Precision Micro drill chuck with hand feed

Recently acquired a hand feed precision drill chuck. For those little detail tasks such as tiny roll pin holes or lockwire holes etc.

Chose the Jacobs with the key as it appeared to have a range from around smaller than 1/16th to 5/32. Other well known brands that are keyless had a lttle less range.

Chose a straight shank although was tempted to go with the morse shank.

Prior to purchase, I wondered just how the extension (given the telescoping style joint) would function in respect to the possibility of radial tolerance .... but I see the telescopic parts are held in rotation unison via some type of spring action that allows it to slip when opposing twisting motion is applied.

(Note: There is also a spring return axially.)



The amount of force to counter-rotate the parts (ie shank vs chuck) is notable but readily done with the hands. The literature on any of these doesn't reveal this characteristic. Not thinking this is a clutch or maybe it is? As well as perhaps a method to compensate for the radial tolerance on that telescope which somehow moves with comparatively little force - just that amount to overcome the return spring.

I will certainly try it out and report back .... but is this feature something that is part and parcel for these items?

I have several of these units, not all the same make. None of them allow the chuck to slip on the drive shaft. The chucks have a tapered mounting hole and the male taper is supposed to be pressed in hard enough that the chuck will not slip and will take major wedging action to remove. Removing a chuck that has been properly mounted is so difficult that you can find a number of old threads on PM about various ways to do it.

If the chuck slips on the taper while drilling, it usually ruins the taper on both the chuck and the drive shaft, so you want the chuck to be properly tight.

Larry

Most likely there is a small drive pin through the outside of the shank to engage a slot on the floating inner shaft. Shouldn't slip there.

HuFlungDung said:

Most likely there is a small drive pin through the outside of the shank to engage a slot on the floating inner shaft. Shouldn't slip there.

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This is exactly right^^^^^^^^^

Also, if you need one of these units, you get what you pay for. I spend around $300 for mine, and its a dream, when compared to a cheep one.

I can drill down to .008 dia holes, 1/8 deep in D2.

The cheep one will not do that on it's best day.

My albrecht slips along the drive shaft via key and slot.

Rickyb said:

My albrecht slips along the drive shaft via key and slot.

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I have the same unit and no slippage. .016 drills. 18 years of use so far.

It also depends on the quality of the chuck. The older jacobs chuck on my High Speed Hammer drilling machine is labeled 0 - 5/32, a gutsy assertion.

Upon reading the comments, a good look with an eye toward a slipping taper was conducted and sure enough that was it. As to why it would slip but not dislodge is somewhat a mystery, but the twist with a decent tug parted the assembly. Cleaned it up and set it, tested it out w a 040 ish drill in some 1018 - produced great results.
Many thanks!

The Servo 'sensitive' drilling machines are structured just like any typical drill press, not a traditional sensitive drill like a Hamilton or HSH which are more like jig borers. On a real sensitive drilling machine the torque of the motor and the feed are isolated from the spindle.
I don't know if mine is really any more sensitive than any other, but i can definately feel when I'm getting almost through the metal.