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GLASS

I didn't really know where else to post this in the forums, but I'm pretty excited about it and wanted to share it for the good it may do others out there.If you've ever broken a drill bit off or had a bolt stuck in a carb body, aluminum head, brass, or anything made from zinc pot metal (like carb bodies) or other nonferrous metals then you may find this useful for removing the bit or bolt without damaging your part.This process uses alum (also known as potassium aluminum sulfate) which is safe to handle and available in your grocery store spice isle to break down the steel bolt/drill bit without affecting the surrounding metal. This works because alum reacts with ferrous metals while nonferrous metals remains unscathed. This seems to be a fairly common method used by clock makers, but I gave it a go and was pleased with the results.If you're interested, read below. Keep in mind, I am no chemist and I cannot say for sure if your parts are safe to use with this method. I tried it with a carb body that was about to get thrown away, so I had nothing to lose. It worked well for me, but be an adult and use this knowledge at your own risk.A co-worker of mine mentioned that her husband was interested in flipping bikes for a hobby/extra income, and I did my best to advise him on what he should look for in a project. As he is a beginner, I looked on the local craigslist posting for motorcycles and gave him my input. He eventually settled on a 1985 GPZ900r, which you may know as the bike that Tom Cruise rode in the movie Top Gun. It sounded pretty straight forward, having sat under a tarp for 15 years or whatever, same old sad story. The bike mainly needed a carb cleaning and battery and I told the owner to let me know if he needed any help.The owner cleaned the carbs up but ran into issues with the pilot jets (part #92064 here: https://www.partzilla.com/catalog/kawasaki/motorcycle/1985/ninja-zx900-a2/caburetor-parts ). Per usual they were stuck, and as may be expected, he broke off the heads of all four jets. He decided the best course of action was to drill out the jets, then use a reverse/extraction bit to remove them. He got all the way to the last pilot jet before he broke the bit off deep in the well of the jet. More than an inch deep, there was just no way to get anything down in there to extract it with, and I offered to take a look before he went off to buy a new carb body.I got the entire bank of carbs, and removed the affected one from the rail. I thought that maybe one of my cobalt bits would do the trick, but after examination I was concerned that I may damage the walls/threads of the pilot jet hole, thus making the carb body into a paperweight. I needed a way to remove the bit without damaging the body, and in the back of my mind I had this faint memory of a video that I once saw about melting bolts and bits from metal.After a few searches, I found this video:The guy uses store bought alum to dissolve a broken steel bit from a piece of brass, and after a day of research it seems to be decently well documented that alum will react with steel while being inert with nonferrous metals like aluminum, brass, copper, and zinc.Now, most carbs are made of potmetal, a primarily zinc alloy with some aluminum or magnesium thrown in. Knowing this, and after some more research to check my sanity I decided to give it a go. The owner was already prepared to purchase a new carb, so there was no real loss to be had.I went to the grocery store and bought some McCormick brand alum, found in the spice isle and used for pickling. 14g of alum is soluble per 100ml at room temp, and I had figured out that I needed about 1.5 quarts to submerge my carb in a pyrex glass pot, so I needed about 210g of alum. I bought 7 of the small 53g shakers, knowing that it became more soluble with heat. Once home, I simply stripped everything that I could from the carb and gave it a good scrub before submerging it in the glass pot and hot tap water. I poured in all 7 shakers of alum and mixed until it wouldn't dissolve anymore. I then placed it on the stove on med heat, accelerating the reaction.At this point, my wife told me that it smelled bad as it got hot so I took the pot off the stove, coming back every now and then to agitate the solution around the carb. I let it set over night, and was interest to find that after the over-saturated alum solution cools, the excess crystalizes all over the place.The crystals easily dissolved with hot tap water, and I was able to clear all the passages in the carb body in about 10 min on flushing with the tap. I then took a paper clip and poked at the drill bit stuck down in the brass, and was pleasantly surprised to produce pieces of bit from the hole.I heated up the solution and placed the body back in the mix and left it over night once more. After returning home I rinsed away the crystals again and was myself amazed when the bit came out in its entirety! All it took was a little encouragement with the paperclip, and it slid right out.Overall, process was pretty cheap and easy. The carb body is a little darker than before the process, but besides that I can see no other impact on the body or any of the remaining brass pieces.You will need:1. your part made from zinc, potmetal, aluminum, copper, or brass with steel bolt or drill bit stuck in it2. apot big enough to submerge the part3. access to hot tap water, enough to cover the part in the pot4. 14g of alum per 100 ml of water minimum. a little more won't hurt, can be bought in spice isle of grocery store5. hot plate or stoveHow to:1. Remove all steel pieces that you want to keep, I advise removing everything that can be removed2. Clean all dirt, oil, grease etc from the parts3. Heat the water in glass pot4. Add part and alum, agitate until alum is all dissolved or until solution reaches saturation5. More heat=faster melting of the steel bolt/bit, don't hurt yourself.6. Keep over at least low heat if possible. If using low heat check every hour or so. If using high heat you may need to check more often.7. If solution cools and crystals form on part, rinse with hot tap water to remove crystals or reheat pot and agitate until gone8. Reheat, agitate, and rinse until steel bolt/bit dissolves enough to be removed.I reheated my solution 2-3 time over 48 hours to remove a small drill bit, your results may vary. During the process my fingers would get black from touching the carb, but after I cleaned it up there was no more residue.In conclusion, I really hope this helps someone out there. If there's a better way to remove a broken bit like this, I would love to hear about it as well. I do wish I had captured some video of the carb in the solution so you could see the bubbles coming from the broken bit, but I didn't think of it until I was done. This process may not be necessary on parts that are easily replicable, but I see some utility especially for expensive or hard to find parts like older model carbs, aluminum heads, and aluminum crankcases. If you give this a shot, best of luck