Engineering details:
1. A normal run of cable may get into the 60 or 70 ft. range and since we find that 1-1/2" of adjustment is good for only about 50 ft. you will have to design another adjustment into the assembly which could either be another "Threaded Stud" or a "Turnbuckle". This all varies quite a bit with the railing design. A straight run is easy to figure. As you get more complicated with an arc (radius), angles, etc. the need to cover yourself with adequate adjustment is important. As an example, the green job at the top of the
"Cable Thumbnail" was an overall 73 ft. and had 8 each 45 deg. turns. We designed it with "Threaded Studs" at each end and one turnbuckle toward the center. Homeowner wanted to balance things out so we added another "Turnbuckle" on one of the short 45 deg. angle sides and had 9" of adjustment which was an overkill, but cheap insurance. We ended up only using 1-1/2" to adjust up to approx. 120# tension which was low, but with the dark paint we were concerned with thermal expansion of the aluminum.
2. Access to the back side of the posts nearest the house dictates the style of fitting. You need almost 4 inches of clearance to
tighten and cut off the threaded studs. If using a "Stanchion Terminal" (CA1020)
then you have to feed the cable starting between the house and post.
3. If the post is next to the house and you can't get behind it, you will need to use a "Face Mounted" fitting such as in CA1040 called a "Deck Terminal" that attaches with two screws into wood or threaded 1/4-20 stainless bolts in a hollow aluminum or steel post. With aluminum posts, you will have
usually have to add a 3/16" aluminum backer to the aluminum posts to hold the tension of the cables
in the threaded holes. With the posts we are showing here a 3/16" x 1-1/2" flat stock works fine. With that you will exceed the breaking strength of even a 3/16" cable. Without the backer the screws pull out easily.
4. As you can see, cable layout along with planning the post configuration and spacing is very important. With two post corners or special 45 degree aluminum posts as one mfg. has, turning corners is fairly easy. Our special nylon grommets for the aluminum posts allow the cable to slide freely in the posts and around corners. We use stainless hollow pins in wooden posts on the angled cable sides to allow the same thing and to keep the cable from cutting into the wood over time.
Recent testing has shown that you can use 2" pipe or 2" square tubing for a
corner and run the cable through it at a 90 deg. angle for your corners if
proper tensioning is planned.
5. Vertical spacing of cables should be at or near 3"
6. Free horizontal runs of cable should be kept to 4 ft. if you want the cable tension kept low. You could have posts at 8ft. and add a cable spreader to keep the cable close together at mid span. There is a nice photo of same on the Ocean Shores job on the Cable Thumbnail page.
7. Tension will be above 120 lbs if you want the cable to feel good. As the span
gets wider you will have to up the tension accordingly. We have tested both
cedar and fir wooden posts and find that of course fir is better, but at 200
lbs. assuming 10 cables you can already see a noticeable bend in the end posts.
Anything above 250 lbs. will probably cause some permanent bending over time.
For that reason we prefer the on-centers to be small and than if one wants a
longer span to use 6 x 6 end posts.
Some explanations of the cable assemblies follow:
A. Each threaded fitting has approx. 1-1/2" of available adjustment. The typical
Threaded Stud then has 1-1/2" and the Turnbuckle with 2 threaded members has
twice that or approx. 3". All of this depends on how well the cable is cut which
dictates the finished length of the cable assembly. Overall length of any
particular run along with number of turns, etc. will dictate type of fittings.
B. Most of this site if developed around the use of 1/8" and 3/16" cable
for use on decks and walkways. Larger cable and different styles of fittings are
available. .
C. The second thru fifth assemblies shown have only one threaded adjustment and
should be limited to an application of 50 ft. or less. These first 5 will do the
majority of cable applications you may have. For longer lengths you should use
add a turnbuckle somewhere in the run.
D. Cable comes in several different woven configurations. Most of the cable used
in this sort of application is 1x19, 7x7 or 7x19. Each has it's own best use and
that can depend on how you run the cables and what you are trying to do. We can
help here.
C. Stainless cable for these applications is available in basically two
different alloys, 304 and 316. The 316 is the most corrosion resistant and the
one we stock, but 304 is available if needed.
D. With only one or two exceptions, all fittings are sailboat marine grade
lifeline fittings or better. Others will be available such as the common "NicoPress"
sleeves, stops and thimbles for making simple ends and for those with in eye.
E. With a small investment in tools, you can have all that you would need to install the assemblies shown on this site. See the tool page.
F. We can provide finished length factory swaged assemblies. We have found that having one fitting factory installed and then cutting the cable and installing one fitting on the other end of each cable in the field has it's advantages. It allows us to run the raw end through smaller holes in the mid posts and to cut the cable to the lengths we need for any particular run. It also avoids any measuring errors as often happens when doing finished cables which can scrap an entire set of cables.
We are finding that to assist you we need a small detailed drawing that shows in plan view the deck layout, levels, stairs, etc. Stairs should include the sloped length and whether they go up or down. If you have existing columns as in an upper deck or roof support they need to be called out and noted that you want the cable running through them or stopping and starting at the post or column.