OMG....07:47 You inserted blades 88-68-90 instead of 88-89-90! Black humor - never gets old. Sorry for that... What a great opportunity for us to have a look at those finely executed operations. Thank you!
Retired USAF Jet Mech here. Love the video. Brings back memories of many many days of detail work in the shop. Jet engine maintenance is a whole different level of mechanic work. Everything must be just so or it is no go. Very little acceptance for deviation from specs or procedures. Part of me misses that work... another larger part of me is glad I do not have to do that work anymore. Countless days going home still smelling like jet fuel wears on ones soul. Thank you for the video. Hope to see more. Work safe, work carefully, work smart, and keep them working.
@@AgentJayZ love your channel, you've taught me so much and all free of charge from the comfort of my soft desk chair. The next time I fly I'll remember and appreciate everything that goes into it! Keep up the great content!
*Thank you, Jay!* I *LOVE* this level of detail! While others might think this is mind numbing, you have over 100K viewers who are absolutely fascinated with it. Thanks again for all you do!
Ok, last few seconds was the icing on the cake. Thanks for showing us how it's done. I never tire of watching a pro at work as you describe in layman's terms how this amazing technology works.
I have no words for you Jay, or many praising words. Its an unbelievable task to accomplish. how the hell do they even design these things anyways?. Its absolutely mind boggling.
There's something wrong with me I find these videos fascinating. Although I don't work on turbine engines I like working on my airplane, cars, motorcycles. There's lessons to be learned here about tools, organization cross-checking, general quality control that applies to all mechanical work.
I'm enjoying each series of videos on each of the engines and their various overhaul processes. They're more meaningful than videos that show a snippet of the overall process.
Just ran across your videos a day ago. I got to tell you I am absolutely hooked and can’t stop watching. I can tell you are a man who loves his work. Skills of a surgeon, patience of a saint. In a laymen’s words I understand the general theory of a jet turbine, but have gained an immense amount of knowledge into the intricacies of the finer details that make it all work. As a 40 yr veteran in HVAC and smithy, plus a fairly accomplished fine carpenter, I’m can really appreciate your skill set and overall mindset of perfection. Not a business for hamfisted bulls in a china closet. As a child well into adulthood I was privileged to have a father who was a private pilot for 30+ years which grew my love of aviation. That and living in Wichita Kansas, I’m surrounded by many friends and neighbors who are in the aviation industry. My neighbor next door was a B1 pilot and the neighbor across the street is a certified aviation power plant mechanic, plus my nephew is a F18 pilot. My own son worked on Citations at Cessna. On my trip to DC my first stop was the Aero Space Museum. I never grow tired of learning, so thank you for sharing your videos.
This is so cool! I am going to ERAU to become an Aviation Maintenance Technician and I am so glad that I discovered your channel today so I am a step ahead for college!
Nickel is magnetic too. Some alloys of stainless steel are not magnetic, it's not the iron content, it's the crystalline structure of the metal that makes it magnetic. Austenitic steel is not magnetic.
i was scanning before i made a similar comment. this would be my vote; same alloy but a heat treatment process resulted in a crystalline lattice structure boundary layer.
@@LogicallyCompromised Nevertheless, the disc and its shaft are supplied as a single unit: as you will see in my other comments, I've checked on this and, when you look closely at the complete turbine rotor, that becomes fairly obvious. However, I think it highly unlikely that the disc/shaft unit is a one-piece forging, which would be extremely difficult to manufacture and horrendously expensive. My very tentative conclusion is that the bi-metallic feature is part of the joining process ..... and it still puzzles me.
The problem with stainless steel is the steel. Iron has a comparatively low melting point, and although you can change that by alloying it with other materials, you're better off to go with different material altogether. The other problem with steel of any kind is creep. All that said, they do totally make turbine blades out of stainless steel. Go figure. =P lol
Thank you, I’m studying mechanical engineering with a concentration in Aeronautics (mostly) and Aerospace in a university that is sadly not certified under the FAA, so I’ll be doing design work (CAD) and what not. I could swear that watching your videos gives me life and keeps me motivated, wish we could get exposed to this type of training!
Too bad about the copy rights, I could see letting the work play out in real time while the album ticks away in the background :) Pink Floyd DSOM while assembling a jet engine... glad you have been so blessed.
Magnetic properties of nickel steel depends on heat treatment / forging process. So the disc may be single material, just processed differently in different parts.
I have a theory that this engine is really into your music too... you're rejuvenating it and making it young again and it shows. I wonder what the people who first put it together listened to. Good video, thanks!
quick question (im sure you answered this in one of your many videos), if the pin is not easily removable how do you get the blades out? do you force the blade out and destroy internal pin?
Being able to read, understand, and follow procedures is the most important thing that was emphasized in both jet training school, and in my evaluation for service as "agent"...
I understand the blades are weighed individually for balancing,but are the locking pins weighed also or are they produced close enough to the same as each other as to not matter that much? Just found your channel and I am very fascinated, can’t wait to watch more of your videos THANK YOU for supplying informational content.
I would think since the pin is so light relative to the blade that the unevenness in weight is so minute it really doesn't matter at all. For example let's say the blades have a 1% weight tolerance. In a 200gr blade that would be 2 grams between the heaviest and lightest blade. That is a significant weight difference. But let's assume the pins are less carefully made and have a weight tolerance of 5%. Still if the pins average weight is 2 grams that would be 0.1 gr between heaviest and lightest pin. (keep in mind that would be the most extreme difference possible) 0.1 gr is the resolution used to weigh the blades themselves. So the average variation in weight of the pins, is less that what you would care to measure anyway and thus can be considered zero. So for all intents and purposes, pins are all the same (as jay said)
What gets me is how good condition these engines are - it looks pretty much new but as far as I know these have not been produced since the 50's (wiki says 1956).
Before you even played the music at the end I was thinking that "Time" would make a great soundtrack for this task. Great minds think a like I guess! Good job!
That bi-metallic turbine disc fascinates, even horrifies me. The integrity of the circumferential joint between the inner and outer portions of the disc must be of the highest order, otherwise a disc burst failure would be almost inevitable. I've explained in the past that there's a concept known as the 'free ring radius, or 'free hoop diameter' in the design of a turbine (or compressor) disc. At a given speed, the material of the disc inside that radius is effectively providing the centripetal force to retain all of the material outside that radius and, the higher the rotational speed, the smaller the radius. Put another way, if the material inside the radius was suddenly disconnected circumferentially from the material outside the radius, then the outer ring would dilate and burst almost instantaneously. So, AgentJayZ, do you have any information on the manufacturing process for that disc?
@@zapfanzapfan I'm still fascinated and horrified, but now I'm also getting suspicious and curious. The junction or interface between the two materials is not uniformly circular, which it should be, if the disc had been formed with an insert into an outer ring. In any case, having thought about this further, I doubt that, back in the 1940s, there would have been any manufacturing technology anywhere near good enough to produce the required high integrity joint, even for a low life disc. I'm now wondering whether the magnetic material is a 'laminated' reinforcement onto the the rear face of the disc. Even so, I'm still horrified by both the irregularity of the boundary between the two materials and the surface finish of the magnetic material. Could it be some form of metal spray or weld deposition, possibly for repair and salvage reasons? Any disc that I've ever been involved with would have been rejected immediately with that standard of surface finish. In most cases, a scratch that could be detected by a fingernail would be cause for rejection. In terms of the relative strengths of the two materials, I can't answer that authoritatively, not knowing what the materials are and their specifications. However, I would have expected one of the early nickel-based alloys of the day to have a relatively higher strength at operating temperature than the available steel alloys. In terms of cost, any potential cost saving from using two materials would, I believe, have been totally nullified by the process and manufacturing costs of joining them. I'm hoping that AgentJayZ can shed some more light on this.
I'm very curious how that is manufactured as well. Your mention of the 'free ring radius', (we call it the 'self supporting' radius or diameter, SSR) made me take a slightly deeper look. I'm guessing from JayZ's magnet test the hub section is a 400 series stainless, a ferritic stainless steel that's slightly magnetic and the outer ring is probably IN718, a pretty common disc material. The SSR for annealed 410SS at 8000 RPM would be almost 9 inches. As 410 can be heat treated to much higher strength levels and 718 is even stronger I'd say the joint is well within the SSR for either material. Also, the stress across the disc joint won't be very large. In spinning discs it the hoop stress that's the big one. Radial stresses are generally less important for the disc than for the blade roots. That being the case I'm still fascinated how it was manufactured. Is it welded, friction, TIG or EB? Is the hub cast in place? I don't believe it's just an interference fit as that would always show cracks at the seam. Thanks for your videos AgentJayZ. They're almost always fascinating.
@@yabojabo8578 Starting with your last comments first, you are thinking in terms of manufacturing processes that hadn't even been thought of in the mid/late 1940s, apart from the 'conventional' welding processes of the day. Henry Wiggin at Hereford, here in the UK, were certainly well advanced with the development of their range of Inco alloys in the late 1940s, before Special Metals took on the range. However, my recollection is that IN718 is more recent than that and, In any case, would the UK government have allowed the technology transfer (they might, considering they allowed GE to have a Whittle engine in 1942)? As a designer (now long retired), I wouldn't have dreamt of trying even a modern EBW process in joining the inner and outer portions of a bi-metallic disc of that size: in any case, the thickness of the disc would probably preclude it. There was also limited understanding of the optimum grain flow requirements in a disc forging back in the 1940s and more than a few engines 'threw' turbine discs as a result. Even as late as the 1970s, R-R lost a few RB211 fan discs, not to mention a couple of HP turbine discs, because of forging problems. You may well be right about the free ring radius/SSR issue, but the fundamental problem remains that any joint in the body of the disc would disrupt the integrity of the disc. There would be no continuity of the forged grain structure and any fusion process would result in a localised 'as cast' structure, with a heat affected zone. I am more and more uncomfortable with the idea of a bi-metallic disc formed from inner and outer rings and I am increasingly suspicious of the irregularity of the 'junction' between the two materials, which suggests to me that it represents material added to the face of the disc. OK, I could be wrong, but .....
@@grahamj9101I agree with everything your saying. I'm a turbine design engineer as well and I would never feel comfortable with a bi-metallic or 2 piece disc like that. That's why I'm fascinated by it. I'm pretty sure the disc JayZ is working with is not original. I'd assume the turbine discs and blades are all upgraded materials from the 1947 originals. The original blades were probably steel alloys with very little life even at relatively low firing temperatures. But that's all beside the point. Could it be that the disc is actually a single part/alloy and there is some processing difference of the center hub vs. outer hub that results in the different magnetism? I've had cold worked austenitic stainless parts that were slightly magnetic as a result of the cold work while machined parts from the same billet weren't. Perhaps the inner hub is as forged and the outer hub was forged with stock on and was then machined to size. That would explain the irregular transition from one section to the other. Very curious.
Great video! So to remove the blades, you remove the shaft from the engine and then hammer the blades towards the rear which shears the pin then you obviously hit the pin through.?
really love your videos man. Just one thing though, the magnetic properties dont depend that much on the metals that make up th material, it really depends on the arrengement of the atoms, that way, by saying that the inner part has more iron because it is more attracted by the magnet may not be always correct!
It’s not a lack of iron that makes some stainless steels non-magnetic. 304 still has a high percentage of iron but it’s atoms are arranged in a way that reduce their magnetic attraction. It’s austenitic rather than ferritic stainless steel.
I know this is a "why-question" that someone decided more than 70 years ago but do you know why the turbine disc is made from two different alloys? Cost? Weight? Manufacturing process?
If you actually look at the equations for gas turbine engines, you'd see that as you increase stagnation temperature in the turbine, the thermodynamic efficiency of the engine also increases. But obviously this temperature is limited by the materials you use. So engineers had to find clever ways of alloying materials or cooling the blades to allow higher temperatures.
The tape and markers concern me somewhat, I worked for a company that manufactured pitot tubes from nickel. We found that residue from tape adhesive and marker ink could lead to embrittlement and cracking when the heaters in the tubes were left on sitting on the ground. Even though the tubes were cleaned before installation. Without air flow of flight, the temperatures would get high enough to lead to the problems. Turbine blades certainly get hotter than any pitot tube. I suppose you would know if one of your engines failed but it is a bit unnerving. Great video as always! I love this stuff and your explanations.
Do these "color" patterns on the ceramic coating correlate to the thickness of the coating? Like, if this was spray paint I would think it was sprayed on unevenly. If they don't, and the coating is uniform, what are these patterns? If the do and the coating is in fact not perfectly even, doesn't that create hot spots on the blades?
The application process involves a lot of heat and produces smoke, which mixes in ans slightly discolors the coating. The coating is of uniform thickness.
It's not necessarily two different alloys. You can achieve the same result by applying refractory clay to the center while heating the outside portion above the Currie temperature and allowing it to cool gradually. If it was a Samurai sword, the boundary would be a hamon.
I have a question about disassembly of the same turbine... Does removing blades necessitate shearing each pin, and punching out the broken pins ?? Or do they get drilled out etc ??
Your videos are awesome my friend，I am a jet engine lover and its great to see you operating them. Maybe you can make some time-lapse videos to show the disassemble or assemble process of a jet engine.😊
A little bit of trivia from Wikipedia on the Canadair Sabre. In 1952, Jacqueline Cochran, then aged 47, decided to challenge the world speed record for women, then held by Jacqueline Auriol. She tried to borrow an F-86 from the U.S. Air Force, but was refused. She was introduced to an Air Vice-Marshal of the RCAF who, with the permission of the Canadian Minister of Defence, arranged for her to borrow 19200, the sole Sabre 3. Canadair sent a 16-man support team to California for the attempt. On 18 May 1953, Ms. Cochran set a new 100 km speed record of 1,050.15 km/h (652.5 mph). Later on 3 June, she set a new 15 km closed circuit record of 1078 km/h (670 mph). While she was in California, she exceeded 1270 km/h in a dive, and thus became the first woman to exceed the speed of sound.
Since the pin has a bevel, does it need to be inserted in a specific orientation? How do you know if the pin didn't roll inwards (like a sleeve) if it got stuck at the edge of a blade. What if the bore where the pin goes is wallored out and your punch actually spread the pin instead of pushing it. What if ... what if... gosh... I can never do this job!
It was designed and manufactured long before the friction bonding process was developed. As I've said in my conversation with Mr yabo jabo, I'm puzzled by what I see.
That would increase the amount of imbalance... maybe even in excess of the allowable amount. It's really important not to get the blade positions mixed up.
You mention that if you mess up with driving the lock pin in that you need to remove the turbine wheel to remove it. Why not install and pin the blades before installing the turbine wheel?
Because when you move the whole assembly around you could damage the blades if they contact anything. Meaning you'd have to dismantle it again and replace the blade that got dinged. Imagine 400lbs of that thing dinging one of the blades, like if it turned accidentally into something.
@@youtubasoarus Thanks and I do get that, but if Jay was to have messed up a lock pin he would have had to remove a partially bladed T-wheel and still run that risk. The device he made to install the wheel into the engine was pretty slick and looks like a good way to handle the wheel with care to the blades and bearings. I guess best practice is to install an empty T-wheel into the engine and make sure you don't mess up installing the blades. Was a very informative video. I worked on B-52's as a crew chief for years and did alot of work on the engines but never inside the engines.
This engine was designed in 1947, and does incorporate any of the many things we have learned since then. We rebuild engines to factory specs. We do not do any re-engineering, except for the thermal barrier coatings.
The blades slid freely into their disc slots, which obviously meant that there was some clearance. The blade locking pins were driven into clearance slots in the blade roots. When the engine is running, the blades will not "wiggle", as each one is being restrained in its disc slot by a force of several thousand 'G'.
Hello AgentJayZ I just started watching your videos. I enjoy them immensely!!!!! My oldest son graduated from BCIT AME course. He wanted to become an airline pilot. (His lifelong dream since I can remember) but we found out he was colour blind! He ended up trying the next best thing, AME. But...it didn’t work out. Basically a huge wage gap between what he is doing now to what ‘might have been his potential’. In any case... I live in Chilliwack and own a 10 bay automobile repair facility and appreciate all your efforts in producing these videos. One day I would love to acquire some engines parts to make some type of unique gift for my son. If you think you can help, please let me know. Thanks again for your impressive efforts!
It's weird seeing these blades out side of the shop I work at. If I had to guess on the materials of the disk I'd almost say that its 2 different grades of Stainless Steel.
Fascinating. Thanks. You were not consistent with the orientation of the split in the split pins. #92 was to the right and #96 was to the left. I've no idea if it matters - presumably not otherwise the manual would say so and you would do so if it was important. However, that's what I noticed. Greetings from Australia. ;-)
Genuinely im curious what is the reason they have to be returned to their original position and what would happen if you ran the engine with lets say, blade 49 in slot 93? I assume its a balance issue, but idk.
I'm only guessing that you are making the most common mistake, and that is calling a turbine engine a turbine. And you really mean to say compressor when you say turbine. If not, then your question makes no sense at all, because turbine stages always are larger downstream. Also, the word random instantly applies a 90% discount...
Someone opined below that moving an already-bladed turbine around the shop would be too risky, is that your 'why' for mounting the wheel first? How did they do this step during original manufacture?
Austerity transformation in the Nickle alloy. Nickle is an austinite stabilizer. Austinite is nonmagnetic. There's a phase change in the alloy. Cool but still same material
There are, but they only get you to the point of starting the direct measurement balancing process. The process of sorting the blades by weight, illustrated in my turbine balancing videos, is equally effective.
Is there any requirement for the orinentation of the roll pin? If you "transmit" tourque with them xou gave to what out where the slit goes because otherwise they wobble out of the hole...
Why wouldn't you use a spray on dye to penetrated that area where the two metals meet and use a spray on leeching agent to pull the dye out of any cracks if there were any. I recall back many moons that I used that method for this same application on larger turbines.
That is exactly what was done... exactly where the overhaul manual specified it be done. No dye penetrant was wasted on fulfilling personal curiosities.
If you made a mistake, couldn’t you just drill out the deformed pin with an undersized, soft drill bit? Rather than disassemble the turbine? Just curious.
If you could be absolutely certain that the drill bit is so soft that it has no chance of damaging the blade or the wheel. Personally I would never consider myself sure about that. What I might try to do is to take an undersized hard screw and screw that inside the deformed pin and then try to yank them out.
MVHiltunen .... That’s a good idea. We use drill bits of specific hardness all the time, so I’d be comfortable with it. I think your idea might work better, unless the deformation of he pin is so great you leave most of it behind.
There is a procedure to remove the pins. Making up a new one because you think it might be faster or easier is the kind of thing that gets you corrected, redirected, and then fired. Got it? When will you dopes get it? There is no alternate procedure, and your ideas are garbage. Don't waste your time typing them.
If you accidently drill away something that is not the pin you will unbalance this piece of equipment at the worst area. as you can see he measured every blade and wrote its weigt in .1 gram steps on it. pretty sure that you will drill to deep or at an ange and get serious problems.
It seems you use regular masking tape to label the blades. We have always been told that graphite pencils and tapes are a big no-no on the hot end because they can cause intergranular corrosion leading to catastrophic failure. Do you take the same into consideration when taping the blades?
That was stressful! I've snapped bolts on my Moto engine a few times over the years and just backing those bolts out creates anxiety. Being 100% is just that. 100%. Sigma 6 doesn't work here. Thanks for the great video!
I must say. I am impressed by your meticulously methodical approach in handling this piece of engineering beauty. Multiple questions arise, such as: 1.) I wonder what the weight of those fins are (individually..and total). 2.) Also..silly question but..do you plan on cleaning your number markers or leaving those on there? Would they affect the balance or something? (I realise it's micrograms in weight..so I assume no balance issues compared to the weight of those fins but can't help but ask?) 3.) Are you gonna ask your boss for a raise? =)
Nicely done, attention to detail pays off when it counts. I know that adding insurance into a process usually takes away from the focus and attention to complete a tedious task such as this. In this circumstance however, would it be beneficial to insert every pin partially around the entire circumference without the blades in place, so that in the event of a pin install error it can be knocked outward from the inside? The pins seem like there is significant engagement before the blade is engaged, just a thought. Out of curiosity, what is the tolerance for the balancing process?
Very exacting and tedious with no mistake recovery. I hope you have limited control on your job deadlines. I would hate to do this under back to back down to the last 15 minute rushed absolute must meet deadlines.
@@AgentJayZ thank you for the reply! Do you have any experience with small engines? I'm working with a company that's building an aircraft with a PBS TJ-100 engine, 1300N thrust. Would be interested to hear your thoughts on the smaller units.
I used to work for Ontario hydro. Nuovopigneone gas turbines. 14000 killos,shipped in sealed vessels. "Air". Those 1/4" ×3/4" long pins that you use..I know they don't brake stait(crack) down the middle. How about laser print them with a Zig.Zag ..maybe ten thou gap.you know EDM as you mentioned. Your videos are totally awesome. Orenda. Brampton Ontario. CANADA. Big big turbines.
OMG....07:47
You inserted blades 88-68-90 instead of 88-89-90!
Black humor - never gets old. Sorry for that...
What a great opportunity for us to have a look at those finely executed operations. Thank you!
I see that he puts a line under numbers so they can't be inverted :)
Yeah, tried to put the timing close enough so that it cannot be easily spotted. You eagle eye :P
Retired USAF Jet Mech here.
Love the video. Brings back memories of many many days of detail work in the shop.
Jet engine maintenance is a whole different level of mechanic work. Everything must be just so or it is no go. Very little acceptance for deviation from specs or procedures.
Part of me misses that work... another larger part of me is glad I do not have to do that work anymore.
Countless days going home still smelling like jet fuel wears on ones soul.
Thank you for the video. Hope to see more. Work safe, work carefully, work smart, and keep them working.
Your experience is respected. Welcome to Jet City!
Content like this is exactly why youtube is so amazing. The internet is the revolution.
Thanks! Welcome to Jet City.
@@AgentJayZ love your channel, you've taught me so much and all free of charge from the comfort of my soft desk chair. The next time I fly I'll remember and appreciate everything that goes into it! Keep up the great content!
*Thank you, Jay!* I *LOVE* this level of detail! While others might think this is mind numbing, you have over 100K viewers who are absolutely fascinated with it. Thanks again for all you do!
Ok, last few seconds was the icing on the cake. Thanks for showing us how it's done. I never tire of watching a pro at work as you describe in layman's terms how this amazing technology works.
Excellent taste in music, sir.
Indeed.
I have no words for you Jay, or many praising words. Its an unbelievable task to accomplish. how the hell do they even design these things anyways?. Its absolutely mind boggling.
There's something wrong with me I find these videos fascinating. Although I don't work on turbine engines I like working on my airplane, cars, motorcycles. There's lessons to be learned here about tools, organization cross-checking, general quality control that applies to all mechanical work.
Your videos are great! "No sticky. Sticky. No sticky. Sticky." You're educational and entertaining. Thank you!
I'm enjoying each series of videos on each of the engines and their various overhaul processes. They're more meaningful than videos that show a snippet of the overall process.
Just ran across your videos a day ago. I got to tell you I am absolutely hooked and can’t stop watching. I can tell you are a man who loves his work. Skills of a surgeon, patience of a saint. In a laymen’s words I understand the general theory of a jet turbine, but have gained an immense amount of knowledge into the intricacies of the finer details that make it all work. As a 40 yr veteran in HVAC and smithy, plus a fairly accomplished fine carpenter, I’m can really appreciate your skill set and overall mindset of perfection. Not a business for hamfisted bulls in a china closet.
As a child well into adulthood I was privileged to have a father who was a private pilot for 30+ years which grew my love of aviation. That and living in Wichita Kansas, I’m surrounded by many friends and neighbors who are in the aviation industry. My neighbor next door was a B1 pilot and the neighbor across the street is a certified aviation power plant mechanic, plus my nephew is a F18 pilot. My own son worked on Citations at Cessna. On my trip to DC my first stop was the Aero Space Museum. I never grow tired of learning, so thank you for sharing your videos.
The turbine rotor disk has a Timken 16-25-6 alloy rim TIG welded to an AMS 4340 steel hub to provide higher strength at the flowpath.
Legend has it he is still finding anti seize smudges in random places.
I'd prefer that to the smudges you're finding...
This is so cool! I am going to ERAU to become an Aviation Maintenance Technician and I am so glad that I discovered your channel today so I am a step ahead for college!
When you make perfection look easy you know it's not. Great vid.
The algorithm did me a solid on this one
hell I wouldn't even know what to search for
You've got yourself a new stalker
Nickel is magnetic too. Some alloys of stainless steel are not magnetic, it's not the iron content, it's the crystalline structure of the metal that makes it magnetic. Austenitic steel is not magnetic.
i was scanning before i made a similar comment. this would be my vote; same alloy but a heat treatment process resulted in a crystalline lattice structure boundary layer.
@@LogicallyCompromised Nevertheless, the disc and its shaft are supplied as a single unit: as you will see in my other comments, I've checked on this and, when you look closely at the complete turbine rotor, that becomes fairly obvious.
However, I think it highly unlikely that the disc/shaft unit is a one-piece forging, which would be extremely difficult to manufacture and horrendously expensive. My very tentative conclusion is that the bi-metallic feature is part of the joining process ..... and it still puzzles me.
@@grahamj9101 The turbine rotor disk has a Timken 16-25-6 alloy rim TIG welded to an AMS 4340 steel hub to provide higher strength at the flowpath.
The problem with stainless steel is the steel. Iron has a comparatively low melting point, and although you can change that by alloying it with other materials, you're better off to go with different material altogether. The other problem with steel of any kind is creep. All that said, they do totally make turbine blades out of stainless steel. Go figure. =P lol
Austenitic steel is also just one step away from molten steel. ;) Hot metal goop in your turbine blades is not ideal. lol
I’m getting my A&P license in April so glad I found your channel ! Love seeing stuff like this so I can use out in the field
good stuff good stuff!
the real mechanics do sheet metal ;)
this is actually a really good channel i just found it myself.
It's a craft and JayZ has mastered it. No one better to learn from than a master.
Thank you, I’m studying mechanical engineering with a concentration in Aeronautics (mostly) and Aerospace in a university that is sadly not certified under the FAA, so I’ll be doing design work (CAD) and what not.
I could swear that watching your videos gives me life and keeps me motivated, wish we could get exposed to this type of training!
I used to come here for the knowledge, now I just can't stop thinking about the Boss. One of the cuteste dogs I've seen
Too bad about the copy rights, I could see letting the work play out in real time while the album ticks away in the background :)
Pink Floyd DSOM while assembling a jet engine... glad you have been so blessed.
Watching a screaming turbojet doing its thing, It's amazing that all the hot gas has to pass through these narrow passages between the guide vanes.
The pins setting the blades on the final tap was oddly satisfying. :)
Magnetic properties of nickel steel depends on heat treatment / forging process. So the disc may be single material, just processed differently in different parts.
I have a theory that this engine is really into your music too... you're rejuvenating it and making it young again and it shows. I wonder what the people who first put it together listened to. Good video, thanks!
Early 1950's so would that have been Elvis, or before?
quick question (im sure you answered this in one of your many videos), if the pin is not easily removable how do you get the blades out? do you force the blade out and destroy internal pin?
You're right!
How about a few over size holes for those roll pins? And how do they come out??
Check out the first episode of this series of videos.
How did he remove the pins to remove the blades?
This video is part of a playlist.
I built an Ikea TV stand today. That's basically the same thing, right?
Being able to read, understand, and follow procedures is the most important thing that was emphasized in both jet training school, and in my evaluation for service as "agent"...
I understand the blades are weighed individually for balancing,but are the locking pins weighed also or are they produced close enough to the same as each other as to not matter that much?
Just found your channel and I am very fascinated, can’t wait to watch more of your videos THANK YOU for supplying informational content.
From my experiences, the pins are all very close tolerance in terms of weight and shape. It is easier to make the pins all the same versus the blades.
I don't know if it's easier or not. What do I know? Pins are all the same, blades aren't. How do I know this? measured 'em!
I would think since the pin is so light relative to the blade that the unevenness in weight is so minute it really doesn't matter at all.
For example let's say the blades have a 1% weight tolerance. In a 200gr blade that would be 2 grams between the heaviest and lightest blade. That is a significant weight difference.
But let's assume the pins are less carefully made and have a weight tolerance of 5%. Still if the pins average weight is 2 grams that would be 0.1 gr between heaviest and lightest pin. (keep in mind that would be the most extreme difference possible)
0.1 gr is the resolution used to weigh the blades themselves. So the average variation in weight of the pins, is less that what you would care to measure anyway and thus can be considered zero.
So for all intents and purposes, pins are all the same (as jay said)
What gets me is how good condition these engines are - it looks pretty much new but as far as I know these have not been produced since the 50's (wiki says 1956).
Before you even played the music at the end I was thinking that "Time" would make a great soundtrack for this task. Great minds think a like I guess! Good job!
That bi-metallic turbine disc fascinates, even horrifies me. The integrity of the circumferential joint between the inner and outer portions of the disc must be of the highest order, otherwise a disc burst failure would be almost inevitable. I've explained in the past that there's a concept known as the 'free ring radius, or 'free hoop diameter' in the design of a turbine (or compressor) disc.
At a given speed, the material of the disc inside that radius is effectively providing the centripetal force to retain all of the material outside that radius and, the higher the rotational speed, the smaller the radius. Put another way, if the material inside the radius was suddenly disconnected circumferentially from the material outside the radius, then the outer ring would dilate and burst almost instantaneously.
So, AgentJayZ, do you have any information on the manufacturing process for that disc?
I was wondering about that disk too. Is the steel stronger than the nickel alloy? Is the steel cheaper? Was this somehow easier to manufacture?
@@zapfanzapfan I'm still fascinated and horrified, but now I'm also getting suspicious and curious. The junction or interface between the two materials is not uniformly circular, which it should be, if the disc had been formed with an insert into an outer ring. In any case, having thought about this further, I doubt that, back in the 1940s, there would have been any manufacturing technology anywhere near good enough to produce the required high integrity joint, even for a low life disc.
I'm now wondering whether the magnetic material is a 'laminated' reinforcement onto the the rear face of the disc. Even so, I'm still horrified by both the irregularity of the boundary between the two materials and the surface finish of the magnetic material. Could it be some form of metal spray or weld deposition, possibly for repair and salvage reasons? Any disc that I've ever been involved with would have been rejected immediately with that standard of surface finish. In most cases, a scratch that could be detected by a fingernail would be cause for rejection.
In terms of the relative strengths of the two materials, I can't answer that authoritatively, not knowing what the materials are and their specifications. However, I would have expected one of the early nickel-based alloys of the day to have a relatively higher strength at operating temperature than the available steel alloys. In terms of cost, any potential cost saving from using two materials would, I believe, have been totally nullified by the process and manufacturing costs of joining them.
I'm hoping that AgentJayZ can shed some more light on this.
I'm very curious how that is manufactured as well. Your mention of the 'free ring radius', (we call it the 'self supporting' radius or diameter, SSR) made me take a slightly deeper look. I'm guessing from JayZ's magnet test the hub section is a 400 series stainless, a ferritic stainless steel that's slightly magnetic and the outer ring is probably IN718, a pretty common disc material. The SSR for annealed 410SS at 8000 RPM would be almost 9 inches. As 410 can be heat treated to much higher strength levels and 718 is even stronger I'd say the joint is well within the SSR for either material. Also, the stress across the disc joint won't be very large. In spinning discs it the hoop stress that's the big one. Radial stresses are generally less important for the disc than for the blade roots.
That being the case I'm still fascinated how it was manufactured. Is it welded, friction, TIG or EB? Is the hub cast in place? I don't believe it's just an interference fit as that would always show cracks at the seam.
Thanks for your videos AgentJayZ. They're almost always fascinating.
@@yabojabo8578 Starting with your last comments first, you are thinking in terms of manufacturing processes that hadn't even been thought of in the mid/late 1940s, apart from the 'conventional' welding processes of the day. Henry Wiggin at Hereford, here in the UK, were certainly well advanced with the development of their range of Inco alloys in the late 1940s, before Special Metals took on the range. However, my recollection is that IN718 is more recent than that and, In any case, would the UK government have allowed the technology transfer (they might, considering they allowed GE to have a Whittle engine in 1942)?
As a designer (now long retired), I wouldn't have dreamt of trying even a modern EBW process in joining the inner and outer portions of a bi-metallic disc of that size: in any case, the thickness of the disc would probably preclude it. There was also limited understanding of the optimum grain flow requirements in a disc forging back in the 1940s and more than a few engines 'threw' turbine discs as a result. Even as late as the 1970s, R-R lost a few RB211 fan discs, not to mention a couple of HP turbine discs, because of forging problems.
You may well be right about the free ring radius/SSR issue, but the fundamental problem remains that any joint in the body of the disc would disrupt the integrity of the disc. There would be no continuity of the forged grain structure and any fusion process would result in a localised 'as cast' structure, with a heat affected zone.
I am more and more uncomfortable with the idea of a bi-metallic disc formed from inner and outer rings and I am increasingly suspicious of the irregularity of the 'junction' between the two materials, which suggests to me that it represents material added to the face of the disc.
OK, I could be wrong, but .....
@@grahamj9101I agree with everything your saying. I'm a turbine design engineer as well and I would never feel comfortable with a bi-metallic or 2 piece disc like that. That's why I'm fascinated by it. I'm pretty sure the disc JayZ is working with is not original. I'd assume the turbine discs and blades are all upgraded materials from the 1947 originals. The original blades were probably steel alloys with very little life even at relatively low firing temperatures. But that's all beside the point. Could it be that the disc is actually a single part/alloy and there is some processing difference of the center hub vs. outer hub that results in the different magnetism? I've had cold worked austenitic stainless parts that were slightly magnetic as a result of the cold work while machined parts from the same billet weren't. Perhaps the inner hub is as forged and the outer hub was forged with stock on and was then machined to size. That would explain the irregular transition from one section to the other. Very curious.
Floyd action! The perfect working music, although a little Black Sabbath isn't bad either. Can't wait to see that engine in the test cell.
Great video!
So to remove the blades, you remove the shaft from the engine and then hammer the blades towards the rear which shears the pin then you obviously hit the pin through.?
really love your videos man. Just one thing though, the magnetic properties dont depend that much on the metals that make up th material, it really depends on the arrengement of the atoms, that way, by saying that the inner part has more iron because it is more attracted by the magnet may not be always correct!
Aluminum, Copper.
It’s not a lack of iron that makes some stainless steels non-magnetic. 304 still has a high percentage of iron but it’s atoms are arranged in a way that reduce their magnetic attraction. It’s austenitic rather than ferritic stainless steel.
imagine having an apprenticeship with this guy. would be awesome.
If it isn't magnetic it doesn't mean that it have no iron. Iron have paramegnetic form too an can be found in some stainless steels
Pink Floyd is always great when working
hell yea
Are you sure that's not the same steel, just effectively heat treated differently from all the thermal cycling?
The manual refers to the discontinuity as the transition zone.
This was oddly satisfying to watch. Patience and dedication.
I know this is a "why-question" that someone decided more than 70 years ago but do you know why the turbine disc is made from two different alloys? Cost? Weight? Manufacturing process?
I'm wondering this myself, but I think it might be weight and/or heat resistance or even thermal expansion.
If you actually look at the equations for gas turbine engines, you'd see that as you increase stagnation temperature in the turbine, the thermodynamic efficiency of the engine also increases. But obviously this temperature is limited by the materials you use. So engineers had to find clever ways of alloying materials or cooling the blades to allow higher temperatures.
Please see my comments on this topic.
The tape and markers concern me somewhat, I worked for a company that manufactured pitot tubes from nickel. We found that residue from tape adhesive and marker ink could lead to embrittlement and cracking when the heaters in the tubes were left on sitting on the ground. Even though the tubes were cleaned before installation. Without air flow of flight, the temperatures would get high enough to lead to the problems. Turbine blades certainly get hotter than any pitot tube. I suppose you would know if one of your engines failed but it is a bit unnerving. Great video as always! I love this stuff and your explanations.
They're ceramic coated. The blades will see high temps so I doubt it matters as any residue will be quickly burned off.
well you should. we use tested tapes and markers and you shouldn't touch it without clean gloves either.
Should is a bad word, but it can sometimes be useful. Example, you should listen to the dinosaur, because he is right.
You make it look so easy, I can't tie my shoelaces 96 times 100% same exact way.
You're smacking a pin into a hole 96 times, be organized and focused. ez
Stumbled onto this feed. Subscribed
this is fascinating, nice work.
Do these "color" patterns on the ceramic coating correlate to the thickness of the coating? Like, if this was spray paint I would think it was sprayed on unevenly. If they don't, and the coating is uniform, what are these patterns? If the do and the coating is in fact not perfectly even, doesn't that create hot spots on the blades?
The application process involves a lot of heat and produces smoke, which mixes in ans slightly discolors the coating. The coating is of uniform thickness.
How do you get the pin out when you want to change the blades? For the song, I used Darude Sandtorm.. What are you doing with this engine?
You'll notice please that this video is part of a playlist about this engine...
@@AgentJayZ OK I'll check it out. I was watching a clip about flying a Mooney and this came up as a suggested video.
Mooneys are cool. Is it just that tail?
@@AgentJayZ Ye, that and they are just sleek machines and a classic. Thanks
The boss is very happy and satisfied !
It's not necessarily two different alloys. You can achieve the same result by applying refractory clay to the center while heating the outside portion above the Currie temperature and allowing it to cool gradually. If it was a Samurai sword, the boundary would be a hamon.
I have a question about disassembly of the same turbine... Does removing blades necessitate shearing each pin, and punching out the broken pins ?? Or do they get drilled out etc ??
This video is part of a playlist...
Your videos are awesome my friend，I am a jet engine lover and its great to see you operating them. Maybe you can make some time-lapse videos to show the disassemble or assemble process of a jet engine.😊
A little bit of trivia from Wikipedia on the Canadair Sabre. In 1952, Jacqueline Cochran, then aged 47, decided to challenge the world speed record for women, then held by Jacqueline Auriol. She tried to borrow an F-86 from the U.S. Air Force, but was refused. She was introduced to an Air Vice-Marshal of the RCAF who, with the permission of the Canadian Minister of Defence, arranged for her to borrow 19200, the sole Sabre 3. Canadair sent a 16-man support team to California for the attempt. On 18 May 1953, Ms. Cochran set a new 100 km speed record of 1,050.15 km/h (652.5 mph). Later on 3 June, she set a new 15 km closed circuit record of 1078 km/h (670 mph). While she was in California, she exceeded 1270 km/h in a dive, and thus became the first woman to exceed the speed of sound.
Since the pin has a bevel, does it need to be inserted in a specific orientation? How do you know if the pin didn't roll inwards (like a sleeve) if it got stuck at the edge of a blade. What if the bore where the pin goes is wallored out and your punch actually spread the pin instead of pushing it. What if ... what if... gosh... I can never do this job!
Wallowed out?
Sounds to me like you've never driven a roll pin... right?
Ok now, let's get back to reality.
@@AgentJayZ right
So why not have some kind of tube around it to prevent it from bending ?
Tube around what? I think you might need a tube. Maybe you are the tube?
Friction weld for the turbine disk?
It was designed and manufactured long before the friction bonding process was developed. As I've said in my conversation with Mr yabo jabo, I'm puzzled by what I see.
Hi, I wonder what happens if you would accidentally swap the blades, would it cause any damage?
That would increase the amount of imbalance... maybe even in excess of the allowable amount. It's really important not to get the blade positions mixed up.
How did you get them out the first time?? Very Cool to watch this. I am now subscribed.
He removes the disc stripes the blade sharing the pin
This video is part of a playlist. Nearer the beginning, I have a video about removing the blades.
@@AgentJayZ Thanks! I will go watch.
You mention that if you mess up with driving the lock pin in that you need to remove the turbine wheel to remove it. Why not install and pin the blades before installing the turbine wheel?
Because when you move the whole assembly around you could damage the blades if they contact anything. Meaning you'd have to dismantle it again and replace the blade that got dinged. Imagine 400lbs of that thing dinging one of the blades, like if it turned accidentally into something.
@@youtubasoarus Thanks and I do get that, but if Jay was to have messed up a lock pin he would have had to remove a partially bladed T-wheel and still run that risk. The device he made to install the wheel into the engine was pretty slick and looks like a good way to handle the wheel with care to the blades and bearings. I guess best practice is to install an empty T-wheel into the engine and make sure you don't mess up installing the blades. Was a very informative video. I worked on B-52's as a crew chief for years and did alot of work on the engines but never inside the engines.
I am confused, aren't the blades wiggly to avoid resonance in the shaft? they felt locked at the end of the operation.
This engine was designed in 1947, and does incorporate any of the many things we have learned since then.
We rebuild engines to factory specs.
We do not do any re-engineering, except for the thermal barrier coatings.
The blades slid freely into their disc slots, which obviously meant that there was some clearance. The blade locking pins were driven into clearance slots in the blade roots. When the engine is running, the blades will not "wiggle", as each one is being restrained in its disc slot by a force of several thousand 'G'.
1:10 There is non magnetic steel. But that part could be inconel.
It's made of Timken 16-25-6 alloy.
probably a good practice to index the split on the roll pin to the 3 or 9 o'clock position to ensure equal pin to blade interface.
Better practice is to follow the manufacturer's instructions to the letter.
Hello AgentJayZ
I just started watching your videos. I enjoy them immensely!!!!!
My oldest son graduated from BCIT AME course. He wanted to become an airline pilot. (His lifelong dream since I can remember) but we found out he was colour blind! He ended up trying the next best thing, AME. But...it didn’t work out.
Basically a huge wage gap between what he is doing now to what ‘might have been his potential’.
In any case... I live in Chilliwack and own a 10 bay automobile repair facility and appreciate all your efforts in producing these videos.
One day I would love to acquire some engines parts to make some type of unique gift for my son. If you think you can help, please let me know.
Thanks again for your impressive efforts!
It's weird seeing these blades out side of the shop I work at. If I had to guess on the materials of the disk I'd almost say that its 2 different grades of Stainless Steel.
Fascinating. Thanks. You were not consistent with the orientation of the split in the split pins. #92 was to the right and #96 was to the left. I've no idea if it matters - presumably not otherwise the manual would say so and you would do so if it was important. However, that's what I noticed. Greetings from Australia. ;-)
Not a significant detail.
That roll pin punch is a lifesaver
Are those roll pins anything special or just standard spring steel?
Genuinely im curious what is the reason they have to be returned to their original position and what would happen if you ran the engine with lets say, blade 49 in slot 93? I assume its a balance issue, but idk.
Yeah it's a balance issue. It's explained in the video. You definitely DK, and can't be helped, apparently.
AgentJayZ lol thank you for answering my query.
@@AgentJayZ only balance or also tuning to avoid flutter?
@@hurrdurr3615 What’s the difference ?
I have a random question in regards to turbines. If the second stage is not smaller than the first, would it cause problems?
I'm only guessing that you are making the most common mistake, and that is calling a turbine engine a turbine. And you really mean to say compressor when you say turbine. If not, then your question makes no sense at all, because turbine stages always are larger downstream. Also, the word random instantly applies a 90% discount...
AgentJayZ nope, was calling up the exhaust turbines. So they need to stage larger. Alright, need to modify my designs then. Thank you!
AgentJayZ actually, I guess I probably am using the term wrong. By larger I mean larger room for air flow with larger blades
From what I understand the outer portion of the turbinewheel is an inconel alloy and the inner shaft is a 300 series stainless.
Someone opined below that moving an already-bladed turbine around the shop would be too risky, is that your 'why' for mounting the wheel first?
How did they do this step during original manufacture?
Hey agent jz how the magnet and non magnetic steel fussed together? Please answer
And how can pull back the pins from their position on disk?
Thanks from your excellent Chanel 🌹
description
Will you be doing a video of the first startup after rejuvenating this engine? I hope so
Austerity transformation in the Nickle alloy. Nickle is an austinite stabilizer. Austinite is nonmagnetic. There's a phase change in the alloy. Cool but still same material
Austenite
2:30 are the blades normally that splotchy? or was some of the coating removed to help balance? or maybe im overthinking it
Is there a computer program that takes in all the blade weights and then tells you which blade goes into which slot?
There are, but they only get you to the point of starting the direct measurement balancing process.
The process of sorting the blades by weight, illustrated in my turbine balancing videos, is equally effective.
I love these hands on video's
Is there any requirement for the orinentation of the roll pin? If you "transmit" tourque with them xou gave to what out where the slit goes because otherwise they wobble out of the hole...
Why wouldn't you use a spray on dye to penetrated that area where the two metals meet and use a spray on leeching agent to pull the dye out of any cracks if there were any. I recall back many moons that I used that method for this same application on larger turbines.
That is exactly what was done... exactly where the overhaul manual specified it be done. No dye penetrant was wasted on fulfilling personal curiosities.
If you made a mistake, couldn’t you just drill out the deformed pin with an undersized, soft drill bit? Rather than disassemble the turbine?
Just curious.
If you could be absolutely certain that the drill bit is so soft that it has no chance of damaging the blade or the wheel. Personally I would never consider myself sure about that.
What I might try to do is to take an undersized hard screw and screw that inside the deformed pin and then try to yank them out.
MVHiltunen .... That’s a good idea. We use drill bits of specific hardness all the time, so I’d be comfortable with it. I think your idea might work better, unless the deformation of he pin is so great you leave most of it behind.
There is a procedure to remove the pins. Making up a new one because you think it might be faster or easier is the kind of thing that gets you corrected, redirected, and then fired. Got it?
When will you dopes get it? There is no alternate procedure, and your ideas are garbage. Don't waste your time typing them.
If you accidently drill away something that is not the pin you will unbalance this piece of equipment at the worst area. as you can see he measured every blade and wrote its weigt in .1 gram steps on it. pretty sure that you will drill to deep or at an ange and get serious problems.
It seems you use regular masking tape to label the blades. We have always been told that graphite pencils and tapes are a big no-no on the hot end because they can cause intergranular corrosion leading to catastrophic failure. Do you take the same into consideration when taping the blades?
No graphite used.
Good music choice. It’s what I would be playing!
That was stressful! I've snapped bolts on my Moto engine a few times over the years and just backing those bolts out creates anxiety. Being 100% is just that. 100%. Sigma 6 doesn't work here. Thanks for the great video!
"Pin" Floyd--good choice. Either that, or Led Zep-pin.
Are the turbine blades "moment weighted" or mass weighted?
You can do it either way. These were mass weighed. A lot of people would say that isn't good enough.
Our balance machine says it is.
How do you "moment weigh"?
how did you get the pins out to begin with?
from his explanation it sounds like you strike the blade at the root joint with enough force to just simply shear the pin.
This video is part of a playlist. The first one is called removing blades.
I must say.
I am impressed by your meticulously methodical approach in handling this piece of engineering beauty.
Multiple questions arise, such as:
1.) I wonder what the weight of those fins are (individually..and total).
2.) Also..silly question but..do you plan on cleaning your number markers or leaving those on there? Would they affect the balance or something? (I realise it's micrograms in weight..so I assume no balance issues compared to the weight of those fins but can't help but ask?)
3.) Are you gonna ask your boss for a raise?
=)
Individual blades weights are written on them.
The smallest weight difference we can effect is 0.1gram.
I am the boss.
@@AgentJayZ I thought the boss was your cute pooch cuz you keep on referring to him as that? Was a joke...
Anyways..thanks for the reply. :)
Nicely done, attention to detail pays off when it counts. I know that adding insurance into a process usually takes away from the focus and attention to complete a tedious task such as this. In this circumstance however, would it be beneficial to insert every pin partially around the entire circumference without the blades in place, so that in the event of a pin install error it can be knocked outward from the inside? The pins seem like there is significant engagement before the blade is engaged, just a thought. Out of curiosity, what is the tolerance for the balancing process?
That is a good idea.
5 grams.
This one is balanced to 0.2 grams
Oh my goodness the boss is adorable your videos need to include the boss much more
Drive in 1 pin = 1 big sip of beer. Repeat until run out of pins or beer.
This process step is taken directly from GE Gas Turbine rebuild manual in the electrical generation Thermal Power Division.
It's also described and illustrated with photographs in the GE J47 overhaul manual.
great music choice to listen to while working
Pink Floyd and engine building! Can I come work for you?.....
Very exacting and tedious with no mistake recovery. I hope you have limited control on your job deadlines. I would hate to do this under back to back down to the last 15 minute rushed absolute must meet deadlines.
I am lucky to be able to take my time to do this job.
Pink Floyd is the best soundtrack for life
Do you use dye or anything to check for cracks or just a visual?
I used dye penetrant on the turbine disc. The blades are new, so no inspection is required.
@@AgentJayZ thank you for the reply! Do you have any experience with small engines? I'm working with a company that's building an aircraft with a PBS TJ-100 engine, 1300N thrust. Would be interested to hear your thoughts on the smaller units.
Is there a similar video for nozzle guide vanes and other parts as well ? I loved this one.
Hundreds of videos on my channel. We cover almost everything. Put those words in the search bar on the channel page, and see what comes up.
About 100 horsepower per blade?
,,, quite a bit more, that's what it takes to drive the compressor section .
Probably nearer 150 horsepower per blade. Compare that to the 1,000 horsepower per blade (according to R-R) in the HP turbine of a Trent engine.
I used to work for Ontario hydro. Nuovopigneone gas turbines. 14000 killos,shipped in sealed vessels. "Air". Those 1/4" ×3/4" long pins that you use..I know they don't brake stait(crack) down the middle. How about laser print them with a Zig.Zag ..maybe ten thou gap.you know EDM as you mentioned. Your videos are totally awesome. Orenda. Brampton Ontario. CANADA. Big big turbines.
No need to re engineer things that work well. The pins shear as they are designed to, despite you knowledge that they don't. They do.