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Stuck Chuck

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Michael Gilligan09/01/2020 17:53:46
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Posted by Steve Crow on 09/01/2020 17:40:51:

I've managed to remove the adaptor.

I used a split nut held in a large vice (at work) and a bar held in the jaws. It was very stiff for the first turn and after that ran free.

There appears to be no damage to the adaptor, I've tried it in my 3-jaw and rotary table and it screws in by hand.

It looked like there was a small amount of damage to the thread in the chuck about 3/4 of the way in but it was hardly visible. I'd ordered a 3/4 ANF tap which arrived today which I ran through the threads and now that is fine.

So, a happy ending with everything left servicable. I'm going to clean up and deepen the slot in the adaptor next.

I'm so glad I didn't do anything destructive and tried a gentle approach.

[…]

.

Great news, Steve yes

MichaelG.

Nicholas Wheeler 110/01/2020 11:07:29
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Is it just me that prefers gentle use of a thread file for cleaning up potentially damaged threads? They're also good for scraping Loctite out of threads. Although they're not cheap, it only takes one job to pay for one - a mangled air fitting on a Yak that would have taken hours of dismantling to replace in my case.

JasonB10/01/2020 11:09:54
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I've never got a thread restoring file to work well on a female threadfrown

Ian P10/01/2020 11:22:48
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2420 forum posts
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I'm glad that Steve has solved his stuck adapter problem but there are two points I am not clear on.

What metal Is this 3 jaw chuck made from? I have a sneaking feeling its not the usual steel or cast iron.

Also I have not come across ANC threads, is that the same as UNC?

Ian P

Michael Gilligan10/01/2020 11:30:30
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16358 forum posts
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Ian,

For your first clarification, try Sherline’s website [*]

For your second ... This is a good summary, I think

**LINK**

https://www.ring-plug-thread-gages.com/ti-N-vs-UN.htm

.

MichaelG.
.

[*] From the link that I posted on page_1 ...

Chuck Body Material 12L14 Steel
Chuck Jaws Material 12L14 Case Hardened Steel

Edited By Michael Gilligan on 10/01/2020 11:34:57

Hopper10/01/2020 13:00:29
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4804 forum posts
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12L14, that's leaded steel so unlikely to be the culprit as far as seizing goes, being "self-lubricated". But it is not as strong as normal mild steel so may be more prone to damage. It is used for its ease of machining, not its superior strength, hardness or durability.

Could be the thread on the adaptor had a bit of a burr on it or even a bit of swarf.

old mart10/01/2020 14:06:18
1980 forum posts
151 photos

Time to buy a metal bottle brush to clean the chuck threads before mounting, and having your own airline is useful if used carefully.

Steve Crow10/01/2020 17:25:00
224 forum posts
70 photos
Posted by old mart on 10/01/2020 14:06:18:

Time to buy a metal bottle brush to clean the chuck threads before mounting, and having your own airline is useful if used carefully.

I would love to have my own airline. I wouldn't buy any of those 737 MAX though...

Seriously, I have put an old toothbrush in the box with my chucks to remind me to clean them everytime they are used.

Michael Gilligan10/01/2020 18:06:33
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16358 forum posts
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Posted by Hopper on 10/01/2020 13:00:29:

12L14, that's leaded steel […]

.

That had me a little worried, in relation to the ‘case hardening’ of the jaws ...

But happily, I found this: **LINK**

http://www.interlloy.com.au/our-products/bright-steels/12l14-bright-mild-steel/

MichaelG.

Howard Lewis11/01/2020 16:20:37
3605 forum posts
2 photos

ANC = American National Coarse.

Effectively superceded by UNC = Unified National Coarse. Same 60 degree thread angle, and pitch.

American practice is to quote the t p i so 5/16 - 18 UNC

The smaller threads are quoted in a similar way, 4-40 UNC etc, although 10-32 is UNF while 10-24 is a non preferred UNC.

Well worthwhile to buy a set of Zeus charts for details of most of the threads that you nare likely to meet, plus some other useful data, and mathematical tables.

Howard.

Neil Wyatt11/01/2020 16:41:56
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Posted by Nicholas Wheeler 1 on 10/01/2020 11:07:29:

Is it just me that prefers gentle use of a thread file for cleaning up potentially damaged threads? They're also good for scraping Loctite out of threads. Although they're not cheap, it only takes one job to pay for one - a mangled air fitting on a Yak that would have taken hours of dismantling to replace in my case.

For metric threads a saw sharpening file works and is cheap.

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