Keyless Chuck for Impact Driver




Introduction: Keyless Chuck for Impact Driver

Had a bunch of dead Harbor Freight 18V cordless drills because the batteries are dead. I upgraded to a Bosch Impact Driver for most of the purposes I used the Drills for. The occasional need for drilling something made me repurpose one of the drills into a keyless chuck for the impact driver. I know I could have bought one, but I think that defeats the purpose of this site and my need to create something.

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Step 1: Take Apart a Retired Cordless Drill.

I opened up a retired drill. On the Harbor Freight (HF) drill there was a left handed thread screw locking the chuck to the shaft. Remove that screw.

The HF drill chuck has a 5MM allen socket. Actually, I could not find my metric allen wrenches and I managed to force a 7/32 allen wrench in there, but it was too tight, so I assume it is a metric 5 MM.

To liberate the chuck from from the drill shaft (soon to be an arbor), I clamped the business end of the drill shaft in a vise and used the allen wrench to unscrew the chuck from the shaft. On the HF the threads were right hand thread.

Step 2: Cut the Planetary End Off the Drill Shaft.

I used a cutting wheel to cut the flange off the end of the shaft. At this point I had a shaft that was round, with a threaded end for the chuck.

Step 3: Grind a Hex Pattern on the Shaft

To get a hex shape on the shaft, I winged it.

I put the round shaft in a pair of vise grips and ground two flat spots on the shaft keeping the vise grips perpendicular to the grinding wheel. This allowed me to get two flat grinds opposite each other.

I ground it to about 5/16 across the two flat spots.

I rotated it approximately 60 degrees. I did this by eye.

I repeated the grinding process.

I rotated again for the final grind.

I got out the caliper and continued grinding until I achieved a 1/4 (.2500) measurement on all six sides.

Step 4: Grind a Rounded Grove About 5/16" Up From the End.

After achieving a 1/4" hex pattern, I put the shaft in a cordless drill and ground a rounded groove in the hex shaft about 5/16" from the end. This allows the impact driver to "latch" onto the shaft.

Thats about it.

You might challenge why spending an hour building something that costs about $7 on Amazon is worth it? My answer is because in the end I have a 3/8" keyless chuck drill accessory for my impact driver and I can say I made it...

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    4 Discussions


    8 months ago

    Have you had problems with the friction rings on the 1/2" wrench?
    I just got that exact unit the other day,
    First time I put a socket on it got stuck and bent the friction ring when taking it of.
    That was my first and last ever ownership of a Bosch. Returned it and returned to Makita!


    4 years ago on Introduction

    veryyyyy usefulllllllllllllll.

    just one thing. does it rotate as a drill without shaking?

    u know! if the hex pattern go a little left or right or ... it will shake and shaking is bad for drilling!


    Reply 4 years ago

    Very true! The degree of shaking depends on how close you come to getting the hex pattern centered in the shaft. I made two and both of them had some wobble, but for slow speed drilling they work fine. If I were to do it again, I would try to setup some kind of jig to control the grind. I thought of using a chop saw with a metal blade and a wood buck to control the arbor, then slide the arbor back and forth taking off the right amount from each side. I decided since my goal was to make something while not taking too much time making it, I would just wing it and take my lumps.