Sunday, November 30, 2008

The Great Woodstove Adventure of Aught Eight

As many of you know we supplement our traditional gas furnace heating by burning wood in a woodstove. Our woodstove happens to be a Dutch West Catalytic Woodstove from Lehmans. The thing to notice here is that it is a catalytic stove. What this means is that is has a platinum (or palladium) coated ceramic honeycombed combustor that reduces emissions, much like the catalytic converter in a car.

Dutch West Woodstove

After splitting some wood of our own and getting a load from someone else, we used the stove for about a week. It didn't seem to be working as advertised in its manual, that the considerate previous residents left for us. There is a thermometer on the combustor and the manual says that it is supposed to operate in the 800-1200°F range and in our week of stoking the fire up I only saw it over 500°F a couple three times. That made me suspect that the combustor had worn out or was damaged. So, naturally, being the capable country boy I am, I thought I would take the top of the stove off and check it out.

Here is where our story becomes an adventure. According to the manual, loosening four simple bolts on the top should get the lid off and grant access to the combustor and other internal bits. Wielding my trusty socket wrench I proceed to easily remove three of the bolts and find it almost EASIER to break the fourth off halfway extracted. DRAT! Despite this, the bolt is far enough out to allow me to remove the lid.

Now, I wish I had taken a picture of the old combustor inside the stove because it was pretty much completely destroyed and crumbled down into the vent between the firebox and stove. This was clearly bad, it was crumbled to the extent that airflow was seriously restricted and probably caused my fires to go out any time I closed the damper, which was about what I was experiencing. After picking the bits of combustor out and tossing it into a bag it looked like this:

Old Crubmling Catalytic Combustor

You can see the metal ring that went around the combustor, a few largish (about 2") bits and a bunch of tiny shards of combustor and ash.

So, we have two problems at this point, the anticipated bad combustor and a bolt stuck in the lid. Thats not too bad. After a bit of searching around, we found a dealer for our stove type that had the right replacement combustor in stock. Cara took a nice drive down to Granville to pick it up.

View Larger Map

It was about a forty minute drive, and she reports that they have delicious frozen custard in town so we will definitely return. She returned full of frozen custard with combustor in hand. Installing the combustor was painless, though next time I get in there I will have to replace some of the ropelike gaskets I think. You can see the combustor set in place, with the clothlike gasket around where it is seated in the following picture:

Catalytic Combustor 1

And a larger view of the top of the stove to get a sense of how it fits in:

Woodstove Top Open

Now to simply put some effort into removing that broken bolt and we will toasty warm. Of course, those of you who have had the pleasure of removing a broken bolt or screw know, accomplishing this task tends not to be simple. I worked on it for an hour or so with penetrating oil, blow torch and vise grips and managed to break every last piece of exposed bolt.

The absence of anything left to yank on left me only the option drilling it out. Now, I had just acquired a fine 7amp corded drill and extractor bits using this task as an excuse, so it was time to put them to work. Remarkably, the extractor bit managed to bore a fairly centered hole in the bolt, so I proceeded to drill until I think I actually made it through the entire bolt. Then I stepped up to a larger bit size and widened the hole. Feeling fairly accomplished, I though to myself, let me try the extractor side of the bit and see if I can pull this out as advertised. Starting slowly I felt the bit actually starting to grab. I got a bit excited, as if I thought I were on the home stretch of this adventure, so I gave the drill a bit more gas and SNAP!, proceeded to thoroughly embed about a quarter inch worth of the hardened extractor into the center of the bolt. Clearly, I am doomed. There is no way to drill through this hardened steel, at least not with my tools. So here is a picture of the bolt, plus extractor bit stuck in the lid:
Bolt stuck

This problem has clearly just escalated itself to the level where professional attention is needed. Though that will have to wait until the next morning.

I begin the next day with several calls around to local machine shops where I tell my story to amused machinists who all conclude that they can't drill it out due to the extractor bit. My options seem to be buying a new lid, having it cut out from the side and rebuild that drill hole, or find someone with an EDM machine. The new lid would take 12 weeks to deliver, so that is clearly no good. I was uncertain about rebuilding part of the lid and the person I talked to didn't seem eager to do the task. So I decided to follow up a reference to someone who had an EDM machine.

Cara sets off once again to another nearby town, where sadly no frozen custard is to be had, to bring the lid to the gentleman with the EDM machine. And EDM machine is an Electrical Discharge Machining Machine. This tool melts and vaporizes the metal using electricity and can cut through hardened metal, like that of the extractor I had so expertly lodged into the bolt. An hour of effort on his part and for a fraction of the cost of a new lid he was able to remove the bolt. So Cara came home victorious with the following, fully functional empty bolt hole.

Bolt removed

Look by golly, you can see threads! Putting a little graphite powder in the bolt holes I bolt it down tight and fire it up. The lid smokes to high hell, of course, due to the liberal application of oil during various steps of the extraction process, but it works! And the stove works wonders, the catalytic combustor gets up to temperature and all is well.

This little stove will help us fend off what the locals call "snow" and "winter". Things which, being a desert rat, I am not accustomed to. I caught this "snow" with my camera here:
Begining to Snow

I remember that day fondly, thinking to myself all day, staring out that window, that someone ought to rescue that poor helpless trashcan that is filling with snow.


Anonymous said...

oh my gosh that snow is gorgeous!

Kimm said...

At least you are now WARM! This is why we rarely attempt home improvement projects that require power tools. Missing you in PHX.