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Jacobs Chuck Choice

Jun 3, 2021
Norwalk, CT
Mark, I'm having a hard time finding a Jacobs chuck bigger than 1/2 in. If you have some time, maybe you can tell me where is a good place to buy one. I found a few on Ebay, I think, LOL, but the big one have a #3MT. I'm not opposed to other brands if they are good. Thank you and Aloha

Hey Emiliano - I was curious and went and found this - no idea quality but price isn't crazy. I have a 3/4" shank drill bit I bought accidentally (needed a > 1/2" cut, didn't realize shank size) would be handy for some projects...I'll give it a shot and report back.

Emiliano Achaval

Staff member
Beta Tester
Dec 14, 2015
Maui, Hawaii
@Emiliano Achaval I correct myself, the part which fits into the chuck body is called the arbor and it is sold separately. The "J" taper is a Jacobs taper, so perhaps that is what makes a chuck a jacobs chuck.
View attachment 40328
Here is my itemized Zoro bill from 2018 showing the separate entries. I note also that my chuck is apparently 5/8" while the shank on my big 3" Forstner is half inch. Thing is, even if I had a bigger chuck at some point the arbor starts to loose its grip on the chuck body or the quill. I think drilling with a 3" Forstner is just a big ask.

I was able to find a lot of information (and refresh my memory) at the Mcmaster.com web site. I suggest you check them out.
Thank you for taking the time to research this!!