So I've had this kid working for me for a while now. He does not have the same work ethic I had at his age. But he is getting better. He is absorbing information. Last week I had him single pointing threads for the first time. First item was a 1 1/2 aluminum pipe nipple. I needed the aluminum pipe cap to thread on loosely so that the end of the nipple would bottom out against a rubber gasket. After showing him how to pick up the threads and doing one my self his job was to do the same thing. First on a solid blank without any threads to get a feel and then the real thing. He did a good job. This was easy though because the nipple only had to be a loose fit in the cap. After doing the first one I discovered that I had ordered the wrong threaded fitting for another part of the same project. The fitting is made of brass and is for a gas connection involving a metal to metal seal. The threads for this part are 5/8-18 left hand on one end and 1/4 female tapered pipe on the other end. The metal to metal seal part on the fitting is part of a .250 radius sphere. These are common fittings. So, I made a sketch and showed him how to cut left hand threads. Most important was that since the threading tool starts in the thread relief if the half nuts are not engaged at the right spot he wouldn't have time to disengage them before the part is scrapped. He practiced cutting air until he was ready to do the real thing. He made a good part the first time! He used a thread mike and I had him make a class
2 thread. The PD was in tolerance when he was finished. After the part was done I smeared a little prussian blue on the contact surface and threaded the fitting into the mating part. After unscrewing the fittings he was able to see the line contact where the bluing was squeezed away by the two mating surfaces coming into contact. It sure made the guy feel good to make a part completely on his own that matched the print and looked better than a store bought part. Since this fitting is now installed in the water cooler line for the TIG machine every time he TIG welds he'll know it's his part that finished the job and that keeps the torch cool. He was so pleased with himself I think he'll tell all his friends about it. Made me plenty happy to see him do a good job too. Eric R Snow, E T Precision Machine- posted
18 years ago