I have an old Mama Bear stove. The bolts to the draft knobs are bent and the caps will not close tightly. How do I replace these bolts? They seem to be welded to the two caps.
I have an old (70's) Mama Bear. The bolts to the draft knobs are bent. How can I replace these bolts
- Thread starter archibald
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check this thread out by our fisher expert, Coaly.
https://www.hearth.com/talk/threads/papa-bear-questions.76429/#post-969655
pen
https://www.hearth.com/talk/threads/papa-bear-questions.76429/#post-969655
pen
If the bolts are welded to the caps, (the caps unscrew from the door and come off in your hand) they are malleable iron pipe caps with a 1/2" bolt "plug" welded to the pipe cap. The bolt rotates in the door and will not have a nut inside.
If it's a newer stove, the draft cap will have fins and is not welded to the bolt. The bolt is threaded into the door and double nutted to the door. The bolt doesn't move, and the cap threads back and forth on the bolt. The outer nut should be a half nut, so reuse it. Some bolts with the later caps that are double nutted to the door were tack welded inside to prevent from turning.
Which type do you have?
If it's a newer stove, the draft cap will have fins and is not welded to the bolt. The bolt is threaded into the door and double nutted to the door. The bolt doesn't move, and the cap threads back and forth on the bolt. The outer nut should be a half nut, so reuse it. Some bolts with the later caps that are double nutted to the door were tack welded inside to prevent from turning.
Which type do you have?
I must have a newer stove. My caps (2) have four fins, of cast aluminum. The bolt appears to be spot welded into the cap. I cannot budge it. It was easy to remove the caps from the stove, from the inside, but I cannot see a way to separate the bolt from the cap in order to replace it. Can these caps be replaced?
Sounds like you removed the bolt with cap from the door, and the cap will not move on the bolt ? Perhaps the cap has been opened tightly against the bolt head?? Hard deposits can form on the bolt threads, or the aluminum draft cap can corrode to the steel bolt. (dissimilar metals) Some caps have a steel insert to prevent wear in the threads and this also prevents dissimilar metal contact. (galvanic corrosion or electrolysis) I would soak it with PB Blaster and wire wheel or wire brush the threads as close to the cap as you can. Put two nuts on the end of bolt and tighten together with two wrenches. This gives you something to hold the bolt with in a vice or with wrench on outer nut. CAREFULLY turn draft cap down bolt, after soaking for hours, and work it back and forth until it spins freely down threads.
The 4 fin cap was the first draft cap invented by Bob Fisher's father Baxter. The original mold is owned by Barr Castings and is still available at a price. You should be able to remove it carefully. The bolt is not welded to the cap, since the bolt is tightened on the door, and the threaded cap spins up and down the threads.
The bolt threads should be greased with high temp grease or silver anti-seize.
Here's the patent for the draft cap. It also describes how it works;
http://www.freepatentsonline.com/4037584.pdf
The 4 fin cap was the first draft cap invented by Bob Fisher's father Baxter. The original mold is owned by Barr Castings and is still available at a price. You should be able to remove it carefully. The bolt is not welded to the cap, since the bolt is tightened on the door, and the threaded cap spins up and down the threads.
The bolt threads should be greased with high temp grease or silver anti-seize.
Here's the patent for the draft cap. It also describes how it works;
http://www.freepatentsonline.com/4037584.pdf
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