When we purchased Soave in 2023, two of her four mast alignment bolts were broken and fused to her mast base casting.
After many more hours than I care to admit ( I think ) I’m at a point where I can declare victory.
The things that didn’t work :
Remove mast base and bring it to a machine shop. NOT. Soave’s mast base is imbedded in epoxy. It would not budge, and I was afraid to get too aggressive for fear of cracking it.
Drill through the center of the broken bolts and use an extractor to remove them. NOT. They were ONE with the casting due to years of unisolated stainless/aluminum corrosion.
As I stepped up from a #2 extractor to a #3, I got better at blind drilling in a confined space. The various sized drilling attempts were fairly well centered and plumb. So I grabbed a 5/16"-18 tap that I had recently purchased for another boat project and used a size “F” bit to enlarge the the holes to the proper size and ran the tap through the (almost) center of the fused bolt.
Considering the hours required, I would NOT recommend this approach… but it did work. Plus it leaves the possibility of stepping up to the original size in the future if I buy or borrow a larger tap.
The full story is documented ( HERE ) in a Goggle Album.
Moral of this story… Isolate stainless wherever it touches aluminum. Especially in hard to reach areas.
Well, at least you now have stainless steel threaded holes for the stainless bolts.
It’d be nice to know if there’s enough extra strength in some of these castings for it to be safe to just give up on these seized bolts and instead drill new holes halfway between the old ones.
I don’t know, and there’ve been a number of situations where I wished I did.
I’m impressed. I’ve freed bolts with lubricants and power tools. I’ve never successfully drilled and extracted one or completely drilled out one, although I have broken lots of bits trying. If you have tricks for doing it, I hope you’ll write them up and share them.
Bob,
No tricks, but working on Soave has taught or reinforced valuable lessons.
I’m not as smart or skilled as I thought I was. Be humbled by the task and by folks with more experience… but keep trying. When folks see you struggle and know you are open to suggestions they seem to show up at the right time to offer ideas. Help others when you can and cultivate a circle of folks you trust… it helps if they have good tools. Loan your tools when someone you trust is in need.
Don’t skimp on consumables. Drill bits are consumables unless you have the patience to sharpen them yourself. Before you start a job check your inventory for consumables and order double what you think you will need. I like to drill pilot holes in hard materials. 5/64" is a good size and you can get them for about a buck a piece if you buy a dozen.
I use LubriCut paste, but I suspect any lubricant will work.
Good tools are handy. One of my hand drills has an adjustment on the trigger so you can lock in a specific speed. For metals a slow speed with steady pressure works best. Sort of mimicking a drill press.
Be committed to the task. Shortcuts are never short.
Sad to say that at 66 I’m still learning stuff like this. But there is always hope.
I’m at the learning stage where small details seem to matter. I’ve learned to use cobalt bits, lubricant, slow speeds, and to work up drilling with incrementally increasing bit sizes.
What I still could use some advice on is:
How deep to drill with the small bits before going to the next size. Where I keep breaking off the small bits is trying to drill an entire small hole and then enlarge it. So, it seems like I should just treat the smaller bits as creating a starter hole rather than piloting the full depth. But, how deep?
If you use cobalt bits to drill out stainless steel seized in aluminum, what bits should you use to drill out cobalt bits broken off and seized in the stainless steel that was seized in that aluminum?
For the mast base job, I drilled all the way to daylight. There is an awkward moment when the tip of you bit starts to poke out the other side, this is when I break most bits. Once you are this close if the bit breaks you can usually tap it back with a small punch. Or drill from the opposite side to get the punch in from behind.
Once you have a small hole drilled all the way through life is good. You always have the option to punch broken bits or extractors out from the far side.
If you have a broken bit stuck before you get through, you’re in for a lot of tricky drilling or abandoning the hole. Sometimes you get lucky and can drill at an intersecting angle to get along side the broken bit and then gradually alter course to parallel the broken bit. None of this is easy or quick.
This is why many folks just abandon the fused bolt and drill/tap a new hole.
This is also why I remove bolts, refresh the isolation layer with TEF45 and then reassemble. I don’t know if I’ll ever catch up with every screw and bolt on the boat, but it’s a nice goal to have.
Bob,
As a life long Machinist I would recommend starting the hole with a center drill. It is a short bit with a pilot center ( very stable with a 60 deg. countersink with a diameter larger then the finish drill ) they come in number sizes starting at 1 thru 6 . They are made of high speed steel and are very effective at starting a drilled hole. If you start with a small drill bit and it breaks then you are screwed. A center drill is pretty good at starting the process because of its rigidity. From there step up the drill size bu a minimum of 1/16 diameter, the larger the better. As long as the previous diameter is less than the amount the bit will not drill properly due to the intersection of the angle of the cutting edge on each side . A normal drills geometry is not designed to remove the very center of the hole. This is what causes small drills to break so easily. Once the drill is supported by the diameter of the hole you are drilling it will not “walk” which is the biggest culprit of broken bits. To drill thru a bit stuck in the hole requires a carbide bit and a very stable target. ( think milling machine vice) . When we had this problem in valuable parts we used a machine called a sodic. It disintegrated the hard bit with electricity.
