Slipping chuck

[Les Symonds]

Help! I have a bench drill which I bought about 3 years ago. It's extremely heavy, being cast iron throughout, and has served me well during that time. However, a couple of weeks ago I had the work table tilted through 12degrees to drill the 1" sockets on the underside of some stool-tops, to take the tenons of the legs. Just as I finished the batch, the chuck dropped out of the drill - which was a bit scary. Problem is, it now keeps happening. It's a 2MT, with the top of the taper ground to what I can only describe as a 'pinched' shape, so it has to be slid into place and rotated until the top locates, then pushed home.....but it now just keeps slipping out.

What can I do to make it stay in place?

Les

[steve w]

maybe make sure the face of both the taper and insert are grease freeand clean and tap in with a block of wood.

[Eric Harvey]

if it has fall off the morse taper,then tapping home gently won`t hurt,but if its the push and twist fitting that has come loose then you might have to disassemble it to see to see if there`s any wear or a broken fitment,quite often there`s a spring somewhere in a push and twist joint,could be the spring has come out or broken,so the joint is loose,and hence it popping off all the time,cheers,

Eric.

[fuzzyturns]

The "pinched" end of the chuck taper is there so that the chuck can be ejected without damaging the actual taper. Most machinery accepting MT2 tapers will either have a hole through which an ejection bar can be pushed (like your lathe headstock) or have a built-in ejection pin that is activated when the spindle is moved right to the end (the zero position). It is possible that your bench drill also has an ejection pin or a drawbar, and it may have moved position slightly, thereby preventing the taper from sitting properly in the chuck holder.
At the top end of the spindle, is there maybe some locking nut or a thing coming out with either 4 or 6 flat sides? This would indicate that you have a drawbar inside the spindle (useful for tapers with a thread at the end), and you may have to see whether this drawbar has moved position.

[Les Symonds]

Thanks, guys, for the info.

Bearing in mind what you've said, I took a closer line and this is what I found.

The rising/falling shaft is geared to the control handle (rack and pinion) that I wind to lower and raise the chuck. That shaft does not revolve, but inside it is a second shaft, driven by the belt and this is the shaft that has the 2MT socket for the chuck to fit into. Both shafts have a slot cut right through them, in line with the top end of the taper on the chuck, and just big enough to put a drift key through. Thus, there isn't any mechanism for securing the chuck...no draw-bar or ejector pin.
I've tried cleaning (dry) both the chuck taper and the socket, replaced the chuck in place and given it a healthy thwack with an oak lump....let's see what happens next!

Les

[fuzzyturns]

I presume you have also inspected the taper on the chuck for any dings or other damage? Morse tapers are designed to be friction driven, and therefore rely heavily on perfect surfaces (to create the maximum amount of friction). Small indentations don't matter, but any small rise in surface (usually at the rim of a ding), will reduce friction substantially. If your chuck has fallen out previously and has ended up hitting the morse taper against some other piece of metal, you are almost guaranteed to have some (minute, but nevertheless important) damage.

[MCB]

I  was told some years ago that the sort of Phosphor bronze brush that's used to clean the barrels of shotguns is  ideal for cleaning Morse tapers.

I  have such a brush screwed to the end of a thin metal rod that I  use to push the brush through my lather morse tapers.

MC Black

[Les Symonds]

...the sort of Phosphor bronze brush that's used to clean the barrels of shotguns is  ideal for cleaning Morse tapers....

Great idea for future reference, might well get one of those.

Les

[Eric Harvey]

teapot spout cleaning brushes work well to and they come in 3-4 differing sizes to.

[Paul Hannaby]

The type with the flat on the end (which is intended to stop the MT attachment rotating)  can only be pushed straight in, whereas the type without the flat can be twisted in, which helps it locate and grip. I had a similar problem with my drill press a long time ago and I resorted to a couple of taps to locate the taper and it has stayed put ever since.

[The Bowler Hatted Turner]

If you never ever remove the chuck you may be able to drill and tap the outside sleeve on the drill and put in a small grub screw. On one of my pillar drills years ago there was a screw put in vertically through the bottom of the drill chuck itself, perhaps more examination may reveal a simpler solution. Good luck.

[Richard S]

Morse Tapers and Dirt are never a happy marriage, this can cause ridges,dents/burrs inside the Morse Taper Sleeve and on the Morse Taper attached to your Chuck.

I invested in a MT2 Morse Taper Reamer and once a year use it on the Sleeve not only in my pillar drill but also in the Head Stock and Tailstock of the Lathe.

Any blemishes on the Morse Taper [Drill Chucks, Lathe Centres etc] are carefully removed using a Fine Abrasive Block.

Using any form of force [i.e. banging it in with a Mallet] will only worsen the situation if the Morse Taper already has some damage.

Richard