boxofbits Posted January 31, 2021 Report Share Posted January 31, 2021 Hi All Has anyone any experience with drilling out broken studs from Mazak? These are usually quite delicate castings I know and difficult to repair or re-chrome but I have a part with snapped 2BA studs. I have a 2BA tap set but before I start has anyone been there before and can it work? It’s not a TR piece but then it’s the same for many Historic vehicle parts including Triumph. Any views welcome. Kevin Quote Link to post Share on other sites
Lebro Posted January 31, 2021 Report Share Posted January 31, 2021 Should be possible, start with a small drill (2mm or so) & make sure it is exactly in the center of the broken stud. gradually increase the size of drill stopping short of going into the threads, then try to pick out the remains of the stud. Good luck Bob. Quote Link to post Share on other sites
Hamish Posted January 31, 2021 Report Share Posted January 31, 2021 Could you try this type of extractor the reverse thread type. Small pilot hole then wind these in as tightens as it undoes ? https://www.screwfix.com/p/bolt-extractor-set-5-pieces/1112V?tc=FC3&ds_kid=92700055262507123&ds_rl=1244066&gclid=EAIaIQobChMI6PvvpqLG7gIVkuvtCh0BpAkPEAQYBSABEgJJvvD_BwE&gclsrc=aw.ds Quote Link to post Share on other sites
RobH Posted January 31, 2021 Report Share Posted January 31, 2021 You may be able to dissolve those steel studs using a saturated solution of Alum. It is a technique used for removing broken taps from aluminium or brass parts. (alum is harmless). It takes a day or so but it helps if the solution is kept warm. Rather than dunking the whole part in the solution it would be an idea to build a dam or cup just around the stud area with clay, and pour the solution into it. The mazac won't be harmed but I'm not sure of the effect on chrome so it would be as well to keep the stuff away from that just in case. Quote Link to post Share on other sites
ed_h Posted January 31, 2021 Report Share Posted January 31, 2021 If you try the drilling method, drill a pilot hole, then use a left hand drill bit. Sometimes It will back the broken stub out. Ed Quote Link to post Share on other sites
RogerH Posted January 31, 2021 Report Share Posted January 31, 2021 Hi Kev, if it is a valuable part then you could consider Spark Erosion. We used it quite a lot at BEA/BA Roger Quote Link to post Share on other sites
boxofbits Posted January 31, 2021 Author Report Share Posted January 31, 2021 (edited) Thanks Guys All very interesting and varied methods. I might go Bob’s route as much as all the suggestions are good, and it going to be tricky either way. My pillar drill clamp seems to grip it well so I’ll try a first drill, see how I get on and report back. Hamish and Ed my only reservation with trying to use an easy-out is the narrowness of the trim and fragility of the material and only being 2BA there is very little between a drill opening and wall. Rob’s suggestion is great but forming a sort of funnel around the stud might be difficult as again a very slender part. It’s a vertical dash trim either side of the speedo on a Morris Minor van. The cars have a similar trim but are deeper as they have glove box lids. Roger, good ones are quite hard to get hold of being the van version but that’s another good suggestion. Would it damage Mazak in any way and is it cost effective? There are two studs snapped. Kevin Edited January 31, 2021 by boxofbits Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 31, 2021 Report Share Posted January 31, 2021 (edited) As it is not structural, only cosmetic could you drill and tap into the broken steel stud and fit say a 4BA stud? This is a smaller diameter and would anchor ok. tapping drill for 2BA is 4mm Tapping drill for 4 BA is 3 mm You could even bodge it with some metric thread! I guess the stud broke when the nut was being removed. Peter W PS are you double dog sure the threads are BA and not UNF? Edited January 31, 2021 by BlueTR3A-5EKT Quote Link to post Share on other sites
Ralph Whitaker Posted February 1, 2021 Report Share Posted February 1, 2021 Just a note of caution, usually the studs on these type of parts are cast into the item, not fitted later, and are sometimes hex or square headed to prevent them turning in the casting, otherwise they would probably have screwed out rather than shearing. I think peters idea of tapping a smaller size into the remains of the stud is the best idea as the new thread will then be gripping on steel. Go bigger and the thread will be only gripping into soft mazak. If they are not available it sounds like an opportunity to use your existing one as a pattern and get some cast in ally to polish up or better still in brass and chromed. Ralph Quote Link to post Share on other sites
ed_h Posted February 1, 2021 Report Share Posted February 1, 2021 The hard part of drilling out a broken stud is getting the hole started in the center of what is probably an irregular surface. If the stub of the stud is proud of the surrounding material, you can make a simple drill guide that has a recess to fit over the stub. Ed Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.