depth of tap hole

[DrTimPerkins]

Two comments:

1. You've gotta wonder how much sap they were getting out of those holes tapped right into stained areas.
2. It's possible that paraformaldehyde (PFA) was used in those old 7/16" tapholes. Made wounds MUCH larger.

[Openwater]

Dr Tim,
Is it possible that both holes in the same column of stained wood were taps placed at the same time/same year? Would 2 taps in the same "column" produce more sap than 1, assuming that in the future, this is all going to be non-conductive wood anyhow? Or would both taps essentially be pulling sap from the same "source wood"? Or what if 1 tap was drilled 1/2 - 1" deeper than the other in the same column? Sorry for all the hypothetical questions.

[DrTimPerkins]

Would 2 taps in the same "column" produce more sap than 1, assuming that in the future, this is all going to be non-conductive wood anyhow? Or would both taps essentially be pulling sap from the same "source wood"? Or what if 1 tap was drilled 1/2 - 1" deeper than the other in the same column?

I chopped off the first question because I was unsure what you were asking. For the rest, it could vary slightly depending upon whether you're on gravity or vacuum. In general, if you drill a second taphole, or drill another taphole slightly deeper, but close to the first, they will draw from the same sap "reservoir" within the tree. On gravity, this will be mostly above the taphole and mostly on the same side of the tree, but spreading slightly as you go up. On vacuum, sap can be pulled much further, so the "reservoir" is larger, and depending upon the point you are in the flow cycle, could be from above (early part of sap run), across (further into the run) or from below the taphole (longer in the run). The total amount of sap you would extract would be about the same from one taphole or two, you're just splitting it across two tapholes. This is true for strong vacuum (25+" Hg) for trees up to about 20" dbh. For very large trees it is somewhat different depending upon the size of the tree, depth of taphole, number of tapholes, etc.

When we tested this (in red maple) over a couple of years, we found that for trees in the 15-18" range, there was no point putting in a second tap if we were using high vacuum. We use 36" droplines and had one going up and the other going down on opposite sides of the stem to get them as far apart as we could. Even then, the average yield was the same from 1 taphole trees as it was from 2 taphole trees. We are repeating that for sugar maple for the next few years to see what we get. After that, we may relocate the chambers and do some really big trees. Doing that is not easy...there is a lot of setup to get the whole thing right.

Putting a second tap exactly within the staining column above (or below) a taphole is really hard. Even drilling 1" above a taphole you will miss stain entirely some of the time. The further you go, the less likely you are to hit the stain perfectly. The side-side extent of staining is limited to just a small amount beyond the width of the taphole, and it is not always perfectly straight. Maple wood frequently has a slight twist to the grain...at least it does up here on the side of a mountain.

[VT_K9]

In follow up to the pictures....the board came from one of two trees on our family property. The 7/16" holes were made with a bit stock and auger bit for buckets (I have one hole which shows the cut of the end of an auger bit). I could not tell you who hung the buckets back then. We used buckets until about 1993/94 when I was off to college and then tubing entered the picture. I returned to the area each season to help set out lines and clean up. I was in college from '91-'95 and remained in the college town until '01 when I moved back to this area and build my house on the family land in '03.

The two trees the boards came from were approximately 24-30" in diameter and I think the would have had 3 buckets on them. They were on a steep bank with poor footing. That would probably explain close proximity of multiple taps. Not that it excuses poor tap placement. I know that area of maples always produced good quantity of sap...had full five gallon buckets every haul when we used buckets. The youth were often send to collect those buckets.

It was a privilege to be able to have the trees sawn into lumber and see what was inside. Some awesome stories...there is an oak on the property which has a tapping story.

Mike