Pin Chuck?

I use one (1") for my roughing, but it threads on. It's the remnant of my old Masterchuck. When I acquired a second Nova chuck I also acquired the "pin jaws," which give me nearly the same capability as the pin chuck. I wish they would grip a bit deeper, helping to align the blank more precisely, but that's not as important as the ability to bore a 1" hole and quickly mount - between centers - pieces up to 12x8. In softer wood, where the starting torque sometimes compresses the roll pin into the wood, they are actually superior to the pin chuck.

Further advantages include good clearance for the bottoms of smaller turnings when the pin jaws are used in their dovetail hold mode and the ability, due to longer interior hold, to quickly align the 1x1 scraps I turn for finials, knobs, Shaker pegs and such in compression.

Other chucks have a pin jaw option. I'd recommend it.

How about starting it between centers? That way, as you get the thing more round you can take a look at what you have and make adjustments. You can jog either the tail center or the drive center to get the figure and balance of pattern you want. When you get it looking good, then make a tenon on the bottom end which can be driven by a face plate or a

4 jaw chuck.

When you drill a hole for a pin chuck or for a screw chuck, you have made a decision about where the center of the bowl is going to be and what the orientation of the grain is going to be. But you have very little good information at that point. Starting between centers allows you to delay the decision to a time when you are much better able to make it. You are also better able to deal with defects which could not be seen at first.

Bill

Woodman It is just as easy to turn the outside and for that matter the inside of the bowl between centers. Take a look at roughing a bowl on my web page. This is by no means new to me. A lot of turners use this method.

I agree with Bill & Darrell that driving a raw bowl blank with a spur and tail support is the best way to begin the outside. Pin chucks might be a more secure way to hold heavy blanks, but to do so they need to be

1" or greater. I am always amazed at the size and weight even a small spur with tail support will securely hold. Like machinist's chucks and metal jam chucks, I think pin chucks have been largely superseded by better holding methods, maybe not for bottle stoppers etc. The d... pins are always hard to find when your turning time is limited and not always easy to extract when (and if) they set and grip properly. Forget using them in soft wood. Drilling the hole takes time and large blanks that overwhelm a drill press or hand drill must be drilled on the lathe, requiring a dance with jacobs chucks & drill bits and centers. Using smaller Morse tapered spur centers is often suggested for various purposes. Perhaps we forget about using larger threaded spurs and tail centers to drive heavy blanks. Two sharpened bolts on a small face plate can provide a secure and adjustable drive and do not permanently alter the faceplate. I see little need for '4 spur' drives. Darrell's method of using tail support til the last gasp seems a useful method for those who don't enjoy the luxury of a modern swivel head lathe. :) As always, Woodsman, these are only my opinions and are subject to correction. Arch

Fortiter,

Hey Arch, think of the advantage to holding the rough by the pin only, especially when making a dovetail recess.

George, What? Me think!

Fortiter,

I'm with Bill and Darryl on this one. Start the piece between centers.

er.. with Bill and Darrell that is... (sorry about the misspelling there)

Jim Ouch! Aargh! My name was spelled wrong! The pain! The infamy! Not to mention the embarrassment of not realizing it was spelled wrong until you corrected it :-).

Arch wrote: (clip) Drilling the hole takes time and large blanks that overwhelm a drill press or hand drill must be drilled on the lathe, (clip) ^^^^^^^^^^^^^ On the other hand, the one-inch hole can be pre-drilled to the proper depth so it acts as a gauge for the depth of the bowl. It also speeds up the removal of material from the inside of the bowl, since it's easier to start your cut at the edge of the hole than at the centerline of the wood.

Drilling on the lathe is the best way, because that's the only way you can rotate the wood for alignment prior to drilling.

I use a laser system to line up the turning axis on natural-edge bowls, so I rarely have to realign the job part way through. An alternative would be to start on a screw chuck, and then drill for the pin chuck if realignment is required. The 1" diameter of the pin chuck vs the 3/8" diameter of the typical wood worm gives you plenty of leeway.

As far as looking for lost screw-chuck pins is concerned, I use cut off nails, which I store in a magnetic parts tray. I still lose them, but it's so easy to cut a new one.

Arch, this is just a friendly exchange of opinions between friends, not an argument. I daresay that anyone seeing a finished bowl will be unable to guess which method was used to hold it.

Hey Woodsman, I hope you have a coin to flip or maybe you ought to use the method that best suits you on a given day and phase of the moon.

Leo, I know you only mentioned using a laser for lining up natural edges. I'm not sure a laser can indicate subsurface conditions in a bowl blank. ie. so as to allow drilling the pin chuck hole thus committing the turning axis without doing some preliminary turning and/or adjusting, ex; bark inclusions, grain whorls, branch and knot locations, internal cracks etc. Sometimes I have to change a bowl's depth during the turning but I can see how a 'reasonably deep' pin hole could speed up yet not screw up things should change be necessary.;) I've never started a blank on a screw chuck and then changed to a pin chuck. I'm not sure how efficiently that gets you to the best alignment. A Forstner bit can solve the difficulty of drilling a larger hole over the smaller (screw chuck) hole, but that hasn't been a good sequence for me. (not referring to increments of small drill bits to get to a large _centered bit in metal)

This isn't an argument. I have read too many of your knowledgeable and accurate posts not to wonder what obvious point I'm likely missing.

Oh well, fools rush in. All best and keep well, old friend. Arch

Fortiter,

I don't think you are missing anything. However, I think that most of the properties of a chunk of wood can be evaluated prior to turning. Once the axis of a bowl is chosen, then minor adjustments are possible, and often made, to obtain the final balance of the low sides of a natural edge. If, after turning the outside of the bowl, you run into a surprise like a bark inclusion, or a knot, or a previously unseen spectacular grain figure, will you still have the latitude to improve things by shifting the axis? If you try to make a very large change, you are going to waste much of the already-turned bowl. If you are going to make a small change, chances are you won't eliminate the problem.

However, I have to admit that most of the above comes out of my head, not from my lathe experience. So, if your experience says I am wrong, as Frazier Crane says, "I'm listening."

Leo, Using my retrospectroscope, I confess that I was thinking only about adjusting the branches of N.I.pine to get a nice star pattern inside an endgrain vessel before turning the outside. I generalized this and stretched too far to make a point. I made those great adjustments for bark inclusions etc. while sitting in my arm chair, and I don't even know where my pin chuck is.;) Frazier, you are right, I haven't made any 'big' corrections once I began the turning. I think we've reached a 'six vs half a dozen' discussion, but I'm a good listener. Arch

Fortiter,

Leo et al Just to jump in here again, I seldom make large adjustments after beginning a turning, but I find that small ones can make a big difference. The centers make it easier to adjust the wood than does drilling a new hole. That said, whatever works works. Go for it. If the blank is too big for my lathe over the ways, I just screw on a faceplate and rotate the head. Any adjustments in that case mean removing the plate and screwing it back on. Too much hassle for me. Turn, turn, turn.

I'm with the between-centers crowd (another fool rushes in)

But today, I mounted a bowl blank this way, although not without some frustration.

My spur center is too small and tends to act as a drill in a large, unbalanced chunk of wood if I try to take too heavy of a cut.

I had heard of using a small faceplate as a drive center, with three sharpened bolts (one in the center), secured to the faceplate.

Didn't have time or patience to put something like that together, so I tried a variation.

I have some faceplates that are only 5/8" thick, I use a setscrew collar behind them as a spacer. I screwed one of these to the top of the bowl blank (the outside of the log, for a natural edge bowl) using two opposing screws--but not tight, I left them proud about 1/4 inch. These were the "drive prongs", they were #14 screws--big enough to fit in the faceplate holes without slop. I put the bowl and faceplate on the spindle, but without the aforementioned spacer. Before screwing it on all the way, I got the tailstock point in, then I turned the faceplate/bowl in more until the spindle nose came out pressing snug against the top of the bowl, while simultaneously cranking in the tailstock. The connection between the faceplate and bowl was a bit loose because the screws weren't snugged down, but it didn't wobble once the tailstock was tightened and it worked pretty good for roughing out the outside of the bowl.

Soon as I get a roundtuit, I'll put a center pin on one of these faceplates to give a little better mounting of the bowl blank.

Ken Grunke member, Coulee Region Woodturners of Wisconsin

Leo, can you please expand on how you use the laser system during this process.

Cheers, Peter

******************************************** ,-._|\ L. Peter Stacey / Oz \ Melbourne Australia \_,--.x/ snipped-for-privacy@melbpc.org.au v

L. Peter Stacey wrote: Leo, can you please expand on how you use the laser system during this process. ^^^^^^^^^^^^^ Leo Lichtman wrote in > I use a laser system to line up the turning axis on natural-edge bowls, so I rarely have to realign the job part way through ^^^^^^^^^^^^^ Gladly. I have a laser mounted to the headstock or tailstock, and arranged so the beam points vertically downward. The wood is mounted between centers, in a tentative position. If I point the laser to one of the *high points*, I can tell easily whether the other *high point* is out of position, and make the necessary adjustments. This much can be done just about as well using the end of the toolrest, and that's what most people do.

At this point, it is desirable to balance the low points, but this cannot be done with the tool rest, because the wood hits the rest, and cannot rotate. So, at this point, most people turn the outside of the bowl, and then make minor changes to balance the low points later. After balancing the high points, I proceed to balance the low points using the laser beam-- the laser beam does not prevent the rotation of the wood.

I can continue to adjust the wood between centers, before doing any cutting, until edge of the bowl is balanced just the way I want it. At that point, I substitute a Forstner bit for my tailstock live center, and drill a hole for a pin chuck. If I attach the laser to the tailstock at this point, and aim the spot at the tip of my Forstner bit, I can observe the depth of the hole as I drill, and use that depth to fix the bottom of the inside of the bowl.

Beyond that, I have devised a technique, using two intersecting laser beams, which allows me to lay out the complete bowl edge on the bark of the wood, before doing any cutting. I have tested it, and it works, but most people, including me, feel that it is more trouble than it is worth. If I had a very intricate and valuable piece of wood, I might go to the trouble of pre-plotting a number of ideas, to see which one produces the best outcome.

As an aside, I have found numerous other uses for the laser beam mounted in this way, but this post is already too long.