Mandrel design

[nodima]

Been trying my hand at turning napkin rings, for my first exploration at something not a spindle.  The ones I'm doing are drilled so that when turned, there is end grain to deal with which I've not previously done.  My success rate is mixed, but after a couple more videos, I've gained some other techniques which work well. 

Question on the mandrels, I've watched several different videos, and everyone has made their mandrel from two parts, a base, which is drilled to accept a tenon on the mandrel sized for the rings.  Is there a reason to use two pieces, vs. a single chunk?  Other than single thick chunks are more expensive?  Also, the mandrels I've made have been out of cedar 4x4 post scrap from a deck project.  Is there an advantage to making mandrels from hardwood instead? 

Any other hints or thoughts on turning these/making mandrels is welcomed, as at this point, so much is new, I'd hate to miss on something due to not knowing I should ask.

thanks

[iclark]

I am not sure what your mean about having to deal with end grain.

Are you starting with flat boards, drilling holes, and cutting out ring blanks with a bandsaw?

If you have something like a chuck with pen-drilling jaws, you can mount a spindle blank, drill the hole for the rings, and then spindle-turn the rings. That approach has the advantage that you can start with a green branch and, if you get lucky, get the quarter-sawn effect all the way around the ring. Make the green-wood napkin ring a bit over-sized to allow for shrinkage and most woods should behave themselves while drying.

[nodima]

I am not sure what your mean about having to deal with end grain.

Are you starting with flat boards, drilling holes, and cutting out ring blanks with a bandsaw?

If you have something like a chuck with pen-drilling jaws, you can mount a spindle blank, drill the hole for the rings, and then spindle-turn the rings. That approach has the advantage that you can start with a green branch and, if you get lucky, get the quarter-sawn effect all the way around the ring. Make the green-wood napkin ring a bit over-sized to allow for shrinkage and most woods should behave themselves while drying.

Thanks, I've seen that approach, but I'm doing sort of the opposite.  Cutting out a 2" square from a piece of 1 1/2" stock, drilling a 1 3/8" hole through it, and mounting that on a mandrel.  The hole is drilled centered in the 2" square side, so the ring ends up 1 1/2" thick.

[MichaelMouse]

Been trying my hand at turning napkin rings, for my first exploration at something not a spindle.  The ones I'm doing are drilled so that when turned, there is end grain to deal with which I've not previously done.  My success rate is mixed, but after a couple more videos, I've gained some other techniques which work well. 

Napkin rings, when a hole is bored prior to turning, are a spindle turning.  That is, if you use something like a home-made pin chuck, or even a slow taper cylinder between centers to mount them.   I wouldn't use a jawed chuck and flip, unnecessarily fussy.

You contend with "end grain" by cutting downhill, as always.  If you've bored a flat piece of wood (recommend after holesawing nearly through), you use a straight-edged tool as if you were rolling a bead.   Start center and cut downhill left then right.  Beading tool, Bedan, straight chisel, or even a 1/4" parting tool will do the job nicely if  you don't have traditional pattern spindle gouges as he does. Bead Turning on the Lathe - Bing video  They're really near-straight edges and really straight cut even better. 

Pin chuck involves a cylinder with a flat filed on it as deep as your chosen roll pin.  Can be 1/8 dowel, or as I use, brazing rod.  Neither will ruin an edge if you overcut.

Note now that I believe you haven't bored endgrain. If the grain runs across the ring, downhill is from center outward, not from the outside toward center. Gouge is safest.

[nodima]

Thanks Michael,

Your last sentence is correct.  I did not bore endgrain, so that when the blank is mounted on the mandrel, there are 2 faces with end grain and two with side grain.  This is why I don't really think it is spindle turning.  What I've had better luck with doing is using a bowl gouge, and starting from each end, working towards the middle.  Once the blank is rounded into rough form, it is smoothed with a skew.

Now that just WHAT I'm doing is sorted out, I'm curious about the mandrel part.

Thanks

[crokett™]

I would bore the middle, then use a pin chuck with expanding jaws to hold it for turning the outside.

[MichaelMouse]

Now that just WHAT I'm doing is sorted out, I'm curious about the mandrel part.

Thanks

Of course, I'm no fan of a skew.  I'd rather a straight, choosing the angle to skew to the work myself.  

However, either snugging on a mild taper cylinder of softer wood to take advantage of the compression, or a pin chuck made of hard stuff, using a roll pin to wedge the ring, will keep you clear of metal to do both sides.  I used the taper for a bit, then, as I thought about it, moved to a wooden pin chuck.  I use a metal type for all kinds of turnings, but only those where one side is turned at a time.  These are made as spindles with enough length either side of the final turning to swing tool handles without hitting the lathe parts.  

FWIW, in my area, they didn't sell worth a darn.  Wine stoppers in a world of beer drinkers, or fancy pens for people who don't push them didn't either.   Gifts.

[iclark]

Had you considered using a hole saw for roughing the outside to round instead of square?

For that thickness, one would probably need to use the hole saw from each side.

If I were trying to do what you describe, I would be splitting way too many rings before the outside got round.

I used the hole saw trick when I was making mahogany friendship rings back in high school.

[nodima]

Had you considered using a hole saw for roughing the outside to round instead of square?

For that thickness, one would probably need to use the hole saw from each side.

If I were trying to do what you describe, I would be splitting way too many rings before the outside got round.

I used the hole saw trick when I was making mahogany friendship rings back in high school.

No, no thoughts about a hole saw - though I did think about using my BS to trim corners, but once I figured out the technique of starting at both sides and working towards the middle with the bowl gauge for roughing, the splits and tears vanished.  The last 4 I did all turned out. 

Sounds like using softwood is ok for the mandrel if for no other reason than compression.

Here is what I’m working with - this one is a single piece, most of the ones I saw in videos used two pieces - one as the base, connected to the chuck, and the other as the actual mandrel.  Not sure if there is a compelling reason to do it differently.