Spline box how-to

Mount a blank on the lathe between centers in face grain (side grain) orientation.  Turn a tenon on each end.  I leave the blank square so the next operation is both safer and easier.

The blank is taken to the band saw and a cut is made that follows the contour of the grain. Blank selection is important as you want the grain has some contour that runs side to side, not diagonally. The end grain should also run as perpendicular as possible to the side grain.

The blank can then be mounted between centers again and turned to a cylinder.  Alternatively each half can be mounted in a chuck and turned to a cylinder independently.  When demonstrating this project I opt for the chuck method as it is safer than turning a blank between centers that has been cut in half.  Can you see the joint in this photo?

There it is.

The 2 halves turned to a cylinder and set aside.  The contour is what makes this box interesting and necessitates the spline technique as it's not possible to turn a tenon on the irregular surface and still have a good grain match.

 

The first half is then mounted in the chuck and the inside is turned.  The body is partially hollowed and a recess is turned around the inside, this will be used to accept the spline that will act as the faux tenon.







The blank for the spline is mounted between centers and turned round.  I usually opt to use the same wood and turned in the same orientation as the body of the box.  In this case the only matching wood I had was in end grain orientation but I used it anyway.  A spline in a contrasting wood is another good look.

The spline is turned to the correct diameter.  It can normally be remounted and carefully turned to get a good fit with minimal runout.  I actually don't mount this between centers.  I jam the blank against the flat face of the spindle and drive it with friction and pressure from the tailstock.  I use the face of the spindle as it will ensure that the blank is perpendicular to the ways.

Once a good fit is attained the spline is glued in place.  The round mark visible here is from the end of the spindle.

The chuck is then returned to the lathe and the center of the spline removed to that only the solid wooden ring is left.  The rest of the body is then hollowed and the spline is blended into the rest of the body.  I opted to reduce the length and soften the edge of the tenon slightly.

The other half is then mounted in the chuck and a recess is turned to match the diameter of the spline tenon.  From here on out the process is mostly the same as a standard box.  We now have 1 half with a tenon (spline) and 1 half with a recess.

The first half is mounted onto the 2nd half and the live center is brought up to support it as the outside is turned.  I round it off and take it down to a little nub.  The top half can be removed to check the wall thickness as work progresses.  The blank centers very well as the contoured joint can only fit in one position.  The dimple from the live center also helps keep it centered.

If the fit is tight enough the nub can be removed without the need for tape.  I rushed through this box so the fit was looser that it should have been so I needed some painter's tape to hold it together while I cleaned up the nub.

The rest of the end half is hollowed and then reversed for for final turning.  I opted to use my vacuum chuck but a jam chuck should also work.  The outside is turned to match the first half,

The 2nd half secured on my vacuum chuck.  My primary vacuum pump pulls 24" of mercury which translates to 12 PSI.  The PVC is 2" diameter which is roughly 3 square inches so there is roughly 36 pounds of air pressure holding this in place.

Turning complete, next up is the texturing that is used to help disguise the joint.

The outside is textured with a round brass bristle brush.  It's held in a jacobs chuck and the lathe rotates it while I hold the box against it.  The softer wood is worn away while the harder wood is left behind.

The finished box.  Another reason I like doing this style of box is that I don't have to sand the outside at all.  The entire surface is textured, more grain is worn away where it's softer but even the harder grain gets some texture.  Any time spent sanding on the outside is completely wasted.

Another view.

Open view.  You can clearly see the end grain orientation of the spline, the grain runs vertical rather than side to side.  If it ran side to side it would blend better with the body and be much less visible.

Ash spline box

Tonight was my first night back in the shop for quite a while. I've spent some time out there recently but mostly cleaning and organizing (not that you can tell).
















This is a small semi spherical box I turned tonight out of some Ash. It's turned side grain rather than end grain so I can use the grain lines to help hide the joint. The joint also isn't straight as it was cut to match the contour of the grain.











This requires a completely different joint as it's not possible to turn the usual tenon and recess on the curved surfaces. Instead I have to turn 2 recesses and join them with a spline. I chose to use another piece of the same wood, a contrasting wood could also be used.










The outside was then textured with a wire brush to further hide the joint line in the grain lines. If I had a sandblaster I'd use it to do the texturing as I believe it would be more uniform and I think I could go deeper into the softer grain.

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Day 335: Testing texture

You may recognize these 3 hollow forms from yesterday.  Today they were hollowed and then textured.

The piece on the right was an experiment, I intentionally cut some grooves on the inside so that they would open up and show through as voids when the piece was textured.  I think there's potential here.  The middle piece was turned with the grain at a slight angle.  I'll probably do another one with the grain running closer to 45 degrees.  The piece on the right has the grain running horizontally and is the most successful of the 3 in my opinion.

Day 334: Dog days

The dog days of summer are upon us here in the Phoenix area.  That means a couple of things, 1) my shop time is limited because of the extreme heat, 110+ is not uncommon,  and 2)  my shop time is limited due to my other hobby: storm chasing.  Phoenix gets hit with monsoon storms every year, they typically run from mid July through the end of August.  Storms typically build over the the Mogollon rim and then sweep to the Southwest into the Phoenix metro area (also called the valley of the sun).  We live on the eastern edge of the valley, not far from the Superstition Mountains and get some of the best lightning in the state.

My shop time today consisted of cutting and roughing 4 small piece of redwood.  3 of them will be small hollow forms that I plan to texture; the fourth will be a spline joined lidded box that will also be textured.  The hollow forms all have the grain running in different directions.  The one on the left has the grain running vertically, the middle is running at a slight angle, and the one on the right has the grain running across the piece.  

Tonight we had the first big storm of the monsoon season.  There was a smaller storm on Friday evening but it died out before it got to me.  I'm sorting through 139 images I took tonight.  If I'm lucky I'll have 2 or 3 keepers.  A really good night would 5 or 6 keepers.

Day 333: Hands on

Today was the July meeting of the Arizona Woodturners Association.  We had a special hands on meeting at the local Woodcraft and it was a huge success.  We had 8 lathes going most of the day, with several turning pens, a couple of turning demonstrations by J Paul Fennell (http://www.jpaulfennell.com/) and Paul Porter (http://paulporterwoodturning.com/).  I also did a little demonstrating, doing a pair of small hollow forms, one with wire brush texture and the second with some wood burning.  In my opinion the best part of the day were the 2 contests we held.  The first was to challenge club members to turn a small cylinder and to get the best cut they could get on some small spindle blanks that I provided.  They were free to use any tool and any turning method they wanted, the only rule was that no sandpaper could be used.  Some of the results were very good and one club member walked away with a maple burl for his work.  The second contest was a group contest, a relay race actually.  We had club members signup for teams of 3.  Each team was provided an identical block of wood and the first member of each team turned for 15 minutes.  They then handed off to the second member of each team who also turned for 15 minutes.  The third team member then took over for the final 15 minutes.  The only rule was that team members were not allowed to talk to each other before or during the relay.  The finished pieces were then judged and the winning team declared and the winning team members won a small prize.  I initially planned to judge the contest but when the third team ended up with only 2 people when the relay was ready to start I jumped in to anchor their team.  Things went well until the last 90 seconds of my time when I had a monster catch that nearly ruined our bowl. The last 60 seconds was a frantic effort to save the bowl and trying to get it finished.  I ended up running out of time and wasn't able to get the bottom finished.  Had I gotten it finished I think we might have won.  I think the catch was a matter of 2 different factors, unfamiliar tools and a large check in the wood.  I'm not saying that it wouldn't have happend with my own tools or with a marginally better piece of wood - catches happen to everyone - but both of those factors together plus the fact that I was rushing was asking for disaster.