Machining a replacement jacobs style chuck key?

I just bought a 2nd hand Jacobs style chuck without its key, a Porta AGP 1.5-13mm. I know the sensible option would be to take it back or ask for a key to go with it which I may still do.

Out of curiosity what would be involved if I wanted to machine a replacement key?

Jon

First you need to match the gear shape/size then decide on the number of teeth required, the diameter of the pin is not so important as you can easily turn it down or add a sleeve if too small.

Perhaps a search for the make and model number will bring up a supplier. (KS2)

Emgee

Edited By Emgee on 19/03/2021 12:50:17

Edited By Emgee on 19/03/2021 12:51:40

I found a replacement key for the chuck supplied with my X2 mini-mill 15 years ago at B&Q. They had 3 sizes so I suspect there are standards for these things

Given the low cost of "4 way" so called "Universal" drill chuck keys such as the one at the link below, I would suggest you save your shop time for your model engineering projects rather than making your own key. There are many sizes, as the data sheet shows. I am sure you COULD make your own, with a lot of careful measuring and multiple trial and error tests, but not sure why your would want to, for a mass produced item.

https://www.mcmaster.com/3175A36/

Miss directed energy but a nice project to do. Be wary of the four way keys available cheaply, they are cast and the metal used is soft. I have tried 2 now.

Funnily enough, I have a chuck (mounted on a Jarno taper ) which is now operated by a "4 way Universal" key. But not so universal that the spigot fitted the chuck.

It did, after a short time in the 4 jaw chuck on the lathe!

The key is definitely the lower quality part of the combination.

Howard

Long time since I heard anyone mention a Jarno taper.

I picked the chuck, a really nice looking none cheap, (£2 )at a show, but could not find a Jacobs arbor for it.

At home on the back of the chuck saw there was "No.2", so took a wild guess that it was a Jarno. Having found that all sizes of Jarno had the same taper, tried setting over the Topslide, by eye. Blued after the first attempt, and resisted the urge to start backing horses, since it was spot on!

Pity that that the Jarno with its constant 2 degrees 15' taper did not catch on instead of the Morse, which changes with every size.taper. But we are stuck with it now!

Now, what else can I grizzle about?

Howard.