Though I didn't spend much physical time in the shop while finishing my degree, I did think about it a lot. One of the things I'd considered was a less costly blower fan for my burner. Now, you're probably thinking "BFD, it's just a fan" and that is true, but I like to aim for efficiencies when I can, and should I need to run this stuff off of a smaller power source, the issue of power consumption would be important. By way of comparison, a venturi burner uses more propane than a blown burner does, but no electricity which is one of the "selling points" when people discuss burner design- you can run it anywhere! If I had a smaller blower, then I could feasibly be able to use my forge wherever I had a car and power inverter- or even a car battery. My long standing blower is a 120CFM unit with a 60CFM side blower that runs off of 110V pulling 1.1A to give 3000RPM. I don't recall if I have any pictures of it in action, but for day-to-day forging, I kept the piece of cardboard over the opening such that there was almost no air getting in (note, there is a side inlet so that the fan never pulls zero air, I assume this is a safety feature to keep the motor from burning out). Last night I tried a 15CFM unit running off of 110V pulling 0.21A at 1750RPM. I was impressed. I made a restrictor plate out of an altoids tin and can adjust the airflow that way. I can choke it down to 1450degF if I mess with the propane input, and I "cranked it" up to 2101degF. That said, if I choked it down too low it would gurgle, burp and then report- so it was drawing propane back into the motor and igniting it. Or, more likely, the heat from the burner pipe was flowing up to the blower, taking the propane with it. If the burner outlet could be outside of the forge then I might be able to run this small blower. A backfire situation is not great, but it gave a lot of warning before it happened, and it's just a matter of not running too much gas with too little air. It also doesn't give welding heat, but I kept the old blower choked out even when I made that billet for the twin seaxs so it was still overkill. I'm thinking something on the order of 30CFM pulling 0.5A might give me the air for welding with the control for "low temp" heat treating IF I were to want a single unit for all of the forging I could conceive of doing. In the meantime, the larger blower will stay on a shelf for those high heat needs. [EDIT: to add, the small blower became too unstable for long term forging. The gurgling and backfiring became an issue when the blower had any noticable restriciton. I have gone back to the larger blower, but will continue to look for a smaller unit.] |
