While I was working on setting up my velomobile to be transported to the MakeFest in Davenport Iowa next month I had to figure out a simple way to tie a plastic tarp down over the vehicle without having to use a lot of rope and a lot of time. I have found that it is always a pain to do this simple task as it always involved a lot of knot tieing and untieing to get the job done. Then I remembered a simple little device that was used on a stuff sack for my sleeping bag that I had used while camping years ago.
This little device is called a barrel stopper. It is a simple little cylinder that is used on a cord or string to hold a bag shut that has something in it. Like my sleeping bag I just told you about. The string is fed through the opening of this cylinder once an inner spring is compressed. The spring moves the cylinder outward and puts pressure on the string to hold the bag closed. Why couldn't I just make this little gadget larger for use with a rope? So I 3D printed one up to see if my idea was sound.
Here is my new larger version of the little barrel stopper. I was able to find a good sized heavy spring that is 1/2" in diameter and 1-3/4" long at my local hardware store. Then I 3D printed two cylinders. An outer and an inner that would hold the spring in place. The smaller inner cylinder has an opening just large enough for the springs outer diameter and the larger outer cylinder has an opening large enough for the smaller cylinder to slide into with very little friction. In the base of the inside of the larger cylinder is another cylindrical opening to hold the bottom portion of the spring in place.
Once the assembly is put together with the inner spring inside, it is just a matter of pressing down on the inner cylinder and lining up the two holes in both cylinders so the 1/4" rope can slide through the assembly so it can be used.
Once the rope has been fed through the two holes the inner spring holds the rope in place and the rope holds the assembly together.
I looked at my enlarged version of the barrel stopper and I think it will do the job nicely of hold my tarp on to my velomobile for transport. The rope is fed through the eyelets of the tarp which is then pulled tight just like the strings on my stuff sack for my sleeping bag only much larger so that the velomobile will now be protected on the inside of this huge plastic stuff sack.
The enlarged barrel stopper with the big spring in it has enough tension on the 1/4" diameter rope to hold the covering tightly closed during transport. To make double sure that the stopper does it's job I can loop the end of the rope around the cylinder as shown above and the tension on the looped rope will lock it even further just to make sure it does not release it's grip.
The dimensions of my big barrel stopper once it has been assembled is 2-1/2" tall and 1-1/4" in diameter. Total cost to make my version of this little devise was only a couple dollars and will save me a lot of time tieing and untieing ropes to hold everything in place. For light jobs like holding this tarp I think this gadget will work just fine. I'm not so sure about something like holding a boat on to a trailer though. I would have to do more testing to give you the answer on that kind of job. In the mean time this will work just fine for the job I have in mind. Have a good one and keep on tinkering!