Instructions To finish this mainspring, you'll need : - Sanding paper, something very fine like 400-500 or more - Ideally, a Dremel to finish it, but you could do it by hand with the sans paper - Maybe a drill and some metal bit, more on that later - The original screw - the original spring OR a 5mm clock spring from a clock Here is a link for the spring. https://perrinwatchparts.com/collections/clock-barrels-and-clock-mainsprings/products/hole-end-clock-mainsprings-4to13mm?variant=40822669711 - the original C-clip or a brand new one - A C-clip tool... or a lot of C-clips and patience... (go get the tool) - a quality Mainspring oil from a clock shop NOT YOUR AVERAGE OIL... Once you seal that thing... you need it to work for another 200 years not clean it every year. So no WD 40 or anything else. - Some fish line, about 0.5 to 0.8mm... strong one... 1. You will need to get to the mainspring of your baby. You need to remove the shell, remove the parts that connect the spacebar (TAKE PICTURES, EXACT ONE or you'll need to try and guess the original tension of the bar when you'll recrew it... yay!), try not to mess up your carriage when you off sync it from the outer frame. 2. Print this mainspring with very good material with a very good resistance to chemical and that will not absorb the oil. Best : Professionally Lazer sintering STAINLESS STEEL. Very precise but costly... You'll need to sand the thread. Good : Professional Binder jetting print This one is very good, but keep in mind that the model may differ a bit because they ''inject'' bronze in the model and it can move from 5% to 10%... You'll need to sand the thread and adjust the holes with the drill... Okay STL nylon would be a good and a cheap idea, but keep in mind that this material is like a sponge... maybe more oil... You'll need to sand the thread. Might work: PLA Maybe not enough strong... I would go with a nylon mix or a carbon-nylon one... You'll need to sand the thread. 2. Receive the piece and be excited and sand the parts and adjust the hole accordingly with the screw and the c-clip. 3. Wear gloves when you put back the CLEAN* spring inside AND AWAY FROM YOUR FACE. *When I mean clean, put naphtha or your favorite oil remover to clean it. Attach the spring in the inner hook, roll it inside and once you put it all, put back the screw and have some fun trying to keep the spring inside. It needs to be all the way in and a bit outside... Or it will maybe snap. 4. Screw back the top, and put the c-clip. THE C-CLIP IS IMPORTANT or your screw will move and add vertical tension to your spring. Get the c-clip tool now because I'm sure you did not listen to me. 5. Screw back the whole mainspring. BE CAREFUL, the block in the carriage is ALUMINIUM, it means you can strip the thread of the hole really fast. If you already stripped the thread... now the fun began, go get some epoxy thread repair kit, some plain epoxy (if you are hardcore) or a stripped thread repair kit and drill that little baby. 6. Take the fishing line, if you have the original one, measure the same length and a 5-6 inch more. (more on that soon). 7. Assemble back the mess you did, but keep the machine outside the shell. 8. Put the carriage ALL THE WAY TO THE EXTREME LEFT. You need to put tension in the mainspring. NOT TOO MUCH at start... If you changed the spring, the tension will not be the same and you'll maybe need to compensate with the fishing line. That's the additional 5-6 inch are for! The trick is simple, put tension in the mainspring WITHOUT turning the line around. COUNT THE NUMBER OF TURNS. After, you have to turn the line IN THE OPPOSITE direction. Hold everything with your four hands or ask for a friend or two. The tension needs to be kept inside the mainspring as you attach the line. DO ONLY ONE KNOT. You'll need to unknot it a lot. And test the thing... Is the tension good? Too much, less turn. Not enough? More turns. Can you go all the way to the right? If not, you need more tension. Yes? GOOD! Now play with the machine... Do you skip the line when you type fast? Too much tension! Is your carriage advancing like crazy? Too much tension! Is backspace working? No? Too much! Is the movement of the carriage good or not? Now try to do what you can do with the tension and once you are satisfied... DO ANOTHER KNOT to the line... Are you done? Yes? Congratulation! You did something INSANELY COOL and that baby is good for another 200 years and your grand-children will maybe... or not that much think about you when banging it. But thank me for the screw in design... I was so angry when I opened my mainspring and that thing exploded that I decided to beat their design (and not being angry with me for being clumsy)... Now your turn to do it ;)