

OK I can see how unscrewing it under load could cause damage, I am still surprised it is catastrophic damage but I can still see the senerio where it could be.
Without knowing exactly what is inside your tail stock I see several possible methods to prevent this in the future.
1. put a pin or screw in the end of the key way. This will loose travel in the fully extended position
2. Put a screw and a washer in the end of the quill to prevent the over extension, depending on internal layout this may reduce travel in the fully retracted position. unless you can add a clearance hole to the inside of the tail stock.
3. Add a dro or other external device to limit travel.
4, Find the max safe point of extension and mark it on the quill, remove the quill and cut a groove just a few thou deep and fill it with red paint. When the red appears you know to stop. On mine, even though there is about another inch of travel after the end of the scale on the quill I never go past the the engraved scale, That is the max extension that the quill was designed for.
5. After 2 times should be lesson learned, lazy is always more work in the end.


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## dewbane (Oct 1, 2020)

RJSakowski said:


> That would be a problem.  Aside from that, it is not a good practice to run to the end of travel as the drilling torque could strip the threads of the lead screw or quill if only a single thread was engaged.


It may indeed be that the threads failed before I had it fully extended. I had never given that a thought, and it's a completely fair point.



Flyinfool said:


> OK I can see how unscrewing it under load could cause damage, I am still surprised it is catastrophic damage but I can still see the senerio where it could be.


I think it was a perfect storm. I've unscrewed it plenty of times, but never as violently as that time.


> 1. put a pin or screw in the end of the key way. This will loose travel in the fully extended position


After considering the danger of over-extension, even without fully unscrewing, which I had never really contemplated, it seems like what I want to do is position whatever stop so that it limits my travel to the end of the scale on the quill, period. I hadn't thought about calibrating it, and that would be a good idea. I have determined through experimentation that the last line on that scale is indeed the end of useful travel. I had everything back from their slathered in red Sharpie, for all the good that did me. It looked pretty while it was spinning. I might want to set it so I can't quite reach the end of the scale, for good measure.



> 4, Find the max safe point of extension and mark it on the quill, remove the quill and cut a groove just a few thou deep and fill it with red paint.


I tried a variant of that idea already, and found that I'm never looking at the quill itself when this happens. I'm always looking at whatever the tool in the tailstock is doing. I've tried improving my discipline on this, and I just find it difficult in practice to keep my eye on both things at once.


> 5. After 2 times should be lesson learned, lazy is always more work in the end.


Oh, I agree that my lesson should have been learned by now. I'm just trying to build a mechanical safety feature that wouldn't be necessary if my machine didn't have a stupid operator. But my machine has a stupid operator. It is what it is.

I never quite liked the "just put a set screw in there" idea, and this thread has given me food for thought. I think I will make a little steel or brass stop block, and secure that with a set screw, rather than brazing it in. If I need to adjust the length of travel, I can adjust the block. Start a little longer than what I think, and sneak up on the right dimension.

Also, I think the tailstock would perform better if I implemented a variation of the setup used on my dividing head tailstock. Make a key for that keyway, and machine a little diameter onto the end of a set screw or some custom made part to engage a hole in that key. A royal bear to assemble, but the key in there would create a lot more positive alignment action. With the bevel-end set screw in there, it's really quite sloppy now. I think this would firm up the action without making it too tight.


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## RJSakowski (Oct 1, 2020)

Here are some links dealing with the tailstock key issue.   The last details my approach to the problem.
https://www.hobby-machinist.com/threads/tailstock-quill-distortion.46920/#post-398327 posts#2,7








						Tailstock on grizzly g0602 very stiff
					

The tailstock on my g0602 is very tight and is a pain to use on fine drill operations. I've taken it apart several times and cleaned and lubed. It seems that when I drive a screw driver in the gap to wedge it open a little it works smoothly. Any ideas on a fix?  I don't have a lot of experience...




					www.hobby-machinist.com
				



https://www.hobby-machinist.com/threads/choosing-a-dro-for-a-lathe.62746/#post-517778 post#23


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