mhearn Posted July 31, 2005 Share Posted July 31, 2005 The pin on the front of my Bo-Mar combat sight for my STI broke in half. This is the pin that runs all the way through the sight and acts as a hinge for the sight so the rear of the sight can move up and down when you adjust the elevation screw. After I got the pin out and took the sight apart by taking the elevation screw out, I noticed a spring that is held in place by this pin. This spring runs through a hole in the front of the sight to a tension pin that works in conjuction with the elevation screw. Here's the question. Anybody know where I can get a replacement pin? Assuming I can get a pin or fabricate a substitute, how do you get the spring back into its hole and the pin through behind it. That spring has to be pushed up into its area and the pin slid pass. Seems impossible. What's the trick? Or should I forget the whole thing and order a replacement sight? MHearn Link to comment Share on other sites More sharing options...
stingerjg Posted July 31, 2005 Share Posted July 31, 2005 That happened to my gun at one time. I thought it was easier to just replace the whole sight. If the pin broke, it was prob under some kind of stress. I would trust a new sight over a replacement sight. Or you could ask Erik Warren what to do. Link to comment Share on other sites More sharing options...
OPENB Posted July 31, 2005 Share Posted July 31, 2005 If it is an STI sight that looks like the Bomar, (should say "STI" on the top), call Chris at STI. He sent me a couple replacement pins and springs no charge. I guess STI sights have a reputation for breaking the pin. The replacement pin is supposed to be stronger, and he told me they are slightly bigger in diameter. I had to ream the hole a little. I depressed the spring through the front of the sight body, (you should see the hole from the front of the sight) with a very small punch, then tapped in the new pin. Whole thing took 10 minutes. You are correct, the spring provides detent tension for the elevation screw. I replaced the pin on my Trojan, and have had no further problems. Link to comment Share on other sites More sharing options...
mhearn Posted July 31, 2005 Author Share Posted July 31, 2005 OPENB Thanks for the tip. Mine is not the STI clone. Its a BO-MAR. I wonder if the STI pin will work. The sights look identical. I'm assumming that you used a very small drill bit to ream the hole. So, you just happened to have a bit the exact size of the oversized new pin! And, a punch the same size as that itsy bitsy spring! Man, you guys have alot more stuff laying around than I do. MHearn Link to comment Share on other sites More sharing options...
SmittyFL Posted July 31, 2005 Share Posted July 31, 2005 I've never had mine apart enough to help you with the spring. But when my pin broke I replaced it with an allen key and lock tite. It's held up over a year with that. Link to comment Share on other sites More sharing options...
konkapot Posted July 31, 2005 Share Posted July 31, 2005 I had several break....BoMar, STI, LPA, and a brand called "Champion." They all broke. Ended up going with fixed sights from then on. Drill bits have worked for some. FY42385 Link to comment Share on other sites More sharing options...
GuildSF4 Posted July 31, 2005 Share Posted July 31, 2005 I've never had mine apart enough to help you with the spring. But when my pin broke I replaced it with an allen key and lock tite. It's held up over a year with that. <{POST_SNAPBACK}> What size allen for the curious amoung us? Link to comment Share on other sites More sharing options...
Kevin Kline Posted July 31, 2005 Share Posted July 31, 2005 When I shot my STI, mine broke and I was told to put an allen key in it also, it worked great. It hasnt broken yet and I'm over 15,000 rounds over it, no probs. Link to comment Share on other sites More sharing options...
achard Posted July 31, 2005 Share Posted July 31, 2005 Try the fishing hook. I had mine replaced with it after the bo-mar pin broke. Cheaper Link to comment Share on other sites More sharing options...
Guy Neill Posted July 31, 2005 Share Posted July 31, 2005 Call Bomar - they will likely send a replacement pin or two, or send the sight to them to reassemble with a new pin. Sorry, I don't have their number at hand, but they are on the internet. Guy Link to comment Share on other sites More sharing options...
fishnfst Posted July 31, 2005 Share Posted July 31, 2005 That happened to my gun at one time. I thought it was easier to just replace the whole sight. If the pin broke, it was prob under some kind of stress. I would trust a new sight over a replacement sight. Or you could ask Erik Warren what to do. <{POST_SNAPBACK}> You don't want to ask him ............... He had his slide welded up and recut for fixed sights............. Link to comment Share on other sites More sharing options...
mhearn Posted August 1, 2005 Author Share Posted August 1, 2005 Thanks. Some good ideas. Here's what Joey Hardy suggested and it worked. I bought a 5/64" drill bit. Just a bit larger than the pin. Used it to slightly enlarge the hole. Then, ground the bit down to length and used it as the new pin. I put a piece of the old pin into the hole after grinding the end to an angle to push the spring up into place. The only hard part was braiding the ends of the pins to secure them into the sight. MHearn Link to comment Share on other sites More sharing options...
schmitz Posted August 3, 2005 Share Posted August 3, 2005 The hinge pin of my Bo-Mar broke for the X-time, blade was loose too, purchased a Chinese knock-off (34 Euro's via HPS) after 1K...guess what... hinge pin broke again. (BTW, this always happens during matches ) Blade is OK, so I decided to repair it myself this time. Springs used in Porsche brake-calipers had just the diameter I needed. I manufactured a hinge-pin using this steel and it worked untill now 10K. Just German steel after all,.... alike my car I lost faith in Bo-Mars quality Link to comment Share on other sites More sharing options...
reneet Posted August 3, 2005 Share Posted August 3, 2005 I've never had mine apart enough to help you with the spring. But when my pin broke I replaced it with an allen key and lock tite. It's held up over a year with that. <{POST_SNAPBACK}> What size allen for the curious amoung us? <{POST_SNAPBACK}> 1/16" if I recall correctly. Link to comment Share on other sites More sharing options...
EricW Posted August 3, 2005 Share Posted August 3, 2005 Does anybody know what the real dia. of the hinge pins are *supposed* to be. I did the 1/16 allen trick, but it's milking around a lot side to side. My calipers show the holes to be somewhere in the .070" range +/- .002". I can buy 1/16" (.0625) rod or 5/64 (.078125"). I just wonder if I ream the hole to 5/64, if I'm simply going to break the entire sight instead of just the hinge. Link to comment Share on other sites More sharing options...
schmitz Posted August 3, 2005 Share Posted August 3, 2005 Eric, that Porsche spring I used measures .0735 of an inch. And it fits perfectly. Henny. Link to comment Share on other sites More sharing options...
EricW Posted August 3, 2005 Share Posted August 3, 2005 I just hope I don't get busted while I'm chopping the front brake caliper off some yutz's Boxter tonight. Link to comment Share on other sites More sharing options...
Bronco Posted August 3, 2005 Share Posted August 3, 2005 As is evident from the number of posts this is a common problem with Bo-Mar type sights. My gunsmith uses the 5/64 drill rod as a replacement with good results. I went with fixed. Link to comment Share on other sites More sharing options...
Flexmoney Posted August 4, 2005 Share Posted August 4, 2005 I just hope I don't get busted while I'm chopping the front brake caliper off some yutz's Boxter tonight. Take your gun along...so that you can show the yutz what you would like to do. Link to comment Share on other sites More sharing options...
schmitz Posted August 4, 2005 Share Posted August 4, 2005 Muhahahahaha, Eric, what you need is the spring that retains the seal covering the brake-piston. Best thing to do is..... Go for the Boxster Sorry serious thread-drift! Link to comment Share on other sites More sharing options...
bountyhunter Posted August 5, 2005 Share Posted August 5, 2005 I can buy 1/16" (.0625) rod or 5/64 (.078125"). I just wonder if I ream the hole to 5/64, if I'm simply going to break the entire sight instead of just the hinge. <{POST_SNAPBACK}> I wouldn't ream anything. I took the broken pin and my calipers to Home Depot and found a bright steel finish nail that was about .002" wider diam than the pin. I cut a piece and filed the ends, then filed the "center notch" for the spring to snap into and drove the "nail pin" in and it is dead tight and rock solid. Nails are made of much tougher steel (also softer) but will last forever. Link to comment Share on other sites More sharing options...
Byron Simpson Posted August 10, 2005 Share Posted August 10, 2005 The pin broke on my STI Bo-Mar clone. I replaced it with a finishing nail. Cut the point and the head off with a Dremel cutting wheel and used a tiny drop of blue loctite. It has held for thousands of rounds with no problems. Link to comment Share on other sites More sharing options...
Middle Man Posted August 10, 2005 Share Posted August 10, 2005 All this talk of broken adjustable sights makes me glad I've resisted the temptation to spend the cash to replace the factory's fixed unit. Link to comment Share on other sites More sharing options...
EricW Posted August 10, 2005 Share Posted August 10, 2005 I'm working on what I think may be a neat solution. I'm going to try and get some special clips worked up that you can push onto each end of the hinge pin to prevent it from walking out. Yeah, it means having a pin that sticks out each side a tiny bit, but I think the end result will be worth it. For now, I've got a box of 1/16" hex keys. I'm thinking about selling little baggies of BoMar "hinges" for a nominal price. Hopefully the fastener will work and I'll have a little hinge kit for people. Link to comment Share on other sites More sharing options...
bountyhunter Posted August 11, 2005 Share Posted August 11, 2005 The pin broke on my STI Bo-Mar clone. I replaced it with a finishing nail. Cut the point and the head off with a Dremel cutting wheel and used a tiny drop of blue loctite. It has held for thousands of rounds with no problems. <{POST_SNAPBACK}> If it is like the Bomar clone on my Trojan, you MUST file a groove in the center for the spring to snap into (the internal spring that puts prssure on the elevation screw detent holding pin). That spring locking into the slot in the pin is also what keeps it from walking out. FYI, you can find a nail a couple of thou oversized of the pin and you will definitely not need Loctite. In fact, it has to be tapped in with a punch. Link to comment Share on other sites More sharing options...
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