94 Pathy Posted June 24, 2005 Share Posted June 24, 2005 :help: Ok all you machining freaks! I'm drilling out some holes/broken bolts for the front skid plate. I used a 5/16" drill bit and now I'm trying to figure out what size of :confused: Tapper bit to use for the threads. Do I go that route or do I screw the threads in with Heli-Coil Inserts? I would think that making the threads permenant would be best. According to the Heli-Coil Insert kit I have, it calls for a drill size "U" (.368). I'm guessing by the size of things that my 5/16" drill is too small, so what size of drill bit is "U"? Thanks for all your help! Link to comment Share on other sites More sharing options...
Duffman Posted June 24, 2005 Share Posted June 24, 2005 For NC threads you want size 18 tap with a 5/16 drill, at least if my memory serves me. Google it and make shure! Link to comment Share on other sites More sharing options...
Runnerman Posted June 24, 2005 Share Posted June 24, 2005 Ok before you tap it. Try an easy out this will take care of most sheared off bolts. This way you can just ream the hole with the existing threads. So punch it (make it a good one) Next take a small drill bit drill in it aways. Now take your easyout and it will come right out. This is the easyway to take these bolts out. Link to comment Share on other sites More sharing options...
Precise1 Posted June 24, 2005 Share Posted June 24, 2005 Hey 94 Pathy, I'm a machinist by trade so I can help... First off, have you already drilled out the holes/ broken bolts ? Second, 5/16 is the nominal core hole size for a 3/8-16 tap so you can just tap the (existing ) holes in that size. What ever you tap with, make sure to champher the hole larger than the tap size, it will help things greatly. Third, heli-coils are great, but maybe unnecessary, are the holes clean metal and how thick is the wall ? Fourth, U drill is the size; american measurement drills come in letter, number and fractional sizes ie, U, #7, and 5/16. It totally sucks and is left over from several industries refusing to standardize. Regardless, any hardware store worth a crap will have a U drill waiting for you. Let me know whats up, I'll pay attention and get you on the right path... Bernard Link to comment Share on other sites More sharing options...
GrimGreg Posted June 24, 2005 Share Posted June 24, 2005 I wouldn't recomend the helicoil since the bolt holes are in thin metal with nothing to stop the helicoil from spinning completely through the hole. Link to comment Share on other sites More sharing options...
94 Pathy Posted June 24, 2005 Author Share Posted June 24, 2005 Thanks everyone! Precise1, Where I'm drilling is where the front of the factory skid plate is bolted, just under the radiator. The middle one is drilled out and the left and right bolts are busted, so I will be drilling those out. I've never threaded a hole before. Is it time consumming? I'm threading these by hand, or should I put the bit in a drill and go slow? I also need to do all this to the bolts that busted when I was taking my hitch off the rear to repaint. The hitch is crap, since the previous owner welded the tongue in and everything is rusted to be hell. Wanting to get a fabbed rockkrawler bumper with hitch built in. Thanks for all your help! Link to comment Share on other sites More sharing options...
94 Pathy Posted June 24, 2005 Author Share Posted June 24, 2005 :confused: Champher is threading, or is that like just the beginning ofthe hole is counter- sunk? I find all this very interesting, but no knowledge or education on this. I'm thinking about going back to school for this.... -bounce- Sorry to put you to for all this mumbo jumbo! Link to comment Share on other sites More sharing options...
GrimGreg Posted June 24, 2005 Share Posted June 24, 2005 I've never threaded a hole before. Is it time consumming? I'm threading these by hand, or should I put the bit in a drill and go slow? Get a T handle for the tap and do it by hand. If you drilled the right size hole it will cut the threads easily. If you want to make it go a little smoother and make the tap last use a little oil on it. Also be sure to run it in far enough that you get past the starter cutters on the tap. Link to comment Share on other sites More sharing options...
94 Pathy Posted June 24, 2005 Author Share Posted June 24, 2005 Thanks Greg! I'm on my way out the door to do some running and then all hell breaks loose! Link to comment Share on other sites More sharing options...
jj big shoe Posted June 24, 2005 Share Posted June 24, 2005 When tapping out the hole, don't just run the tap in as if you're putting a bolt in. Tap a little then pull the tap out to remove the metal shavings and tap some more. Continue doing this until you can run the tap in all the way. It's not too hard, just take your time. Link to comment Share on other sites More sharing options...
Precise1 Posted June 24, 2005 Share Posted June 24, 2005 Ditto to what JJ said... Definitely use oil on the tap and try to make sure you are straight to the hole; the tap will try to lean sideways when you first start. Pushing the tap in while turning helps this. Dont use enough force to flex things or you will be drilling again... :o It's really quite simple. GL B Link to comment Share on other sites More sharing options...
GrimGreg Posted June 24, 2005 Share Posted June 24, 2005 When tapping out the hole, don't just run the tap in as if you're putting a bolt in. Tap a little then pull the tap out to remove the metal shavings and tap some more. Continue doing this until you can run the tap in all the way. It's not too hard, just take your time. Yep, I generally go 1/2 turn in then back 1/4 turn, repeating till there's no resistance, then run it in about 6 turns to make sure the threads are clean. Link to comment Share on other sites More sharing options...
94 Pathy Posted June 24, 2005 Author Share Posted June 24, 2005 -bounce- -bounce- LIKE A GLOVE! The front holes are done for the skidplate. Time to move on to the back :sniff: where the hitch bolts are. Thanks you guys for your help! Link to comment Share on other sites More sharing options...
Precise1 Posted June 24, 2005 Share Posted June 24, 2005 See, easy as pie ! Glad you learned a trick, good job. B Link to comment Share on other sites More sharing options...
Duffman Posted June 25, 2005 Share Posted June 25, 2005 dont break the tap off in there, that can be a real pain, go very slow becouse just when you get overconfident something ****** happens, metal can smell fear. Link to comment Share on other sites More sharing options...
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