Author Topic: Four Jaw Tip  (Read 1669 times)

Online Tennessee Whiskey

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Four Jaw Tip
« on: January 09, 2019, 04:01:26 PM »
I think a lot of problems people have with indicating material in a four jaw chuck starts with a not so accurate jaw presetting. If you just kinda eyeball it or use the rings on the chuck or whatever and you put the indicator on it and the hand starts spinning like a cartoon clock, well it gets a lot of folks in a tizzy. I have started measuring the stock closely and either use my scale or calipers in the method shown. Its cut my time for indicating unbelievably.



Cletus

Offline Roger B

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Re: Four Jaw Tip
« Reply #1 on: January 09, 2019, 05:31:44 PM »
I normally roughly set the jaws to the rings or the by amount they protrude. I then align the piece by sight against the bed before I bring the DTI into play. As you say this avoids mad spinning. I can usually get better than 0.5mm by eye this way.
Best regards

Roger

Online Dan Rowe

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Re: Four Jaw Tip
« Reply #2 on: January 09, 2019, 06:17:38 PM »
That is why there are concentric rings on the face of the chuck. They only help if the od of the work is symmetrical to all four jaws.

The tip that really improved my 4 jaw chuck work was to make a second key. Then you can adjust a pair of jaws at the same time to half the indicator reading.

Cheers Dan
ShaylocoDan

Offline kvom

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Re: Four Jaw Tip
« Reply #3 on: January 09, 2019, 07:36:20 PM »
Quote
The tip that really improved my 4 jaw chuck work was to make a second key

X2

I also try to mark the outside center point somehow.

Online steamer

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Re: Four Jaw Tip
« Reply #4 on: January 10, 2019, 02:01:10 AM »
Always work jaws in pairs.   Having a second wrench helps, but always work in pairs

Dave
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Online Tennessee Whiskey

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Re: Four Jaw Tip
« Reply #5 on: January 11, 2019, 07:01:03 PM »
Hey guys, my intent was to show how important a good pre-setting  was. You can use the two chuck keyes or whatever, once you get the clock gage introduced, but a very accurate presetting is just going to make your life easier. By nipping up my scribe in the tailstock and working to the fanny hair on my scale, all I pretty much have to do is tighten down the highs. If I use the calipers, it only gets closer. Yes, the rings and such give a concentric idea, but, if you try and work in a precise manner, its only gonna make things easier

Cletus
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Offline Florian Eberhard

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Re: Four Jaw Tip
« Reply #6 on: January 11, 2019, 07:51:55 PM »
Hi Cletus

Your tip is pretty good. Although the two-key method reduces the "pain" of centering the workpiece for a huge amount. But still - good preparation is always making life easier!

And since we are talking four jaw chucks, there is another very good one I'd like to mention right here which is about centering non round workpieces in the four jaw: 

Jump to 3:40 for the "trick".

Florian


Offline Neil-Lickfold

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Re: Four Jaw Tip
« Reply #7 on: January 11, 2019, 08:08:31 PM »
Make a pair of small Jaw keys that can be easily held in each hand, and adjust from the front and back simultaneously. Another easy trick, is to make some common marks on the side of the jaws in a couple of places. Then add some more reference lines on the face of the chuck body. This will give you a very quick and easy reference for where each jaw actually is.  If the work piece is not centred, so you are making an offset feature, make a block up that will fill the amount being offset. That way the jaws are all at the same position, and the block means that from side to side, the indicator will be reading zero. Thinking about what you are making and planing ahead often pays dividends. Sometimes it is easier to pre drill in the drill press a starter hole or take out some material before setting up the part to turn, especially if it is something that can only be turned at a couple of hundred rpm at most, and is most likely going to be bored anyway.
Hope this will help someone.
Neil

Offline mike44

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Re: Four Jaw Tip
« Reply #8 on: February 25, 2019, 12:17:08 AM »
I think a lot of problems people have with indicating material in a four jaw chuck starts with a not so accurate jaw presetting. If you just kinda eyeball it or use the rings on the chuck or whatever and you put the indicator on it and the hand starts spinning like a cartoon clock, well it gets a lot of folks in a tizzy. I have started measuring the stock closely and either use my scale or calipers in the method shown. It’s cut my time for indicating unbelievably.



Cletus

Another method that works well for me and is fast. I layout the centerline on the work and use a spotting drill on the DP first. Then center drill . Next I install the work in the 4 jaw and bring the Tail stock with a center close to the work. I use two wrenches and adjust the jaws til the live center meets the layout hole. I snug the jaws up. This usually gets me very close to perfect center. Then I made a 3/8" round with a 60 point on one end and centered drilled the other for the TS center. I install the pointed end into the work and the other end into the live center. I use an indicator mounted on the compound. Then adjust jaws 1 &3 til they read the same and 2&4 the same way.
Between layout and drilling the center , installing in the chuck and centering I would guess it would take 5 minutes or so .

mike
« Last Edit: February 25, 2019, 02:36:30 AM by Kim »