|
|
Hi list,I did a repair on a block yesterday. The client had broken out a starter mounting hole when he attempted to force a larger bolt into the hole when the old one stripped out. I was able to build up the area, drill a hole and cut new threads. However when the client went to tighten the starter bolt, he stripped the threads. My question has to do with how hard the nickel deposit is in relation to the original cast iron?Is this typical? Should built up holes such as the one I did yesterday be tightened gently? When I tested the hole and actually put in the bolt, it tightened down tight (without forcing it). When the starter was first turned over, I suggested to the client that the bolts be rechecked as the torque may have shifted the starter into its correct position or moved it so that the bolts needed to be tightened down again.He did so and the bolts had loosened so that's when he stripped the newly cut threads when he re tightened it.I have always brazed such repairs but lately have been using Ni rod with equal results. This is the second repair where I used the nickel rod in this fashion (to rebuild holes and tap them).Any thoughts on this?I got paid for my work and I suggested to the client that he go one size larger with a new bolt and tap for the new size and to use loc-tite on it. He was going to work on that today.Thanks,Tony
Reply:There should have been no problem at all until they used a breaker bar to tighten the bolt...Snug and then 1/2 turn is all that's needed....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Hi Zap,thanks for the reply. That's what I needed to know.Tony
Reply:was the hole really deep enough for the bolt length ?miller thunderbolt 250vlincoln square wave tig 175 prolincoln idealarc mig sp250everlast tig 210EXTeverlast power plasma 50chicago electric (hf) 130 tig/90 arcchicago electric 90 amp flux wire3 sets oxy/acet
Reply:I don't think it was. The hole was about 3/4" deep and I used a bottoming tap to take thread down the entire depth. The hole is just below a water jacket and going deeper would have penetrated it, or at least would run the risk of doing so. I did not want to risk it. However it tightened well so I considered it strong enough. I think the guy put too much pressure on it when he attempted to make it tight.Tony
Reply:Heli-coil the hole full depth. That should fix it better than going up a bolt size. The coils "jam up" in the hole and will hold more than a standard thread will in cast iron and nickel.
Reply:Originally Posted by 12V71Heli-coil the hole full depth. That should fix it better than going up a bolt size. The coils "jam up" in the hole and will hold more than a standard thread will in cast iron and nickel.
Reply:Nickel rod is HARD to drill and really hard to tap. Not sure why the threads would fail. I just did a similar repair on a bolt hole for an exhaust manifold. Had to make well over 1/2 the ear out of the nickel rod. In my case the hole I tried to create while building up the nickel surrounding was not completely round. I decided to drill and tap for a heli-coil. I had to sharpen the titanium nitride drill bit about 4 times before I finally got through the 3/8" deep hole. The tapping was a nightmare. I used plenty of cutting oil but managed to break the special heli-coil tap off in the hole. Ended up blowing the tap out of the threaded hole with the oxy/acetylene cutting torch. Strangely, the torch completely eliminated the broken tap and left the threads in the nickel undamaged. By the way, you CAN insert a heli-coil into a hole that is only 1/4" deep, you just have to zap off the excess with a zip wheel.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:No pro here, but the customer sounds pretty dumb. I guess he's great if he doesn't mind paying everytime and lousy if he expects you to fix every mistake he make on each repair after the first payment.
Reply:99% Nickel filler work hardens quickly and easily. The 66% Nickel alloy cast iron rods are easier(somewhat) to machine. That same 99% nickel doesn't cut with an oxy-fuel torch. Just like stainless steel and the high alloy cast iron alloys won't cut. Your tool steel tap is still pretty much pure iron; so it cuts with a torch very nicely. This is why you were able to blow the tap out of the hole without melting the new threads. Actually a really lucky turn of events for you. Originally Posted by DougAustinTXNickel rod is HARD to drill and really hard to tap. Not sure why the threads would fail. I just did a similar repair on a bolt hole for an exhaust manifold. Had to make well over 1/2 the ear out of the nickel rod. In my case the hole I tried to create while building up the nickel surrounding was not completely round. I decided to drill and tap for a heli-coil. I had to sharpen the titanium nitride drill bit about 4 times before I finally got through the 3/8" deep hole. The tapping was a nightmare. I used plenty of cutting oil but managed to break the special heli-coil tap off in the hole. Ended up blowing the tap out of the threaded hole with the oxy/acetylene cutting torch. Strangely, the torch completely eliminated the broken tap and left the threads in the nickel undamaged. By the way, you CAN insert a heli-coil into a hole that is only 1/4" deep, you just have to zap off the excess with a zip wheel.
Reply:The nickel rod should be more than hard enough to hold a thread. This is not a welding problem. It's customer-inflicted damage. Whoever he is, he likes to tighten things up "real good, so's they aint comin' loose". Typically a guy like this will tighten bolts up until they strip and then back off about an 1/8 of a turn. Miller Millermatic 252Miller Syncrowave 200Liincoln AC-DC 225Victor O-A Set
Reply:I take it he subscribes to the TTTF (Torque Till Turns Freely) method of tightening bolts. Let the guy use a torque wrench and have him see just how tight he's going, then show him what it's supposed to be torqued to.
Reply:Hi all,Well.....the client got a hold of a thread repair kit from and industrial supplier here in Phoenix which is some type of epoxy based material that "forms" new thread around the bolt when screwed in gently. He said that after it dried it tightened well and he was comfortable with how it turned out. My guess is that this time he did not turn it as hard as the first time. Thanks for the feedback. Now I know that the ni-rod (machinable type) can be tapped normally and will hold.Thanks,Tony |
|
发表于 2021-8-31 23:09:37