Coring hardwoods

[Clark]

In my current work I will have to core quite a few sugar maple.  I hate coring sugar maple.  Getting that borer started requires a sharper bit than I have, more weight or a trick of the devil.  Maybe a combination of all three.

I'm looking to hear from any other foresters if they've got tricks for coring the really tough hardwoods?  Some things I have considered but haven't made the commitment yet:

-Trying to touch up the bit on a stone? But considering the exact dimensions that it is machined to and the cost of a new bit I'm very hesitant to put the bit to a stone. 

-Buying one of these starters.  Anyone have experience using one?  Does it help and is it worth the cost?

Any other ideas besides cutting the tree down?!

Clark

[WDH]

Most of my increment boring has been in pine, so I cannot be much help.  The one thing that I learned is that when you take the core in hardwood, immediately back out the bit before examining the core (as is your first tendency) or you will be needing go buy another increment borer because the tree will claim that one as a prize  .  It will get much stuck.

[Ron Scott]

Are you using a 2 thread or 3 thread bore? The 2 thread bore usually works better in hardwoods. Also use a lot of beeswax when starting the bore. Also back off the bore as WDH stated.

I've never used a bore starter, but one might be worth a try. I might have used one if they were available during my era.

[clearcut]

For a research project that I worked on, we had to bore several hundred California oaks (live, blue, valley, and white). Keeping the bit sharp was the single most important thing we did. We used a borer honing kit with a flat stone, cone shaped stone, a wedge shaped stone, and honing oil to touch up the edges twice a day. We broke several bits until we began to hone them regularly.

Lubricating the bits with bee's wax helped.

And yes the borer starters were helpful, making it easier to guide the borer in straight.  I don't remember them being quite so pricey though. A nail hammered through a rounded, sanded piece of wood might work just as well.

[chevytaHOE5674]

Use bees wax liberally and it will help. Then just hit the Gym and you'll be all set.

[beenthere]

....................-Trying to touch up the bit on a stone? But considering the exact dimensions that it is machined to and the cost of a new bit I'm very hesitant to put the bit to a stone. 
.......Clark

Clark
Why worry about the slight change in the "exact dimension the borer is machined" ?? 
If measuring density of extracted cores, the exact dimension (diameter) of the borer was important (we used a graduated tapered insert to get that diameter). 
But if just counting rings, the diameter should not be much interest.
However, having a sharp bit will sure beat a dull one, especially when getting it started. The bit stone to hone that bit is a good tool to have.
To keep a sharp bit, not busting through the bark will help. Have used a punch to remove a plug of bark before starting the increment borer.  Are you becomming a silivical seducer? 

[Clark]

Thanks for the replies!

I hadn't considered the two vs. three thread thing, Ron.  Naturally mine is a three-thread variety.  Next time I buy I'll just have to go with two.

Sounds like I should get the sharpening kit and beeswax and see how that treats me.  Like every other Scandinavian made piece of forestry equipment the starter does seem pricey for what it is.

beenthere- The inside of the borer is smaller at the tip of the bit.  It widens out just a slight bit to allow the extractor to fit between the core and the bit itself.  That is the part that is machined to very tight tolerances.  The problem with sharpening is that it is very tempting to the sharpen the bit from the inside out.  This takes away that tight tolerance and soon the extractor doesn't want to extract.  So you can do it but it leads to premature borer death.   And of course they sell a round sharpening stone that only encourages users to sharpen their bits so they go through them faster. 

Clearcut - What was your method for sharpening the bits?  I presume you didn't sharpen them from the inside out?...

Clark

[clearcut]

The idea is to hone rather than sharpen. Keep the edge crisp rather than let it get very dull and try to sharpen it. If it takes more than 10 minutes then you have let the borer get too dull.

Forestry Suppliers has instructions in a PDF here:

     http://www.forestry-suppliers.com/t01_pages/pdfs/M0004.pdf

Haglof has instructions here:

     http://www.haglofsweden.com/products/Incrementborers/incrementborer.pdf

The USFS has instruction here along with plans for a jig to hold the stones at the correct angle:

     http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr25.pdf

Use the flat stone for any nicks or unevenness in the tip - these were rare on a well honed borer.

Use the wedge stone to touch up the treads.

The conical stone hones along the bevel of the outside of the bit - this is the most difficult to get right.

Use the conical stone to lightly remove any burr created when honing the bevel.

[SwampDonkey]

We don't core much hardwood up here, sometimes yes if your doing PSP establishment. Have done a bit of aspen and birch coring, those rings are hard to see. At college we were threatened with a "for sure" likelihood you would get a bill for a new borer if you busted it in a hardwood.

[beenthere]

......beenthere- The inside of the borer is smaller at the tip of the bit.  It widens out just a slight bit to allow the extractor to fit between the core and the bit itself.  That is the part that is machined to very tight tolerances.  The problem with sharpening is that it is very tempting to the sharpen the bit from the inside out.  This takes away that tight tolerance and soon the extractor doesn't want to extract.  So you can do it but it leads to premature borer death.  And of course they sell a round sharpening stone that only encourages users to sharpen their bits so they go through them faster.  ........Clark

I agree.
And as clearcut said, the stones are to just hone the edge, to keep it from getting dull. When too dull to hone anymore and the extractor doesn't fit, time to get a new replacement. They won't last forever.  

[Clark]

clearcut - Thanks for that information.  I never imagined that sort of information existed.  I just ordered a set of sharpening stones and will probably make that jig later this week.

SD - Like a bad (or is it good?) psychologist you remind me that I have broken a borer before.  In a sugar maple, the dead of winter.  What sickening feeling that was.  What will be the cost to continue these "therapeutic" sessions?

Clark

[bill m]

A long time ago I was boring Sugar Maples for root starch analysis to determine sugar content for tapping. We would clean the dirt away from a root about 6 inches below grade to do the sample. Had to make sure it was clean so the increment borer stayed sharp.

[RynSmith]

Wow, I sure don't envy you that.  As many trees as I've cored, I'm glad I never had to core a root!   

[Clark]

After digesting all the clearcut had to offer (Thanks!) I came up with a method to sharpen (or touch up) a bit with a minimum of prep work.  The plans offered in one of his referenced articles would certainly work but I lacked the tools to make such a jig.  Granted, the jig would be nice to have in the field but normally I don't need it there.  Having something at home to touch up the bit is fine for my work.

To that end I devised this set-up:



As you can see, two brads hold the bit in a fixed position.  The clamp holds the stone(s).  Fixing the stones to the correct position is the most difficult part of the operation.  Using a hammer to lightly tap them into the correct angle after the clamp has been tightened eliminates the frustration of clamping the stone into the exact position required.

To sharpen the bit, roll the borer towards the brads while pushing it toward the stone.  In a minute or less you can have a nice, shiny, sharp edge on that borer.  Remove the brads and clamp from your desk/work bench/counter top and you're done.

Clark

[WDH]

That is slick!

[Clark]

After going through the sharpening stones and finding a nice improvement there I was still having problems, especially when daytime highs were reaching ~5º and every tree became that much harder.  So I ordered the starter which is quite slick but it didn't seem to help that much.  Kept everything nice and straight but I was still have difficulties.

So I ordered a new borer, went with the two-thread version and then consoled my pocket book.  Now that I can compare the new vs. the old borers it's no wonder I was having troubles.  The threads on the new borer are sharp whereas the old borer they very flat and finger friendly.

What it boils down to is that I now have to figure out how to sharpen the threads themselves so an old borer can truly be sharpened.

One problem solved, another problem revealed.

Clark

[Stephen1]

A long time ago I was boring Sugar Maples for root starch analysis to determine sugar content for tapping. We would clean the dirt away from a root about 6 inches below grade to do the sample. Had to make sure it was clean so the increment borer stayed sharp.

hate to steer away from the topic, but what did you find out? Did the testing of the roots point out the trees to tap? Inquiring, sugar producer asking?
Stephen1

[bill m]

Yes, it did show which trees should be sweeter in the spring but we only did it one year. We should have done it for about 3 to 5 years in a row to see which trees were sweeter all the time. Then we could have saved seeds from the sweeter trees and started a new sugar bush so I would have some good trees in about 40 years.

[SwampDonkey]

Yes, it did show which trees should be sweeter in the spring but we only did it one year. We should have done it for about 3 to 5 years in a row to see which trees were sweeter all the time. Then we could have saved seeds from the sweeter trees and started a new sugar bush so I would have some good trees in about 40 years.

    Not chuckling at your projection, just adding your age to that 40.

Up here it would be at least 60 to get to 8"-10"

[bill m]

Yea, I thought of that too and decided it wasn't going to work so gave up on it.