Home Made Anchors

Today I have a couple pics of some anchors I made at home. I was able to procure some 6″x6″x0.25″ plates of 6061-T651 aluminum. I cut these down into 2″ strips, laid out some hole patterns, and drilled/milled the stuff until I was left with two pieces for each anchor.

A trip to the hardware store, and I put these together using shoulder bolts, spacers, and nuts. I still need to add some sort of strap to them for connection to the tree, my plan is to sew some dog-bone style straps to one end of the anchor.

Each anchor replaces a rap ring and a carabiner, and the eventual goal is to use this type of anchor on a longer line (> 100′).

So far, I’ve made three of these, and they work great for the 50′ lines I usually set up. I don’t have a method for testing their break-strength, but calculations show they are fairly heavy duty. Here are a couple photos:

Slackline A-Frames — No Trees Required!

 

See my update to this design here.

Today’s post is about making Slackline A-Frames. I developed these for use when there are no trees around, or when you want to attach to the base of a small tree, or to a vehicle’s trailer-hitch*. The following picture shows the general idea of using A-Frames for Slackline. Photos of the real thing are down below.

Each A-Frame is made from one piece of 2×6 lumber, 8 feet long. These can be purchased at local home improvement centers for about $5 each. In addition, I use a piece of 3/4″ plywood, some nuts and bolts, and a piece of 1/2″ black iron pipe.

These A-Frames disassemble for ease of transport.

Parts List (enough for two A-Frames):

• Qty 2, 2x6x8′ lumber
• Qty 2, 12″x10″ plywood, 3/4″ thick
• Qty 2, 12″ piece of 1/2″ black iron pipe
• Qty 2, 1/2″-20 x 3″ eyebolts
• Qty 4, 1/2″-20 x 3″ bolts
• Qty 6, 1/2″-20 wing nuts
• Qty 12, 1/2″ washers

Using 4-foot legs results in the Slackline being 3 feet off the ground when suspended between the frames and tightened for walking.

To make an A-Frame, follow these steps:

1. Cut one of the 2x6s in half, resulting in two 4-foot lengths of 2×6. Two 4-foot lengths make one A-Frame.
2. Cut a 60 degree half-lap in each leg. It is important to be sure you make two identical pieces. In other words, cut the half-lap in each piece using the same orientation. In the picture below, you can see the cut-out diagram. The white parts are the waste. Look carefully, all four pieces (for two A-Frames) are identical.
3. Carefully cut the ends off the 2x6s at 60 degree angles, but in the opposite direction of the half laps. See picture below. Pay very close attention to this detail. If you cut the ends of the legs in the wrong direction, you will have to start over!
4. Clamp two half-lapped pieces together, and drill a 1/2″ hole in the center of the two half laps.
5. Drill a 1/2″ hole in the center of a plywood piece.
6. Insert a bolt through the plywood and the A-Frame and tighten.
7. Orient the plywood to the A-Frame, and drill two more 1/2″ holes in the plywood and the A-Frame legs.

At this point, you can assemble one of the A-Frames and it should look like the picture below.

Notice that the eyebolt goes in the plywood’s center hole, and the Eye faces the anchor point (in the ground, or at the base of a tree). Connect an anchor line (with carabiner) between the eyebolt and the same point on ground or tree where the Slackline connects. This prevents the A-Frame from falling inward.

The other two bolts can go either direction. All three bolts have a wing-nut and washers for added stability.

Be sure to include one of the 12″ pipe lengths under the Slackline at the top of the A-Frame (see picture above). This prevents the edge of the plywood from wearing out the Slackline due to a friction rub. I tried putting a quarter-roundover on the edge of the plywood, but the wood rubbed the line too much. This is why I added the pipe.

Here are a few more pictures showing the setup and use of these A-Frames.

This first picture shows the whole setup, and although we used large enough trees, the point was to attach the line close to the base, and use the A-Frames for complete support. These first two pics were taken before I decided to add the 12″ pipe (to prevent friction rub on the line).

If you make these, please tell me how you did. I find these to be a great way to setup a Slackline, and look forward to using them in places where there are not big trees.

See my update to this design here.

* Be extra cautious if you use a vehicle’s trailer hitch to anchor a Slackline, the last thing you want to do is move/drive the vehicle while the Slackline is connected. That’s a great way to destroy a Slackline. You have been warned!

Expanded Fixed End Anchor Technique

Today’s post includes a video below.

Expanding on my thoughts about the “double-bight” line locker, I have modified the method I use to attach the fixed-end of my Slackline to a tree. Thinking about how this works, I was able to eliminate the water knot and replace it with a double-bight line locker

This method has one advantage, and one disadvantage as compared to using a traditional water-knotted anchor.

Advantage: there is no knot in the line. In general, knots tend to weaken the anchor. I am not sure how much, and I know the weakness is reduced if you use a third strand of webbing to beef up the knot. (See here)

Disadvantage: There is only one level of webbing going around the tree. With a traditional water-knotted anchor, the anchor is doubled around the tree. This puts less stress on the anchor itself. However, for shorter lines (< 100 ft), I am not sure how much of an issue this is. Here is a photo of a fixed anchor some guys made (red line) to secure a 70′ Slackline. It uses only one wrap around the tree (similar to my method) but uses a knot (which my method eliminates).

Below is a photo and link to a short video (1 min) describing what I’ve done.

I consider this an extension to my series on Anchors.

New Fixed End Technique

I’ve come up with a technique for using a Rap Ring as a line locker. I am not sure if this is an original idea, but I thought of it on my own, and I don’t recall seeing this on any other Slackline pages. That doesn’t mean it is my idea, of course!

[EDIT: browsing Adam’s website a second time revealed his method for making the fixed-end anchor with one carabiner and two rap rings.]

Basically, my method is what I call a double line locker, or a double-bight line locker. Not sure how it should correctly be called. I came up with this method to save myself a carabiner when anchoring the “fixed” end of a primitive Slackline. I wanted to anchor a second line, and wondered if I had enough equipment to do so without buying more carabiners. The trick was to prevent tri-loading, without using a carabiner (see my post on eliminating tri-loading here). Below is a picture of the final rigged line with the new technique. Further down the page I describe how to create this anchor point.

In the picture above, we see the yellow Slackline, and a purple anchor coming from around a tree. This solution uses two Rap Rings and one carabiner, whereas my previous posts and videos use two Rap Rings and two carabiners at the fixed end of the line. This is a somewhat significant cost savings – mostly because I buy the $11 carabiners, while Rap Rings are under $5. The purple anchor line is wrapped around the tree/tree-protection. There are no other carabiners or equipment. Only the requisite water knot.

The method.

[Edit: after reading this post, you may be interested in a similar method that eliminates the water knot in the anchor.]

The next few pictures show the steps to assemble the Rap Ring to the anchor once the anchor has been passed around the tree (or other stationary object).

Start with an anchor.

Wrap the anchor around a tree. I haven’t done so below, but if you can imagine a tree being between the two ends, that will suffice.

Now bring the two ends together…

…and place one inside the other. It doesn’t matter which one ends up on the inside, but keep the line from twisting when the two are combined.

Now, we basically have a bight. Of course this is really two bights, one inside the other, but the principle works the same now as when installing a line locker in the usual fashion. Slip the ends through a Rap Ring.

And pass them around……and back through the Rap Ring.

At this point, insert a carabiner through the center of the whole thing, just as is done for a regular line locker.

In the picture below, we see the blue anchor, the double-wrap line locker, the carabiner, and the Slackline (represented here in purple).

Here is the picture of the actual setup in use at a park (again).

One thing I have figured out is that as the line wraps around the tree, it is vertical. Once it comes to the dual-bight line locker, it needs to go back to horizontal (because we want the Slackline to be horizontal). I have noticed the line stays very flat, and the one-quarter turn twist resulting from the mismatch in horizontal and vertical is not a big deal. You can reduce it by carefully determining the best way to route the anchor pieces before sending them into the Rap Ring. If you eliminate all twists, the line will lay quite flat when everything is tightened.

I’ve used this setup successfully on my 50′ primitive line.

Another place I’ve found this useful is on my wife’s 50′ line that has loops sewn at the ends. On her line, we use a slip-knot around a tree. This makes it quite difficult to get the Slackline flat because of the way the slip knot works. I’ve been using an anchor at the fixed end instead of the slip-knot setup. This helps keep her line very flat.

Here is a picture:

Have you seen or used this setup before?

What are your thoughts on it?

Rap Ring Replacements

After viewing this article over on NWSlackline, I decided to try my hand at using chain links instead of rap rings in my Slackline setup. I ventured out to my local Lowe’s home improvement store and bought one foot (nine links) of 5/16″ 3900lb working load limit (WLL) chain*. Total bill was $2.89 including tax. After cutting every other link I will have 5 good links, so the cost comes out to about $0.58 per link – not bad when you compare the cost of a rap ring at $4.75 (plus tax). A rap ring weighs about 30% less than a link, which is why climbers probably wouldn’t do something like this, but chain links are perfectly useful for Slacklining.

I used a grinder and a cutoff wheel (and some safety equipment) to cut the four odd links. This left me with 5 links for use as line lockers.

I filed down the weld on each link. As Adam points out, over time the weld on each link can cause damage to the Slackline. (Click on the picture above, and zoom in, to see the welds on the links)  Using a file, some 80 grit sandpaper, and some elbow grease I removed the weld protrusion. The following picture shows a link after the process.

After smoothing things over with the link, I replaced two of the rap rings in my Slackline setup, one at each end. This picture shows the fixed end using a chain link instead of a rap ring. (The rap ring seen in this picture is part of the system to remove the tri-loading, and cannot be replaced with a chain link).

For size comparison, here is picture of a link and a rap ring:

Chain links are nearly 1/10th the cost of rap rings, and two links can eliminate both rap rings of a basic primitive setup. This saves about $9 and gets the job done quite well.

* Note: I used 5/16″ Grade 43 chain that has a 3900 lb Working Load Limit (WLL) and a breaking strength of over 11,000 lbs (52kN). You’ll also find 3/8″ Grade 43 chain available with a WLL of 5400 lbs, and a break strength over 16,000 lbs (72kN). Either of these are good choices, and both accept a 1″ wide Slackline. I stayed away from the chain with lower rating (ie. 2650 lb WLL) and went with the Grade 43. More information here.

Anchor Basics Parts 2

Today’s entry includes video below.

This is the second entry in the series on slackline anchors. (click here for Part 1)

The Part 2 video below describes three types of anchor setups for the adjustment end of a slackline (the part where you tighten it).
Now, get out there and start slacking!!

Inspiration for this idea is taken from Adam’s “Strength of 3 men…” video on NWSlackline.

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Slackline Anchor Basics

Today’s entry includes a video below.

Today, I decided to add a video about Slackline setup. This is part one in a two part series on anchors. We discuss the anchor at the fixed end of the line (the end without the pulleys/tightening system).

Here is the short (2 min) video:

More Info:

Want to learn more about making anchor slings and water knots? Click here.

Want to learn more about Rap Rings? Click here.

Want to learn how to setup a basic primitive Slackline? Click here.

(again, thanks to Adam over at NWSlackline for these great instructional articles)