Problems with Cole Jaws

[Dave Rudy]

Since I'm a novice turner, I wanted to get some more experienced views about Cole jaws.

I had two small bowls blow up today using Cole Jaws (the last step in the process, unfortunately that even included sanding and finishing. :confused::(

Is this a normal occurrence? Is there a preferred way to hold a bowl for the final removal of the foot or whatever held the bottom in the chuck?

I was turning at about 1000, trying to take small cuts (although I suspect I had a catch both times).

The third try worked fine, but 1 out of 3 is a bad ratio!

Thanks

[robert hainstock]

one way to avoid the blowup is ti use the live center on the back side, remove, as you said, carefully as much wood as you can from the tenon, and then I use a sharp carving tool to cut through the last 1/4 in or so. :)
Bob

[Ralph Lindberg]

Dave, I think part of the problem is speed.

Both of my Cole jaws say 800 RPM (MAX), your ~1000 might be an issue.

[Bernie Weishapl]

I run my cole jaws at 500 to 600. Tailstock up until you get down to the last detail.

[Norm Zax]

One word: Doughnut
here's one example: http://azwoodturners.org/DoughnutChuck.pdf

[Gordon Seto]

IMO, the Cole Jaws is the less effective way of reverse chucking. People have more airborne using Cole jaws than any other method.
It has limitation on the rim design and can't be used on natural edge or when the bowl is out of round.
Reduce your speed and get some insurance. Use some tape or stretch wrap to wrap around the edge of the bowl and between the slots of the jaws to prevent it from launching after you remove the tailstock. Take every light cuts and use the tailstock as much as you can.

I like friction jam chuck. It is fast, easy. Just save the center point before reversing.

Watch the "Turned Bowl Made Easy" DVD from Bill Grumbine, it has several reverse chucking methods demonstrated. Vacuum chucking is in his second DVD. I highly recommend them, especially the first one. It is the best.

Join a local club would also shorten your learning curve.
AAW Local Chapter Listing - The American Association of Woodturners (http://www.woodturner.org/community/chapters/members.pl?submit=Chapter+List)

[Steve Trauthwein]

Dave,

I agree with Bernie, 500 rpm's. Another factor to consider with the cole jaw is how the rim is angled. If the rim is straight, not curved in, and at least twenty degree angle from the base, the jaw will hold better. If the rim is straight or curved in then forget the cole jaw without some assist. Duct tape is a good assist, the tail stock is better. Very sharp tools and small cuts. I found a pull cut would work better for me in these circumstances.

Regards, Steve

[Les Kuesel]

It could be you are tightening the jaws to tight, this would put a lot more pressure on the bottom. Slow down and use your tail stock.

[Steve Schlumpf]

Dave - lots of good advice! I used Cole jaws for a long time and had a few launch experiences like you did. I use a Talon chuck and the max RPM on the jaws states 1200 RPM - which is WAY to fast! I had better luck running the lathe at 500 rpm, using the tailstock as long as possible and taking very light cuts.

The next method I migrated into was the donut chuck - as per Norm's suggestion - and found that it works great for most 'regular' shaped bowls but limits your access to the outside of the bowl and that can lead to an unplanned variation in the outside curve.

Next - and final option - is the vacuum chuck. No doubt - there is an expense to this option but the ease and simplicity of use is what makes this type of chuck so prized. Just something to consider once you have some more experience turning and know a little more what styles of turnings you want to create.

Understand - we have all been there, done that and all the different methods listed above work. If possible - get with an experienced turner and find out what is causing your launches! Best of luck!

[Will Hunt]

You didn't say what kind of holders you were using -- I assume the 1/2" high black rubber things that come with the jaws.

I found these very unreliable except for power sanding and questionable even there. My solution. Hard (maple) wood blocks roughly 1 X 1 X 1" -- but with one side angled in about 15 Degrees. Best done by cutting a shaft with the angle on 1 side, then popping them off at 1 " intervals. Drill holes through the pieces for fastening to the cole with bolts and wing nuts -- the angled side will face in. On the angled side glue on pieces of PC mousepad with ridged face out.

Note: with this set up, the angle will work either to grab the outer or inner sides of the bowl wall.

Will Hunt

[Dave Rudy]

Thanks for all the informative replies. Appreciate the help.


Steve (or anyone) -- is the holding power of a vacuum chuck significantly greater? What is the max speed with a vacuum chuck?

Thanks

[Ron McKinley]

What the others have said—all good advice. I use a small sharp scraper to remove the foot when using the Cole jaws. Nibble away at it by pushing in on the edge of the foot, taking no more than 1/16" at a time. This keeps the bowl on the Cole jaws by pushing against the headstock........Ron

[curtis rosche]

i would say that yes the power is a lot greater just because so many of these guys use them, but i dont have one so i can really speak about it. another solution to your problem it to keep the end in the chuck longer so you can part it off instead or having to reverse the bowl, works for me pretty well, then just sand the bottom a little

[Bill Bolen]

Better safe than sorry. Bring the tailstock up for as long as possible, slow speed, 500 or so. Cole jaws or longworth makes no difference. Haven't lost one since I slowed down and use that tailstock till there is just a nub. I made a long slender wood "pin" to mount in the live center so I don't have that little hole from the metal pin....Bill..