# Jacobs Chuck With 3/4 -16 Thd Mount



## dgehricke (Mar 25, 2015)

Well the title says almost all of my problem,Does anyone know where I can purchase or locate an arbor for this chuck or better yet an R-8 collet with the 3/4 -16 Thread for mounting the chuck.
The chuck is in very, very good condition ,probably due to the fact that any kind of arbor in so diffucult to locate so its gotten very little use.
Any help or info would be GREATLY appreciated. Thanks in advance.
Regards
dgehricke


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## JimDawson (Mar 25, 2015)

Why not make one? Sounds like a fun little project.  I'm assuming you have a lathe.


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## ogberi (Mar 25, 2015)

Check LittleMachineShop.  3/4x16 is the same as Taig, and I know you can get MT tapered arbors for it. You could also probably fashion one from an R8 boring head shank.  Turn off the existing threads and single point thread it to 3/4x16.  I've never seen a drill chuck with that large of a thread.  How about some pics?


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## dgehricke (Mar 25, 2015)

So far so good,I did think of making adapter with 3/4-16 threads X a JT 33 so it would fit an R-8 collet X JT33. I don't think my machining skills would be good enough to guarantee an adapter with no run out and no wobbles in the finished product.
I looked very where except LMS and I forgot all about the Taig and the Sherline line of tooling I'll give it a look see and ask if they have any ideas.
Here are a few pic's for the curious and again thanks for the info so far.
Thanks
dgehricke


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## JimDawson (Mar 25, 2015)

I would not make an adapter, I would make the whole arbor, R-8 shank and all.

Just make it all in one setup, don't take is out of the chuck until it is finished.  Unless there is something drastically wrong with your lathe it will come out perfect.  You can cut both left to right and right to left in a lathe.  You just need to grind left and right tools.  Good practice grinding tools.

The way to get the machining skills you need is ''Just Do It''.


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## darkzero (Mar 25, 2015)

Not sure what a R8 collet with 3/4" thread is so I'm assuming you mean a R8 arbor? I've never head of a R8 arbor with 3/4"-16 threads. R8 arbor with threads are commonly larger for boring heads. I recently needed a R8 arbor with 15/16"-16 threads so I purchased a 1-1/2"-18" boring head arbor & rethreaded to to 15/16"-16. Sure you can make one from scratch but it's easier to get a 7/8" R8 boring head arbor & modify that, they're cheap & will save you a lot of time.


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## mattthemuppet2 (Mar 25, 2015)

another option would be to make a 3/4-16 threaded straight shank arbor to fit what ever collet you use the most on your mill (probably 1/2 or 3/8). I've read about people doing that for convenience, doubly so in your case if it's hard/ impossible to find an arbor.


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## dgehricke (Mar 26, 2015)

Thank you all for all the helpful info, the boring head adapter I didn't even think about it. darkzerto I guess a collet is a collet when it has a hole through the center and can grip items inserted in it as in R-8 collets and  I guess it becomes an adapter/arbor when something is adapted to the end,I'm not sure what the definitions are.
You were right I just found a boring head R-8 SHANK with 7/8-20 which can easily be modified to 3/4-16 for the chuck  for the totally ridiculously low price of $17.00.
And to think I've been putzing around with this thing for almost a year.Again Thanks to everyone for the info.
Regards
dgehricke


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