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Four Jaw Tip

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Tennessee Whiskey:
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, it’s only gonna make things easier

Cletus
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Florian Eberhard:
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: 
http://www.youtube.com/watch?v=cZ_Ag-tSpvg

Jump to 3:40 for the "trick".

Florian

Neil-Lickfold:
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

mike44:

--- Quote from: Tennessee Whiskey 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. It’s cut my time for indicating unbelievably.



Cletus

--- End quote ---

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

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