Don Fry Posted February 26, 2021 Share Posted February 26, 2021 I acquired a second hand OS 120 Surpass Mk111 some time back. It was as cheap as chips, nice condition, undamaged, little used, and runs well. Now it’s going in a Spacewalker, 1/4 scale, I plan to build. Next up on the bench. One problem. The front, deeply buried rocker cover bolt is rounded, it’s a hex, shallow head. Not me, as received. I can’t cut a slot in it without cutting the rocker cover I would prefer to resolve this problem before mounting in an airframe. How to extract. Good workshop, access to lathes, industrial puller drill, tools. Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted February 26, 2021 Share Posted February 26, 2021 i had the same problem with my OS91 f/s......i used a drill slightly larger than the hole for the allen key,and drilled the head off leaving the bolt stump in the head which i then took out with some plier's...job's a goodin...no damage and new bolt...away i went. ken anderson....ne...1........job's a goodin dept. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 26, 2021 Share Posted February 26, 2021 Try drilling the head off with a left handed drill. If you’re lucky it will come out before it even removes all the head. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 26, 2021 Share Posted February 26, 2021 Have you tried a Torx bit Don, they often get it out, may have to tap it in gently first. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted February 26, 2021 Author Share Posted February 26, 2021 I’ve tried a torx ( that comes out as Tory on the spell checker). Brand new bit, Bosch, heated bolt, knocked in, faintest grip, then fail. Martin, is a left hand drill different to an screw extractor? I didn’t think extractors came small enough for this thing. Kens’ system is favorite at the moment, especially is he says there is enough left to get pliers on. BTW, what is the size (diameter) of these bolts. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted February 26, 2021 Author Share Posted February 26, 2021 Arrrr, I note, having looked, that left handed drills exist, and a can buy a set of 11 for a reasonable sum, down to a 1/16 inch. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted February 28, 2021 Share Posted February 28, 2021 (edited) Be careful what you order. I bought a set reasonable priced on eBay described as "left handed drills" they turned up as a set of easy outs and normal drills ! Tracy tools sell proper left handed drills and you probably won't need to buy a set . Pretty sure they are 2.5mm bolts. Edited February 28, 2021 by Engine Doctor Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted February 28, 2021 Share Posted February 28, 2021 Don you could try this... Take an Allen key the next size up and carefully grind a shallow taper on each face until the tip just engages with the head of the bolt. Then tap the key into the head of the bolt with a hammer. If you can force it in to a reasonable depth, you may find that you can now get enough purchase to unscrew the bolt. A. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 28, 2021 Share Posted February 28, 2021 You can also buy a product called “Screw Grab” which is diamond dust or similar in a greasy substance which can provide enough grip to remove a slightly rounded socket head screw. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted February 28, 2021 Share Posted February 28, 2021 Heating the screwhead with the tip of a soldering iron can sometimes help too. I'm surprised the Torx bit didn't work, I've never had it fail - touch wood! If I can't find a suitable size torx bit I've sometimes found that an imperial key will tap in tightly enough to get the screw moving. I think that the impact of hammering it in helps to break up any crud holding the thread. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted February 28, 2021 Author Share Posted February 28, 2021 Cheers Andy, I will have a go with the grinding option. Bob, it’s a ruined hex, I think the problem started when the previous owner didn’t clean the socket out before use. I’ve tried heat, I’ve got a tiny gas torch, used for small workshop jobs, and caramelising things in the kitchen, with a torx, and while it gave a bit of grip, nowhere near enough to shift even a screw just nipped up. I’ve got a set of (proper) left hand imperial left hand bits coming, of use as I really should have some imperial bits, even after this job is sorted. Doc, you are right, 2.5 metric course, 15mm. Idiot here remembered that the motor was boxed, with instructions, then idiot also remembered the other cover bolt is undamaged, and measurable. Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted February 28, 2021 Share Posted February 28, 2021 don,5 min it will take,if that with the drill...no mess or damage... ken anderson...ne..1...get that drill on the job dept. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted February 28, 2021 Author Share Posted February 28, 2021 Andy, just tried the tapered hex. Mounted motor in a test clamp, so I could mount it in a vice, so it does not move, and tapped it in with a dead blow hammer. Didn’t work, really is a ruined head. I think I will be patient. Drill it out with a left hand drill, in the pillar drill. It either shifts or the screw head cuts off. If the later, I revert to Ken Anderson’s method, or carefully cut a slot in the headless stump. No hurry, as I won’t the need the motor for a couple of months. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted February 28, 2021 Share Posted February 28, 2021 Sounds like the left-hand drilling is now the best option. If all else fails you might be able to use Alum to dissolve out the bolt if you can remove all the other ferrous parts or keep them out of the way. A. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted February 28, 2021 Author Share Posted February 28, 2021 Thinking (for once), the pillar drill is a stupid idea, it revolves the wrong way. So, it’s a battery drill, with a bit of care. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 28, 2021 Share Posted February 28, 2021 Unless you've got access to a small mill/drill with a reverse function... Quote Link to comment Share on other sites More sharing options...
cymaz Posted March 2, 2021 Share Posted March 2, 2021 Have you tried silver soldering a rod onto the top Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 2, 2021 Author Share Posted March 2, 2021 Yes, I’ve also tried gluing a hex into the hole. But, silver solder will, at least mess the rocker cover finish up. I’m going for the patient approach. When the new left hand drills arrive. Heat, then, left hand drill, will either get it out, or cut off the head. If the head comes off, revert to Ken’s plier extraction, or I can cut a slot in the top of the stub. or even, heathen like, hold the cover down with one bolt. No one will see it under the cowl. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 2, 2021 Share Posted March 2, 2021 It's almost certain that once the load is off the thread that the stub will extract with consummate ease - Ken's pliers will be more than enough. I doubt that you would get on very well trying to cut a screwdriver slot. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted March 2, 2021 Share Posted March 2, 2021 For the hell of it I would get the next size up Torx bit, grind the diameter down a little, till it tapped in tightly and give it a go. Or drill out the bolt head a little to suit next size Torx bit. Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted March 3, 2021 Share Posted March 3, 2021 hello again Don,a couple of turns with a normal 2-3mm drill in a battery hand drill will have the head off...then when you remove the rocker cover(undamaged) the the stump aprox 6mm long will come out with a pair of pliers no problem. ken anderson...ne..1..stump dept. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 3, 2021 Author Share Posted March 3, 2021 Arrrrrrrr, Ken, thank you. I did not realize there is that much stump. I’m off flying any minute, maiden of a 2 meter Stik. I will have a go when I get home. For information, slotting a bolt is achieved by slitting a slide on brass tube, (Dremel, might not get it first time, continuue til you get it right), The slit then holds a junior hacksaw in place, central, until the job is done. I’ve got an old Laser 75, broken main needle, so slotted, has been for years. Much smaller than 2.5 mm. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 3, 2021 Share Posted March 3, 2021 Cunning technique but I doubt that it would allow much torque to be applied! Much easier and a lot quicker to use pliers! Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 3, 2021 Author Share Posted March 3, 2021 The maiden is done. It’s new to me, but a second hand airframe. Usual list of programming alterations to be done, and happy. Not great, as I left the batteries at home for the other aircraft I took. Filled car on way home, bought whiskey. And my considered opinion is Ken Anderson is perfect. Job took no more than a minute. Thank you gentlemen. 1 Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted March 3, 2021 Share Posted March 3, 2021 Ken Anderson is perfect. Job took no more than a minute. ...................................... well done Don........its now official i'm Perfect ? ken anderson...ne..1....... perfect dept. Quote Link to comment Share on other sites More sharing options...
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