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Old 08-12-2018, 08:40 PM   #1 (permalink)
 
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Default Drilling on lathe question

We finally got a nova g3 Chuck and pen jaws to try drilling on our lathe.

My question has to do with the tailstock. (For reference we use the jet 1221 vs lathe). We move the tailstock up so the bit is close to the blank and then lock the tailstock to the bed. We leave the spindle lock loose so we can advance it with the wheel.

The problem seems to be when the spindle is not locked the is a lot of play in it as it moves forward on the shaft.

Is this normal or how do you avoid it?
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Old 08-12-2018, 08:51 PM   #2 (permalink)
 
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This is .... semi-normal. You'll want to tighten the spindle lock just enough to take out most of the play ...

You will also NEED to keep your left hand ON THE DRILL CHUCK as it advances in order to keep it from spinning in the tailstock taper and scratching it up ... also, you'll need to keep it tight against the tailstock in order to keep it from pulling out of the taper and spinning as you retract the bit by backing the wheel on the tailstock. This is a safety consideration, as you DO NOT want that tailstock chuck coming out and then getting flung across the room or right into you.


On a metal turning lathe, the tailstock is on it's own bed that can be moved forward/backward for drilling operations. The tailstock's spindle is locked, and the drill chuck is secured by a device called a "draw bar" ... this item is screwed into the base of the taper from the back side of the tailstock and locked in place with a nut, drawing the chuck securely into the tailstock's taper and eliminating any possibility of it coming loose or spinning.

You then turn the crank that advances the entire tailstock as a unit or retracts it as a unit, with one hand, while the other is free to control delivery of coolant/lubricant to the item being machined.

(added a bit here)
You can simulate this effect on your wood lathe by beginning your drilling operation as described above in the first paragraph ... and then once you have gone an inch or two into your blank you can lock down the spindle and then UNLOCK THE TAILSTOCK ... you then keep one hand on the tailstock and move it back and forth to drill the hole and clear the chips, while keeping the other hand on the drill chuck to guide it. This method has the added benefit of being able to drill MUCH FASTER through softer materials or with sharp bits, as you can clear the drill's flutes much more quickly and then get back to drilling much more quickly. It is more difficult to do with harder materials, as you are using your own muscle power (your arms) to push the bit into the work, rather than the mechanical advantage of a screw feed.



Before any drilling operation, ensure that the stock is SECURELY FASTENED in the chuck assembly. Pen Jaws are somewhat long, so they are easy to overtighten and bend ... bend them back if you can, and/or help secure them by wrapping with duct tape or good rope so that you have good contact all the way down the sides of your blank.

There are only 2 jaws for grabbing the blank, because if your blank is out of round or out of square (rectangular or some other odd shape) then the chuck jaws SHOULD still be able to grab it and center it for drilling. If you wish to drill "off center" then wrap the blank with something else along the side you wish to bias and then clamp it in the jaws, and wrap the jaws well to prevent slippage.


Always remember .... as long as the drill chuck's taper is still well within the morse taper of the tailstock, you should easily be able to stop the lathe safely, or just GRAB the drill chuck and push it back into the taper before it starts wobbling loose. This works even if the bit gets grabbed by your material and the whole drill chuck is spinning. DO NOT let your drill chuck's taper spin against the interior of your tailstock's morse taper ... you do not want it getting scratched up.
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Old 08-12-2018, 09:00 PM   #3 (permalink)
 
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Quote:
Originally Posted by Talltim View Post
We finally got a nova g3 Chuck and pen jaws to try drilling on our lathe.

My question has to do with the tailstock. (For reference we use the jet 1221 vs lathe). We move the tailstock up so the bit is close to the blank and then lock the tailstock to the bed. We leave the spindle lock loose so we can advance it with the wheel.

The problem seems to be when the spindle is not locked the is a lot of play in it as it moves forward on the shaft.

Is this normal or how do you avoid it?
Make sure your drill chuck is snug in the spindle and then snug the spindle lock but not tight so that it still can advance. Then as you advance the drill bit hold the drill chuck with your left hand to steady it as you get it started. It will find its own pathe after it gets started.
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Old 08-12-2018, 09:25 PM   #4 (permalink)
 
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Default Drilling on lathe question

Thank you both for giving very complete answers. I am always impressed with the time people here take to take others.
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Old 08-12-2018, 09:54 PM   #5 (permalink)
 
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Tim--I used to move the tailstock to "close" like you described. Enough play in mine before locking it down that if could start slightly off center. I now advance the bit about a half turn, move the tailstock up to my center mark, lock down, then retract the bit that half turn (so i'm not in contact when I turn on the motor. Gets me dead center every time.

Hope that made some sense. I had to drill a few blanks on my drill press last week--now that I've been using the lathe for the past year, I don't know how I ever thought the DP was functional!!

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Old 08-12-2018, 10:10 PM   #6 (permalink)
 
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Did you put a divot dead center on the end of the blank with a skew? It will guide the bit instead of it wanting to follow the grain. I’m not a fan of brad point bits either because I think they tend to wander, especially when drilling into endgrain. A standard HSS bit works great when the divot closely matches the tip.
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Old 08-12-2018, 11:53 PM   #7 (permalink)
 
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As Skie stated. hold on the the Jacobs Chuck. I dodged mine 3 times before I learned.
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Old 08-13-2018, 07:22 AM   #8 (permalink)
 
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My experience with drilling is that there can be backlash in the tailstock, and there are a few simple things that will help avoid problems:

1. Start by putting a small dimple exactly on the center of rotation before starting to drill. Mount the blank in a chuck on the headstock, face off the end, and use a skew to cut that dimple exactly on the center of rotation.

2. Make sure that the Jacobs chuck taper is firmly seated in the tailstock quill. My lathe has the automatic ejection feature, and there is a gap between the point where the taper is fully seated, and the point where it ejects. I always start by advancing the quill to the point where the taper is fully engaged. In my case, that seems to be very close to the zero point on the calibrations engraved on the side of the quill, but I don't know if you can always trust those engravings to determine the depth of the hole being drilled. (In his book on pen turning, the late Richard Kleinheinz recommended measuring how far the quill advances for each revolution of the handle, and then counting revolutions rather than using the calibration marks.) But the key is that if the chuck taper isn't fully engaged with the taper in the tailstock, there will be some sloppiness.

3. Move the tailstock up to the point where the drill bit almost touches the workpiece, and then center the bit on the dimple BEFORE locking the tailstock down to the bedways. There can be some 'wiggle' caused by a slight mismatch between the spacing between the bedways and the width of the alignment block on the bottom of the tailstock - in the case of my lathe (a 12" Turncrafter), I have less than 1 degree of rotation, but that's enough to cause a hole to be off center unless I carefully align the bit to the dimple before locking the tailstock down.
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Old 08-13-2018, 09:04 AM   #9 (permalink)
 
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Sorry, but I think UNLOCKING the tail stock is asking for Big Trouble! What's so difficult that you can not turn the handle to move the bit into and out of the wood!! Philip
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Old 08-13-2018, 09:32 AM   #10 (permalink)
 
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Sorry, but I think UNLOCKING the tail stock is asking for Big Trouble! What's so difficult that you can not turn the handle to move the bit into and out of the wood!! Philip

Interesting thought.

It's not unusual to use a loose bit held in vice grips, or embedded in a handle, to drill a depth hole in a hollow form. I don't see any problem with that.

But if you want to drill a precise hole - that is, one where the diameter is consistent throughout its depth - I think the bit needs to be held in a Jacobs chuck in the tailstock. If the bit is not aligned with the axis of rotation, and goes in at a slight angle, the diameter of the hole can vary along its depth.

That said, however, I think Skie's point was that if you start the bit with the tailstock locked down and drill part of the hole, you can then loosen the tailstock and drill the rest of the hole by simply pushing the tailstock toward the headstock. The idea is that bit will be kept on axis by the initial portion of the hole. While that may theoretically be true, the objective of that approach is to speed up the process of drilling the hole, and my experience is that if you want a straight, precise hole, you have to take your time and drill slowly. Do it too fast, and you get to do it over.

By the way, I've seen a few videos where people have put a bit in a Jacobs chuck mounted in the headstock, and then drilled the hole by pushing the blank onto the spinning bit. That's scarry - if that bit wanders off axis, it can go through the side of the blank and into the hand holding it.
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