Dr. Robert
member
Reged: 09/10/09
Posts: 39
|
|
Hi all,
I've noticed that wooden tripods are made from a wide variety of woods. For example, this tripod here is available in your choice of four different types of wood:
please click here
My question is whether certain types of wood make a more stable tripod than others. Do you know?
Thanks,
Robert
|
MacRoberts
sage
Reged: 08/25/05
Posts: 421
Loc: Redlands, CA
|
|
I looked into this once myself a few years back and I was curious enough to look around again tonight after seeing your post. There just isn't anything I can currently find that is exactly on point.
Here's what I learned.
Most hardwoods are fine - ash, walnut, mahogany among them - and even good old pine softwood. The only negative comment from one poster on a photo forum said beech was a lousy choice because high frequency vibrations (ringing) were poorly damped.
I suspect the hardwoods fare well in tripods due to generally good low and high frequency damping characteristics as well as good field resistance to moisture (tight grain).
Ash is used far more frequently than other woods.
Tak uses Luay Mahogany for its tripods.
I use a Televue cum KB Systems walnut Gibralter and am very happy with it. I have used the ash variant and noted no noticeable difference in damping between it and my walnut tripod.
Posters who seemed to analyze the problem best framed it in terms of low frequency vibrations (rapping a tripod leg) and high frequency vibrations (for instance, constant wind pressure or that caused by a motor drive). I suspect vibrations induced by manual focusing to mostly be of the low frequency variety.
What may be much more important than type of wood is the design of the tripod, especially at joints where leg sections meet and where the legs mate to the top plate. Poor designs allow flexure at these critical points which induce much longer damping times regardless of wood choice. Fair (but not excellent) design can sometimes be mitigated by careful tightening of screws, bolts, and other fasteners at these locations as well as where spreaders and trays attach to the legs. It is also important to assure that any bolt(s) securing the head to the top plate of the tripod are as tight as you can get them. All of these measures promote stiffness in the tripod assembly which is highly desirable to reduce the duration of low frequency vibration.
Other ways to improve vibration damping, assuming the assembly is as stiff as you can make it, include anti-vibration pads, hanging weight from the underside of the top plate, or pushing the tripod's foot pins/spikes into turf or soil.
Probably TMI, but there you have it.
--------------------
Jim
"When I consider thy heavens, the work of thy fingers, the moon and the stars, which thou hast ordained; what is man, that thou art mindful of him?" Psalms 8:3-4
TV Refractors
Fuji Binoculars
|
Dr. Robert
member
Reged: 09/10/09
Posts: 39
|
|
Mac,
Thank you for the excellent information you provided in your post(s). That is very helpful indeed. As such I think I'll get the walnut tripod because I think it looks nice with the black hardware.
I love Cloudy Nights!
Robert
|
Carl M
scholastic sledgehammer
Reged: 02/21/07
Posts: 907
Loc: Vermont, USA
|
|
Jim's correct, but stability of wood is important as well, especially for any joints. Ash, Walnut and Mahogany are very stable. Ash is the hardest of the bunch and used frequently, but it's not as pretty.
--------------------
Carl
JStar 12" Truss Dob w/Swayze Mirror
StellarVue SV50 "Little Rascal"
SV102ED
SV80ED(NHNG )
SV70ED
LS60THa/B1200
AT66 (Chrome)
G-11 Gemini, GM-8
AT, WO, and TV eyepieces
Lake Runnemede Observatory
|
Al Canarelli
Carpal Tunnel
Reged: 12/06/07
Posts: 2611
Loc: Central New Jersey
|
|
When selecting a wood specie for a tripod, there are several areas to consider...
PROPERTIES OF WOOD. Hardness, strength, integrity over time and price.
AVAILABILITY. Some woods have a more interesting grain pattern, color, and perhaps natural oil content than others. These woods fall into the general heading of exotic woods, which will not necessarily make the tripod any better than a more readily available hardwood, but will certainly enhance the looks of the finished tripod.
WORKABILITY. Some woods are so hard that they will dull your sharp cutting tools much quicker than other hardwoods. Such woods could be a nightmare to sand and finish, as it could take forever to do so. The oil content of some woods (such a teak) is so high that it becomes extremely difficult to glue the wood unless some time consuming measures are taken in the gluing process.
PRICE. Probably the best wood considering these parameters is Red Oak. It's very hard, easy to work and relatively inexpensive. As an example, Red Oak can be purchased almost anyplace that sells hardwoods and usually (depending on where you live) for about $3.00/ board foot. Compare this with some of the exotic woods, which are not readily available and will cost up to $20 or more per board foot.
|
Darenwh
Pooh-Bah
Reged: 05/11/06
Posts: 1224
Loc: Covington, GA
|
|
I really think Jim summarized this very well. Though wood selection is important, I believe that the design of the tripod is just as important if not more so. Insuring that all connections are strong and secure is of utmost importance. Any play that is left in any part of the tripod will result in decreased performance. When completed you should be able to try to twist the tripod and nothing should move.
--------------------
Daren
Covington, GA
|
roscoe
super member
Reged: 02/04/09
Posts: 192
Loc: Northwestern Mass
|
|
I've built around a dozen, using everything from common 2x4 framing lumber (worked fine, but dented easily) to walnut (looked gorgeous, but rather pricy). I like maple a lot, it is hard and looks nice, doesn't seem overly resonant, and the light color shows up better in the dark (so I don't kick the legs so often...) My nicest ones have been a combination of maple and cherry, a visually attractive combination and a combination of differing densities and vibration damping characteristics for enhanced stability. Most anything sturdy will outperform all but the best stock metal tripods. I tend to avoid ash, because it is so springy......which is why it works well for tool handles.
--------------------
Antares/Vixen 812 120mm f/8 on reworked CG-5,
Celestron/Vixen C-80 80mm f/11 on Polaris,
Sears/Towa 60mm f/15 on reworked Towa,
assorted Ultrascopics and Orthos
homemade tripods, chairs, EP cases, observatory
|
Dr. Robert
member
Reged: 09/10/09
Posts: 39
|
|
OK, I did a little research of my own, if anyone cares. Found a book called The Encyclopedia of Wood published by the USDA that you can actually read online.
The Encyclopedia of Wood
Here is chapter 4 of that book entitled Mechanical Properties of Wood, taken from another site that is a little easier to read:
Mechanical Properties of Wood
Its mostly Greek to me but on pages 4-25 and 4-26 it discusses vibration properties of different woods. The two relevant factors are (1) speed of sound, which is the rate of transmission of vibrations through the wood (I think), and (2) internal friction, or damping capacity.
The book states that "There is no recognized independent effect of species on the speed of sound", which I believe is consistent with what Jim and others have said above. It goes on to say that "The internal friction mechanism in wood is a complex function of temperature and moisture content." The rest of it is a bunch of mathematical gobbledygook that is beyond my feeble brain's ability to decipher. The chapter does have a huge table describing the strength characteristics of many types of wood but no details regarding vibration characteristics of different woods.
FWIW
|
Dr. Robert
member
Reged: 09/10/09
Posts: 39
|
|
Well, I looked at the huge tables of mechanical properties of different wood species in chapter 4 of the Encyclopedia of Wood and found that, of the types of wood used in the tripods I've considered, the hardness and strength of the woods fall in this order (hardest first):
purpleheart > jarrah > ash > walnut > mahogany > alder
(Purpleheart is used by KB Systems and jarrah is used by Oberwerk)
I suspect, as others have already stated above, that the design and construction of the tripod are more important than the type of wood, as individuals have reported excellent results with woods on the softer end of this scale (e.g. the walnut Gibraltar). However, it seems intuitive that, all other things being equal, a harder wood would lend itself to a more stable tripod. What do you think?
The reason I ask is that I am leaning toward getting a KB tripod (the maker of Televue tripods, link), and some of their models are offered in your choice of ash, walnut, mahogany or purpleheart. I'm not sure if I should factor anything other than aesthetics into my decision of which wood to get.
Thanks,
Robert
|
macular hole
super member
Reged: 08/12/09
Posts: 146
|
|
Doc,
The highly regarded Berlebach tripods are made from Ash. Check out the Uni 28, the planet, and the ash/carbon fiber sky. Open the 2009 pdf catalog for the best info on their website. Teton telescope is the US distributor. They use Ash particularly for the properties you list above.
|
Dr. Robert
member
Reged: 09/10/09
Posts: 39
|
|
Thanks, I hadn't seen the PDF link on their website. I don't see a UNI 28 there. I was considering the UNI 24 and the 29.
|
macular hole
super member
Reged: 08/12/09
Posts: 146
|
|
Dunno about the 29. Teton telescopes lists the 28, but no 29. maybe a typo. Looks like the 24 is only 2 lbs lighter than the 28 and not much less expensive. The planet makes a big jump in both price and weight, but is the most stable, according to the Berlebach website. The sky is definetly sky high! I like the optional ball feet for hard surfaces and interior floor protection. I ordered some for mine.
|
Dr. Robert
member
Reged: 09/10/09
Posts: 39
|
|
Doh! My bad. The 28 and the 24 are almost identical - I think the only difference is the 28 has a pin for an equatorial mount and the 24 has a 3/8" threaded stud. The 29 is a photo tripod with a geared central column, shown on the Berlebach website but not at Teton. The planet and sky models are out of my league.
|
macular hole
super member
Reged: 08/12/09
Posts: 146
|
|
It is my understanding that you can get almost any top mounting plate you want for the 24,28, planet, and sky. You might have to order and wait a bit though. Give Teton a call.
|
Bart
professor emeritus
Reged: 05/28/06
Posts: 592
Loc: Inside the (DC) Beltway
|
|
Quote:
PRICE. Probably the best wood considering these parameters is Red Oak. It's very hard, easy to work and relatively inexpensive. As an example, Red Oak can be purchased almost anyplace that sells hardwoods and usually (depending on where you live) for about $3.00/ board foot. Compare this with some of the exotic woods, which are not readily available and will cost up to $20 or more per board foot.
I'll second the Oak choice. That's what I've used and it worked very well.
--------------------
|
Dr. Robert
member
Reged: 09/10/09
Posts: 39
|
|
Who makes oak tripods? Did you make your own?
FWIW, the Encyclopedia of Wood lists 9 different types of red oak grown in the US! The strength and hardness of the different types appear to vary somewhat greater or less than ash, but all are greater than walnut.
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
