When I am close to as deep as I intend to bore I check by holding the Spoon along side the tree with the end level with the end of the tube.
When I believe I have gone at least half way through the tree in order to sample the pith I level the handle parallel to the ground. I insert the spoon. At this point, the core in the tube is oriented properly so that the view into the core is as though looking down through the tree.
I seat the spoon and turn the handle a little each way to break the core off. Then with the handles level again I partially extract the core. I use an indellible pencil and make a line all the way along the lengh of the core. This helps me orient the core when I mount it (but I always double check with a microscope before I mount a core) and also helps me put the core together when I mount it if it breaks. Quite often the cores break in one of more places.
A tip on how to find the pith
All limbs point back into the tree to the pith. Observing the branches above (and below if possible) will indicate the path you will want your corer to take to get to the pith. This method should get you at lest close enough to the pith to be able to 'read' the rings in the pith.
Handling the core in the field
I use the cheap straws used by most restaurants. They can be gotten from Sam's Club - 3,000 to a case for very little cost.
I remove the white paper sleeve before taking to the field. The sraws are almost exactly the size of the cores. That makes getting them into the straw difficult and if the core isn't broken it will be by the time you get it into the straw. Therefore, I have an letter opener in my field kit and slit the straw with the opener. The core will go into the straw without difficulty and the straw closes around it tightly enough to keep all parts together and prevent the core from sliding out of the straw. The slit also allows the core to start drying.
I then use a fine tip felt tip pen to put the speciment number on the straw and put the core in the slot in the kit I use to keep tree coring stuff in.
I use to plug the holes after coring. after recent research into the work of Dr. Alex L. Shigo concerning the healing of wounds to trees I have modified my protocols when coring trees.
I will be more judicious in coring, doing it only when I have a specific reason for coring. Additionally, I will no longer plug the hole. According to the research of Dr. Shigo, plugging the hole will only inhibit the natural healing mechanisms of the tree and could even be harmful.
When the cores are dry I lay a bead of glue in the grove and clamp the core back into the mount. When the glue is dry I process the cores in the shop in the basement as follows:
1. I sand the portion of the core above the surface of the core mount down to the core mount level using a belt sander.
2. Then I run the mounted core across the disk sander to ensure everything is square and that it is sanded down to the same level from end to end.
3. I clamp it in a jig I made for this purpose. I adjust an adjustable clamp on one end to hold the mount firmly and sand the mounted core with 5 grades of sandpaper starting with 180 grit and ending with 800 grit. I then polish with polishing paper in 6 steps from 1 to 30 microns. At that point the core (and mount) have a finish that appears to be almost glass like.
I clear the mounted core with canned air to remove any loose dust particles from the pores.Reading the pores is easy with a strong glass or a microscope.
Taking increment core samples at ground level
Taking increment core samples from the bottom of a tree can be done with ease with a few modifications to the basic instruments used to take tree cores. I had an old corer that was not going to be used again. I cut the handles off leaving two inche stubs on either side. I milled one end of a metal rod to be used as a handle fitted into one of the handle stubs. This handle can be switched from one side to the other to rotate the corer half a turn at a time. Since the stub of the handle opposite is only 2 inches the core sample can be taken within 2 inches of the ground.
The method is as follows:
1. Seat the corer in the tree (I use the rope method described on this website)
2. Once the corer is anchored in the tree insert the handle on the left side and turn the corer 180 degrees.
3. Take the handle out and switch it to the stub that is now on the left side and repeat. Keep doing that until the corer has reached as deep as desired and extract the corer in the usual way reversing the switching pattern.
I found it works beautifully and took a core from 2 inches above the ground. It was harder work than coring at breast height in the normal manner as you work with your hands instead of your arms and at ground level. Leverage is difficult to achieve. However, it is a way to get a core at ground level which gives the true age of the tree. Adjustments can be made for cores taken at breast height but not that yields an approximate date of establishment which can be off by a number of years. Digging a ditch to allow the handle to rotate can damage roots and is not necessary with this method.