Tailstock Quill Distortion

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HBilly1022

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I've been doing a fair bit of drilling on the lathe lately and have run into some issues with the tailstock. Tonight I figured out what the issue is. When drilling the quill wants to turn in the tailstock but that is prevented by the set screw that rides in a slot cut into the top of the quill. However when using larger size drill bits, like 1/2" and bigger, there is a lot of torque and that causes the sides of the quill groove to distort where it contacts the set screw. Then it becomes almost impossible to get the quill to move because the distorted edge rubs against the tailstock housing. Today's project involved making a 1" diameter hole in some mild steel. I center drilled, then used 1/4" bit, then 1/2" bit then 7/8" bit and the rest was done by boring. The 7/8" bit really aggravated this matter and it was sharp.

This lathe is a King KC1022ML (identical to a Grizzly G0602).

Anyone have any ideas on how to fix this issue?
 
My apologies for stating the obvious - don't hold large drills using the tailstock. Get a MT holder for the QCTP. May even be able to turn down a MT adapter sleeve straight and hold in a boring bar holder. Make a holder.

When drilling a large hole with the carage you get power feed and rapid pull out for chip clearing (works great). It doesn't need to be lined up real perfectly (after all, drilling is pretty rough anyway).
 
Thanks RJ but I'm not a member and can't seem to join. Do you have another route to see this?
 
Chipper5783 said:
My apologies for stating the obvious - don't hold large drills using the tailstock. Get a MT holder for the QCTP. May even be able to turn down a MT adapter sleeve straight and hold in a boring bar holder. Make a holder.

When drilling a large hole with the carage you get power feed and rapid pull out for chip clearing (works great). It doesn't need to be lined up real perfectly (after all, drilling is pretty rough anyway).
Click to expand...

Have you done this? I would be afraid to use the power feed in case something jams.
 
There are lots of things you can do to help open up big holes, like using a lathe dog on the drill bit with the tail resting on the compound, you can connect the tail stock to the carriage to power feed the drill, or, as stated above, you can use tooling in the tool post to drill the hole. You must remember that there is a weak point in every system, and if you keep pushing the limits, something will let go. The more you beef up the setup, the more expensive the damage will be when something breaks. "A man has got to know his (and his lathe's) limitations." At some point it is wise to change to something slower but less risky, like a boring bar. If you are in too big of a hurry to get the job done, you might end up waiting for getting the lathe repaired, which can be a whole lot longer. Try to keep the weak point in your setup something that fails soft and is easily reset. Keep firmly in mind that the purpose of hobby machining is enjoyment...
 
HBilly1022 said:
Thanks RJ but I'm not a member and can't seem to join. Do you have another route to see this?
Click to expand...
I'll see what I can find. Basically, what he did was to mill the keyway in the quill to .200" depth and drill and tap the M8 hole in the tailstock for an M10 screw. He then turned the end of an M10 screw to fit the keyway for a distance of .210". This gave a solid surface to bear on the keyway rather than the thread. From a photo, it looked like the screw was a round head so It could be tightened against the tailstock instead of floating as the OEM setup does.

You should be able to join although, as I recall, there is some delay in processing. If you have a 602 clone, it would be worth your while in joining as they discuss a wide variety of topics concerning the 602.
 
Bob,

I like the idea of using a lathe dog on the bit and will have to get some dogs.

I am new to this machining stuff and don't know the right or best way to achieve an end goal. So given my experience and the size of my lathe what would be the best way / sequence to make large holes, in mild steel? Is using the toolpost the right place to mount drill bits? What maximum drill size before switching to boring? I have had problems getting a boring setup just right and find it easier to get it working when I start with a larger hole. Even with a 7/8" hole for boring start up it took me a few tries to get the tool undercut, height and angle just right. If there is a better way, I am all ears (well, eyes on the forum).

I seem to get rubbing and squealing quite often. I am starting to understand when something is not right and getting better at finding a cure but this will only come with more experience and helpful guidance from the only place I can get it, here on this forum.

RJ

Your description is good and I understand it. I will try joining the forum again. I have also tried to join Projects in Metal several times and cannot get on. They have a lot of G0602 info too.

It looks like my approach to making large holes may be wrong and there may not be a need for me to beef up the tailstock, at least not right away. I have a lot of other projects that need attention too.
 
Personally, I would learn to bore a hole rather than risk damaging my tailstock.
 
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