Is it normal for lathe tailstock drill to lift up when contacting work?

machinistnoob said:
Yes. His approach is on the the pedantic side but it is necessary for precision. Furthermore, he addresses the dynamic nature of drilling a hole. Whether using a hand drill or precision equipment. It's all the same.
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I have never thought of Joe P as pedantic... He is teaching, he's not showing, always teaching.. so he takes great pains to show you the right way.
He may shortcut some when he can, but he'll show you the right way.
 
woodchucker said:
I have never thought of Joe P as pedantic... He is teaching, he's not showing, always teaching.. so he takes great pains to show you the right way.
He may shortcut some when he can, but he'll show you the right way.
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Pedantic as in a precise manner. As in throughly addressing all relevant issues on the subject. Love Joe and his manner of presentation on things. He has become my go-to source.
 
epanzella said:
To get more tailstock travel before ejection I cut the tang off one of my MT# 3 drill chucks and it would slip once in a while with large drill bits (1.00 plus). I ended up welding the tang back on again. No more slippage. If the tang was not to prevent slippage, why is the tang a rectangular shape and why is there a matching slot to receive it inside of the tailstock. My live centers don't have tangs and they still eject just fine.
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woodchucker said:
I have never thought of Joe P as pedantic... He is teaching, he's not showing, always teaching.. so he takes great pains to show you the right way.
He may shortcut some when he can, but he'll show you the right way.
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Do you still believe the right way is that the drill can move 1/32" until it is 3/4" in? We can all easily draw the precise increasing land engagement to prove it is a ridiculous claim.
 
Parlo said:
Do you still believe the right way is that the drill can move 1/32" until it is 3/4" in? We can all easily draw the precise increasing land engagement to prove it is a ridiculous claim.
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I don't know why you quoted me but since you dragged me into this a drill can definitely move around until it's full diameter is in the hole. The movement is just the chatter of a form tool. Have you never had a chamfer bit chatter?
 
Lots of good advice in this thread!!

Regarding the original theme:

Illinoyance said:
It indicates the centerdrill is below the spindle centerline.
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benmychree said:
It is a number of factors that add up to being below or off center
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This is surprisingly common. My Leblond lathe was manufactured with the tailstock being .003 above centre line, in order to accommodate wearing in of the veeway and flatway. After 40 years, it still is about .0025 high. I just compensate for that with a boring head when needing a dead centre.

Yes, one day, when I need a new project (number 4005 or so) then I'll scrape in the tailstock to be .0005 high.

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Now concerning the idea of drilling, and deviation: like anyone with experience, the answer is: It depends. A normal length inexpensive 2 flute drill will never cut a 'rubbing' hole, but will cut several thousandths oversize. This is partly because of imprecise sharpening of the two flutes - but even if the flutes are perfect, there is still a tendency to wander at some angle a little bit. The extra space will allow the drill to find its own direction somewhat, resulting in a hole that isn't perfect to the centreline.

Starting a hole with a spot drill, and then a short series drill (which is far more rigid) can easily help this situation. While a spiral drill will never be as straight as a high-pressure gun drill with ground inserts, it is possible to drill a 1/4" hole 6" with less than .015 deviation. I have done this many times.

If you *must* have a straight DEEP hole to a tight tolerance, then you have to drill a hole undersized to around 3-4Xdiameter, then bore it to size or slightly undersized, then peck drill with a short series CARBIDE drill, then you can follow up with a regular sized drill. this 'pilot' hole will serve as a stiffener for the drill bit, and help get the hole straight. NOTE. this builds up heat, even with good lubrication, so regular extraction of the full drill bit and flood coolant are essential to not breaking your drill. I have had over 95% success in 20X+ deep holes.

Why Joe is right: he insists on using a centre drill to start his holes - nothing wrong with that, if you don't mind your hole starting just a tiny bit off centre. even a .001 deviation will help get the angle wrong. But by drilling holes Joe's way, I'm afraid you have to expect Joe's result.

Anyone, even a beginner, can do better than what Joe is proposing by following the above suggestions.
 
Parlo said:
Do you still believe the right way is that the drill can move 1/32" until it is 3/4" in? We can all easily draw the precise increasing land engagement to prove it is a ridiculous claim.
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I believe the drill can move 1/32 ... I don't know about the 3/4 .. ok, you draw the precise increasing land engagement... I'll just go by my observations, that it lifts..

Ridiculous? really?
 
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