Rebuilding Keyed Drill Chucks

I have a number of drill chucks from drills salvaged from waste bins throughout the years. Surprisingly the reason I get the chucks is most people don't know how to repair, replace, or rebuild a drill chuck. Rebuilding a plain bearing drill chuck is not much different than replacing a bearing in an electric motor or the wheel spindle of your car.

Most of my drill chucks are Supreme and Jacobs ¼, ½, and ⅜ inch chucks, they are constructed and rebuilt in the same manor. However in this Instructable I will demonstrate rebuilding a vintage Jacobs Plain Bearing chuck, and Multi Craft drill chuck.

This Instructable is different from the Instructable, How To Disassemble A Keyless Drill Chuck.

https://www.instructables.com/id/How-To-Disassemble-A-Keyless-Drill-Chuck/

I have two basic keyed drill chucks; Multi Craft and Plain Bearing drill chucks. Drill chucks where the gear teeth and the split ring nut is one piece, and the tin sleeve is a separate part, is a Multi Craft, like the Jacobs chucks on the left.

Plain Bearing drill chucks are like the Jacobs chucks on the right where the gear teeth and sleeve are one piece, and the split ring nut is a separate part.

The more common of the two drill chucks to rebuild are the Plain Bearing drill chucks. Most modern plain bearing drill chucks are easy to buy rebuild kits and sleeves for. However few people rebuild or repair Multi Craft drill chucks, they are cheap, easy to replace, and you cannot get rebuild kits, so I am just going to dissemble and clean the Multi Craft drill chuck.

A hydraulic press, bearing splitter, and brass spacers would be nice; you can even use a bearing puller to dissemble a plain bearing Jacobs chuck. But if you don’t have these tools, a vice, a brass bushing, and a hammer will do.

You may need a pin punch to push the jaws out of the chuck if they are seized.

Wire brushes for cleaning rust and dirt off the parts; I used a 22 caliber brush from my gun cleaning kit, and a wire wheel on my grinder.

Since I have the spindle and arbors, I will be using a spindle to dissemble the Multi Craft drill chuck.

See my Instructable Drill Chuck Replacement.

https://www.instructables.com/id/Drill-Chuck-Replacement/

Whether it is a male mount or a female mount plain bearing chuck; they disassemble in the same manner.

Open or close the jaws of the chuck to about half way.

Adjust the jaws of the vice so they only catch the sleeve of the chuck.

Put the brass bushing over the jaws of the chuck to the body of the chuck and whack it with a hammer.

The sleeve should come right off the chuck and the ring nut should fall out in two pieces. Don’t worry the ring nut is not broken it is made that way.

If the jaws do not slide out of the chuck with ease, use a pin punch to push the jaws out of the chuck body.

Use only soft wire brushes to clean the parts of the chuck; if you use sandpaper or files you can take the parts out of tolerance and this will ruin the chuck.

After cleaning; inspect the parts, you are looking for chips out of the threads and excessive wear like belling.

Belling is when the grip of the jaws are worn so the chuck will not hold a bit properly and the drill bit warbles. Belling makes a characteristic bell shape in the jaws when the jaws are closed. Looking at the grip of the jaws, the grip of the jaws will be wider at one end then at the other.

If the jaws are belled you may want to buy a rebuild kit.

You can buy rebuild kits from Jacobs or other suppliers all you need is the information on the chuck. However with vintage chucks like this vintage Jacobs, model: MC2G41, 0 - ¼ inch chuck, it is next to impossible to find one.

http://www.jacobschuck.com/

The rebuild kit will have 3 jaws and 1 split ring nut.

With most of the kits the jaws are marked so you can tell jaw 1 from 2 and 3.

The jaws are numbered so they will align up with the threads of the ring nut when the chuck is assembled. If you look at the threading on the jaws there will be a small step at one end of the threading of jaw 1, a big step on jaw 2, and no step on jaw 3.

When you reassemble the chuck; put jaw 1 in one of the jaw slots and going clockwise, put jaw 2 in the next, and put jaw 3 in the next.

Dab a little grease on the threads; I like to use graphite grease, put the ring nut on making sure you do not miss thread the jaws.

Holding the ring nut on with your hand thread the jaws out until they are closed, if you got it right the first time the ends of the jaws will line up.

If the ends of the jaws don't line up; take the ring nut off and switch any two jaws. Then put the ring nut back on and thread the jaws closed. This time the ends of the jaws should line up.

When the jaws line up place the sleeve over the chuck body and ring nut; make sure the jaws move in unison as you ease the sleeve over the ring nut. The sleeve should almost completely go on the ring nut by hand.

Adjust the jaws of the vice so they catch the ring gear; place the chuck on the vice jaws mouth down and using the brass bushing, tap the sleeve the rest of the way over the ring nut and chuck body.

And there you have it a rebuilt or refurbished plain bearing chuck.

Multi Craft chucks are not made for rebuilding, so most are discarded and the drill or chuck is replaced.

A bearing separator would be nice if you have one; but you can get along without one, just remember whatever you use make sure it only grips the lip of the chucks sleeve.

Again you will just need a couple tools.

Spindle and arbor you can get from a dissembled drill; or a brass pin punch.

A vice

A brass bushing

And a hammer

I used the spindle from a disassembled drill to remove the sleeve of the Multi Craft drill chuck.

Place the chuck in the vice so the jaws of the vice only catch the sleeve of the chuck.

Hit the spindle with a hammer pushing the sleeve off the split ring nut.

Remove the jaws and clean the chuck the same way as you cleaned the plain bearing chuck.

The Multi Craft drill chuck reassembles in the same manner as a plain bearing chuck; however the jaws on the Multi Craft chuck are not numbered one to three so, they can be hard to tell apart. The only way to tell 1 from 2 or 3, is to look for the steps in the threads.

Place the chuck on a table mouth down when you reassemble the chuck; put jaw 1 in one of the jaw slots and going counterclockwise, put jaw 2 in the next, and put jaw 3 in the next.

Dab a little grease on the threads and put the ring nut on.

Holding the ring nut on with your hand thread the jaws out until they are closed.

If the ends of the jaws don't line up; take the ring nut off and switch any two jaws. Then put the ring nut back on and thread the jaws closed. This time the ends of the jaws should line up.

Slip the sleeve on the ring nut as much as you can making sure the hole in the sleeve lines up with the spindle mount.

If the hole in the sleeve doesn’t line up with the spindle mount tap the sleeve lightly until it lines up.

Adjust the jaws of the vice so they support the sleeve of the chuck; but not so tight the jaws will catch the spindle mount when it comes out of the hole in the sleeve.

Place the brass bushing on top of the chuck and tap it with a hammer. The sleeve should slip right on the split ring nut.

And you are done one refurbished Multi Craft drill chuck.