- Joined
- Mar 2, 2018
- Messages
- 232
Go ahead and grab a beverage, pull up a chair, and set the tone with this background music:
After going back to work, and having a dreadful week, I finally got some shop time. Time to turn a gear to mate to that other one, and prove I know what I'm doing, so I can start making parts for real projects! Woo!
My target for the gear blank was 1.938", and by crikey, I hit 1.938" like a machining BOSS! I took the blank over to the mill, dialed in the setup, and went to work setting the sector arms for a 29-tooth gear. I marked the holes with a sharpie, and I even did a dry run for five holes where I grazed the blank at my zero setting just enough to leave a witness mark. Everything looked copacetic.
I dialed in my tooth depth like a BOSS, booyah! I cranked and turned and cranked and turned and cranked. Every tooth was emerging as the very vision of perfection, and everything was looking spectacular! Then I came back to my starting point, and I wasn't at the end of the run. Uh? Maybe you don't end up at your origin on an odd-number gear? I kept going, and I cut a beautiful 31 1/2 tooth 29-tooth gear.
Did the math and realized I set the sector arms to 10 holes instead of 11. It worked out perfectly to explain what happened. Okay, even though I was anal about the setup, I obviously wasn't anal enough. So noted.
The other problem on the agenda for today was my live center. It's very hard to bash out of the tailstock, and I think the fact that the taper ends in a threaded hole is a big clue why that is so. I decided to turn something to thread into that hole. After some faffing about (to borrow a brilliant term from our British friends), I concluded that this thing was an M11-1.5 thread.
I don't work in metric much, but no problem! It's M11, so I'll just turn the OD of the threaded bit to 11mm. I got it to 10.98mm or something that seemed close enough, considering this is going to thread in once stay there forever. I got out my handy dandy GearWrench tap and die set (yes, I know, these dies are for cleaning up threads, not cutting new threads, but they're what I have, and they work), I installed the correct die in a holder, and set everything up on the lathe for a die threading operation.
The way I do this is I run the Jacobs chuck jaws all the way down to a point, ram them up the butthole of the GearWrench ratcheting tap wrench, and I crank the die wrench handle while I take up the slack with the tailstock. When I get the threads started, I put a T-wrench in the chuck, and I work the two back and forth, taking advantage of the ratcheting action. I know I'm probably not supposed to manually drive the chuck with a wrench in one of the square bevel gear drive hole thingies, but it works really well, and I don't have a way of locking the spindle. I need to make a spindle lock one of these days, but that is not on the horizon anytime soon.
So anyway, click turn, click turn, click turn, I should be making great progress. At some point, the whole shebang just kind of falls apart, and I find I'm turning some weird conical taper on the end of the brass round bar I'm trying to thread. Wait, what?
I mean I know diddly squat about the units the entire rest of the planet uses. I just figured M11 = turn to 11mm. I try to figure out the correct outside diameter, because this obviously was off by miles. After some googling, I'm not really feeling that much more enlightened, but it looks like 10.968mm to 10.732mm ought to be good enough. I take a stab at whisking some millimeters off this diameter, and end up with 10.728mm, measured with my digital calipers, because I don't have no stinking micrometers in no stupid standard the entire planet uses. It's undersized, but, again, this is just going into the wrong end of a live center, so as long as it threads in at all...
It was at this point that I realized when I tried to thread the first time, I was... Wait for it.... Wait....
Keep waiting....
Wait a little longer......
I WAS TURNING THE DIE WRENCH BACKWARDS! Are you SERIOUS?! Am I SERIOUSLY THAT fricking stupid?!?!
Why yes, yes I am. The name, ladies and gentlemen and gender fluid whatevers, is DuMass.
So I set the wrench to turn the right way, cut some threads on an OD that was way undersized, and then I tried to thread my live center onto this thing.
It went right through, with zero resistance. The thread isn't remotely close to M11-1.5. I'm thinking now it's some flavor of 7/16" imperial thread after all.
That was the moment when I decided to take a break and come broadcast my shame for the world, so people could get a laugh out of my incompetence and misfortune.
I mean this really has been a comedy of errors. The way I look at it, errors where you can do an autopsy and figured out where you screwed the pooch are fine. It's the errors where you don't have a clue that are scary. I'm good.
After going back to work, and having a dreadful week, I finally got some shop time. Time to turn a gear to mate to that other one, and prove I know what I'm doing, so I can start making parts for real projects! Woo!
My target for the gear blank was 1.938", and by crikey, I hit 1.938" like a machining BOSS! I took the blank over to the mill, dialed in the setup, and went to work setting the sector arms for a 29-tooth gear. I marked the holes with a sharpie, and I even did a dry run for five holes where I grazed the blank at my zero setting just enough to leave a witness mark. Everything looked copacetic.
I dialed in my tooth depth like a BOSS, booyah! I cranked and turned and cranked and turned and cranked. Every tooth was emerging as the very vision of perfection, and everything was looking spectacular! Then I came back to my starting point, and I wasn't at the end of the run. Uh? Maybe you don't end up at your origin on an odd-number gear? I kept going, and I cut a beautiful 31 1/2 tooth 29-tooth gear.
Did the math and realized I set the sector arms to 10 holes instead of 11. It worked out perfectly to explain what happened. Okay, even though I was anal about the setup, I obviously wasn't anal enough. So noted.
The other problem on the agenda for today was my live center. It's very hard to bash out of the tailstock, and I think the fact that the taper ends in a threaded hole is a big clue why that is so. I decided to turn something to thread into that hole. After some faffing about (to borrow a brilliant term from our British friends), I concluded that this thing was an M11-1.5 thread.
I don't work in metric much, but no problem! It's M11, so I'll just turn the OD of the threaded bit to 11mm. I got it to 10.98mm or something that seemed close enough, considering this is going to thread in once stay there forever. I got out my handy dandy GearWrench tap and die set (yes, I know, these dies are for cleaning up threads, not cutting new threads, but they're what I have, and they work), I installed the correct die in a holder, and set everything up on the lathe for a die threading operation.
The way I do this is I run the Jacobs chuck jaws all the way down to a point, ram them up the butthole of the GearWrench ratcheting tap wrench, and I crank the die wrench handle while I take up the slack with the tailstock. When I get the threads started, I put a T-wrench in the chuck, and I work the two back and forth, taking advantage of the ratcheting action. I know I'm probably not supposed to manually drive the chuck with a wrench in one of the square bevel gear drive hole thingies, but it works really well, and I don't have a way of locking the spindle. I need to make a spindle lock one of these days, but that is not on the horizon anytime soon.
So anyway, click turn, click turn, click turn, I should be making great progress. At some point, the whole shebang just kind of falls apart, and I find I'm turning some weird conical taper on the end of the brass round bar I'm trying to thread. Wait, what?
I mean I know diddly squat about the units the entire rest of the planet uses. I just figured M11 = turn to 11mm. I try to figure out the correct outside diameter, because this obviously was off by miles. After some googling, I'm not really feeling that much more enlightened, but it looks like 10.968mm to 10.732mm ought to be good enough. I take a stab at whisking some millimeters off this diameter, and end up with 10.728mm, measured with my digital calipers, because I don't have no stinking micrometers in no stupid standard the entire planet uses. It's undersized, but, again, this is just going into the wrong end of a live center, so as long as it threads in at all...
It was at this point that I realized when I tried to thread the first time, I was... Wait for it.... Wait....
Keep waiting....
Wait a little longer......
I WAS TURNING THE DIE WRENCH BACKWARDS! Are you SERIOUS?! Am I SERIOUSLY THAT fricking stupid?!?!
Why yes, yes I am. The name, ladies and gentlemen and gender fluid whatevers, is DuMass.
So I set the wrench to turn the right way, cut some threads on an OD that was way undersized, and then I tried to thread my live center onto this thing.
It went right through, with zero resistance. The thread isn't remotely close to M11-1.5. I'm thinking now it's some flavor of 7/16" imperial thread after all.
That was the moment when I decided to take a break and come broadcast my shame for the world, so people could get a laugh out of my incompetence and misfortune.
I mean this really has been a comedy of errors. The way I look at it, errors where you can do an autopsy and figured out where you screwed the pooch are fine. It's the errors where you don't have a clue that are scary. I'm good.
