I've been roasting for some time and can probably help out here. Thirty minutes is too long for a roast. Try and get it down by at least half that. Ideally, should be done roughly 13 minutes or less. You should have first crack by 6 minutes or so give or take..depending on the bean. Around first cracks is a very light roast. Taking the beans past first cracking will give medium, into second crack you will have a dark roast. Much further is charcoal...like Starbucks! If you're judging by sight, you want to take those beans off the heat a bit sooner than what you think you'd like them to be. Example - If you're looking for a dark roast, do not wait until they are dark in the pot, especially oily. They will be burnt. Take them off at a nice med to slightly darker brown. They will darken up after a bit, and you'll soon see oils coming to surface. Same goes if you're looking for a medium roast. Take them off at a med. brown. This will be more critical depending how quick you are cooling after heat. It is best to cool them fast. The quicker they cool, the closer to your desired roast level. The beans will obviously continue to darken the longer they stay hot, as they are still cooking on the inside. I like to put a couple colanders in the fridge or freezer while roasting and will dump them in there straight away after, alternating back and forth between each. Those beans of yours although probably baked, might taste better after degassing a few day as well. Compare the taste after roasting to a couple days later. I find mine usually taste best after a few days up to a week even with some.
A stainless steel whirly pop works better fwiw, more even heat, although you can definitely have success with yours. As I'm sure you've found out, it will get pretty smoky depending how far you take it. As far as popcorn makers go, I found the hot air popper to be easier to control and have had more luck with it. You do not have the same capacity as a whirly pop though. If you're thinking of trying hot air poppers, look for the kind that blow from the bottom sides, as opposed to straight up. This way you will have more agitation and spinning around of the beans, affording a more evenly roasted bean. I think I paid $5 for one on kijiji. You can pretty much roast beans any method that creates enough heat. There's some pretty creative methods kicking around the internet...rotisseries on the bbq, heat guns in big stainless steel dog bowls, breadmakers, etc, etc. I eventually settled on a dedicated, small home roaster.
Roasting your own coffee is great. I consider myself a bit of a coffee snob, and tend to get bored of the same origins/blends after more than a few cups. I used to try different coffee subscriptions, etc, but that can get kind of pricey, depending of course how much you drink. Hence getting into roasting. I'll often roast two or three origins a week, having up to five or six different origins on hand at a given time. This way I'm never bored of my coffee with a lot to choose from. It does work out cheaper than buying roasted beans if you buy larger amounts of green, smaller quantities not quite as much. If you have any more questions on roasting or different brew methods, fire away, I've got some experience
