Mounting Drill Chucks

Looking for opinions on the the best methods to mount drill chucks on different size Jacobs arbors I recently acquired. Heard use chalk, warm them up for a shrink fit and other advice. Let me know what you think.

Thanks, Glenn

I clean both really good and heat the chuck to about 250 deg F and then set it on the arbor, give it a tap, set it vertical with the chuck up to cool. The newer ones I disassemble first, the ball cage looks like nylon and may not do well heating.
If it doesn't hold, use a bearing fit Locktite.

Dave

I clean the female taper in the chuck and the male taper on the arbor with a solvent like automotive brake parts cleaner or acetone. This is done to remove any oil or preservative, as even the thinnest films can cause a chuck to break loose from its arbor. I wipe things clean using paper towels or toilet tissue and give a second round of solvent washing.

When things are dried off, I usually just place the chuck on the arbor and give the end of the arbor a good smack with a brass "bumping bar" I use in the shop. Then, I place a piece of thin copper sheet on the anvil, and pick up the arbor with the chuck pointed upwards. I give a good swing and hit the tang-end of the arbor hard on the copper sheet on the anvil. I repeat this a couple or three more times to be sure things are driven tight together. I've had only one chuck work loose on its arbor when I used this method. I cleaned things up, re-drove it on, and it worked off the arbor again. I keep Loctite 603 (cylindrical parts setting compound, permanent grade) in the shop. I cleaned the tapered fit with solvent, put the Loctite 603 on the tapered surfaces and drove things back together using the anvil. That was over 10 years ago, putting a 1/2" heavy duty Jacobs chuck onto an R-8 arbor. Never had a problem since then with that chuck coming loose on the arbor. I've mounted quite a few other chucks without heating them, though the method makes perfect sense to me. I mounted a 3/4" Jacobs chuck and a 1" jacobs "super duty chuck" on arbors with just driving things on cold using the anvil. I think hitting the tang end of the arbor on something as massive as a 200 lb anvil has to really drive things together. I give a good swing and come down hard when I drive the tang end of the arbor against the anvil. Isaac Newton's laws work quite well for this sort of thing.

For those that like to "heat shrink" their shanks on, just remember, the only way to get them off is to cut them off and bore out the dutchman. I always drill a sizable hole thru the chuck body such as a 17/32 " hole. That way, you can use a drift to drive the shank off without damage to the shank or the chuck body. Installing them, follow Joe's method, always worked for me, never had one to come loose on me.
I have a older No. 20 Jacobs chuck that came from the factory with a 1"-14 thread thru the body of the chuck so you could a big set screw or equivalent to drive it off the shank. Ken

Instead of heating the chuck, I put the arbor in the freezer.

Andy

Thanks for all the info I'll give it a try and let you know what happens.

From Jacobs:

John

Andy FitzGibbon said:

Instead of heating the chuck, I put the arbor in the freezer.

Andy

Click to expand...

The only problem I see with "freezing" is that when you take it out of the freezer the humidity in the air will condense (most likely) on it while you are trying to install it.

JMHO

-Ron

The condensation and melted frost will produce a "rust lock".

We used to chill smaller parts for shrink fits with dry ice and alcohol. The alcohol, being a liquid, gives much better heat transfer between the part(s) being chilled and the dry ice. The alcohol also tends to prevent the frost from forming on the part when it's pulled out from the dry ice/alcohol.

My two cents on the matter is simply that Jacobs (along with any number of other designers and users of self-locking tapers) never relied on any shrink fitting to improve the connection across one of their male/female tapers. As long as there is no film (such as oil or preservatives) between the mating surfaces, and as long as the mating surfaces are properly machined and ground with no burrs to prevent good metal-to-metal contact, locking tapers should do what their name says.

MetalCarnage said:

The only problem I see with "freezing" is that when you take it out of the freezer the humidity in the air will condense (most likely) on it while you are trying to install it.

JMHO

-Ron

Click to expand...

I wipe the surface and install it immediately, before condensation can form. I've disassembled a couple I put together this way, and observed no rust issues.

I clean both parts and then use a little fine grit lapping compound and give it a good lap. Then clean again and check for the fit. Then use the aforementioned alcohol to chill the morse taper and put the chuck under a drop light (75 watt) for an hour. Then put the parts together with a solid bump.Been working for 50 years.

JH