Last night before I fell asleep the thought crossed my mind to bring the materials and tools for a valve guide I need to make to work with me. This morning I miraculously remembered to bring the tools and materials, and today at lunch I began the construction of the second valve guide for my dad’s Fairbanks-Morse hit and miss engine. I had already made a set of guides from cast iron to go in the cast iron head. Those guides didn’t work out, so I decided to try bronze this time since I have successfully used bronze guides in cast iron Harley heads when I worked for a dealership. And since I need stuff to blog about, you can suffer through it with me….. lol.
That’s a 1″ diameter chunk of solid bronze rod all ready for me to abuse it and coerce it into some kind of usable object. to begin i need to put it in the lathe and turn one of the ends flat. The process of turning on of the ends flat is called ‘facing’, probably because we are dressing up the ‘face’ of the material. When done it looks like this
The next thing to do is to make a dimple in the exact center of the area I cleaned up so that when I go to drill through the material the drill bit stays centered. It may seem weird to think that a drill bit almost 1/2″ in diameter would flex and drill off center, but they do. It’s a strange thing to see in person, but I have and it will mess up whatever you are working on really quick. So, out comes the center drill (funny they would name the tool that) and I get it set in the tailstock chuck. Center drills look a little odd, not like a regular drill bit.
The shape gives the tool extra strength so it won’t flex or move, perfect for doing it’s intended job.
Now I can run a drill down the center of the bronze and get the bore for my valve opened up. Pop the center drill out of the tailstock chuck, get a 27/64″ drill bit in there instead and start drilling!
Wait….. WTF?!?! Really? Dammit! Remember what I said about drills wandering earlier? That is just what happened. The drill bit is a little bent, not enough you can see it but enough that it is cutting off center and leaving a little cone of material right in the middle where there should be a hole. Now I have to center drill the mistake out and try with another 27/64″ drill bit.
The ‘cone’ in the middle is removed, borrowed a bit from one of my co-workers, let’s try drilling that bore again.
Oh yeah, now we are getting somewhere. It took another 15 minutes to get this hole all the way through the rod. You can’t rush this kinda thing or you break tools, machinery, and parts in a very impressive way. Usually the results of carelessness or ignorance is a shower of drill bit shrapnel, broken or badly damaged drill chuck, and a mangled part with some of the drill bit still stuck in it. All that accompanied by a sound like a large firecracker going off. Overall, not a pleasant experience and I’ve had my share.
The hole is rough, and it’s still slightly undersized by design. The next step it to use a reamer to make the hole a precise size and make it smooth through the entire bore. I have a chucking reamer for this purpose and it goes in the tailstock chuck where the drill bit was. By doing all of these steps without taking the material out of the machine I have the best chance of keeping all the separate tools traveling down the same path to make the hole, and keeping the hole kinda precise.
Dang, lunch break is over. This will have to be continued in another post…..