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I mentioned in a thread about these a month ago that I wanted to try a hotter cartridge. I had to run my iron on High and wait about 15 minutes to get it hot enough for a tight bend, and even then, it didn't seem to have enough heat.

The stock heat cartridge is 200W. I replaced it with a 400W. I also replaced the thermostat switch. And since the block of wood (poplar, I think) was very charred after years of use, I replaced that, too, with a block I cut from a walnut stump. The white heat shield stuff fell apart, so I replaced it with 5/8" sheetrock (with most of the paper peeled off). The cartridge was not a tight fit, despite being the same dimensions as the old one (which wasn't tight when I tried inserting it again, either); I wrapped aluminum foil around it a couple of times to get it snug. I bored the walnut block with Forstner and sawtooth bits.

Well, I just did a tight cutaway in pernambuco. It is not that hard a wood to bend, but it was still like night and day compared to the old iron. It was hot in about 4 minutes. I had to turn it down from High because it was scorching too easily; ended up keeping it on about 6, then down to about 5-1/2. There was much more heat available; the wood easily turned plastic when previous bends of the same wood felt like they had to be leaned on for a while, and then were prone to fail from being forced too much. I suspect that the old switch might have worked about the same; I think that in the time the switch is on, much more heat is getting into the iron, so even if it cycles at about the same temperature at the switch, the iron is getting hotter. Also, the switch may be a bit better insulated from the iron in my new version. It did not cycle so rapidly as the old one did. After about 10 minutes of bending I had bumped the switch down a couple of notches.

I did get some scorching. This is a hot rod, right? You need to be careful with all that heat available and keep the work moving, and spritz as needed with water. This may be why the manufacturer chose the 200W; the new iron is working closer to the edge of burning the wood. But that's what I wanted, and I didn't get any scorches that won't sand off. I'm very happy with the change.

For those who are interested, the cartridge is Grainger part # 4njj3. The switch is Grainger # 6kxf5.

The usual disclaimers about working with electrical parts and things that get hot. Be careful.