Thread: dumb ? - changing a drill chuck

Number of issues to deal with here.
Because you are trying to retrofit to existing equipment, you need to be sure that the replacement will fit the mounting on the drill. I assume that you are dealing with a handheld drill rather than a drill press as I am not aware of any B&D drill presses from their past.
For a handheld, the chuck is normally screwed onto the spindle of the tool, and there is often a retaining screw fitted from within the chuck body into the spindle as a locking screw to prevent the chuck winding off the spindle. The retaining screw is normally left hand thread.
There are a range of mounting diameter and thread combinations, and this is what you need to match to the spindle. If you are very lucky, the instruction manual (if you still have it) might include the mounting thread size for the chuck and spindle, or you might locate the information on the net. Otherwise you would have to remove the original chuck to identify the thread before you can get anywhere.
Drill presses are normally easier as they have Morse Taper spindles, and any chuck combined with a suitable arbour matching the chuck and spindle taper can be made to fit accurately without much hassle.
Once you know what mounting thread you need, you can locate a replacement on the internet, at a tool or industrial supplies supplier or possibly a hardware store. Fitting is basically screwing onto the spindle and fitting the retaining screw.

What is the problem you are having with the original chuck, poor grip or runout? These can be interrelated if the chuck jaws are damaged. If either happens on its own, for poor grip it is normally strained or damaged jaws, or swarf in the chuck mechanism. For runout, particularly if the unit was sound when new, it is most likely to be worn spindle bearings in the drill itself, or a bent shaft caused by dropping on the chuck and spindle once to often.

Hope this helps.

If your drill is old as you say there may not be a retaining screw, if not fit the chuck key and smack it sharply with a timber offcut, it should come loose, by memmory you hit clockwise

Thanks guys.

The chuck is jamming when I try and tighten it with the key.

I can't find any locking screw though. By the looks of the shaft you must hold it with a spanner and then unscrew the chuck.

I am presuming it will have a left hand thread.

Get a large allen key andfit it into the jaws of the chuck and tighten as best you can.

If you are able to put aspanner on the flats that will help as well.

Make sure just the chuck and spanner are sitting on the egde of the bench because if you try to hit the allen key with the body on the bench you could bend the drill shaft.

Now position the chuck on the bench and have the allen key at about 45 degrees and hit with your hammer as hard as you can.

It may take a couple of belts to free it up depending on how rusted the joint is betwee the chuck and the shaft.

Take the chuck and drill to a power tool specialist shop so you can match up the correct chuck and spindle size.

I think your time/moneys better spent buying a new drill. Can get a makita keyed version for under $100.

Finding a new replacement may be your biggest problem if its real old the thread may be old world Not metric

On virtually any drill with a threaded arbor, the thread is a "normal" righthand one. Which means that, when holding the drill with the chuck pointing towards you, you will fix it by turning clockwise and unscrew it by turning it anti-clockwise. Only when a drill model with a threaded arbor has reversible rotation, the thread will still be righthand but as a rule the arbor will have an inner thread as well, to secure the chuck on the arbor with an inner screw, to prevent it from loosening itself when reversing. This screw is visible deep in the back of the chuck's borehole; should the beaks be stuck and partially closed, than you might still be able to see it with a torch. Should this screw be present and you cannot access it with a screwdriver (it may be a slot type, phillips type or allen type), there is little other option than to grind the chuck to pieces and "peel" it from the arbor in bits and pieces. I once did that on an old and collectible Siemens drill, and patience and a bit of care helped me to succeed without any visible damage. This retaining screw and the inner arbor thread are lefthand as a rule, so the screw inside the chuck has to be loosened clockwise.

But the above could be academic, because your B&D is old and will probably not be a reversible model. So there is only the thread. Standard thread gauges are 3/8 " for drills up to 6 or 10 mms capacity, 1/2 " up to 13 mms capacity and 5/8 " for 16 mms.
The number of turns on one inch are 24 for 3/8", 20 for 1/2"and 16 or 5/8". Due to the high torque of large drills, the 5/8 can be a huge pain, but your B&D will probably have 3/8 x 24. Sometimes the thread type is stamped somewhere on the chuck. Jacobs (the standard chuck deliverer for B&D for many years) used to do that early on.

A way to loosen a thoroughly stuck chuck is to heat it, but i'm not fond of that, since the heat will also transfer to the bearings and gears and grease. Not much of it will reach the armature and coils, though. If only the chuck itself is heated with care, also the drill's paint job will not suffer and will not discolour (which is less of a worry on old scathed drills or bare aluminium ones but moreso with nylon housings, which might distort).
Another way that is often suggested is, to stick the original key in one of the holes (provided that it is a keyed chuck) and give it a quick sharp blow with a hammer. But on a Skil drill, such a stunt with a bit too much force cost me a gear tooth once and i ended up chucking the whole machine. Still, this option might work for you. A stuck thread is often so because of very high friction and torque (turned too tight over the years) and/or from rust or clogged substances in the thread. The two factors combined often make the difference. Sometimes the thread itself is relatively clean and it is just the face of the chuck's hind end and the arbor face at the thread's end, that are fretted together. For removal of cloggings and loosening of rust, a special combination of lubricant and solvant (in Europe we have WD 40 and IMAL and Molykote, but you're bound to have similar stuff over there) will penetrate the thread because of high capillary action and it's very thin fluidity. Spray the joint of arbor and chuck several times, over several days. Kerosine with a few drops of very light machine oil is a substitue, but not as good, since it lacks the additional active chemicals present in the readymade solutions. The better it soaks in and penetrates to do its job, the better.

When it is time for a try, support the arbor between the drill collar from underneath, preferably on something sturdy and rigid. I once used a heavy spade and put it with its handle on the stone floor of the shed, with its blade sticking up in the air. I clamped it in the wood workbench, to fix it steady upright and to make sure all the downward force of the hammer blow would be transfered to the floor. Than i used the blade's edge as a steady support for the arbor. Without such a support to take the blow, the brunt would be on the front arbor bearing.

Turn the chuck so that, when it points towards you, one of the key holes will be at 9 o'clock. When the drill is two speed, select the low one. Insert the key in the hole and rest the arbor against the support. A quick sharp blow should do it. A 400 grams bench hammer will suffice, a momentum hammer (the one with the pellets inside, did i get the name right?) is even better. If one blow has not loosened the chuck, rotate the chuck for 1/3 of a turn, to expose another keyhole and other gear teeth to the second blow or successive blows. Several blows on the same keyhole and gear mesh, will burr the keyhole and provoke higher chance of tear or shear of the particular teeth involved.

lots of success!

gerhard

Hi Ivor,

i reread all posts and saw a detail that i had overlooked. The arbor of your drill appears to have flat sides that will probably fit a spanner or standard nut key (my native tongue is Dutch, so forgive my odd choice of words now and then). So much the better, this spanner will be your support and will relieve the gear teeth from the momentum forces of the blow. That is a definite advantage.
Clamp the spanner upright in a vise, making sure it's other end rests on something solid (like the lower part of the movable vise beak), to transfer the momentum to. Lay the drill's arbor in the spanner's beak so that its fits the flat sides, making sure one of the keyholes is positioned somewhere in a 8 to 10 o'clock position. Insert the key and whack it. When you are sure that the spanner indeed fits the arbor and its flat sides snugly to properly absorb torque forces, you may also whack it wee bit hardeer without fear of damage. While hammering, support the drill's weight by holding its motor housing, of course. When its bulk hangs loose on the spanner, damage may occur or the arbor may get bent. The more secure everything is held in place, the better the hammer blow effect will be and a minimal amount of blows will be necessary.