Anyone still use center drill Holders

[Glenn Brooks]

Hi all, just reading my old SB How To Run A Lathe book this AM. It mentions using a 'special center drill holder' instead of a three jaw drill chuck to hold center drills.

Does anyone use these things these days? Are they significantly more accurate than modern tail stock drill chucks?? If so, where would I find holders for sale? (I have two lathes for restoration having MT 3 tailstocks and one shop lathe with tailstocks using MT 5.)

Thanks
Glenn

[Steggy]

Hi all, just reading my old SB How To Run A Lathe book this AM. It mentions using a 'special center drill holder' instead of a three jaw drill chuck to hold center drills.

Does anyone use these things these days? Are they significantly more accurate than modern tail stock drill chucks?? If so, where would I find holders for sale? (I have two lathes for restoration having MT 3 tailstocks and one shop lathe with tailstocks using MT 5.)

Thanks
Glenn

You are looking for something like this. It appears that it is an item no longer stocked by tooling distributors.

I used them a lot years ago when I used to do one-off tooling. In theory, the center drill will be closer to absolute concentricity than it will be in a chuck. In practice, I doubt that you will get into a situation were absolute concentricity will be critical.

[SteveHGraham]

I had no idea that existed.

[neanderman]

Very interesting. I'd like to hear more about any advantages to these.

[GlennW]

Looks like a good way to break the tip off if the tailstock isn't perfectly aligned.

Center drills will find the center of spinning stock if you let them.

[Russ Hanscom]

I have a set of assorted sizes and use them as intended - thought that was the only way!

[Harold_V]

I have a set of assorted sizes and use them as intended - thought that was the only way!

Nope! Not the only way, and is to be discouraged for small center drills. Read Glenn's comment on breakage and consider how the added rigidity of the holders can restrict the ability of a center drill to seek center. You can get away with it on center drills larger than a #2, assuming the amount of error isn't significant, but it's a sure recipe for breaking center drills if there's a little misalignment of the tailstock, and there usually is. This condition presents the center drill to the spinning stock off center, so it must behave like a boring bar, which it is unable to do, so the tip breaks off.

When I center drill with small center drills, I go so far as to grip them only by about 1/8" of their cylindrical body. That allows the center drill to oogie in the chuck enough to find center without breaking the tip. I also only hand tighten the chuck, so it can move easily. This has resulted in the virtual elimination of breakage of small center drills.

For small center drills, it's important to pick up the material slowly, so the center drill has time to seek center, and the feed rate doesn't overwhelm the tip.

Harold

[SteveM]

Looks like a good way to break the tip off if the tailstock isn't perfectly aligned.

Before I learned how to align my tailstock, I was using a carbide spotting drill in the lathe. I heard a crunching noise, pulled the tailstock ram back and the entire point of the drill was gone.

I don't use those on the lathe anymore (I've since picked up some HSS ones) and I have the tailstock aligned better now. It's very slightly off in the vertical plane but good front to back, so much better bit not perfect.

Steve

[SteveHGraham]

Dang. Glad I don't use them.

[BadDog]

I've never used them, seems way too much trouble to me. The only place I see a benefit is when working on a smaller lathe when you often need to work at or near capacity between centers. The center drill holders are only about the the same length as the tail stock center, so little or no extra bed is required to mount and use them. Assuming your goal is to actually use them for their purpose, making center sockets for between center or center supported work, then it makes sense. On the lathes I've had (well, the "real" ones which were 11x37 and 17x60) the bed length was never an issue, and the tail stock slides easily (and frequently), so the last thing I need is another specialty "no real need" tool taking up space.

It gets even worse if you intend to use center drills for starter/spot drills. Now it's WAY shorter than the drill setup you are likely to be using, and you have to move the tail stock quite a distance back and forth (or LOTS of quill movement) to make use. I would quickly fling that across the shop and just use a chuck, sometimes several with one dedicated to spot drill use (particularly if the drills include MT taper or drills that need held in heavy key chucks). Though it occurs to me that having a longer setup, something like an MT adapter from a larger to smaller size (twice as long stick out), might be of use, particularly on a large lathe where the tail stock is a bit of work to move.

[super7b]

To the contrary of most of the posts on this subject, for the last 30-35 years it would never occur to me to put a centre drill in a chuck! I have holders for 6 different sized centre drills for both lathes and have never had any any issues at all. Simply made each one from a redundant taper shank drill. Chucks are made to a price or a quality and the degree of accuracy is a choice of your pocket, a decent taper shank drill is far more accurate than a drill in a chuck. All down to personal choice.
If your tailstock alignment is a problem, then correct the alignment and the problem goes away.

As with many things in life it's often worth trying something before deciding against it!

Lawrence

[Harold_V]

To the contrary of most of the posts on this subject, for the last 30-35 years it would never occur to me to put a centre drill in a chuck! I have holders for 6 different sized centre drills for both lathes and have never had any any issues at all. Simply made each one from a redundant taper shank drill. Chucks are made to a price or a quality and the degree of accuracy is a choice of your pocket, a decent taper shank drill is far more accurate than a drill in a chuck. All down to personal choice.
If your tailstock alignment is a problem, then correct the alignment and the problem goes away.

As with many things in life it's often worth trying something before deciding against it!

Lawrence

While I agree with your comments in principle, I certainly don't in practice. For starters, misaligned tailstocks are commonplace, and are often not capable of being corrected without considerable effort, if even then. In such a case, a drill chuck permits the very thing that is required for operation without breaking the center drill.

It is easier, by far, to remove a center drill from a drill chuck than it is to remove the taper from the quill. That's particularly true if one uses Albrecht or Albrecht type drill chucks. If one is engaged in multiple part machining, a good deal of time can be saved by not using any type of tool that requires being removed from the quill. Needless to say, if time is not of importance, the time required makes little difference to many. Speaking from the position of one who has worked for gain, even a second trimmed from an operation can spell a huge difference in the outcome of a project, so there are times when it certainly can matter.

As you said "As with many things in life it's often worth trying something before deciding against it!"

The benefits of using a chuck may have been lost on you "for the last 30-35 years it would never occur to me to put a centre drill in a chuck!"

I have used both methods, and each has its place. I use a holder for the bed turret of my Graziano, often of proper length for the given setup.

Harold