Pietenpol-List: Bunji Struts
Posted: Sat Mar 06, 2004 5:37 pm
Original Posted By: Andimaxd(at)aol.com
Subject: Pietenpol-List: Bunji StrutsSince there's not much going on, on the list, I thought I'd send along the text that I wrote for Max Davis, on how I tie my bunji strut loops. It's a longpost, so be warned !! I finally got done with re-tieing, and installing my bunji struts back on the plane. Installing the bunji's on the struts, is one of the most difficult 2 man chores that I do alone, as regular maintenance. Last year, I pulleda tendon in my right elbow, this time all I did was pinch my finger (it only bled a little bit), and now only have achy forearms from pulling and fixing theloops over the struts. This is the last time I'm going to re-tie the bunji's...I'm building spring struts !!! It's difficult to put it in text, how I tie the loops, so I've taken a lot of digital pictures, and will send them direct to anyone that contacts me direct. The instructions I'm giving here, is for the PLANS DIMENSIONS of the bunji strut suspension. It took me 2 or 3 tries my first time, before I was satisfied with how the loop turned out. Start out using two wraps of medical tape where you plan on cutting the bunji chord with a sharp knife, or the bunji chord will unravel before your eyes. Cut up a piece of scrap to see how this stuff is made. It obviously isstretched quite a bit, before the cloth weave is applied to the many small strands of rubber bands. The 5/8" bunji chord from AS&S is part #06-12600. Ifit's all in one length, you can use the medical tape centered where you wish tocut, then just cut right down through the medical tape, leaving half of the medical tape on each piece. I use a waxed chord from a leather company called'The Leather Factory'. The wax chord from them has a part # 1220-01. Roll out16 feet of the wax chord, and double it up. If you pull it through your fingers, it will kind of stick together as a single chord. Use the doubled upwaxed chord, as a single chord. An airport buddy of mine showed me how to tiethe loops, but I've learned most of this stuff by trial and error, and keeping records of each process, and a sample of how the knots are tied. Measure backfrom the tip of the cut bunji chord to 7 3/4", and make a mark with a black pen. This is where you loop the tip of the bunji back to, to make a loop. Usea zip tie, cinched down tight, to hold the loop, while you tie the loop with the waxed chord. I started out using cut bunji length of 34". They loosened up, so I took them apart and when I cut off the waxed chord of the tied loops, they had stretched to 36" cut length !! I shortened them that time to 33", but they gotloose again. On 7/19/03 I re-tied them all to 31". They have loosened up again, so now I've cut them all to 29" cut length. Tied length on all four isnow is 21 3/8" to 21 1/2". That's from the tip to tip of the end of the loops. Here's the hard part to describe...tying the knots. The tied up portion that the waxed chord covers, is 1" to 1 1/8". Measure up from the cut end of the bunji 1" to 1/18" and make another mark. This is where you start to tie your knots. Start out by taking one end of the waxed chord, up under the zip tie, to the tip of the loop of the bunji and tape it there. Bring the length of waxed chord down past the cut end of the bunji about 3" past where you madeyour first mark, and loop it back up almost to the zip tie. Make the first knot in the waxed chord closest to the bunji loop. Make a loose loop around your first two fingers, and twist it counterclockwise one turn, and loop it backover top of the loop of the bunji. Take up the slack with the long end of thewaxed chord, and line up the first knot closest to the bunji loop. You can't make this one very tight, because there is nothing to tighten it up to. Work each knot away from the loop of the bunji. The second knot, third, and so on, will be able to tighten it up, with a leather protection for your hand, orthe waxed chord will cut the skin...gotta get it really tight !! For each knot, you make a loop around the first two fingers of your left hand, and twistit one turn counterclockwise, and loop it back over the loop of the bunji. You have to line up the knots of the waxed chord, along the seam where the bunjichord loops back to the cut end of the bunji chord. Your initial waxed chord will be under the knots you are tying. Maybe 20 or 30 knots later (I haven't counted them), you will have reached the cut end of the bunji, making the tied portion about 1" to 1 1/8" long. Now you take what's left of the waxed chord (about 3"), and thread it through the loop that you taped down past the cutend of the bunji. With the first end of the waxed chord that you inserted up under the zip tie, pull the other end up under the set of tied knots, bring the ends together with a couple of square knots. This keeps the assembly of knots tied together. You may be able to get away with a bunji chord cut lengthof 30", because new chord isn't stretched out yet. As far as getting it streached around the struts...do it when there are no women or children around !! Tape the jaws of the vise to secure the strut,and be careful not to over tighten the vise to the point where it crimps the metal, but plenty tight enough to hold it secure. This is a two man job...oneto keep stretch on the chord, the other to keep working the slack around the loops with a huge 24" pair of channel locks - with tape on the jaws so it doesn't damage the bunji cloth. I used a small rope through the loop, and backup around the other end of the bunji strut, to keep stretching the bunji, and keep it from stretching back. Good Luck, and HAVE AT IT !! If you find an easy way to do it...Please let me know. I hope you can understand all this. Fire away with any questions !!Chuck GantzerNX770CG________________________________________________________________________________
Subject: Pietenpol-List: Bunji StrutsSince there's not much going on, on the list, I thought I'd send along the text that I wrote for Max Davis, on how I tie my bunji strut loops. It's a longpost, so be warned !! I finally got done with re-tieing, and installing my bunji struts back on the plane. Installing the bunji's on the struts, is one of the most difficult 2 man chores that I do alone, as regular maintenance. Last year, I pulleda tendon in my right elbow, this time all I did was pinch my finger (it only bled a little bit), and now only have achy forearms from pulling and fixing theloops over the struts. This is the last time I'm going to re-tie the bunji's...I'm building spring struts !!! It's difficult to put it in text, how I tie the loops, so I've taken a lot of digital pictures, and will send them direct to anyone that contacts me direct. The instructions I'm giving here, is for the PLANS DIMENSIONS of the bunji strut suspension. It took me 2 or 3 tries my first time, before I was satisfied with how the loop turned out. Start out using two wraps of medical tape where you plan on cutting the bunji chord with a sharp knife, or the bunji chord will unravel before your eyes. Cut up a piece of scrap to see how this stuff is made. It obviously isstretched quite a bit, before the cloth weave is applied to the many small strands of rubber bands. The 5/8" bunji chord from AS&S is part #06-12600. Ifit's all in one length, you can use the medical tape centered where you wish tocut, then just cut right down through the medical tape, leaving half of the medical tape on each piece. I use a waxed chord from a leather company called'The Leather Factory'. The wax chord from them has a part # 1220-01. Roll out16 feet of the wax chord, and double it up. If you pull it through your fingers, it will kind of stick together as a single chord. Use the doubled upwaxed chord, as a single chord. An airport buddy of mine showed me how to tiethe loops, but I've learned most of this stuff by trial and error, and keeping records of each process, and a sample of how the knots are tied. Measure backfrom the tip of the cut bunji chord to 7 3/4", and make a mark with a black pen. This is where you loop the tip of the bunji back to, to make a loop. Usea zip tie, cinched down tight, to hold the loop, while you tie the loop with the waxed chord. I started out using cut bunji length of 34". They loosened up, so I took them apart and when I cut off the waxed chord of the tied loops, they had stretched to 36" cut length !! I shortened them that time to 33", but they gotloose again. On 7/19/03 I re-tied them all to 31". They have loosened up again, so now I've cut them all to 29" cut length. Tied length on all four isnow is 21 3/8" to 21 1/2". That's from the tip to tip of the end of the loops. Here's the hard part to describe...tying the knots. The tied up portion that the waxed chord covers, is 1" to 1 1/8". Measure up from the cut end of the bunji 1" to 1/18" and make another mark. This is where you start to tie your knots. Start out by taking one end of the waxed chord, up under the zip tie, to the tip of the loop of the bunji and tape it there. Bring the length of waxed chord down past the cut end of the bunji about 3" past where you madeyour first mark, and loop it back up almost to the zip tie. Make the first knot in the waxed chord closest to the bunji loop. Make a loose loop around your first two fingers, and twist it counterclockwise one turn, and loop it backover top of the loop of the bunji. Take up the slack with the long end of thewaxed chord, and line up the first knot closest to the bunji loop. You can't make this one very tight, because there is nothing to tighten it up to. Work each knot away from the loop of the bunji. The second knot, third, and so on, will be able to tighten it up, with a leather protection for your hand, orthe waxed chord will cut the skin...gotta get it really tight !! For each knot, you make a loop around the first two fingers of your left hand, and twistit one turn counterclockwise, and loop it back over the loop of the bunji. You have to line up the knots of the waxed chord, along the seam where the bunjichord loops back to the cut end of the bunji chord. Your initial waxed chord will be under the knots you are tying. Maybe 20 or 30 knots later (I haven't counted them), you will have reached the cut end of the bunji, making the tied portion about 1" to 1 1/8" long. Now you take what's left of the waxed chord (about 3"), and thread it through the loop that you taped down past the cutend of the bunji. With the first end of the waxed chord that you inserted up under the zip tie, pull the other end up under the set of tied knots, bring the ends together with a couple of square knots. This keeps the assembly of knots tied together. You may be able to get away with a bunji chord cut lengthof 30", because new chord isn't stretched out yet. As far as getting it streached around the struts...do it when there are no women or children around !! Tape the jaws of the vise to secure the strut,and be careful not to over tighten the vise to the point where it crimps the metal, but plenty tight enough to hold it secure. This is a two man job...oneto keep stretch on the chord, the other to keep working the slack around the loops with a huge 24" pair of channel locks - with tape on the jaws so it doesn't damage the bunji cloth. I used a small rope through the loop, and backup around the other end of the bunji strut, to keep stretching the bunji, and keep it from stretching back. Good Luck, and HAVE AT IT !! If you find an easy way to do it...Please let me know. I hope you can understand all this. Fire away with any questions !!Chuck GantzerNX770CG________________________________________________________________________________