Large Bolts

This week at work I made 7 rather large bolts. I started with 3.25 diameter 22 inches long, round shaft material. It was 415 type steel. First in a large manual engine lathe I faced and turned one end of the shaft back about 1.5 inches to a finished Dia. to 2.812. Next I turned the shaft around and faced the other end to finished length and center drilled it. I did this to all 7 parts and they are a bit heavy.

Now they are ready for the CNC Lathe. In this lathe I clamp in the chuck on the turned 2.812 dia. I type in M23 and push start and the tailstock moves into position. So now the center of the tailstock is inserted into the centerdrilled hole I drilled earlier. It is ready to machine into a Bolt.

I had run these before so the program was already done, all I did was reload it to the machine control. I rough turned the part, it is always exciting to watch through the window the metal just being peeled away by the carbide cutter. The specs of cutting it: 439 SFM, feed rate .017 ipr, depth of cut .15 .

After roughing I used another tool to finish turn it. Next I needed to put on the threads. For that I use a threading carbide insert. It is shaped like a V with the tip doing the cutting. It takes many passes to get to the finished size of the thread. The thread is metric, 15m x 1.5. I have a nut to screw on to make sure the threads are good.

I deburr the part and it is done. I cut alot of metal on this job which I like...I'll post photo's on my Facebook page...