Manufacturing of an increment borer

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jcruddat
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Manufacturing of an increment borer

Post by jcruddat » Mon Jan 01, 2018 1:34 am

Hi all,
I have recently taken on the challenge of machining a 28" to 30" long increment borer at the CNC machine shop of my school, Worcester Polytechnic Institute, for the purpose of drilling closer to the pith of the 150+ year old tulip poplars, 250+ year old sugar maples, and other old growth trees here in Connecticut. So far I have made a fair virtual 3d representation of the threaded tip in a CAD program called SolidWorks which is available to view or download at https://grabcad.com/library/increment-borer-1. I you wish to view the file but do not have access to SolidWorks then I can upload the file here in a different format such as in the .STL or .OBJ file format, viewable in free software. Right now I am trying to refine the design of the threads since the rest of the borer is pretty straight forward. I am currently trying to base the threads on the JIM-GEM style borer which looks very similar to the old Djos/Suunto style borer. I prefer the JIM-GEM borer over the more common Haglöf borer because the spreader bars are made in-line with threads instead of the behind the threads. This allows for much easier backing out of the borer from the tree since there are still threads behind the cams re-engaging with the sometimes soft or rotten wood. The previously compressed walls of the wood surrounding the hole from the spreader bars tends to spring back into place and can sometimes lock the Haglöf borer in place. I have had the Haglöf borers get stuck multiple times, usually when hitting a pocket of rot or cavity within the tree, but almost never with the JIM-GEM borer. The hardest part of modeling the threads is the fact that the geometry of the threaded borer tip is very difficult to measure such as the curvature of the face of the cone/barrel that the threads are made on, along with the geometry spreader bars that are in-line with the threads. Does anyone have information as to the dimensions of the tip of the borer or the process in which they are machined? Also, if anyone has some input as to the most effective style of increment borer then that would also be very helpful. So far I have not been able to find much useful information on the internet as to how they are machined or how they are dimensioned other than one simple schematic and a cross section view both attached at the end of this post. I assume that the threads are machine on a 5-axis CNC mill or lathe and then welded to the shaft along with the square end that fits into the handle. I have heard that the old Djos, Mattson, and particularly the Sandvik increment borers were of well respected and rarely broke or got stuck. The Djos style borer looks similar to the JIM-GEM style borer I am using now but I have not been able to find any information or photos on the geometry of the old Sandvik borers. Perhaps someone has one lying around and could post a picture of the threads or some insight as to the schematics of such devices?

Regards,
Jack Ruddat
Attachments
JIM-GEM Style Increment Borer Thread Dimensions.png
JIM-GEM Style Borer Cross-sectional view.jpg

DwainSchroeder
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Re: Manufacturing of an increment borer

Post by DwainSchroeder » Tue Jan 02, 2018 1:04 pm

You have taken on a very challenging project. Years ago, I toyed with the idea of making a 30" borer to look at growth rings on a giant burr oak in Goll Woods Preserve (northwest Ohio), for a precipitation history study. The tree was already dead but still standing The Preserve has a strict "no disturbance" philosophy though I believe I could have gotten permission to bore the dead tree. Long story short - I gave up on the idea after considering the design difficulties including that the wood would be somewhat dry and very hard; and also my interests moved on. I was in Goll Woods this Spring, but my failing memory won't let me recall if that tree has fallen yet....

Unfortunately, I don't have any specific details on the design aspects of borers to offer, but I still would like to respond. I have a 14" long "Suunto" borer which has worked well for me. I believe it was made in Sweden. It has three screws which I have been told, but it is not necessarily obvious to me, allows for easier and more efficient engagement than a two screw design. I believe what you call spreader bars, are located between the threads, but the last thread is tapered to allow for easier extraction. I believe that 28"/30" bores are available commercially but are quite expensive, and the idea of a do it yourself project is always interesting and educational.

I'm sure you already know, but material selection would have to be critical for your project. Borers are subjected to very high stresses. A 30" long borer may also be somewhat vulnerable to a "torsional squirm buckling" action - perhaps not, but something to look at when calculating the required wall thickness.

Good Luck!

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jcruddat
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Re: Manufacturing of an increment borer

Post by jcruddat » Tue Jan 02, 2018 4:52 pm

Hi Dwain,
Right now I am considering making the shaft out of 4130 chromoly steel and the threads out of some hardened 4340 chromoly steel. This is what was suggested to me by some guys in the discussions I started in the PracticalMachinist and CNCZone forums (http://www.practicalmachinist.com/vb/cn ... el-339531/ and http://www.cnczone.com/forums/machinist ... 4-cnc.html). I am also going to do a simulation in SolidWorks to determine the maximum torque that can be applied without significant twisting or breakage of the increment borer. Your giant burr oak reminds me of some large white oak wolf trees I came across once in Cowles Park, East Granby, Connecticut. I might be interesting to see how old those large trees are in order to determine when last the forest was a pasture.
Large field grown white oak #1
Large field grown white oak #1
Large field grown white oak #2
Large field grown white oak #2
Jack
Last edited by jcruddat on Tue Jan 02, 2018 9:44 pm, edited 1 time in total.

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Larry Tucei
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Re: Manufacturing of an increment borer

Post by Larry Tucei » Tue Jan 02, 2018 9:19 pm

Hi Jack- I hope you succeed on your Project 4130 will work but the wall thickness and length will be the issue. I thought about doing this about 2007 when I first joined NTS but never got around it. I'm a Welder with access to our Machine Shop. Keep us posted on your results. Some of the Hardwoods will be difficult to core. Good luck Larry

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jcruddat
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Re: Manufacturing of an increment borer

Post by jcruddat » Tue Jan 02, 2018 9:43 pm

Hi Larry,
I agree that the wall thickness is definitely something to consider when it comes to very long increment borers. Do you know if the wall thickness increases with length on Haglöf borers? I hear that Sweden has access to some very high quality iron ore deposits which they use to make what one guy described as high yield "unobtanium" alloyed tubes from companies such as Sandvik.

Jack

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Larry Tucei
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Re: Manufacturing of an increment borer

Post by Larry Tucei » Mon Jan 08, 2018 9:41 am

Jack- I'm not sure what the thickness is on their longer Borer. Perhaps you could contact them.. If you are successful yours would be the one I would purchase. One note Unobtanium is a term coined by NASA referring to rare metal back in the day. It's a fancy name for titanium which would be lighter but not stronger than Heat Treated 4130 of 4140 steel. Larry

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jcruddat
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Re: Manufacturing of an increment borer

Post by jcruddat » Sun Jan 14, 2018 4:39 pm

Looks like I finally finished the model and It's as close as I can get to the actual thing. The tapering of the cone changes slightly near the shaft but that seemed to me to be unnecessarily complicated for such a part so it was overlooked.

Jack

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BeeEnvironment2020
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Re: Manufacturing of an increment borer

Post by BeeEnvironment2020 » Tue Mar 16, 2021 4:07 pm

Hi Jack,
How did your project of manufacturing the borer turn out?? I hope it worked out well for you!

I am currently in High-School, and unfortunately the increment borers on the market (18 inches long), are just too pricey for me, and I am unable to afford all of them (There are no student discounts either, sadly).
Where I live in SE Pennsylvania, there are many old trees in some forests that may be old-growth (especially the unblighted Beech, Oak, and some Tulips) that would be very interesting to have a tree-ring analysis done, especially the Beech.

Anyway, I have one quick question for you.
If you did manufacture the borer, and you don't mind me asking, how much did the production of it cost? Was it more than buying a 28-30 inch increment borer outright from Haglof?

Thanks very much, and
Best Regards,
BeeE.

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jcruddat
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Re: Manufacturing of an increment borer

Post by jcruddat » Sun Aug 22, 2021 5:50 pm

Hi BeeE.,
Thanks for reminding me about this. I actually was able to finish in early May this year using my schools CNC machine shop. The results are promising for conifers and other soft-wooded species, but may require some peck-drilling for hardwoods trees. The reason being is that I designed my own bit with spreader bars that shear more than they compress, which caused a build-up of wood chips half-way down the tapered threads in oak trees. Attached is an executive summary of the device and several photos. It is hard to say how much it cost given the fact that it took a lot of trial and error over the course of four years at college. Outsourcing the threaded tip and handle insert for welding to the shaft cost me ~$190. I also had to buy the stock metal, a few parabolic-fluted cobalt drill bits, and a 3/32in diameter, 60° tapered carbide end mill. That puts the total to at least $300 to make a 12in, 24in, 32in, and 39in bit. This all assumes that you have expertise and access to a modeling program (SolidWorks), CAM program (Autodesk HSMWorks), CNC machinery (Haas lathe, vertical mill, 5-axis and 4-axis rotary, and the necessary cutting tools). A 28in increment borer will cost you $600 for the bit alone (https://cspforestry.com/products/haglof-increment-borer-bits.html) but is worth it in the long run provided you take exceptionally good care of it. If you do end up buying a borer, I recommend a 2-threaded borer as they are less likely to get stuck in a tree, especially in hardwoods such as sugar maple, American beech, oak, tuliptree, etc. In the end, manufacturing the borer was worth it for me given my resources, time, and interest in manufacturing engineering and design.
Otherwise, I would love to see photos of those trees if you have any! Pennsylvania's old-growth forest have long been on my bucket list of places to visit in the Northeast. Up here in Connecticut we do not find forest-grown tuliptrees much larger than say 3 ft. in diameter or many blight-free beech for that manner.

Jack
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Manufacturing an Increment Borer.pdf
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IMG_7581.jpg
Picture1.jpg
Picture2.jpg

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BeeEnvironment2020
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Re: Manufacturing of an increment borer

Post by BeeEnvironment2020 » Mon Aug 23, 2021 6:33 pm

Hi Jack!

Thanks so much for responding! 300 dollars for all those bits is definitely a good value, but a lot of work, like you said!

I don't have any access to those programs you mentioned, or a proper lab area to make them even, but the process is fascinating! I don't believe I will be able to buy a increment borer for a while, just due to their sheer cost, but I will keep you advice on 2 thread versus 3 thread in mind for sure! I am volunteering at a local land conservancy in Chester County Pennsylvania, and there are often many large and old trees around, but not many old-growth forests in southeastern PA.

Yeah, I have taken a lot of photos of old-growth trees, mature forests, "witness" trees, etc... from here in Pennsylvania, and many of the forests are fascinating! If you want, I can send you a email with some impressive trees (like a few tulips, unblighted beeches, White Pines, etc...), I have measured and their data/photos. Most of these are from Pennsylvania (actually, I think they all are from PA). Most virgin/old-growth does not occur until the mountains in the state (which were mainly heavily logged in the 1800s) but there are areas where I have found there might be some unknown old-growth, like the 11 some acres at Hickory Run State Park (see http://ents-bbs.org/viewtopic.php?f=115&t=8865#p45323), but those trees would very likely need at least some increment boring to determine if it is a old-growth remnant.

Anyway, thanks for all the info and resources! I hope to hear from more of your finds from your borers in the future!

Russ A

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