Reply to post by Russ Carlson, on December 17, 1999 at 20:21:55:

No offence taken.

I didn't put enough thought into my phrasing of the questions. one of the problems with the medium we are using.

I start out trying to be detailed, but run out of paitiance with my hunt & peck lack of typing skills.

My hackles raise only if someone calls me supid, and wont explain why.

(not to say I thought you were in any ways calling me stupid)

Reply to post by Scott Cullen, on December 19, 1999 at 01:27:19:

Everyone sais "Drillbit" I use a 29in ship auger (home depot has a 17in on shelf for 22bucks) does any one use different type?

since i dont do many or big ones, I climb with with a slow speed high torque corded DeWalt. With the sharp auger it goes through hard Maple "like butter".

for the rod I by Kummerlings tree rod. It is rather pricey but the thread is cut square so it seems it would be stronger than regular treaded rod.

the formula for voluom of a cylinder is (pi*r squared)*length just in case someone forgot the area formula

FOr a comealong on small jobs i use a heavy ratchet cargo strap.

Reply to post by Scott, on December 19, 1999 at 11:43:27:

Thimbles can be oversized, but never undersized, as Scott said.

When I was trained to install cables, before the Tree Grips were in use, I was taught to pinch the thimble around the eyebolt, and bend the cable tightly around the thimble. It would never come losse this way. With the tree Grips, pinching the thimble shut can cause problems. The gap it creates can allow the Grip to flex as the eye of the grip is pulled and released. This can lead to fatigue at the back of the eye- the place where they are most likely to fail and the location of greatest strain. Leaving the thimbles slightly spread reduces the flexing, and prolongs the useful life of the Grip.

When inspecting older cable installations, carefully check the back of the eye, on both spliced and Gripped cables. Make sure the thimble is in place, and that there is not any wear on the inside of the cable eye. Make sure the bolts are tight against the tree.

Reply to post by Russ Carlson, on December 19, 1999 at 17:57:16:

Russ, in addition to bending the cable tightly around the thimble the key (with hand wrapped splices) is for the the wraps to pull the two pieces of cable tightly together where the two sides of the thimble pinch together. The trick I was taught was to pre-bend the cable to go around the thimble, then add another bend on each side to about 90 deg. just about the length of the thimble from the first bend. The second two bends have the two ends of the cable (short splicing end and long standing end) pointing away from each other. Then slip it through the eye and bring the two parts of the cable back together to be wrapped. It creates a nice tight pinch around the thimble.

BTW, one of the most irksome things for me was always opening up the thimbles to put them in the eyes. I guess the manufacturers figure everyone uses lags!

As to inspecting older cables.... bolt (eye I assume) against tree is not an absolute. If the cable is pretty much in line with the bolt and the drilled hole there will be no lateral bending force on the bolt and it should be just fine. If the cable does pull off at an angle to the bolt you need to assess the condition of the bolt (is it already bent, how much sticks out, what's the angle of pull?) and it's size vis-a-vis the size of the supported stems. If all this points to a risk of failure of the bolt you are faced with partial or complete replacement of the system.

Reply to post by JPS, on December 19, 1999 at 06:52:59:

I had to check a couple of older sources. Some seem to describe a "ship auger" or "ship point" as an auger with a coarse lead screw and no side cutting lips (those little protrusions that score the circumference of the hole). Those old sources show a coarse lead screw with a single side cutter as best in wet wood or with a difficult grain. I think that sort of bit may be sold today as a "ship auger." Another characteristic is that they are "hollow core," a helix with a lot of open space for the chips. They do not have a solid core with the helix "wrapped" around it (most are actually milled from a solid blank but there are bit patterns with a solid tool steel core and a more malleable wire stock actually wrapped around into a helix and welded in place.... I have use them for rod installations). I think HD stocks Irwin bits in the "ship auger" pattern in the tool crib areas, but you may find they stock Greenlee in the electrical department. I've had good performance from both brands. Anyway, the bits I've used are mostly coarse lead screw, single side cutter, hollow core.

The 29" bits are great if you have to drill that deep (no extension, full length worm). But a little awkward in the tree if you don't need the length. The shorter length is pretty handy for lots of cable holes.

Do you always set up the generator and run your cords or do you find that you need a minimum number of holes to make it worth the effort instead of just using a hand brace?

Which DeWalt are you using with slow speed-high torque? I've found some DeWalt and Milwaukee models that are rated as VS from 0-x,000 RPM that really are hard to keep running slow. Slow speed is better, but one thing about high torque is you can get slapped around if the bit jams.

Reply to post by Russ Carlson, on December 18, 1999 at 18:11:33:


>6) When using the come along, are slings used at the ends to protect the cambium?

Yes. Use a Havens grip (cable-grabber) makes it easier, since you don’t have to return to the first side of the job to retrieve slings and winches.<

Russ, what size slings would be appropriate for most jobs, for this purpose? I was looking at Blair's book section on cabling to see the cable grips, but I have not seen one in action.
I imagine the hardware and one end of the cable are in place, then the cable grip is used. But how? Is it linked to the cable winch and a sling for the second end near the eyebolt? If so, how much loose end of cable projects from the grip to be worked around the thimble, or is this technique perhaps used with tree grips only?
Blair shows a logging tape for use in measuring spans and getting diameter readings to calculate needed length of through bolt. Is the measurement usually taken, given to a person on the ground for cutting, then a length of cable taken up into the tree? Or, perhaps, is a longer piece than needed taken up, with the excess cut off in the tree?
When augering, what is the method you use to align the bit so that the hole lines up with the second attachment point? Is some kind of visual target put in place, such as a string line or chalk mark, or is it all "eyeballed"?

Reply to post by Mark Goodwin, on December 19, 1999 at 01:27:19:

When I use a cable grab I do the hard end of the cable first. That is determined by what I am going to be standing on. Since the second end takes longer it is nice to have a branch to stand on. A two inch wide webbing sling should be considered a minimum. If a rope sling is used there will be too much force on the bark and the risk of girdling is increased. Think of snowshoes vrs. spike heels. I slide the grab out onto the cable as far as I can reach. Then I put the come a long between the sling and the grab. I like to have the sling choked very close to the tree and the garb far away. This keeps the come a long out of my way.

To determine cable lenght you can stand under the attachment point and look up. Kind of an upside down plumb bob. Put a mark on the ground and do the other end. Add a comfortable fudge factor and cut the cable.

Another method is to use a throwline. The climber will setup at the first end. Toss a throwline through a close crotch, pull the bag up, mark the distance back to the limb and measure it out. The climber can also drop the throwbag as a plumb bob.

In the end, cable is cheap enough not to bother getting too close. You will have to cut off the second end anyway.

When I set up the angle of the lags or bolts I just eyeball. I came up with anohter idea but have not had the opportunity to use it yet. Use a laser pointer taped to the top of my cordless drill as a back sight. My pointer is not too powerful so it would have to be a darker day or thick crowned tree.

Using Cobra eliminates a lot of this fiddling around.

Tom

Reply to post by Tom Dunlap, on December 20, 1999 at 18:14:45:

Tom, your description of cable grab use was just what I hoped for. I have read many times about the Cobra system, but I still have no clear understanding of it, except that it involves rope and no drilling. Would you be so kind as to describe it and its installation? Also, can you tell me a source for a list on tree species that are known to be poor compartmentalizers. I'm guessing Silver maple is on the list, and maybe water oak.

Reply to post by Russ Carlson, on December 18, 1999 at 18:11:33:

I found this interesting re: wood weight.
http://www.agcom.purdue.edu/AgCom/Pubs/FNR/FNR-109.html

Reply to post by Mark Goodwin, on December 19, 1999 at 01:27:19:

Tom did a good job describing some of the stuff in your questions. As to the cable grip ( or grabber), it is simply a cam lock device, much like an ascender used on ropes. It slips over one side of the cable, and when pulled it locks onto the cable. Push it as far out from the work area as you can reach, to give yourself some room. A rope/sling/come-along is attached, and used to pull the cable to the tension needed. You will need to lock this positioin until you finish attaching the cable, then release it (slowly, so it doesn't snap).

Sighting is not critical. While you want a direct line on the hardware, a few degrees off won't make much difference.

Sling width should be enough to prevent crushing the bark/cambium. Thick bark will make a difference.

Reply to post by Mark Goodwin, on December 19, 1999 at 01:27:19:

From the Forestry Handbook, 1955-

Utilization & Wood Technology, Ch. 14, Table 15

Weight per cubic foot, green

red alder 46
white ash 48
baldcypress 51
basswood 42
beech 54
paper birch 57
redcedar 37
eastern cottonwood 49
Doug-fir 38
American elm 54
balsam fir 45
hemlock 50
hickory 63
black locust 58
red maple 50
sugar maple 56
red oak 64
white oak 63
white pine 36
loblolly pine 53
redwood 50
sweetgum 48
walnut 58
yellow poplar (tuliptree) 38

Many other species are listed, but this gives you a good idea of the weight ranges. The weight I gave before (68) was from memory- a bit high.

Reply to post by Mark Goodwin, on December 19, 1999 at 01:27:19:

Russ and Tom makes good points.

Concerning slings: Now that slings are part of everybody's tool kit using them is good practice. But I have to point out that for YEARS, the common practice was to use rope, maybe with a mechanical come-along maybe with a rope tied come-along. As Russ points out thick bark makes a difference, so does common sense and the amount of force required. I can't recall having been back in a cabled tree and seen bark/cambium damage where a rope attachment might have been used for the draw-up. You can spread the force by making multiple turns with the rope.

Concerning drawing up: What takes a little practice is setting the working end tie-off enough above or below the hardware to allow working room for the splice.... especially if wrap-splicing, you need room to rotate the pliers. If you are cable-gripped to the cable then you are pulling the cable a little off finished line and you need to adjust slightly for proper final tension when you let off the drwa-up and the cable settles back into line. IF you can work both sides easily from a single high crotch some times it is easier to set slings above both hardware points for draw-up and just swing back over to release the first side when done.

Concerning length measurement: another technique if working with a ground-person is for the climber to estimate cable length against a known-length pole saw if the cable is in that length range... ground-personm just duplicates it. If a team gets good at estimating length the ground person can even splice both cable ends to finished length while the climber drills the holes and sets the come-along.

Reply to post by Scott, on December 19, 1999 at 19:56:44:

I happenned to be at HD today and checked. The longer Irwin and Greenlee bits are hollow core with NO side cutter lips. The Irwins are labled "ship auger," the Greenlees "nail eater" and appear to be a special electricians' line. Interestingly neither were stocked in 9/16 which is the proper size for 1/2 bolts.

I dug out my old 9/16 x 29" Greenlee and it is hollow core with a single side cutter.

Reply to post by Scott, on December 20, 1999 at 07:30:01:

My 29in looks to be milled peice with the charicturistics you mentioned, I use it for the bracing for the eye bolts I use a smaller one that looks the same, cant remember the name (brad point?). Pretty sure both are Erwin.

My brotherinlaw is a Gen. Contractor, so I borrow his DW130. And since I choose my battles, I make sure that there is going to be power avilible to plug the extention into. I just tag the drill off to the tree so the cord stays out of my way when not in use.

Most of my jobs are limited to no more then 12 holes, and that would be the biggest I've done. So that is why I use only the LONG auger.

If I remember the Electritiens bits have carbide tips.

I've felled that torque! lucky for me I'm 250#. (tho it is a problem limb walking )

Reply to post by Mark Goodwin, on December 19, 1999 at 01:27:19:

Having typed in that abbreviated chart, the current issue of Arbor Age arrived in today's mail. An article on bull ropes includes a wood weight table. About the same figures I listed.

Reply to post by Russ Carlson, on December 18, 1999 at 18:11:33:

Russ, Since a branch, limb, or trunk is not a uniform diameter cylinder, I guess the use of a cylinder volume formula assumes that the additional weight of laterals and foliage makes up the difference?
Also, is the choice between lag-threaded rod or National Coarse threaded rod with nuts and washers determined mainly by the presence of decay or the poor compartmentalizing ability of species? Or is there "always" a superior performance by the through bolt?
Does anyone do any increment boring in association with augering for brace bolts to rule out otherwise hidden decay?

Reply to post by Mark Goodwin, on December 19, 1999 at 01:27:19:

I can't answer that question authoritatively, but I'd say intuitively that not adjusting for decreasing diameter in some fashion accomodates lateral branch weight. The much bigger issue I think is the potential additional weight of foliage, water on the foliage and limbs, or ice and snow weight. That thin film of water may sound insignificant but think about the last time you handled wet brush with leaves on it... was it noticably heavier? Then factor in branch angle to really understand force on the crotch.

My points are, weight calculation is a very inexact business and most systems are not designed to support dead weight anyway... they are stopping the moment. In practice I think you will set certain thresholds for cable size/type and limb sizes builing in some conservatism-safety and seldom actually do the weight calculations. It's a good exercise to understand and check yourself on from time to time but maybe not an everyday working necessity.

What do you think Russ (or anybody else)?

Reply to post by Mark Goodwin, on December 19, 1999 at 01:27:19:

Mark, you've asked a good question but mixed up two different issues.

COARSE THREAD vs NC MACHINE THREAD. "Rod" comes in both patterns. You can get and install nuts and washers in both patterns. There may be a theoretical difference in holding power but I doubt there is a practical difference. I would guess that the coarse thread nut might back off more easily (in fewer revolutions) so peening thread is more important with coarse thread rod. Both are installed in a 1/16 oversize hole and theoretically you can draw up a split (but you better draw most of it up first so the hole you drill is in line in the drawn up position).

Another installation, sometimes described as "screw rod," uses a 1/16 undersized hole with coarse thread rod which is screwed into the wood, which provides the holding power. The installation can be "through and through," that is to daylight on each side or can dead-end in one side. (I understand that the new A-300 is clarifying this). No nuts and washers are used so there needs to be sound wood to screw into and I'd be concerned about long term performance if you drill through decay on the way to sound wood.

THROUGH BOLT vs LAG (as anchor for cable). Most eyebolts today are NC machine thread but you may still see coarse thread eyebolts. The issue is not thread pattern but installation through an oversize hole and using a nut and washer. Lags are installed in an undersized hole and must have a coarse thread for holding power in sound wood. I recall some theoretical pronouncement years ago (maybe from Davey research) that a lag in sound wood had more holding power than a through bolt with nut and washer. I can't cite any data and don't know if it's true, but if true I can't imagine that is matters. I have never seen a nut and washer fail (I guess the nut and washer would have to strip the threads right off the bolt???). Think of the millions of through bolt-nut and washer installations in utility poles and docks and piers. I think in sound wood it really comes down to personal preference, maybe cost of hardware, length of hole to be drilled, how you tension the system. The real issue is the presence of decay or potential presence of decay. If there is any risk of that then through bolts are indicated.

I don't know if anybody does increment bores or other tests to identify decay. I certainly never did. If you suspect decay you probably should be prepared to switch to a through a throughbolt installation if you encounter any evidence of it when drilling your lag hole.

My own company - probably because of the way I was trained - just used through bolts as the standard installation so pre-testing, field crew judgment and risk were just out of the equation. Occasionally, in small shrubby material; or if hardware cost was really an issue; or given angles and relative stem sizes that made a through hole on one side unnecessarily difficult or damaging we did use lags.

Russ?

Reply to post by Scott, on December 22, 1999 at 20:41:09:

Scott, my reference to lag-threaded rod vs. NC threaded rod came from a reading of Blair's book (pg 61, chp 8). When he stated that "lag- threaded rod may be dead-ended or through-bolted" I wondered whether he was refering simply to going all the way through both sides of the crotch, or if he was implying that there are nuts with lag threads available. I do not know.
The screw rod you mention sounds to me like the lag-threaded rod refered to by Blair. Are the "coarse thread" and "screw thread" you mention the same or different from each other?
It seems that it would be handy to have a rod that could be used either in an under-size hole as screw rod, or as a through bolt in an over-size hole with nuts and washers. Is this the case?

Reply to post by Mark Goodwin, on December 23, 1999 at 07:50:48:

Here is the difference in lag and machine threads. Lag threads have more threads per inch and the threads themselves have a deeper V cross section. The V allows the thread to cut its own thread into the wood and not have to rely on the flat of a washer. Machine threads are much finer number per inch and not as deep. You must use a nut and washer to secure the bolts.

The maximum holding power of a machine thread, in metal, is attained by using a nut that has the same height as the diameter of the screw. IN other words, if you are using half inch rod the nut would be a half inch tall. This is a mechanical engineering factoid.

Why are you recommending peening? How is the nut ever going to unscrew? If you are using 5/8-11NC threaded rod the nut will be 5/8" thick and the rod has 11 threads per inch.This translates into 6.875 revolutions of the nut onto the rod to get the nd to come out flush with the nut. There is no way that I can imagine a nut turning one revolution without some help much less almost seven full revolutions. Peen for appearance, not to keep the nut on.

Here is a quiz:

What is the difference between a screw and a bolt?

Clever and humorous replies are encouraged along with the correct answer. I will answer the question on Monday.

Peace and prosperity to all tree lovers in the new decade!

Tom

Reply to post by Mark Goodwin, on December 19, 1999 at 01:27:19:

Correct on limb weight. It is only a gross approximation.

I used lag-thread rods when drilling the hole 1/16th inch smaller than the rod, and threading it in. That will make a man of you real quick, if you're doing a 3' oak [g]. If you are using nuts and washers, it doesn't really matter which thread guage you use.

Reply to post by Scott, on December 22, 1999 at 20:41:09:

I agree, Scott. The published standards have a safety factor built in, as do most engineering specs.

Limb weight is mostly an approximation, and not intended to be exact. But when you get down to the actual physics, calculating the moment of force and the stresses applied to a particular point (bolt, cable, limb, etc.) then you need to be a little more exact. I've been wrestling with the numbers on that for a few years, off and on, and haven't got it finalized yet.

Reply to post by Mark Goodwin, on December 23, 1999 at 07:50:48:

Mark, I don't have "Blair," but the quote does allow you to reach different conclusions. You can install coarse thread (I think "screw thread" or "lag thread" are usable interchangably) 1) in an oversized hole drilled through and through with nuts and washers; 2) in an undersized hole threaded into the wood a) through and through or b) dead-ended on one side; 3) I suppose, though I've never done it, also threaded into wood in an undersize hole on the far side then an oversize hole on the near side with a nut and washer to take up the split.

Nuts and washers are available for the coarse-lag-screw thread rod.

I think the idea of stocking coarse thread rod and being able to choose installation method makes sense. Of course if you are convenient to a supplier or can get quick delivery that's not as big an issue. I think the coarse thread rod may be harder to find, you may have to go to a specialty supplier, while machine thread is available everywhere, so that may be a factor for some installers.

Reply to post by Tom Dunlap, on December 23, 1999 at 19:04:20:

Tom, did you mean to say that lag threads have fewer threads per inch?

As to peening, I checked my message and what I suggested was "I would guess that the coarse thread nut might back off more easily (in fewer revolutions) so peening thread is more important with coarse thread rod." You're right, it's much less likely with NC machine thread. But, as we seem to have debated in another part of this thread, nuts can back off from vibration or impact against the nut and washer. That's why many mechanical installations use split or star type lock washers, locking type nuts, or some preparation like Loctite (TM). Aircraft installations (lots of vibration, big consequences) use fixing wires. Peening is more that aesthetic, it's cheap insurance and good practice.

Interesting factoid about nut height. You will find a difference in nut height and diameter between cheap-consumer-hardware store stock and industrial stock.

A SCREW is meant to be threaded into the material being fastened or fastened to. In wood or plastic or sheet metal, etc. the hole is drilled undersized and the fastener cuts its own threads. These threads are typically coarse. In metal and other materials too the undersized hole can be pre-tapped with a thread matching the screw. These are typically finer than the self tapping or cutting type. While many people would visualize a wood screw or sheet metal screw with a sharp point and tapered body as typical you can also have a machine screw (full threrad) or cap screw (partial thread, plain shank above) in machine thread. A BOLT by contrast is intended to pass through an oversized hole and be fastended by a nut and washer. At least that's the theoretical difference. You will often find fasteners with a coarse thread, a point and a taper descrided as a "Lag Bolt" when they really are screws. Maybe it's because they tend to be heavier or often are installed with a wrench (they have square or hex heads) rather than a "screw" driver. Head type however is not the defining characteristic; carriage bolts, for example, are truly bolts to be installed in an oversize hole and secured w/nut and washer, but require no tool at the head which lodges itself in the material being bolted.

Reply to post by Russ Carlson, on December 23, 1999 at 07:17:47:

I think that's a pretty complex calculation in practice. You can stop the moment with quite a small amount of force or small body.

I always remember the example my father learned working for the Pennsylvania RR before WWII: if a steam locomotive's wheel slip as they rotate so that it happens to stop with both drivers in the neutral position (i.e. at full extension) you can put a nickel under the wheels and that train won't go. Small device stops the moment.

BUT if the train has any momentum at all it will roll easily over the nickel. A little more momentum and it will squeeze it into foil.

SO the cable and hardware likewise need to withstand shock loading much greater than the minimum force they need to exert (or restrict) to stop the moment. If the hardware fails it's not there to stop the moment. The secondary issue where weight may be more important to consider is the "backup" function of a cable to restrain the supported limb in the tree and away from targets in the event the crotch or the limb itself does fail.

Assuming your safety factors have addressed shock loading of hardware as a minimum, then I guess additional capability (if any) is a question of the liklihood that the system might fail (say sideways or from lightning or whatever circumstance you can invent) even if the moment is effectively stopped in the vector perpendicular to the crotch... then maybe you do want to support full, wet weight with some additional shock loading as it falls.