# Probably A Stupid Question About A 4 Jaw Chuck



## ShinerTX (Aug 24, 2016)

Hi again everyone,
Probably a stupid question, so please try not to laugh,
I am in the middle of installing a Köping S10C lathe into my shop which was given to me by a friend who has owned it for many years. I'm re-powering it, etc, all of which is on another thread and photo album that I just created and is pending approval.  Anyway, the lathe is big... 10" swing, and came with a massive 4 jaw chuck. 
I like 4 jaw chucks... The diversity is great and I really never had much of a problem centering work... I'm slow, but eventually get there. I do occasionally have a need for a 4 jaw...but typically most of my work is smaller, however, and doesn't require the holding power or off center features of  the 4 jaws.
Is it considered bad to chuck a smaller 3 jaw in the 4 jaw and use that? Changing the chuck is not impossible, just a pain, heavy as all get out and expensive.  I'm just looking for ways to make this big lathe more user friendly for my work without breaking the bank. My work isn't that dimensionally critical. 
Thanks in advance. I love this site and forum... Learning lots...
Jim


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## JimDawson (Aug 24, 2016)

Just kidding, there are no stupid questions on The Hobby Machinist

I have seen that done.  Not as robust as mounting the 3-jaw on the spindle, but there is no reason it won't work.


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## mksj (Aug 24, 2016)

Yep, that is a big 4J. Might ultimately consider a smaller chuck if you do not need that large a swing. If you have a chuck, you should only need some type og adapter plate to the spindle mount. You may see some more angular TIR mounting one chuck within another, you also have all that spinning mass near your hands if you are doing something small close in.  It is not uncommon to use a collet holder in a larger chuck for turning small stuff, like a 5C or ER-40.


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## ShinerTX (Aug 24, 2016)

Thanks for the replies. In my search for info on the Köping lather, I googled them and there was a video of someone testing a S12C that had a 3 jaw chucked into a 4 jaw, which got me thinking (and posting). I'm still researching and getting to know this machine, I've got no idea if the spindle mount for the chuck is standard, or some weird Sweedish size or thread. 
Thanks again,
Jim


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## dlane (Aug 24, 2016)

30hp motor on a 10" swing lathe , someone please approve that thread , my 10" swing SB 10L has a 3/4 hp in it .


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## ShinerTX (Aug 24, 2016)

Your welcome to question it... But it is indeed a whopping 30 HP, 380 Volt 3 phase motor that was on it, verified by the machine manuals and motors data plate.  It ain't no Southbend...  Köping built 3 models of the same lathe, an S8C (8" swing) a S10C (10") and the S12C (12")   They are extremely rigid, heavy machines capable of deep cuts. This thing weighs a little over 8000 lbs.


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## JimDawson (Aug 24, 2016)

dlane said:


> 30hp motor on a 10" swing lathe , someone please approve that thread , my 10" swing SB 10L has a 3/4 hp in it .



I think that is what we would call a 20 inch swing.  European lathes are measured by the swing radius, rather than the diameter.  But still....30hp is a lot of motor!  That is one heck of a machine!

Would look really good sitting in my shop


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## ShinerTX (Aug 24, 2016)

That is correct, it'll turn a 20" diameter piece.


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## Tozguy (Aug 25, 2016)

ShinerTX said:


> Your welcome to question it... But it is indeed a whopping 30 HP, 380 Volt 3 phase motor that was on it, verified by the machine manuals and motors data plate.  It ain't no Southbend...  Köping built 3 models of the same lathe, an S8C (8" swing) a S10C (10") and the S12C (12")   They are extremely rigid, heavy machines capable of deep cuts. This thing weighs a little over 8000 lbs.



Would you have a link to your thread on repowering this lathe?


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## 4GSR (Aug 25, 2016)

Like others have said, and I've done it myself and still do at times, put a smaller three jaw in the 4-jaw chuck or even a smaller 3-jaw in a larger 3-jaw chuck.
If and when you decide to mount a 3-jaw chuck on your lathe in place of the 4-jaw.  I have a 12" Bison Set-Tru chuck here I'll sell to you.  Won't have to worry about shipping, just a 45 mile trip to Victoria to pick it up or I could bring it up to you.  It currently has a L-1 mount but can be removed and any adapter put in it's place. Ken

Edit: Lets see, if I come up there to Shiner, I could go over to the brewery and drink some Shiner Brock while I'm there.  Wonder if they have some Shiner Strawberry Blonde at the brewery?


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## ShinerTX (Aug 27, 2016)

Tozguy, I don't have a thread on repowering the lathe yet. There are a few factors I'm considering, the most noteworthy is the motor. A neighbor has disassembled cotton gins in our area and has a bunch of electric motors of various sizes  that he has basically given me in the past when I needed one for projects. I haven't been able to see what he has, and won't really decide a course of action until meeting with him. Also, a few years back, I bought a motor that  was advertised as a Baldor off the internet for a whole hog rotisserie we built. The motor fried itself during the testing stage in the first few minutes of running. I took it to our local electric motor/armature rewind shop and they said it was Chinese junk disguised as a Baldor motor. Needless to say, I am skeptical about buying motors that I haven't seen, or the source.
Another consideration is the oil  circulation pump.  My Swedish manual says its 110 volt, but I can find no other reference. I'm waiting for an American manual to arrive. I would have thought a wiring schematic was simple enough to translate from Swedish, but I'm not able to, so hopefully when the manual comes in it'll be better explained.


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## Tozguy (Aug 28, 2016)

Thanks Shiner, wish I could help but when it comes to electrical stuff I am all ears.
Good luck.


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## Reeltor (Aug 28, 2016)

I've gone the other way putting a smaller 4-jaw in the 3-jaw and thought it was an half-a$$ way of machining but I've recently watched several YouTube videos from the "experts" and see the same thing.  IIRC they put some brown paper bag between the jaws of the larger chuck to get a better grip.
30 hp powering your lathe, Holy Cow that's a lot of power


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## Tony Wells (Aug 28, 2016)

Pretty common where I come from. Had only one failure that I remember. Power 3 jaw (hydraulic) holding a 4J or a smaller 3J, can't recall. This happened to be a very experienced hand who took chances a lot. He was peering through the sight window, was a little Kia Seiki CNC. It didn't have but about 1/2" length of grip, so when it got near speed, it came out, bounced around and eventually hit the window, which has small steel bars across it. The impact knocked the whole sliding door (some of you know how heavy they are) up off its tracks and it hit him square in the face. Broke his nose and loosened a few teeth.  

Yep, it can be done.


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## 4GSR (Aug 28, 2016)

They always blame it on night shift... Well I have a similar story to Tonys that happen on night shift at a place I worked at in 1999-2000.  The machine operator, (I wouldn't call him a machinists because of this accident) chucked up a 15" 3-jaw in a 18" power chuck on a Puma CNC lathe.  He took on a job that was for another machine with the proper chuck arrangement.  But the power chuck didn't have extended reach jaws of the job, so he put the manual 3-jaw up in the power chuck holding on to about 1/2" length, too.  As murphy's law goes, what shouldn't happen did happen the moment the turning tool touch the work.  Every piece of sheetmetal on the enclosures has extensive damage, including damage to the ways on the lathe.  But it contained the chuck until it settled down into the chip conveyor, messing it up too.  Cost of repairs was close to 25K to replace all of the sheet metal and other damaged parts.  They took a air grinder and smooth out the damage areas on the ways.  I don't think that machine ran right ever again.  

So I guess the moral to the story is to make sure you don't get yourself in an accident holding onto a chuck by only 1/2" of griping length.  My rule of thumb is if you cannot grip on the full OD of a smaller chuck without turning the jaws around, don't do it!


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## TOOLMASTER (Aug 28, 2016)

THERE GOES THE ELECTRIC BILL


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## dlane (Aug 28, 2016)

I try to use tools as intended , But when I don't I start slow and am ready to duck


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## Reeltor (Aug 29, 2016)

Back in Jr. High School we had to rotate through the shop classes and were shown safety movies (yes, film movies for you younger folks) I still remember bits and pieces of them today.  Even the guy two seats up who passed out from the recreation of some accidents.  
What I'm trying to get at, is the one where someone started a grinder while standing in front of the machine.  As the grinding wheel came up to speed it let loose hitting the operator in the face breaking every bone and turning his face into a bag holding in the fragments.

We were taught to always stand to one side when powering up a machine.  Something that I still do today 50+ years later without even thinking about it.  The lathe has a clutch so that the spindle can be engaged while well away from the chuck rotation (if you stand in the "right" place).

Anyone else learn to power up machinery while standing away from the direction of rotation?


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## Tony Wells (Aug 29, 2016)

Absolutely.....100% of the time! I saw those movies too. But even handheld tools I "point" them away from me and kind of squint out of habit. Been worth it a time or two.


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## catsparadise (Aug 29, 2016)

Reeltor said:


> Anyone else learn to power up machinery while standing away from the direction of rotation?



That is standard practice for turning wood. It's a habit that's stuck with me when machining metal.


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## Str8jacket (Sep 2, 2016)

Reeltor said:


> Anyone else learn to power up machinery while standing away from the direction of rotation?



I must have seen similar videos! I have been questioned on that habit at work. Take one look at the condition of the grinding wheels in our boily shop youd start them with a broom handle if it wasnt for the deadman switch!

Speaking of old safety vids, did my time at a CAT dealership and they used to play these clips 

"Old three finger Joe"

Some good politically incorrect stuff there.


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## Reeltor (Sep 3, 2016)

Str8jacket said:


> I must have seen similar videos! I have been questioned on that habit at work. Take one look at the condition of the grinding wheels in our boily shop youd start them with a broom handle if it wasnt for the deadman switch!
> 
> Speaking of old safety vids, did my time at a CAT dealership and they used to play these clips
> 
> ...


Here's (one of) the YouTube link


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## Str8jacket (Sep 3, 2016)

Shake hands with danger..... pure gold


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