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Two methods that are faster are the use of heat and chemical strippers. A propane torch or heat gun will soften the paint so that it can easily be scraped off. This may generate toxic fumes, though, and should be done outside or with a respirator. Also, when dealing with metal, the heat will be retained for a long time making the risk of getting a wicked burn on the metal a definite and scary reality!!
Chemical strippers don't work quite as fast as a torch but are just as effective, maybe even more so. If the paint contains lead, chemical strippers allow you to remove the softened paint without releasing lead into the air as would the torch or mechanical sanding or grinding. There are two types of chemical strippers, those with methylene chloride and those without it. Non-methylene chloride strippers are much less toxic and can be used inside with modest ventilation. Methylene chloride strippers, however, are very toxic and should not be used inside without very strong ventilation.
Read the labels on the products to get a feel for their usage. Both types have become generally available and should be next to each other on your hardware store's shelves.
When you are satisfied that the metal has been thoroughly stripped, wipe it down with lacquer thinner... a trade-accepted way of removing any traces of oils from the metal prior to painting.