Tightening keyed drill chucks.

[tonyfoale]

Tightening a keyed Jacobs style drill chuck would seem to be an action that is in little need of explanation. However, I have often seen people struggle with this and there are countless workshop videos on the net in which poor practice is the norm. This video demonstrates a simple trick which will ensure the best results, everytime.

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[Toolmaker51]

There is a hard to find chart that lists pilot diameter and tooth count of chuck keys. Some chucks [name brands] list correct key size. Some bevel engagement can be cured, lightly - minimally pressing the sleeve toward the chuck nose. Retract jaws and press with a short proper tube or bar so relieved.

My chuck technique is from an OLD machinist, used especially in large sizes.
Open the chuck sufficiently for bit. 'Rattle' the bit some while hand closing the jaws, helps insure small bit contacts all three, very helpful with hand-tight chucks. Then just as Tony emphasizes, lever position perpendicular to axis, I tighten at first hole. Not necessary to exert tremendous force, and never a cheater. You'll now be surprised as you proceed to hole two and three, exerting same force yet achieving more jaw grip. Provided jaws haven't spun too many shanks [usually taps], it will be far less able to do so.
Hand tight chucks work more on torque to hold securely, and they lose it reversing. So tapping [other than hand turned] is rarely successful.
I won't tap with a drill chuck other than initial start by hand, more or less like a tapping stand.

[tonyfoale]

I won't tap with a drill chuck other than initial start by hand, more or less like a tapping stand.

I agree completely.

[skibo]

I do not like the new hand drill today,with their hand tightening chucks, they never hold a grip,even my heavy duty 1/2 inch Delta!

[tonyfoale]

I do not like the new hand drill today,with their hand tightening chucks, they never hold a grip,even my heavy duty 1/2 inch Delta!

Yes most are terrible. Made down to a price. The keyed chucks fitted to otherwise similar drills are plain awful too, they generally come with ill-fitting keys.

[DIYer]

Thanks tonyfoale! We've added your Keyed Chuck Tightening Method to our Miscellaneous category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

Keyed Chuck Tightening Method by tonyfoale

tags: chuck key

[uv8452]

The rattle and the initial closing the chuck by hand is important. Let me add: The more force you have to exert to the key to clamp the bit the more worn out ist the chuck. Don't try to defeat the chuck - buy a new one.

[desbromilow]

OK - how about tips and tricks for opening a tight jacobs style chuck? I have an old chuck on an older drill which is "frozen". It gets soaked in deisel every time I walk past it, gently heated occasionally - but still no movement in the chuck. Any suggestions?

Thanks,
Des

[tonyfoale]

There are penetrants more effective than diesel. The question that comes to mind is; why is it stuck? Is it rusted, was it over tightened, did it get a bash. Different approaches for each. How are you applying the opening torque, with the chuck key or stillsons etc. Try more than gentle heat.

[IntheGroove]

A Jacobs chuck can easily be disassembled even with a bit in it...