Jacobs Drill Chuck.

jcdammeyer

John
Premium Member
Yeah. I don't need 3/4" all that often but it's nice to have for that occasional use.

The one that is normally on the drill press is a no name brand but the chuck key has missing teeth.
And I haven't found a key that fits all that well. A K3 sort of does but not quite.
DrillPress16mmChuck.jpg
WornChuckKey.jpg
I have this one that came with the mill. 1mm-16mm with a M18 taper (~5/8"). It came with an R8-M18 arbor but what I really need is an 3MT-M18 to be able to use it. Haven't found it at KBC yet. I should check Aliexpress.
New16mmChuck.jpg
 

David_R8

Scrapper of metal
Moderator
Premium Member
I have several keys that I inherited but don't fit any of my chucks. Have a look at them tomorrow.
 

Tom Kitta

Ultra Member
Rebuild kits for Jacobs chucks are expensive even on auction.

Expensive == like $50 for rebuild kit for 1/2 in chuck

More then $50 for 3/4 ball bearing chuck.

Essentially once rebuild some old beaten up chuck ===> brand new Jacobs chuck.
 

jcdammeyer

John
Premium Member
Done. Should be here Saturday.

I don't use the Craftsman drill press enough to justify a ball bearing chuck like the one I splurged on for the mill.
I have only one 1/4" chuck with a TT holder. I'd like to get a few more so I can have more than one drill bit in the tool rack.
 

jcdammeyer

John
Premium Member
Rebuild kits for Jacobs chucks are expensive even on auction.

Expensive == like $50 for rebuild kit for 1/2 in chuck

More then $50 for 3/4 ball bearing chuck.

Essentially once rebuild some old beaten up chuck ===> brand new Jacobs chuck.
Not sure that rebuild stuff would fit though on a no name chuck.
 

Tom Kitta

Ultra Member
Not sure that rebuild stuff would fit though on a no name chuck.

Rebuild is only for same type of chuck - so Jacob chuck say no 34 would have its own rebuild kit.

I just acquired another Jacob chuck and its 6A with an E taper... Yeah, who knew there was an E taper. Its JT E. Bet you did not know about it. They are super rare and feel like they are all before WWI, right after Jacobs started making chucks. Have to post it on machinist FB forum.
 

jcdammeyer

John
Premium Member
The MT3-M18 arbor arrived today. I dug out a couple of spare plastic holders since this one came in one too. I'll file them away in a corner where I'll likely forget about them for a few years. DrillChuck.jpg
 

Degen

Ultra Member
Premium Member
I just switched from a Jacobs style chuck to a keyless one and am impressed. Reason for the switch was simple, chuck came off the jacob taper R8 shank and did damage to it (first time this has ever happened to me, I suspect it was the heat transfer from drilling to break it free).


Replace the arbor with new but added a new chuck, good to have backup just in case.
 

Tom Kitta

Ultra Member
I just switched from a Jacobs style chuck to a keyless one and am impressed. Reason for the switch was simple, chuck came off the jacob taper R8 shank and did damage to it (first time this has ever happened to me, I suspect it was the heat transfer from drilling to break it free).


Replace the arbor with new but added a new chuck, good to have backup just in case.

If you are going to drill hard you may consider freezing the jacob taper and heating the chuck (or reverse). The mating is a bit ... harder to break (or near impossible).

There are chucks out there with integrated MT shank.

Keyless has its uses - it is nice for casual drilling. It is a chuck that not only hand tightens but also self tightens when the drill starts to slip. Main issues are:
- need a spanner wrench when chuck over tightens - so you are not free of "key"
- cannot reverse drill or reverse a tap etc. As self tightening feature becomes self loosening
- a bit more travel time is needed to change from one size to another.

Note that keyless has been around just few years less then Jacobs. Both are over 100 year old designs.
 

Degen

Ultra Member
Premium Member
If you are going to drill hard you may consider freezing the jacob taper and heating the chuck (or reverse). The mating is a bit ... harder to break (or near impossible).

There are chucks out there with integrated MT shank.

Keyless has its uses - it is nice for casual drilling. It is a chuck that not only hand tightens but also self tightens when the drill starts to slip. Main issues are:
- need a spanner wrench when chuck over tightens - so you are not free of "key"
- cannot reverse drill or reverse a tap etc. As self tightening feature becomes self loosening
- a bit more travel time is needed to change from one size to another.

Note that keyless has been around just few years less then Jacobs. Both are over 100 year old designs.
Well that may be, but the good chuck require mounting. The idea of heat and cooling to mount is actually very good and sound. However heat buildup in the chuck will counter that for the same reason and methodology.

Having tried the keyless chuck I am impressed. I find I have less slippage compared to a keyed chuck (even cranked down). I am also impressed with the tolerances (keyless is from Accusize and the keyed is from KBC and German made) the keyless compared to all
my keyed chucks and one true Jacobs, the keyless is way tighter and easier to operate.

IMHO (including research on what machine shops use) it truly becomes a personal preference based on experience.
 

Tom O

Ultra Member
I have 3 keyless ones for my mill and haven’t had a problem. I did read somewhere that the drill shouldn’t be bottomed out because as it’s tightened it pulls it in more.
 
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