Mysterious Morse Tapers

[PippinParticipant @phillspowart84010]

We’ve had a couple of interesting items in some tool donations up at Crich recently. Two strange Morse taper sleeves

The top one is a normal 1-3 sleeve, except it is made of plastic. The makers information is moulded into the end, google doesn’t reveal anything useful

 

The bottom one is a 3-4 sleeve, made by Moore, but it has a flat all the way up the inside. This is very obviously made like that, it hasn’t been battered (ignore the dent at the 11 o’clock position, the flat is at 6 o’clock). The rest of the bore is tapered in the usual way, as far as I can see if you milled a flat on a No.3 morse taper to match it would fit together. It must have been a difficult thing to make.

Does anyone know what they are for?

[Clive FosterParticipant @clivefoster55965]

The socket with the internal flat is probably what is (colloquially?) know as a “use-em-up” socket intended to extend the useful life of large drills with MT tapers so damaged that the dill will no longer drive via the taper under normal axial loads. Next stage of desperation after twisting the tang off I guess.

Idea is to first clean distressing raised dings or other damage by some suitable means, clearly a tool and cutter grinder would be best but I guess careful use of abrasives and files might do. With an adequately resurfaced MT shank a flat can be added to match that in the socket providing positive drive.

Presumably the setting up and absolute accuracy needed in the machining process to add flat is less than simply re-grinding the whole shank to fully restore the surface.

Objectively only worth the effort for big drills.

Mrs Google says the flat is created by a swaging process.

Clive

[Pete RimmerParticipant @peterimmer30576]

Use-em-up sockets. I found that I had one in my collection when I went to load a drill into it in my tailstock. It went in the bin.

[BazyleParticipant @bazyle]

It could be for ensuring that a tailstock turret goes in and stays at a particular orientation.

[egaParticipant @ega]

The plastic one could perhaps be used with a damaged male taper thus preventing damage to the machine female taper.

BTW, I use plastic male tapers with helical flutes to clean MT sockets.

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