Upgraded Slackline A-Frames: New Design to Hold the Line Steady

My first set of Slackline A-Frames work fairly well. I’ve set them up and used them multiple times so far. However, one thing became clear after I started using them with people who do tricks – the ends of the Slackline are not held static where it passes over the A-Frame. This is an important feature to have: a steady, non-sliding line. I came up with a way to add the feature to my A-Frames.

IMG_2741First, I’ll describe the problem. As shown in the above photo of the original design, the Slackline passes over a piece of 1/2″ pipe. The pipe is 12″ long or so, and there is nothing to prevent the Slackline from sliding sideways (left to right). This happens predominantly when a slacker on the line does a move called “surfing”. They kick their legs out sideways and swing their feet back and forth in an oscillating motion. This action causes the Slackline to slide back and forth on the 12″ piece of pipe. The biggest downfall of this is that it abrades or melts the line just at the point where it crosses over the pipe. In addition, it makes for non-static ends on the Slackline. This is opposite of a tree-based Slackline, where the ends do not move left to right when in use, even while surfing.

The solution I came up with is fairly simple to implement. and can be made of parts from a hardware store. First, I made two of the U-brackets shown below. Each U-bracket is made from 1/2″ black iron pipe and some fittings. Each one uses the following parts:

  • four 90 degree elbows
  • two 4″ nipples (although any length under 6″ is OK)
  • one 3″ nipple
  • two 2″ nipples.

The only critical part is the horizontal 3″ nipple. The goal is to have 2″ (width of the Slackline) between the two 90 degree elbows once they are screwed onto the 3″ elbow. I was able to get the elbows to screw in 1/2″ on each end of the elbows, leaving 2″ for the Slackline. I used parts that I had laying around as well as pieces I bought at the store. Screw all the pieces together so they look like the picture below*.

IMG_3615

The second thing I did was drill two more holes in the top of each A-Frame to accommodate the U-bracket. These are 7/8″ diameter holes, to accept the 0.840″ outside diameter of 1/2″ black iron pipe. The holes go all the way through the plywood and the 2×6 legs – that way you can use longer nipples if you prefer (instead of the two 2″ nipples).

IMG_3616

The picture below shows the solution in use. The whole idea is to create a channel where the Slackline sits as it goes over the iron pipe. As you may notice, the channel I have created isn’t quite 2″ exactly in width. That is mostly because of the way black iron pipe is put together. Threads at the joints of black pipe are tapered. For industrial applications, fittings are screwed together until the tapered threads seal together. The joints are not an exact science, so the fittings don’t always end up completely seated, or even seated by the same amount. This is one flaw in my design, and it means I need to tighten my fittings a bit more (one or two turns, by the looks of it).

IMG_3612

 

In any case, the idea was to use off the shelf parts to create a steady point for the Slackline to pass over the A-Frame. Here is another picture of the setup in use.

IMG_3614

Of course, the length of all of the pieces of the U-brackets can be adjusted to fit your needs. As long as the Slackline clears the top of the A-Frame, things will be fine. I should probably shorten the 4″ nipple to reduce the leverage the U-bracket has on the A-Frame itself.

Hope you get the idea.

*You may have noticed that my 3″ nipple going horizontally in the U-bracket doesn’t quite look like a piece of black iron pipe. This is because I milled the 3″ nipple to remove the extra threads present once the 90 degree elbows are tightened to this nipple. You can get around this by wrapping the 3″ nipple with duct tape, or possibly by filing the threads down by hand. Otherwise, the threads will cut the Slackline and reduce its life.

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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.

SlackHorseB

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.

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

IMG_2741Notice 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).

IMG_2712IMG_2718IMG_2744If 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!