Malleus
Far west of Siegen
End mill. On a mag base.
Bolt drilling tips
- Thread starter namsag
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How does the mag base work? I have never used either of those tools, but a quick google search makes me think this might be a good option. Part of the reason I broke the extractor was because the area is tough to work in because the headlight is in the way. I had to cut the handle on the the extractor t-handle and put it in a socket. Not sure if I can get the mag base in there for the same reason.
Malleus
Far west of Siegen
Then your only option is to remove the part and do the work on the bench. Post some pics.
Malleus
Far west of Siegen
Okay, since I was in the middle of this job anyway, I thought it would be useful to document the process.
Malleus the Younger and I have been removing the port installed trailer hitch, which has never been a real effort. Until now.
We broke two of the weldnuts from the frame one one side and had to cut the bolts to remove them. The other four took a week of penetrant soaking, two hours of hammering with an air impact (thanks again @roadstr6) and a half inch drive breaker bar.
Just to get there, we had to remove the bumper end caps, because the rearmost hitch bolt wouldn't clear the end cap. A big thanks to the west coast port installers.
Malleus the Younger and I have been removing the port installed trailer hitch, which has never been a real effort. Until now.
We broke two of the weldnuts from the frame one one side and had to cut the bolts to remove them. The other four took a week of penetrant soaking, two hours of hammering with an air impact (thanks again @roadstr6) and a half inch drive breaker bar.
Just to get there, we had to remove the bumper end caps, because the rearmost hitch bolt wouldn't clear the end cap. A big thanks to the west coast port installers.
Malleus
Far west of Siegen
So here's the dilemma:
This is the passenger's side, where we managed to break both bolts, not just the one we broke on the driver's side. The lower (left side in the photo) bolt broke off proud of the frame, so I was able to file it flat. The upper (rightmost) sheared off inside the hole.
I apologize for the photos. I turned them, but they turned themselves back.
This is the passenger's side, where we managed to break both bolts, not just the one we broke on the driver's side. The lower (left side in the photo) bolt broke off proud of the frame, so I was able to file it flat. The upper (rightmost) sheared off inside the hole.
I apologize for the photos. I turned them, but they turned themselves back.
That's what I was afraid you were going to say. I will see what I can do with it when it warms up. It's still held in place with the three bolts that I didn't break, so it's not a top priority at the moment. The one that snapped goes into the fender, which I was planning on removing to patch a little rust hole this spring, but I want to wait until I can do paint work to it too, or it will just get rusty again.
Malleus
Far west of Siegen
So, to start I centerpunched the broken bolts, to give the drill a place to start.
That's the best I can do by hand.
That's the best I can do by hand.
Malleus
Far west of Siegen
I wasn't so lucky on the top bolt:
Malleus
Far west of Siegen
Since this is a M8 x 1.25 bolt, I want to end up with a 0.250-inch drill bit, which will give me 90% material removal of the bolt. (you can check my math) I want to do this in three steps, starting with a 0.125-inch drill bit, which will remove 1/3 of the diametral material. If I haven't centered the drill bit (and I already know I missed the top bolt), this will allow me to see how much I can move up in size, without damaging the weldnut threads, which is the goal.
This is the general procedure, regardless of size.
This is the general procedure, regardless of size.
Malleus
Far west of Siegen
So far, so good. I finally found a use for the worthless rubber floor mats the PO left me:
Malleus
Far west of Siegen
Now on to the 0.1875-inch drill bit (the next fractional size up)
This is what happens when everything works as planned:
And this is what happens when it doesn't:
So much for that titanium nitrided drill bit.
This is what happens when everything works as planned:
And this is what happens when it doesn't:
So much for that titanium nitrided drill bit.
Malleus
Far west of Siegen
After a little judicious persuasion with a small chisel, I was able to replicate the top bolt removal success story:
All that's left is to clean up the threads in the weldnuts.
All that's left is to clean up the threads in the weldnuts.
Malleus
Far west of Siegen
So before we get into a philosophy debate, I will stipulate that all the machinists out there are correct: I shouldn't be using a tap to clean the threads. Taps are for cutting new threads, thread chasers are for chasing threads. The thread classes for machine cut threads and rolled fastener threads are different, and shouldn't be mixed. As a former machinist, I do know better, but I have my reasons for doing the work this way:
1) I don't have any thread chasers, in every size I need, and I'm not going to buy any.
2) The threads in the weldnuts are so corroded, that I'm cutting new threads in the waste material.
3) This is a truck, not the space shuttle.
I could go on, but you get the idea.
This is why I prefer pilot projection weldnuts. The tap is parallel to the bolt (trust me on this).
FWIW, I did try an Easy Out. No joy.
Better, but not good, IMHO.
Pilot projection weldnuts are the only way to fly. This never happens when you use them.
So there you have it, broken bolt removal 101. (which implies there will be a 102, but maybe not) Thanks for paying attention. I'll be here all week. Don't forget to tip over your waitress.
1) I don't have any thread chasers, in every size I need, and I'm not going to buy any.
2) The threads in the weldnuts are so corroded, that I'm cutting new threads in the waste material.
3) This is a truck, not the space shuttle.
I could go on, but you get the idea.
This is why I prefer pilot projection weldnuts. The tap is parallel to the bolt (trust me on this).
FWIW, I did try an Easy Out. No joy.
Better, but not good, IMHO.
Pilot projection weldnuts are the only way to fly. This never happens when you use them.
So there you have it, broken bolt removal 101. (which implies there will be a 102, but maybe not) Thanks for paying attention. I'll be here all week. Don't forget to tip over your waitress.
I got lucky when I removed the hitch on mine yesterday. It took longer to gather the tools and get the compressor up to pressure than it did to take the thing off. The bolts just flew off and the engaged threads still had their yellow chromate coating!
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Malleus
Far west of Siegen
Show off.
Having lived in the Rust Belt all mu life, I've done a lot of rusted bolt removal with broken bolts, but fortunately only four broken screw extractors and three broken drill bits still in the hole.
Amazingly enough, the best way I have found to remove the screw extractor is by pounding on the PART (not the extractor) to set up a vibration and drive the parts AWAY from the extractor. This has even worked on a heavy part. I use a light hammer and pound next to the hole without hitting it.
As far as broken drill bit, they make drill bit extractors (specialty tool stores) but those stores are never open at 10:00 at night or on Sunday when you need them. Then you realize you must buy a full set at $300.
I usually resort to grinding out with a carbide bit. Good luck!
Yeah, I am usually pretty good at not breaking anything, much less having things go off the rails as quickly as they did last Friday. For starters, the bolt was in an area that isn't visibly rusty at all, so I wasn't thinking I would have an issue just removing the bolt the way the first two came out, which was very easy. Then I snapped the bolt off(these are little buggers, 10mm) which should have been an easy fix. I drilled it out just fine, but then I thought I would get cute and try to drill all the way through it to be sure I was going to get a good hold on it with the extractor. Of course that lead to the first snapped bit. Then I drove another cheap bit in next to that one, which snapped again. Then I decided to go bigger which worked alright until that one caught and snapped off. I was able to get that one out enough to try the next biggest extractor which I applied too much force to and maybe twisted it a bit and it snapped. What I should have done was add heat and some penetrant to the mix, but because of the plastic part of the headlight was still in the way and I didn't want to melt that and because I was worried about botching the paint, I thought I could cut a corner and that was a bad decision.
I will get it out eventually when I go back in for some other projects this spring, but it was a humbling reminder that even the most diligent efforts to manage rust can go off the rails. What should have been a twenty minute job to find out why the adjusters on my headlights aren't working ended up being a three hour swearing fest and I still haven't been able to adjust the headlights. I did buy some better bits for this application and another handful of extractors. I may end up just drilling the whole thing out and tapping a new hole with a larger bolt and just forgetting about it once I get the headlights to cooperate.
I am going to try your tapping method as I had thought about that and it's good to hear that you have had some success with it. Thanks for all the tips!
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The worst one I ever had was trying to drill and tap a NEW threaded hole into a NEW cast iron engine block. (GM crate engine) There is a location for a spark plug heat shield I needed that was not in the new block. It had the boss, so....easy peazy right? Go slow, know CI is a bit more difficult....
Drilled the hole fine. Took my time. Tried some of the titanium nitride bits......Too brittle. Broke off all of them with little to no effort. Picked up some carbide bits...MUCH better. Fortunately none got stuck in the hole.
Started to tap was all the way in on the blind hole and had already decided to stop in another half turn.......... TINK! The tap broke off at an angle, all INSIDE the hole. I tried to find tap extractors, make my own, heat, everything. Ended up spending 4 HOURS with carbide and grinding bits with a Dremel to grind out as much as I could. I eventually drilled the hole larger, tapped it to the larger size, and left the hole extremely shallow. I had probably three threads holding it. Fortunately it was not a structural hole.
Well if the bolt could turn you could use a left handed drill and pull it out, but obviously it's rusted and just needs to be drilled, I work on several 80's from all over and some are rustyer than others and I have fought bolts PB Blaster is my fave for bolts
are those the rear frame bolts that go through the side of frame? If so just drill them out, they are so tiny anyways like m8. I drilled mine out to m12, made a plate to reinforce and then just welded new nuts to the plate.
Still the easiest way is welder, then the diamond bits.
Still the easiest way is welder, then the diamond bits.
