Broken Bolt - Vermont Castings Defiant Encore 2140

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New Member
Dec 17, 2023
Glastonbury, Connecticut
Hello Everyone. I'm brand new to this forum, but I've read some of your postings, and I think you're wonderful!

I was trying to remove the access plate for the catalytic combuster, on the back of my Vermont Castings Defiant Encore, Model 2140, and I broke one of the bolts. The bolts are round head Philips style. One of the other three bolts came out easily, but the remaining two are frozen. I've tried to loosen them with Blaster solvent, a hammer and a Mapp gas torch, but I'm afraid to heat them up too much, because it might weaken the metal. Can anyone suggest better ways to loosen the remaining bolts? Also, has anyone had experience with drilling out or extracting a broken bolt from the back of a Vermont Castings stove? Thanks in advance for your answers!
Give the penetrant a while to do its stuff. It doesnt hurt to heat it up an give it another squirt then wait for a day or so. The best thing for drilling out broken screws are cobalt left handed drill bits. They are designed to cut in the opposite direction of a regular bit and are stonger steel. When they are cutting into the screw they are also vibrating it loose. If you are lucky the broken thread will start coming out before you have drilled through it. You also need a sharp center punch to mark the center of the drill bit and if its not flat you may need to grind a flat on it. Its important to drill the center of the bolt so you miss the threads.

Most auto supply places will have kit for taking out broken bolts which includes an assortment of left handed cobalt bits and screw extractors that screw into the hole that was drilled and allow it to be removed. Wear safety glasses during the operation as the chunks can be flying.
And drill straight, slowly! Those thin bits are easy to snap! Then you have a really hard drill bit stuck in it.
Many thanks to Peakbagger and EatenbyLimestone for your wise counsel. I will wait for the stove to cool down and give the penetrant another try. Since we're having unseasonably warm weather, today might be a good day for it!
Welcome to the broken bolt club. Two kinds of people in the world: those who have and those who will. My decades of experience is commented above. A couple more ideas. A couple years back I bought a can of WD40 penetrating oil. It has become my go-to. I think its better than PB Blaster which I think is very good. Everyone seems to have a personal [preference. But something else to try. I would agree with the ideas about not breaking off an easy out or tap. No use in making a lousy situation worse. If you got to drill here's my ideas. As noted do your best to find the true center. I have used a dremel with a cutting disc to grind a small indent in the bolt. Then be sure to do your best to use a center punch to locate the hole to start drilling, and again, as noted, go as straight as possible. I would never start with a huge drill but no smaller than 1/8", too much chance of snapping the bit. And use cutting oil, flooding the drill bit as you go. Use a new or newly sharpened bit, Change it out if it seems to be dulling. Take your time. If you got to tap a new thread, I would try to get exactly the right size drill for the tap to be used. Here again. slow, in-out, flooding the cutting tap with lube. An old(er) timer told me way back when doing these things...... go slow, back and forth, go slow. Think about what is less work: trying to get out a broken tap or taking 20 minutes to go nice and slow? Or a broken bolt? Or what ever...... good luck and welcome to the club. When you reassemble I have a rule. Nothing goes together without either Never-Sieze or thread locker, as appropriate. Someone will thank you next time. One more observation. I just changed my flue collar from 8" oval to 6" round on my ancient Vigilant. Two bolts. One, not much of an issue. Second one came out but the stove's threads were I guess too badly corroded to hold the replaced bolt tight. So I retapped the stove to take the next size up bolt. I think cast iron is not a bad material to tap, just go slow.
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I have used an impact driver on the bolts that hold my cat cover to loosen them. I replaced them with stainless and use anti-seize on them when I install them.
The stainless idea is not bad but depending on the stainless might have less strength than a gd 5 or 8 bolt. With never sieze I think regular steel bolts are better. Another personal preference I suppose.