For sure, it involved respecting safe areas and proper tool use. In high school I worked part time in a machine shop making carbide-tipped tools. One day a 14" wheel running at 1800 RPM on a surface grinder blew up and the sound was like a rifle shot. The pieces of the wheel made square holes through the wheel guard and the roof on their way to I don't know where they ended up...fortunately no one was hurt. Norton Abrasives sent engineers to investigate and they were in high damage control mode, gave us all frisbees, hats and a feel-good talk.
I don't know how heavy the flying chunks were, but it shook me up pretty bad to see the penetrating power of a piece of grinding wheel moving at 110 ft/S (33 m/S).
Stay out of the plane of a grinding wheel.
Howie
When they built JET they were very concerned about the braking system for the flywheels. The flywheels are designed to store a couple of GJ for delivery to the tokamak and are spun up with a multi-MW motor. They worked out if a bearing failed the flywheels first landing would be about 2 miles away as it skimmed across the oxfordshire countryside.
Luckily 30 years on they are still working. Still 775 tons running at 200RPM is not something I would want to stand close to.
And yes I know I've told this story before 😛
Luckily 30 years on they are still working. Still 775 tons running at 200RPM is not something I would want to stand close to.
And yes I know I've told this story before 😛
Howie,
A 1" thick 14" diameter wheel weighs about 10 pounds. 1800 RPM on a 14" wheel is a bit less than 70 MPH. My betting is if a big chunk hit you it might not be a hospital visit. After all ambulance drivers get razzed for not delivering corpses to the morgue. (Even worse razzing if the other way!)
Glad to hear no injuries. I do have two surface grinders recently added will be sure to mention your experience.
I did have a table saw throw a piece of white oak through the 14' off the ground woodshop window and it landed 120 feet away. There is a reason I changed to a moving table saw with a work piece hold down and riving knife.
I don't know if you ever saw a wheel press. One of the most dangerous pieces of large shop gear. They use a massive rotating wheel to store energy that is then tapped by a clutch to bend or punch metal. Just imagine what can happen with a few tons of wheel rotating at a few hundred RPM! Clutch engaged it can instantly amputate bits or misused toss a few hundred pounds of steel at you.
A 1" thick 14" diameter wheel weighs about 10 pounds. 1800 RPM on a 14" wheel is a bit less than 70 MPH. My betting is if a big chunk hit you it might not be a hospital visit. After all ambulance drivers get razzed for not delivering corpses to the morgue. (Even worse razzing if the other way!)
Glad to hear no injuries. I do have two surface grinders recently added will be sure to mention your experience.
I did have a table saw throw a piece of white oak through the 14' off the ground woodshop window and it landed 120 feet away. There is a reason I changed to a moving table saw with a work piece hold down and riving knife.
I don't know if you ever saw a wheel press. One of the most dangerous pieces of large shop gear. They use a massive rotating wheel to store energy that is then tapped by a clutch to bend or punch metal. Just imagine what can happen with a few tons of wheel rotating at a few hundred RPM! Clutch engaged it can instantly amputate bits or misused toss a few hundred pounds of steel at you.
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Since were talking about spinning things coming undone......I was helping the neighbor who had inherited his fathers farm, with it came a a old track sawmill powered by a 6-71 Detroit that ran a 60” circular blade on a shaft held in place by pillow block bearings driven by belt with a hand lever slip clutch.....in other words you had to stand fairly close to run the clutch.
My neighbor was feeding, I was catching, and another feller was in the middle running the clutch......one of the bearings let go at full steam and the blade took off towards the clutch man so fast there’s nothing anyone could have done.....the shaft grazed his head and luckily he only had a mild concussion and needed a few dozen stitches, he was knocked out for a minute or two and we didn’t know the extent of his injuries at the moment.
We were out in the middle of nowhere.... took the volunteer f.d. around 20 minutes to get there, they choppered him out eventually.
This was almost 20 years ago and it still makes my hair stand on end just thinking about it.
My neighbor was feeding, I was catching, and another feller was in the middle running the clutch......one of the bearings let go at full steam and the blade took off towards the clutch man so fast there’s nothing anyone could have done.....the shaft grazed his head and luckily he only had a mild concussion and needed a few dozen stitches, he was knocked out for a minute or two and we didn’t know the extent of his injuries at the moment.
We were out in the middle of nowhere.... took the volunteer f.d. around 20 minutes to get there, they choppered him out eventually.
This was almost 20 years ago and it still makes my hair stand on end just thinking about it.
I watched a video the other day, someone was grinding aluminum.
The techs at work absolutely stress that you should never, ever, grind aluminum. Apparently it fills the wheel, leading to failure.
I never doubt the techs I work with, they are very very good at what they do.
yah, exactly two miles away...closer is better in the event of a bounce or two, just don't buy a tall house in case you have to duck..
jn
The techs at work absolutely stress that you should never, ever, grind aluminum. Apparently it fills the wheel, leading to failure.
I never doubt the techs I work with, they are very very good at what they do.
yah, exactly two miles away...closer is better in the event of a bounce or two, just don't buy a tall house in case you have to duck..
jn
Yes, in general grinding aluminum is a bad idea, in particular the 1000 serries alloys. However, grinding wheels can be cleaned after, if absolutely necessary.
Aluminum has a lot of weird properties, it cannot be milled or drilled with otherwise superb TiN coated carbide tools, bad results with 4 flute end mills, ideally needs special angled tooling for turning, breaks bits (drills, taps) easier than stainless steel, etc... Unfortunately aluminum machining is the most common task for DIYAudio people.
My favorite metals to machine are brass and zamak.
Aluminum has a lot of weird properties, it cannot be milled or drilled with otherwise superb TiN coated carbide tools, bad results with 4 flute end mills, ideally needs special angled tooling for turning, breaks bits (drills, taps) easier than stainless steel, etc... Unfortunately aluminum machining is the most common task for DIYAudio people.
My favorite metals to machine are brass and zamak.
Bob: Your story reminds me of a slightly mad venture my mother's boyfriend got involved with in the early 80s. He bought a sawmill to make fence panels. Silly floppy things we have in UK that blow over in the first gale. The saw blade was about the size you mention, powered by an old truck that was on blocks with the belt off the rear wheel. We had a labrador at the time and it used to lie in the sawdust under the wheel whilst it was running! I stayed out the shed whilst it was running.
No one lost any body parts and luckily the venture didn't make any money so had to be sold on after 6 months. Damn that dog was stupid though.
No one lost any body parts and luckily the venture didn't make any money so had to be sold on after 6 months. Damn that dog was stupid though.
Speaking of aluminum, I just had some small 1/4" thick heatsinks fab'd that I use for the stk-0050 modules. I had them waterjet cut at a place called ACWaterJet, wonderful job. I had some coming from a shop in LasVegas but wanted a local supplier instead. These were done in a few days and I could pick them up.
I still have to tap some holes for the bjts because they would not do it. I have a M3x0.5 fluted chipping drill tap from McMaster-Carr, it works fine with the 2.5mm holes. I used a dab of 3;1 machine oil I had hanging around, a dab on each side and the DeWalt hand drill, easy peasy.
They do all kinds of cutting, they even water cut wood signs, nice 3D rendering, they looked really nice. They can do engraved panels!!
I still have to tap some holes for the bjts because they would not do it. I have a M3x0.5 fluted chipping drill tap from McMaster-Carr, it works fine with the 2.5mm holes. I used a dab of 3;1 machine oil I had hanging around, a dab on each side and the DeWalt hand drill, easy peasy.
They do all kinds of cutting, they even water cut wood signs, nice 3D rendering, they looked really nice. They can do engraved panels!!
Long ago when I learned machining is that aluminum requires alcohol as cutting fluid, kerosene is also ok, that was back then and I thought that was weird but it works, a sticky metal though.
Pure alumninium?
It depends on the grade/alloy. Some of the tooling plate alloys are beautiful to machine.🙂
While we're in this neighborhood, can any of you recommend a good reference guide, something like The Art of Electronics but for machinists? I know we're supposed to be able to learn everything on YouTube these days, but...well, you know. 🙄
1000 series “alloys” I mentioned are essentially pure aluminum.
Try to machine any aluminum alloy with a carbide TiN coated bit, you’d better give up before breaking expensive bits that would otherwise cut stainless steel like butter. Any aluminum alloy that I tried sticks to these bits like hot glue, 2 flute carbide uncoated work fine, but you need to spin an 1/8 sucker at 16k RPM, otherwise the cut looks like ****.
And don’t even think of using a tapping head to tap buried holes in aluminum, keep it for steel only. Taps are breaking way too often when auto reversing, and I’m talking about a Procunier head, not some Chinese junk. Hand tapping with methanol or WD40 is ok, not much fun when you are facing 50+ holes.
Here in the US there is a cutting fluid called TapMagic which works really well with aluminum, especially the older stuff with trichloroethane. We had to examine tapped holes in parts we made for the US Govt with a microscope to ensure no tear-out, and that stuff gave the cleanest threads...the old timers used what they called lard oil which worked almost as well but had to be renewed every few turns.
Aluminum can be ground with fully flooded wheel, but cutting rates have to be kept very low.
Howie
+10, I freewheel my mill and hand tap blind holes...I need to feel how the chip build-up in the bottom is going. A few years ago I broke my TapMatic tapping head output shaft when I accidentally bumped the Y axis feed mid-tap...and the replacement was $$$...so painful...but you cannot mill tap in production without a reversible tapping head.
Howie
Howie,
Lard oil is lard dissolved in kerosine. An old standard, but messy and flammable. Tap Magic is great stuff.
But 1100 series aluminum is pretty much useless for anything I can think of. It is just cheap. 6061 is the most common alloy because it can be welded. 2024 or 7075 are great for machining.
Boeing has the technique of using big pieces of aluminum and milling it to shape rather that using riveted pieces. This goes from small pieces like the food shelf supports up to full wings! Turns out to be economical to actually take a giant hunk of aluminum and mill it out. Lots of scrap to recycle.
Most if the aluminum we use around here is 5052 intended for sheet metal and forming.
I have in the past used 6063 structural shapes. It was nice because when I bought it Alcoa did a run for me on special lengths. Aluminum is usually sold by the pound. Most I have bought at once was just under 15 tons. Did get a good price.
Steel on the other hand I usually buy by the ton. My supplier is nice enough to make sure it is palletized in small tonnages, so as to not overload my forklift. Amazing how small a ton of steel can be!
I just finished punching 1,000 small cases, the scrap punchies were about 200 pounds!
As to tapping aluminum I can't reliable tap #4 but can do #6 in aluminum with my tapmatic setup. But for my 1,000 cases Aluminum front panels I am using PEM nuts. The stainless ones are compatible with aluminum. But they are expensive, as much as $.16 each for some sizes more normal ones run $.056 each. Of course that doesn't include installation.
The "automatic" inserters are expensive and still require quite a bit of manual operator work. But inserts are clearly the best way to put threads in aluminum.
Lard oil is lard dissolved in kerosine. An old standard, but messy and flammable. Tap Magic is great stuff.
But 1100 series aluminum is pretty much useless for anything I can think of. It is just cheap. 6061 is the most common alloy because it can be welded. 2024 or 7075 are great for machining.
Boeing has the technique of using big pieces of aluminum and milling it to shape rather that using riveted pieces. This goes from small pieces like the food shelf supports up to full wings! Turns out to be economical to actually take a giant hunk of aluminum and mill it out. Lots of scrap to recycle.
Most if the aluminum we use around here is 5052 intended for sheet metal and forming.
I have in the past used 6063 structural shapes. It was nice because when I bought it Alcoa did a run for me on special lengths. Aluminum is usually sold by the pound. Most I have bought at once was just under 15 tons. Did get a good price.
Steel on the other hand I usually buy by the ton. My supplier is nice enough to make sure it is palletized in small tonnages, so as to not overload my forklift. Amazing how small a ton of steel can be!
I just finished punching 1,000 small cases, the scrap punchies were about 200 pounds!
As to tapping aluminum I can't reliable tap #4 but can do #6 in aluminum with my tapmatic setup. But for my 1,000 cases Aluminum front panels I am using PEM nuts. The stainless ones are compatible with aluminum. But they are expensive, as much as $.16 each for some sizes more normal ones run $.056 each. Of course that doesn't include installation.
The "automatic" inserters are expensive and still require quite a bit of manual operator work. But inserts are clearly the best way to put threads in aluminum.
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Ed
It is the Europeans that were and are all for machining.
Boeing was traditionally for riveting and or chemical milling, then forged parts. For technical reasons but labor intensive. Now they do more machining than 20 years ago. (when not CFRP)
George
5 axis is a thing, as is the need for homogeneity. I'm surprised more things aren't forged and machined on aircraft (or they are).
Aluminum likes a big chip, which is basically what Syn08 says in more condensed form. 🙂 Single flute cutters on higher rpm machines are a godsend.
Aluminum likes a big chip, which is basically what Syn08 says in more condensed form. 🙂 Single flute cutters on higher rpm machines are a godsend.
George,
I have done projects in Seattle, thus more familiar with Boeing. Carbon Fiber Reinforced Plastics is as far as I know a military spinoff, used for lots more than aircraft.
I have done projects in Seattle, thus more familiar with Boeing. Carbon Fiber Reinforced Plastics is as far as I know a military spinoff, used for lots more than aircraft.
Within Boeing, yes. Their Defence & Airspace branches were the first to embrace CFRP. Aviation branch followed.
In industrial scale, carbon fiber development and production was Japan based. (still is one can say, as 90% of CFRP is PAN-based)
George
In industrial scale, carbon fiber development and production was Japan based. (still is one can say, as 90% of CFRP is PAN-based)
George