Help! Tailstock wobble!

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fireforce

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Joined
Mar 10, 2019
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1
Location
Texas
So, I'm a beginner to turning. In an attempt to try my hand without dropping a thousand dollars, I bought a Wen 8"x12" lathe. I was told that to bore a straight, centered hole, it was best to use a lathe. I bought a centering chuck as well as a MT1 drill chuck (I don't know what else to call it). I attached the bit to the tailstock to bore the hole and locked the tailstock down.The tailstock is centered, but the quill inside it has some play, so when I start boring the hole, it creates a ring and I have to move the quill into place with my hand to get it started.

I called customer support and they said that it is supposed to have a little play in it. Am I making a newbie mistake? How can I fix the issue?
 
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monophoto

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Mar 13, 2010
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Saratoga Springs, NY
The situation you have encountered is very common.

The bottom of the tailstock has a rectangular protrusion that rides between the bedways of the lathe. The protrusion is very slightly narrower than the spacing of the bedways, which means that it can wobble just a bit. And this can lead to centering problems when drilling - problems that get worse as the gap between headstock and tailstock increases (due to the size blank you are drilling, the length of the drill bit, or how far you have extended the tailstock ram).

There are two things that you need to do. First, you need to make sure that your tailstock lines up with your headstock in the vertical direction. To do this, put a cone center in your tail stock, and a spur center in your headstock, and move the tailstock up to the point where the points almost touch. While there can be some mismatch in the horizontal plane that changes as you wiggle the tailstock, the points should be aligned vertically. If not, you may need to loosen the bolts holding the headstock to the bedways, and insert some shim material under the headstock to bring the points into alignment. This is something that you need to do once, but that you may not need to revisit on a regular basis.

Next, you have to be very careful (and disciplined) about drilling.

1. Mount the blank in the headstock chuck, and square off the face before starting to drill.
2. With the blank rotating, use a skew to cut a dimple in the exact center of the blank.
3. Mount the drill bit in the jacobs chuck in the tailstock, and slide the tailstock up to the point where the drill bit is centered in that dimple BEFORE LOCKING DOWN THE TAILSTOCK. That assures that the tailstock is exactly centered to the axis of rotation of the blank.
4. Finally, advance the tailstock ram to drill the hole SLOWLY, backing the bit out frequently to clear the swarf building up in the flutes of the bit.
 

frank123

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Joined
Feb 5, 2012
Messages
586
Location
Colorado
Are you starting the hole with a center drill or a long drill?

Try using a center drill and just move it in to put a small dimple in the piece you're drilling and see if it makes a single spot or wobbles around and makes one larger than the tip of the bit. If it makes a single spot try starting the hole with it and switching to the other drill and see if this solves the problem and drills a good hole. If it doesn't more investigating the cause is in order.
 

magpens

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Feb 2, 2011
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9,975
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Coquitlam, BC, Canada
Follow Louie's suggestions for drilling.

I find that it is very important to have the end of the blank square with the turning axis.
And use a center drill to make a dimple before you start using the larger size twist drill.
Make sure that the drill bits are accurately centered in the Jacobs chuck jaws. . For drill bits under about 5/16", it is possible to get the drill off center in the Jacobs chuck.
 

monophoto

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Mar 13, 2010
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1,439
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Saratoga Springs, NY
Make sure that the drill bits are accurately centered in the Jacobs chuck jaws. . For drill bits under about 5/16", it is possible to get the drill off center in the Jacobs chuck.



That is very true. And it is also possible to break smaller drill bits if they are not inserted squarely into the Jacobs chuck, and then the chuck jaws are tightened. DAMIKT
 

MiteyF

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Joined
Jan 27, 2018
Messages
131
Location
Bay area
I have the same lathe, that I have shimmed (both the head and tail stock, plus a few other modifications) to get it very close to "proper". I have not however, had good luck drilling with it. The tail stock is just too wobbly. I have had no problem turning accurate pens, but drilling is a no-go. It's far easier for me to drill on the drill press anyway, so that's what I do.
 
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