Introduction: Drill Chuck Adapters

Why would you need a chuck adapter or use a chuck adapter on your power drill or drill press?

Drill presses made for swapping out the chucks are expensive; and with them swapping out the chuck, is no harder than changing a drill bit in the chuck. But not all drill presses are made equal, and swapping back and forth between the two chucks can be time consuming as well as hard on some drill presses.

If your drill press is like mine; (Cheep) the chuck just won’t grip a drill bit as small as 1/16 of an inch. The flats on the jaws of the chucks make too large of a gap when the jaws are closed. Old and large drill chucks are notorious for these gaps in the closed jaws. My drill press is a royal pain to swap out the chuck for one with tighter jaws, and I want the larger flats for when I am using a larger tool in the chuck for grip.

Using an adapter is no harder than changing a drill bit and this Instructable is on making your own chuck adapters from discarded drills.

This is a little different from this Instructable on making a tapered tailstock.

Step 1: Tools

The tools you will need for dissembling the drills for parts and making the adapter arbors are:

Phillips screwdrivers

Standard screwdrivers

Torx screwdrivers

Chucks and keys

Allen keys or Hex keys

Bench vice


Pin Punch



Wire Brush

Step 2: Parts

I salvage from peoples waste bins; this is how I get my tools and parts for free. When I have decided if a tool is worth fixing or not, I ether repair the tool or dissemble it for parts.

The most important parts for a drill adapter; is the spindle for the chucks, and the drill chucks.

The bits and pieces I salvaged from drills in the waste bin:



Spindles and Arbors



Drill Chucks and Keys

Step 3: Chucks

There are more makers of 3 jaw drill chucks than Jacobs; however the basic design is the same as a Jacobs 3 jaw drill chuck. Whether keyed or keyless, internally there is very little difference in the design.

The good chucks I have are:

½ inch reversible plain bearing ½ inch 20 thread spindle

½ inch reversible Multi Craft ⅜ inch 24 thread spindle

⅜ inch reversible Multi Craft ⅜ inch 24 thread spindle

⅜ inch reversible plain bearing ⅜ inch 24 thread spindle from a vintage power drill

¼ inch reversible plain bearing ⅜ inch 24 thread spindle from a vintage power drill

⅜ inch reversible keyless chuck ⅜ inch 24 thread spindle

½ inch nonreversible plain bearing ½ inch 20 thread spindle from a vintage power drill

⅜ inch nonreversible U4G41 ⅜ inch 24 thread spindle from a vintage power drill

¼ inch nonreversible MC2G41 ⅜ inch 24 thread spindle from a vintage power drill

Step 4: Removing a Good Chuck

See my Instructable Drill Chuck Replacement.

Step 5: Disassemble the Spindle Assembly

If you are like me; you like to keep the chuck and spindle assembly assembled when you store them for later use, so remove the chuck from the spindle and arbor assembly.

The Makita cordless reversible drill makes great adapters arbors; the chucks spindle assembly comes apart easily with just one locking pin and one snap ring holding the gears, bearings, and other parts, on the ⅜ inch shaft. The ⅜ inch shafts make good adapter arbors since they can be used in a ⅜ inch chuck or a ½ inch chuck. If you use a ½ inch spindle and arbor you can only use the adapter in a ½ inch chuck.

Step 6: Press Fitted Gears

To remove the bearings and other things behind a press fitted gear on the spindle assembly; place the spindle assembly in a loose vice, and punch the shaft out of the gear with a pin punch. This may take some force so use a pin punch just smaller than the hole in the gear.

Step 7: Sort the Spindles & Arbors

For a spindle and arbor; you can use a ⅜ 24 thread per inch bolt or a ½ 20 thread per inch bolt cut down. However the adapter will not be a secure reversible adapter, and it can come apart in reverse.

The best spindles for making adapter arbors have straight shafts like the ones in the Makita cordless drill; but do not throw out spindles with tapered arbors, you can use them to make a tapered tailstock, they make great holders for when you are cleaning the chucks with a wire brush, and you can use them to rebuild drill chucks. Surprisingly the wire brush in this pic is spinning as I clean the chuck.

Step 8: Sort the Chucks

Sort the chucks by closing the jaws and seeing if they are tight enough to hold a drill bit as small as 1/16 of an inch or smaller. Most ⅜ inch chucks will hold a 1/16 drill bit but not all of them will, and some of the jaws will be belled. (Worn out so the chuck will not hold a bit properly.) You can compare the chuck to a 1/16 drill bit to check the chucks grip, or put the drill bit in the chuck and close the jaws tight to find out.

Many ¼ inch chucks and some ⅜ inch chucks will hold drill bits even smaller than 1/16 of an inch so if you want chucks that the jaws will hold a 80 gage or a 1/64 inch drill bit tight you might want to look for a 0 to ¼ inch Jacobs chuck.

Step 9: Gather the Parts for the Adapter

You will need a chuck and key; and a good spindle arbor and setscrew.

Grind any nibs or other obstructions off the spindle arbor.

Step 10: Assembling the Adapter

The chuck should go on the spindle easily turning it clockwise and the setscrew goes in the spindle easily screwing it counterclockwise. And you are done, a drill chuck adapter with tight enough jaws to hold a 1/16 inch drill bit or smaller.

I like to have a ⅜ to ½ inch adapter; just so I don’t need multiple drills, I mounted the ½ inch reversible Multi Craft chuck with the ⅜ inch 24 thread spindle. Now I have 3 adapters, a ½, a ⅜, and a ¼ inch reversible drill adapter.

Step 11: Chuck on Chuck Adapter

OK I like to do this just because I can; and I have the parts, a male spindle chuck mated to a female spindle chuck. This adapter will have a strong grip in a keyless chuck, and since I used a 0 to ¼ Jacobs chuck it will hold a 80 gage drill bit.

Choose two chucks that take the same key to make things simple.

I started with a 0 to ¼ inch Jacobs chuck model MC2G41, it is a nonreversible chuck from a vintage power drill.

Next I selected a ⅜ inch chuck that mounts to a male spindle, this chuck is tight enough to hold a 1/16 inch drill bit.

Mate the ¼ inch and the ⅜ inch chucks, just screw the male into the female spindle mount.

Next select an Allen key or Hex key the largest you can find that fits into the ¼ inch chuck, if you use a Allen key that will only fit the ⅜ inch chuck, you will only be able to use the ¼ inch chuck for drilling.

Cut the Allen key to about 2 inches long; put the Allen key shaft in one chuck and the chuck key in the other chuck for safe keeping.

There you have it; a chuck on chuck adapter that will hold a drill bit as small as 80 gage. As odd, as this adapter looks, it is surprisingly simple to make and it is very accurate with no wobble in the chucks. The down side of this adapter, it is nonreversible and it takes up about 4 inches of a drill presses slide.

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