there are much more mistakes, but this show is for non-technical people to watch, as i did 11-12 years ago as kid that got me into studying mechanical manufacturing engineering.
@alanhowitzer You can made them from wood. My Grandfathers father build windmill about 120 year ago, there was 2 gears, one with 10 tooth and another 32. Both made from hardwood. It is quite big but it works. You can shape wood by saw, axe, knife etc.
You are right, thanks. I checked wikipedia and it says that steel is made by combining iron with carbon (between 0.2% and 2.1%), and that higher amounts of carbon produce an alloy called cast iron.
@Saltaren Actually they dont use cutters to cut them again after heat treatment, they grind them. you are right though cutting them with regular inserts would destory both
Secondary machining, like you said, is used a lot for when a powdered metal part has a mating surface to another part or needs holes drilled, threaded, or extreme tolerances. However, majority of pm parts, including gears, are finished once they are sintered. I've run a few secondary jobs through my shop in the past. I've had the great misfortune of being stuck in the tool and die end of this industry for 20 years, lol. It has paid some bills I guess, but I hate it with a passion.
@alanhowitzer the machines that make the gears are CNC (computer numeric control) machines in other words programmable machines, they are or were made by hand at one point which made them expensive and so werent very common then as more CNC machines were made they too could make parts for CNC machines and other mechanical applications So what started as a purely human task requiring immense amounts of time and money is now mainly a machine based job but it costs a lot!
They make them on a different machine, duh. But I'm not sure what makes the gears in *that* machine. ;-) I did once see a fascinating documentary, one small part of which was a little old mad-scientist-type man who was making gears with very specific numbers of teeth from sheet brass, using only tin snips, a pair of dividers, a file and a magnifier. He was incredibly skillful and wonderful to watch. I think he said it took about 15mins to make a gear that could go in a clock.
It was made in the exact same manner! - Except that It was made out of a different type of tool steel then heat treated afterwards to increase its hardness. If the cutters are carbide then they were ground with a stone wheel to final dimensions. :)
dtlssm The first gears were made with ink, compass, scribe and file. You would use the compass to scribe a circle in the ink. Cut most of the excess off, leaving a little so it’s easier to make marks on the perimeter of the circle scribe. Then you would set the angle of the compass to a smaller size, estimating based on the size of teeth you expect. Then you would walk the compass around the perimeter, scribing as you go. If the compass was set too big, then reduce the angle and try again (redo the ink so only the new scribe marks shine). Rinse and repeat until you’re satisfied that the markings are accurate enough. Then sand/file the rest of the excess off. Now you have a circular slab with markings around the circumference. At this point, you file each tooth to your satisfaction. This is a lot of work to do, and it is very difficult to get consistent teeth. That’s why you would use a shaper, like Sarvesh says above. A shaper is just a machine with a table and vice, and it has a reciprocating arm which you mount cutters on. Your are able to move the vice up and down so that you only cut a little at a time. This way, you can at least get consistent teeth, but only straight, no helical gears. Similarly, a mill can be used to cut the teeth using a vertical rotary table. Now because the original procedure of marking out the teeth being so tedious, and with limited precision (you can do pretty good, but in automotive and similar applications, really high precision is needed if you want quiet smooth meshing), people made indexers, which can be used to rotate a very specific amount. The critical part of these is an indexing plate, which you can either buy, or make using that original marking procedure. Usually a thread is used that makes the table turn once every 40 turns of the handle, or some similar number, so the precision of the original marking method is increased by that amount. Helical gears can be made by coupling the travel of the mill table (with, you guessed it, a bunch of gears) to the rotary table, so that it rotates an amount proportional to the travel of the table. This also means that the pitch of the cutter needs to be set appropriately. TL;DR People with a LOT of elbow grease and determination
dtlssm The way that they show here is the way that factories make gears. Machinists do things quite differently usually. This is because a factory needs to make thousands of the same exact part, while a machinist generally needs to make completely custom parts. So a factory can afford to spend 10 thousand dollars on a gear cutting machine that can only cut a certain type of gear, while a machinist will do things a slower and less efficient way, because they cannot afford a ten thousand dollar machine for every new order they take. A gear hobber on its own is a quite expensive piece of equipment, and it can only be used to cut a specific gear. So machinists pretty much never use them. If you’re a real DIY kind of person, you could make a basic disk shaped gear cutter (only cuts one groove at a time) without much difficulty, but professional machinists would usually just buy a set of this type of gear cutters, because you can use such a set to cut most of the gears you might need to.
Because the number of teeth on the gear and the angle at which they might have a "helical cut" is different every time. You'd have to have a sand casting and pattern for each one. It's quicker to just cut them using tools and a lathe.
the video is correct, the internal was shaped could also have been broached, and the external is hobbed, but if a bigger hob was used they could have done it in one pass
Sure, but a lot of the time sintered gears still require some post-production machining work, especially if the gears require extremely precise tolerances or crazy shiny surface finishes.
Machining is not a waste. All the metal is recycled. Sure you got to remelt the shavings but usually places with big kilns keep them going 24/7 for energy costs. If only we could recycle like this with plastics instead of sinking barges in the ocean.
I think when the world's oil supply dwindles (whether demand falls because of fusion, or environmentalists cordon it off) people will be mining landfills for plastics to recycle.
Noah Dobson Actually it's possible to ban most of the plastic in food industry. Pass the law that will force all beverage producers to use standardize glass bottles, that u can reuse. Same with bags, you can make bags out of marijuana which grows super fast, weed ropes are one of the strongest ropes.
avednamada That would be true, except that our politicians are being elected by companies who save money using plastic. Also, I doubt that hemp will be used industrially without further contributing to youth vagrancy.
To the guy attempting to begin the cycle of gears making gears. As with all machinery. The first parts/machines are made by hand. By qualified 'fitters' these parts are put together to form machines which in turn can produce other parts. Mind = blown. I am a mechanical engineer. That's how I know this.
@Cdabek It would be a waste of money to heat treat all gears if some of them won't met the specifications anyway. It is also because untreated metal doesn't cause as much wear on the manufacturing tools as heat treated / hardened metal.
Absolutely! Things of no small complexity have been made in the past and the technology lost for generations. Oftentimes the methods were deliberately hidden to prevent other nations gaining an advantage. I remember one example of the Philistines who had developed iron weaponry which was superior to softer bronze. They forbade the use of that technology in the lands they conquered in order to maintain that advantage.
Yes, it would be quicker, but it would be close to impossible to get it to the right shape. Air bubbles, thermal expansion, and surface tension naturally work together to make sure that filling a mold results in a sloppy, inaccurate lump of metal (in comparison to milling as seen here) instead of a precise mechanical component, unfortunately.
The best example is the Antikythera mechanism from about 65 BC which was an especially fine piece of work. That technology didn't turn up again for another 1000 years. Bottom line is that they cut the gears by hand. I didn't believe this until I actually watched someone make a very accurate gear that way.
Looked like some of the procedures did NOT use coolant for the tooling. Drilling the four holes for lightening, or the initial facing of the blank. I used to operate a CNC lathe. We used coolant for EVERY step. Even carbide tools appreciate coolant.
Chickens don't eat enough calcium to justify the shell of the egg they lay. Chickens can transmute other elements into calcium for the shell. So, either iron or magnesium, etc. can be convertd to calcium inside the chicken. Particle accelerators can't do this, they claim. Do you ever see a chicken eat calcium?
I used to inspect gears north of seattle. Italians bought the company and chased all the gear machinists away. too bad. you cant push these people around. they will just go across the street and work if they have to. But they like making gears. I like inspecting them. they were mostly manually manufactured. no cnc. they do now though
The very first gears, like machine tools were made by hand. By craftsmen. CNC is just modern day methods not how things were first done. Go to Blacksmithing and you will see a real trade that is still practiced, these people are the ones that made the first machines and did the old school heat treatment. Cheers from John.
Most of these machines are not cnc. A hobbing machine is based on manual hobbing, it is basically the same thing but without a motor. The only 2 cnc machines are the lathe and the inspection machine.
shdw1858 Hey man. I am a sophomore who is pursuing his mechanical engineering. I am working on a project which includes manufacturing micro gear on a micro milling machine. Do you think if gears could be manufactured using milling?
Corn doesn't have high levels of calcium. Eagles, seagulls, etc. don't eat corn, but they lay calcium shelled eggs. The birds that peck at the roadside are getting stones for the gizzard but may also be getting magnesium, etc. to 'transmute' into calcium. Bone eating vultures get lots of calcium. Anyway, not all birds depend on man for food. Tricalcium phosphate is the best dietary form of calcium. I guess it doesn't matter.
4:00 Aperture technologies remain safely operational up to a temperature of 4000 degrees kelvin. Rest assured that there is absolutely no chance of a dangerous equipment malfunction prior to your victory incandescence.
-DTP2A- our question 1- what is the function of oil is placed on the center of the hole gear? 2- why of the project should be placed into the oven fire is burning? do not that if do like that? 3- what is the temperature used when the gears is in the oven? 4- how long of a gear to be completed? 5- what is the speed of the tool used for turning gearyang desired pattern?
The oil is used to lubricate the cutter, extending tool life and surface finish. The oven is used to heat treat the steel, making it harder and more abrasion resistant. Overall tougher after heat treatment.
Dalila Dst And the rest of your questions, it always depends on the material used, or size of that gear, and in your last question, also what tool you have. So no exact answers :D
