The Home Machinist!

Needing a Chuck Key for a Old 3/8 drill.
Anyone know where to find a Key Size chart?
Everything that I can find on the internet only says the Pilot size.
What about the "Gear" size and tooth?
Jim

Unless a real oddball, most chuck keys will be listed by pilot size. I tend to replace the bent coathanger type of key with a cross drilled type, although I have broken teeth from the cheeper home store variety. I find an old round shoe lace tied to a key for the hand drill by the cord plug, not only reminds you to unplug before changing bits, but make the wherabouts of the key close at hand.

My local home store carries a 4 way key, that I keep around the lathe, as it is mostly universal, and one in the tool box fro the occasion I have a helper that puts the key anywhere. (Grrr).

Flybynight wrote:Needing a Chuck Key for a Old 3/8 drill.
Anyone know where to find a Key Size chart?
Everything that I can find on the internet only says the Pilot size.
What about the "Gear" size and tooth?
Jim

The gear sizes (diameters) and tooth-counts are similar but not quite standardized.

For this reason, when re-assembling a Jacobs-type chuck--you need to nudge the outer collar up and down while test-fitting the key until it fits right again.

Doug4d3s wrote: The gear sizes (diameters) and tooth-counts are similar but not quite standardized.

For this reason, when re-assembling a Jacobs-type chuck--you need to nudge the outer collar up and down while test-fitting the key until it fits right again.

yes I have a 4 way and two have the right size pilot hole, but one gear works, and the other is too large. I want to buy a Tee handle key but don't know what to order?
I guess there is not chart any where.
Thanks
Jim

There is a chart in the Enco catalog. use-Enco.com But it's for Rolm, Jacobs and "jacobs like" chucks. You haven't stated the make on yours. For Jacobs chucks, the model number will tell you which key fits.

Thanks. I have seen the list of chucks.
I don't know the make of mine.
I have a 4 way that works. But I would like a good T handle one.
That is why I needed a chart that tells the hole size along with the tooth size.
Like I stated doesn't seem to be a chart like that.
Thanks again
Jim

What's the size of the pilot and the pinion on the key? I'll check my Jacobs key collection and see if it matches to a particular #. Here's my guess, it's a KG1, K2, K30 or K32

The pilot is 1/4 inch.
But I have TWO 1/4" on my 4 way. One works and the other the gear is to big.
Thanks
Jim

What is the size of the pinon of the key? That should determine the key number.

How do you figure the pinon size?
By mesaurement, or number of teeth?
Or something else?
Jim

There's a listing of the various Jacobs chuck keys in their website, but of course it only references the pin size and the chuck model number to match them up.

http://www.jacobschuck.com/images/produ ... essory.pdf

I guess you've have to have some Jacobs chucks kicking around to be able to gauge the tooth size and match to a key for other makes of chucks.

Flybynight, just measure the od of the pinion. If you want to give me a tooth count, that will verify the correct key. I've got a number of spare keys, I've picked up.