chuck jaws

[Wally Wenzel]

In some of the topics where chuck jaws are talked about the term profiled jaws comes up and I don't quite know what is meant. I have Talon chuck and a psi chuck. The two jaws both have ridges or grouves, but the talon is different, maybe that is what profiled means. Can some one clear that up for me? Thanks Wally

[Alan Trout]

The way the Oneway jaw is designed it gives maximum contact within the range of that jaws opening. That is the thing I like the best about Oneway chucks. I really like the jaws and the work very well for the kind of work that I do. If I was using a recess a properly sized dovetail is the way to go IMHO.

[Dan Forman]

The profiled jaws are sometimes called serrated, and as far as I know are only available from Oneway. Most of the other jaws will have a dovetail shape and are smooth, requiring the tenon or recess to have a dovetail to lock onto. I much prefer the serrated Oneway jaws for tenons, don't do many recesses.

Dan

[Thom Sturgill]

Personally, I thought the 'profiled' term referred to the fact that the OneWay Jaws were not simply circular when viewed from the top. Several manufacturers (PSI included) make serrated jaws but theirs are circular when viewed straight on.
oneway_chuck_250px.jpg
You can see from this image that the oneway always grips at 8 points, but does not dig in at the corners like most other designs.

I prefer dovetails in most cases, but they require a closer fit.

[steve worcester]

I will chime in, I had the serrated jaws for years and switched all of my chucks (7) to dovetail. Main reason is the serrated are difficult to remount and get the same registration, and they don't really hold better. For dovetail jaws the tenon would have to deflect the difference in thickness of top to bottom to come out. So at least it gets popped out of registration before popping out of the chuck and flying. Now for shearing off the tenon, I have has that on both types.

[Michael Stafford]

I have always used dovetail profiled jaws and have never had a tenon pop out as long as my tenon was sized correctly. The tenon is supposed to be sized so that when the dovetail jaws are closed to the point where they form a circle the jaws are in contact totally around the circumference of the tenon.

I frequently dismount and remount pieces of wood. I always identify the jaw locations on a tenon so that I can put the wood back in exactly the same place when I remount it. Like Steve I have found it nearly impossible to do that with the profiled jaws.

P.S. The chucks I use Nova and Vicmarc make serrated jaw sets that grip tenaciously on tenons. I much prefer these serrated jaws for larger/longer pieces of wood when mounted in a chuck.

[Jeffrey J Smith]

I also changed all my Oneway jaws to dovetail jaws as well. It was after using a set of Vicmark jaws for a while. Registering when remounting was a consideration, but I also found that when roughing wet wood with the serrated jaws, I lost a few tenons here and there. Haven't lost a tenon since switching and mounting is always secure. I do use the tower jaws that are aggressively serrated and profiled when I need extra reach, but usually just use the dovetail at the top of the jaws.

[David C. Roseman]

In some of the topics where chuck jaws are talked about the term profiled jaws comes up and I don't quite know what is meant. I have Talon chuck and a psi chuck. The two jaws both have ridges or grouves, but the talon is different, maybe that is what profiled means. Can some one clear that up for me? Thanks Wally

Wally, I have both the profiled jaws and dovetail jaws for our Strongholds and Talons. I've always thought the term "profiled jaws" is just something Oneway uses to refer to the way the inside corners of their serrated jaws are swept back at an oblique angle, rather than 90 degrees. So they don't dig into the workpiece, and supposedly are better suited to grip "square" stock that may not be perfectly square. I don't think "profiled" necessarily implies serrated; rather their profiled jaws are serrated.

David

[Dan Forman]

One of the problems I have with dovetail jaws - how can you have a perfect fit on a green bowl, and again after it has dried? When you true up a dry tenon, you lose diameter, and the bowl may not fit in the chuck again. If you allow extra tenon diameter when green, you lose the perfect fit. Personally, I have no qualms about the grip of the serrated Oneway jaws, they grip at least as good if not better than dovetails, no matter what the tenon size.

Difficulties re-chucking a bowl might stem from the fact that the serrated jaws may not be precise in the outer face, and consequently register differently on the bottom of the outside of the bowl. A friend showed me how to take care of this, simply bring the jaws fully closed with nothing in the chuck, mount it on the lathe, and face off the outer jaw surface with the late running, using a scraper or a square carbide cutter. You can watch as the blackened surface is removed, and tell when they are true when the faces of the jaws are all shiny. After facing the jaws, a bowl will run true when remounted. If you change jaws, then you will have to mark the jaws so that you can put them back on in the same order - Oneway doesn't number their jaws, only the jaw stations.

Dan

[Michael Stafford]

Dan Forman, if you leave a center mark on the bottom tenon you can center the rough turned bowl on wooden blank turned to a convex/curved end and padded with leather or mouse pad material using that point and re-true the dovetail tenon to ensure concentricity of the bowl. I routinely do this trick which I learned from Jamie Donaldson.

One of the first things he had us do in his class was turn a wooden blank between centers with a tenon on one end; mount the tenon in a chuck and form a gentle curve on the other end to which you could adhere leather or other material to drive the rough bowl between centers. Mounting the roughed bowl in this manner allowed one to re-turn the outside of the bowl as necessary. Once satisfied the bowl can be reversed and mounted in the chuck to re-turn the inside to finish.

Re-turning bowls in this manner seems to allow for much better centering and results.

[Wally Wenzel]

thank you all for answers to my question I learned a lot from it all, and to big Mike I also in returning a roughed out bowl do make certain I leave he center point on the tenon from roughing then close the chuck all the way and place the bowl over the closed chuck with the tail stock live center in the center mark and true the tenon up and turn it around and procede. Wally

[Mark Levitski]

Wally, forgive us for getting off topic a little. Hope you are getting answers and then some .

As far as chuck jaws, I have all Teknatool chucks. I slightly dovetail my tenons. I do not do too many recesses.

Naturally, I follow the basic advice to put the face of the jaws bottomed out on a nice flat surface. And in order to do this I watch how long the tenon is so that it doesn't bottom out on the "floor" of the jaws instead of their face.

When I return a roughout, I just use the chuck w/ jaws to seat against as I true the tenon. Why bother to insert another step? This has worked for me w/o any problems at all. All I do is then reverse the piece into the same mounted jaws and finish. I even return the outside against the jaws (it doesn't seem to matter if they are open or closed when doing this). In eight years of turning, I have turned hundreds of bowls and other pieces this way.


Dan, in order to rough out tenons I would not worry too much about them fitting "perfectly" (IOW, nearly fully closed, but not quite so). When you rough a tenon, then leave it as big as you can for those jaws. So what if it isn't perfect as described. I have never had any failures because my jaws were opened, even almost all the way, when I roughed out my pieces. So what if the jaw edges bite in a little because they are not forming a true circle as open as they are. This is a ROUGHOUT, with emphasis on rough. Done in this way, you won't have to change to different size jaws (i.e., smaller) depending on the species and how it behaves in drying of course.

As long as you find a way to keep your pieces remaining in the chuck while you turn them rough, get it done in the fastest way and get on with other turnings. It is when you go to actually finish those pieces you can figure in the jaw marks and such. Even then, when finishing, I often have jaws that are open a bit. No problem, especially if you intend to reverse again somehow to finish the bottom.

My message is that you don't need a precise fit, only a useful one. This is not machining for aircraft parts. It is wood. Wood moves all the time, even as we are turning it. Our bowls need not be perfectly round, and they probably are hardly ever. We could put ourselves inside out with all the efforts and concerns with some of the details. Let it go, relax, do what's safe, create a beautiful end product "imperfect" as it is.

[Dan Forman]

I'm not sure if my last post was understood in the spirit it was written.

My point was simply that in my experience, the serrated jaws hold just as well as if not better than dovetailed jaws. In order to fully take advantage of the supposed extra strength of the dovetails's hold, you would have to size the tenon such that the jaws would be fully, or nearly fully closed. If not, the jaws would only actually touch the wood at the outer corner of each jaw. This in my opinion is not as secure as the hold of the serrated jaws, especially in green wood, which is more easily deformed under the forces of a catch. I have launched bowls with catches from dovetails, but not from the serrated jaws. Fortunately I don't get that many catches anymore though. Actually the main reason I like the serrated jaws is that it's just easier for me to to turn a straight tenon, and I can size it however I want without worrying about holding power.

This has been hashed and rehashed in many threads over the years, and comes down to a matter of personal preference. I think the main factor of choice should be whether one wants to create dovetail tenons/recesses or straight tenons and recesses, rather than the holding power of the jaws. People should not fear that straight sided tenons are not as secure as dovetailed tenons. Use what you feel most comfortable with.

The main disadvantage of the Oneway chucks are the geared key over the hex key for operating the jaws. I find a hex key much more user friendly than the geared key. If I could use the Oneway jaws on the Vicmark chucks, that's how I would go.

Big Mike --- I do something similar to return warped bowls, but just use a piece of 80 or 100 grit sandpaper over the face of the the chuck, with the jaws expanded appropriately for the size of bowl. It works very well for me. For those times that I forget to leave a dimple on the tenon (if I have to shorten the tenon after the tailstock has been removed), I turned a wooden plug with a hole through it, which fits into the spindle adaptor of the chuck. I use a center transfer punch of the same size as the hole bored in the plug, to put a new dimple in the center of the tenon. Comes in very handy, and makes remounting the once turned bowl much easier. I'll post a picture of this later today.

Dan

[Michael Stafford]

Dan, the sandpaper will work just fine as long as the bowl is not too deep. I used to do just that with a mouse pad section and sandpaper until I learned the trick from Jamie. Now I use that because it seems to apply pressure closer the to the drive point and if I have any trouble with the "drive" slipping I can tighten up without fear of undue pressure on the bowl.

As the old saying goes there are many ways to skin a cat and one of the things I have learned while wood turning is that there are many ways to do the same thing. And it doesn't hurt to know a lot of them because some work better in some instances than others.

[Thom Sturgill]

I have launched bowls with catches from dovetails, but not from the serrated jaws.
Dan

FWIW, my experience is the exact opposite. In addition I have had serrated jaws tear off the tenon where the serrations bit into it.