Hey guys! I am taking some machine shop classes this year and would like to show you what I have been doing. No CNC machines yet, but we have worked with different bandsaws, lathes, and milling machines.
We started out with a basic T-slot cleaner. We had to accurately blue up and mark the part, send it through a vertical bandsaw and drill press, and file it down to size. Although it sounds simple, it was much harder in practice to maneuver the bandsaw around tight curves and edges, especially if you have never worked with heavy machinery. The metal quickly became too hot to touch (we had to touch it anyways.) My first project ended up closer to a shiv than a cleaning tool and was woefully lopsided.
T-slot cleaner attempt
The next project was creating a pair of dice out of a type of machinable plastic, lovingly nicknamed “Hamiltonium” after our professor. This time we used a milling machine, a type of circular cutter that rotates while your part moves underneath it, useful for taking large precise cuts or for cutting grooves and keyways.
Here’s a classmate using the manual wheel to move his chunk of Hamiltonium to the right while the milling machine shaves off the top. Our cutter was tipped with carbide which meant we could cut much faster and therefore save time and money.
The final dice. The dots were cut with a ball end mill and the edges were rounded with a radius cutter.
Next we got to move onto the lathes. Lathes spin pieces and touch them with a cutting tool, similar to a ceramics wheel. We used these to make a dead center, a tool that looks like a dreidel and is used to keep tools like a lathe cutter or a tap exactly on center.
Here’s a friend indicating the lathe, which basically means “making sure it spins exactly true to center so it doesn’t start wobbling and ruin everything.”
Unfortunately, with a new beast comes new challenges and the lathe was, at first, very difficult to work with. Blue-hot chips would fly at me and burn through my skin and hair (thank goodness for safety glasses,) but I had to grimace and bear it rather than risk shaking my arm and ruining the project. Along with that, simple inexperience led to some weird results.
That wasn’t supposed to happen…
It didn’t help that the lathes were positioned right next to some of the CNC machines the seniors commonly worked at, who kept whispering to me to slip them the part, that they’d cut it perfectly in minutes. The temptation!
An added difficulty was cutting threads into the base. “Threads per inch” refers to how many ridges there are around a screw. “Tapping,” the act of cutting internal threads, is such a delicate operation that one little twist too far or at the wrong angle could break the cutting tool inside of your part, which is next to impossible to remove. You often have to scrap the whole part and start from scratch.
I forgot to take a picture because the drama was just too intense.
Finally, painfully, after four restarts, I eked out my dead center and it was beautiful.
Dead center perfection!
Finally we move to our last official project, officially called a “5T-Block” and unofficially called a “paperweight.” This tested a lot of the skills that we had learned this semester—drilling, tapping, reaming, countersinking, counterboring, milling… wait, don’t go away, I promise those are real things and they’re actually pretty cool. But what was even cooler was the fact that in earlier projects, these tasks seemed next to impossible. Now, it just felt like I was running through the motions. I didn’t have to restart once and finished up the project in under a week and a half.
A tapping operation, using the dead center we had manufactured earlier in the year. The dead center is aligned exactly with the hole and is crucial to keeping the tap both centered and perpendicular. The tap handle is then turned manually, cutting nice even threads.
Two holes were carefully shaped to fit the irregular screw and bolt heads.
Final 5-T block.
So ends my first semester in a course where everything was so foreign I might as well have been in Antarctica. Next semester, rumor says they’ll let us move onto the CNC machines. Let’s hope!