egg boxes

[Bob Strand]

Trying to make egg boxes. Looked at several videos and appear to be going about it correctly but, ta, da, the pieces don't match up perfectly all the way around. They must be put together exactly the same way each time or there's a slight overhang on whatever edge. I turn the piece round off a steb center, make a skew cut to divided the long and short end, then part it and put the short end in a chuck and form the contour and hollow out the center then true up the surface and sand. Then I put the long end in the chuck, make the tenon by back and forthing with the short end for a tight fit then hollow out the center. Then I put the two together and bring up the tailstock and true up both pieces together. Smooth all the way around then I turn each piece around, separately, and put them in the chuck and finish off the remaining tenon that was used to hold them in the chuck. When all is said and done they don't fit true again. I'm not the brightest bulb in the string but I am bewildered by this. Any help???

 

[Mike Johnson]

Bob,

Each time you remove the piece from the chuck you are introducing a slight change in the orientation
of the piece in your chuck. It does help to mark the piece along with the orientation it was mounted in
your chuck so it gets mounted in the same location. Depending on the wood type you will also get some
movement while hollowing both pieces which will have some impact on the two halves fitting together.
Each progressive step adds a small amount of error in the final concentric fit of the two halves. Larger
work pieces are less noticeable, while small pieces will magnify the errors incurred. The more pieces
you work on will help refine your process and the end product.

There are a number of approaches used to resolve some of these issues.
Normally you want to match the wood grain of both halves and make the fit perfect in that orientation.
If you want or need the two pieces to be concentric at every orientation you will need to take extra steps
during the turning process to guarantee a perfect fit no matter how the two pieces are aligned.
When turning a hollow sphere I usually need to rotate the piece between different axis while turning and
reducing the piece to the desired diameter. In a similar manner you can mount the two halves at opposite
orientations and turn and sand the outer surface and repeat this process to get a perfect concentric fit of the
finished item.

 

[Clifton C]

I understand your process and it will work, however, if you’re taking box making to the nth degree, here are a few things that might help.
It’s just another process among many. Dry wood is a given.
Start between centers with base of box toward tailstock. Rough round, turn tenon at tailstock end.
Install chuck, grip tenon. Do not use tailstock/live center. Turn tenon at top of box (now at tailstock end) and part off top.
Rough hollow base, remove from chuck. rough hollow lid, remove from chuck. set aside to rest for a few days. Three maybe? A week?
I’m too impatient for that but I try to wait a day.
Install top of box back in chuck, tool and finish inside, mortice in lid should have perfectly parallel sides to fit tenon on base, if there is any error the opening should be the smaller measurement, but not by much. Remove top from chuck. Install base in chuck, tool and finish inside. Cut tenon,fit top to base. Not too tight, but defiantly not too loose. The fit has to be tight enough that you can tool the top to completion without bringing up the live center. Once the top, and most of the box is finished, final fit the top to the fit you want by lightly trimming the tenon. Supper sharp tools and light cuts. A rubber band around the top will help remove a tight fitting lid till you get the right fit. Now you can jam fit the box bottom into a scrap piece of wood and tool the bottom (end) of your egg box. Key things are not using the tail stock (after the first tenon), and letting the box relax after roughing out the interior. If the box gets warm when sanding the inside, or if using a friction finish, let the box cool off before cutting the tenon. The join will be perfect for a day or two, but then will be out by a few thou. That is why a lot of box makers use a bead or a quirk or some other method to disguise the join.

 

[Bob Strand]

Mike, Clifton. Thank you. It would appear that I'm expecting too much result from not enough input. Hadn't considered the need to allow the pieces to "rest", and, like you, Clifton, patience isn't my long suit, but can certainly agree with the logical need for that. Hopefully by Easter I'll get a better result!

 

[Mike Johnson]

Bob,

On some of my turned boxes, I will cut a small groove at the mating joint and use a wire
to create a friction burned line at the joint. You can also just cut several fine detail lines
at or near the joint to create a decorative detail and provide a presentable finished item.
You can then use these detail lines to contain a texturing element to the piece.

 

[Tom Albrecht]

Sorry for my density on this, but when you say "egg boxes" are you talking about a two piece box that is shaped like an egg? As in the nesting eggs that fit inside one another?

 

[Bob Strand]

Good idea Mike, give a little leeway for error. And yes, Tom, a two piece box shaped like an egg but not the kind that stack up together into one another.