View Full Version : Jacobs Chuck Arbors

03-09-2004, 03:49 PM
Is there a chart that shows the size of the different cJacobs chuck arbors. I was thinking about buying a arbor to adapt to another project, but don't know what the sizes really are.



Ironland Spline
03-09-2004, 07:30 PM

The following link shows the dims of the standard "Jacobs tapers" that are on the arbors:



03-09-2004, 07:35 PM
Thanks that answers what I need to know.


03-09-2004, 09:56 PM
Can I thread an arbor, I need a R8 shank with a 1/2 standard thread, I thought going with a Jacob #6 to make this.

Is there an R8 shank with a 1/2 thread out there?



03-09-2004, 10:03 PM
why not just thread a shaft and use in a standard r-8 collett?

03-09-2004, 10:14 PM
I was thinking of that also.


03-11-2004, 06:58 AM

I don't like the $50 price taf for threaded arbour either, I buy bison JT6 and machine them to the 1/2" thread . I also cut off the tang and drill & tap for 3/8" drawbar - if I need to use it in a tailstock or drill press I just loctite an allen setscrew in and forget about it. Total cost $2 for a hardened & ground shank. (I dig through the bargin bins you know!)

John Stevenson
03-11-2004, 07:39 AM
When I first got my Bridgy I was short of special tooling for it so I took about 10 lengths of 30mm bar about 12" long up to the local CNC shop with a R8 drawing and got them to double end me these bars.
That gave me 20 blank holders, no thread and no keyway to keep costs down.
Can't rememeber the price but it wasn't expensive.
I also had a few large ones done out of 2" for making into shanks for boring heads etc.

I have made all sorts of weird holders out of the blanks.
BTW a 1/2" x 20 UNF as well as holding chucks will also hold the thread hole saws if you drill the shank of the R8 for a pilot drill.

Usual pics later. http://bbs.homeshopmachinist.net//biggrin.gif

John S.

[This message has been edited by John Stevenson (edited 03-11-2004).]

03-11-2004, 12:30 PM
I am working from two approaches on this idea, one by taking a less expensive arbor and threading it, and taking a piece of 3/4" 01 or A2 stock and turning it to the right diameter, then cutting the thread. If I could stop coughing and sneezing, I would try this out.

03-11-2004, 02:17 PM

don't try threading O1 - it will fail. Us the A-2 and have it hardened at a shop or in an atmosphere controled heat treating furnace (stinless steel tool wrap foil works but is damn expensive

03-11-2004, 10:34 PM
I do much of my own hardening work, I know that SS Foil Wrap isn't cheap, because I have 4 rolls in the shop at the moment.
I have a couple of methods for HTing, some generalized and some very precise, but it's the cost of energy that determines the price of the HT. Tools I am very precise on and knife blades not so precise on. My problem is that I don't own a Rockwell tester.



03-11-2004, 10:37 PM
I am going to work on it!!!
As well I will tell you one of the Big Three lies will regards to your share:
"Check is in the mail!"
Thanks John!!!