I thought I had an original idea in this hinge but it has been posted before by Diemai. Not sure how strong it will be but I am putting one in a junk balsa lure and will hang it from a scale with some weight to see when and if it distorts or fails and at what weight the hinge or the twist pins will pull out of the balsa wood. The hinge is made from 105 lb. Test .031 spring temper Stainless Steel.wire . I think that any line that I use would snap before this hinge would fail. But I am curious to see what happens as I add weight to this thing. The twisted tow eye and rear hook hanger are also made of this same wire and are imbedded in the balsa 1¼ inch they are glued in with thin CA. I am expecting one of these hangers to fail before the hinge does. I think this hinge if successful will lend itself to easy installation in split baits or a one piece bait. I drilled the holes for the hinges slightly deeper than the hinge arms are long. I hardened the insides of the holes by injecting them with thin CA. After it dried, I redrilled the holes and filled them with D2T epoxy. I then inserted the hinge arms in the holes about ½ way and slid the two PVC hinge spacers over the arms and pushed the hinge arms the rest of the way in. Remove the spacers and let cure. I have always planned to stress test tow eyes and hook hangers but have never done it yet. So, I guess I will kill two birds with one stone. You can see by the pics how this hinge is made and installed.
Thursday afternoon 2/19/2009 at 3:30 pm I started the weight/stress test today. I added weight until I reached 20½ lbs. and the bucket was full. I will let this hang for 16 hrs until I got off work Friday morning.
Friday Morning 2/20/2009 at 10:30 am The hinge is still not deforming and I see no sign of the twist pins or hinge pins pulling out. I am going to leave it a few days to see what happens
Tuesday Afternoon 2/24/2009 at 3:30pm It has been 5 days now since I have checked on the hinge. Iwent out to the man cave to see how the hinge was holding up under the 20½lb load. I didn’t see any signs of deforming or anything coming apart so I got a larger bucket and put the bucket of wheel weights in it and reattached it to the lure and set a bucket of bolts in it also. This pulled the scales down to almost 30 lbs. I still didn’t see any signs of stress so I started adding more wheel weights The scales passed 0 a third time and locked at 34lbs. They are designed to weigh 30lbs max. Next, I got the bathroom scales and started adding more wheel weights a few at a time. I finally started seeing the gap between the first section of the lure and the hinge coil widen. I stopped adding weights and weighed the bucket of weights. It weighed in @ 45lbs. I hung it back up and added more wheel weights until the hinge started pulling out again this time it slid out rather quickly about an inch and stopped again. I stopped and weighed the bucket. It weighed in @ 54lbs I picked it up by the hanger and gave it a couple of hard bounces and the lure finally finished pulling apart.
As you can see in the last picture, The coil had tightened up on its end wraps (I believe that a larger hinge pin would have not permitted this to happen, the hinge pin that I used .031 was only ½ the diameter of the hole in the coil .062). Also the hooks in the hinge arms had straightened out. I think that hardening the inside of the hinge arm bores with the CA gave those hooks a little more grip on the wood. (maybe someone else would have some insight on this.) Another thing, the upper rear hinge pin arm had started to pull out also. I think both of these things happened when I gave it the hard bounces to get the hinge arms to finish pulling out. Also, you can see that neither the twisted wire tow eye pin nor the rear hook hanger have budged.
This lure was cut from a junk piece of soft balsa wood it has not been hardened with the wood hardner and does not have any epoxy top coat on it. I think a top coat and a dip in the wood hardner would have strengthened the assembly even a little more.
I have always worried that a twisted tow eye or a hook hanger might pull out of one of my lures with a big fish on. I don’t catch that many big ones but always expect the next strike to be the fish of a lifetime.
After performing this stress test, I feel that I have nothing to worry about from my balsa lures that have not been thru wired. I think that any fishing line that I use would break long before I would have lure failure. The exception to this would be slapping the lure on the water to clear it of moss or weeds. After having two lures explode from this procedure, and some good advice from JawJacker. I don’t do that anymore.
Pete, looking at the results of this coil and pin hinge test, there is no telling how much weight you could put on your DNA hinge before it would fail. If you could somehow secure it to keep it from pulling out of the lure, I bet it would easily support 100 lbs or more.
Hopefully, this was not confusing but if it was, let me know and I will try to explain.
I also hope this test helps someone to feel a little better about using homemade twist pins and hinges when building or assembling their lures. John
Hinge stress test pictures by JBlaze1952 - Photobucket
Edited by JBlaze, 25 February 2009 - 04:47 PM.