Ziaenyr

For tapping holes First you must use the proper size drill,for that you referance your handy chart http://www.brokenbolt.com/images/starrett-inch-metric-tap-drill.pdf For example a 1/4-20 requires a #7 drill,but you can also use a #6 or a #5 thread strength is still there and its easier on the tap,any bigger than that and you lose too much thread strength. Drill hole straight,preferably using a mill or drill press,can be done by hand,then lube up tap making sure it stays straight and go to town,thread it in and backoff and clear chips as you go especially in a blind hole or deep thru hole. A die is used for cutting new threads,can be used to clean up threads as well. Most tap and die sets you find around are carbon steel which arent that great(depending on the threaded material) but if you dont use them often work just fine. HSS is preferred but you will pay more best for sizes you use most,as with taps make sure to use some cutting oil. To fix stripped threads you need Helicoil(thread repair kit) kits of the proper size,they come with what you need. just dont try and use the helicoil tap also known as an STI tap to tap your regular holes or you will be hosed. Also you can redrill and retap to a larger size if possible. The Gearwrench tap and die handles are awesome i have a kit https://mechanicguides.com/best-tap-and-die-set/ of those and many other styles. The Gearwrench die stocks hold hexagon dies,there are round ones too so be wary of that. Ive tapped and threaded and rethreaded thousands of holes over my career. Here's a vid i found on youtube for you:

I've often thought of replacing the alternator with a deep cycle battery, and a large series of peltier modules that run off of the exhuast. The exhuast gets really toasty (especially if you wrap it upstream) and there is this beutiful supply of cold air running along most of it for the cold side heatsink. Problems i can see with this? 1) You'd have to run two modules in series, possibly three to get to 15V which is about where you'd have to be to completely replace the alternator 2) You'd have to integrate your own smart charging circuitry. Charging at 15V at all times would place an undue strain on your battery, and you'd be chewing through batteries every few years (which i guess isn't terrible) 3) If you were doing a lot of short trips, you'd run into issues. 4) I have no idea how much power would be required. Most i could see you generating in this fashion would be 500w (ish) and that would be a LOT of modules 5) You would have to engineer the thermal coupling to the exhuast to ensure that the peltiers didn't approach the melting temperature of the solder used to create the junctions If anyone knows what kind of load it takes to run a car, i'd be curious.