HELP-- I 'm stuck at work = Weld thread inserts

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This is my dilemma : The cast couplers on the front of transit consist of a knuckle & latch pin mechanism fasten to a collapsible telescopic tube known as a deformation tube. The outer tube OD is 8 ¼” and the inner tube ID is 8 1/16”. There are four bolts located at 12:00, 3:00, 6:00, & 9:00 these bolts pass through the OD tube and thread into the inner tube, these are 5/8”-11 shear bolts. This piss poor design is suppose to work (fails) so that whenever the coupler is struck hard the deformation collapse 23 inches adsorbing the blow. This happen often, sometimes all four bolts go. My problem is that when these bolts shear off it is usually 1/2'” below the surface and harder than the hubs of hell to drill out, not sure the grade of bolt but they will eat up a cobalt drill bit after three holes. I can drill these out with centering bolt and sometimes re-thread them but we are talking about 2 to 3 hours on a bad one.The mechanic before choose to send these tubes back to the original manufacture spending untold dollars on these units and 6 to 8 months  (no ****tt) they’d  comeback. I can tell by their fix they are drilling out oversized hole and welding in a thread insert & grinding back the weld. This will be easy to do because both sides have limited access (thankfully).But I cannot find the process for doing this, how to keep the slag out of the hole and how much bevel if any to place  on the weld seems ?Also I cannot locate 5/8’-11 weld thread insertsThx JS
Reply:Could you post a pic?  Sounds like an interesting problem to sort out.Dave J.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Instead of weld in threaded inserts why don't you just use standard threaded inserts. Drill and tap the hole over sized then put the insert in to bring it back down to the right bolt size. They're made in lots of different sizes and styles. http://www.mcmaster.com/#standard-th...nserts/=lmyyrzMillermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:If the original threads are still good and the only problem is the broken bolt, there is a technique using a stick electrode and nut that will allow you to thread them back out.  Essentially, you place a nut over the top of the hole, then weld a spot to the top of the bolt and build a column up to the nut on top.  The nut then acts like a bolt head allowing you to remove the assembly.
Reply:Get some small "unichrome" or similar rod. This rod the spatter etc will not stick the threads. Buid up the broken bolt until you can weld a nut to it let it cool and remove. I have removed many many bolts this way. In some cases you do not even need to weld the nut on use a pipe wrench or good plier and remove the bolt.