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So, does this mean that when replacing a faulty nh36 movement , I need not concern myself with the crown position on the replacement movement, as long as my old day wheel is intact and can be used in the New Movement?

I recently came to the same realization after buying one of your practice watches and deciding to replace the movement. When looking at the two options available for the NH36, they were for 3 and 3.8. Being a watch mod newbie and a detail junkie, I had to reconcile the difference before buying. I appreciate what you are doing and all of the content you put out. Thanks Marc.

Great video Marc! I had the same realization about 2 years ago and when I explained the math to a buddy his eyes just glazed over. You are a better teacher than I am.

Absolutely fascinating episode Marc! Always love seeing you flex those engineer muscles 💪 You totally need to put “It’s not a 4 o’clock crown, it’s a 3:46:27 crown” on a t shirt or something!

He's made me appreciate watches and I picked up a few but I don't think I'm really a "watch guy" but I just love seeing someone who is passionately nerding out about some weird thing about a thing he's interested in that no one else should care about, and yet you're taken along by just his questioning and persistence and how much he cares. It's like a universal language.

I’m a data analyst at a big utilities company in the NJ/Long Island areas and I find myself thinking of little details from my work as I doze off to sleep. This is such a small detail, I love it. Great video!

I was shopping for dive watch cases just a couple days ago for a Seiko mov't. and was wondering why some of them were described as either 3 o'clock or 3.8 o'clock. Now this confirms what I figured. Thanks, Marc! :D

HAHA! Thanks Marc, that was a fun clear refresher. It's amazing how most of us labored through so many maths from childhood to college then forget almost all of it by the age of 30.

All I know is, the fact that the day and date line up perfectly on my SKX means it’s a keeper for life. Bought it at LIW.

Loved this episode! Could not stop smiling all the way through 😅😂🤣

Great episode, I would love to see more of this kind.

Thanks, now when I hear people say 4 o’clock crown I’m going to correct them vigorously.

Love the Red October Watch! Keeping my eye out for a possible “Re-Release” of that one!

Great video! Many thanks for sharing. The older Seiko 7002 has a very similar case to the SKX (you can put the same bracelet on etc), but it has a only date movement and the crown is exactly at 4:00.

different date wheel??!? Why can't they just have two sets of holes/slots on the wheel so that it can be aligned either way?

Great video showing the difference. Thanks for taking the time. I prefer the NH38 or Miyota 9039 myself. I'll choose a no-date, no ghost position every time when the option is offered. If the time should ever come to replace the movement I don't have to worry about matching the date disc colors, etc. Finally, not having a cut out on the dial just gives the trinket dial better symmetry to my eyes. One of the favorites I own is the OMEGA Railmaster with the no date 8806 movement. It's essentially the same as the 8800 minus the date. The dial on that is a thing of beauty without the date.

I definitely feel like a need now. Have not thought about math this much since college.

Seiko used to make 4 o'clock crowns like the original Willards and 6105-8000s but for some reason they switched to 3:45. Some Chinese companies make homages to vintage seiko drivers with true 4 o'clock crowns which can mess up the day window if you swap out the dials

No need to apologise,I watch and learn....very informative and interesting.Thank you.

When they came up with offset crown positions, Daini went with 3:46 and Suwa went to 4:00. The new Seiko Land Turtles seem to have a true 4:00 position on the crown

The most deserved 👍 ever. Thanks!

Lol. I’m not sure I ever needed to know or ponder that but now I know. Somehow it was interesting enough to keep watching.

I love the sweaping hand wall clock

Brilliant! Watching the day/date line up at 4 o'clock (sorry, 3.46!), was revelatory and strangely satisfying. Call it geekery, call it smarts - there ain't enough of it in the YT horology universe!

Like being back in school, it's a lesson that needs to be learned. Instead of always handing out the lesson. Thank you.

Thanks for an interesting video. A question I have: My SKX007 has a 7S26A movement. I read here in the thread that the A and B versions cannot use the existing wheel when converting to an NH36 work. Is this correct? and is there anyone who can answer how I can best get an NH36 to show the day and date correctly in my old SKX007 from 1999?

Tuesday 29th still didn't line up on the 4 o'clock crown NH36 movement. 😂

I tried to stuff the movement and dial from my ISL-21 in to a Seiko SNK80x case and the hands were too tall but I discovered how you keep your chapter rings lined up. Simple. I'd do the same with the bezel, put pegs on the insert so it locks in perfectly aligned into the bezel then put the teeth onto the actual watch case so it is perfectly aligned. Then put the click spring that jumps one tooth to the next on the bezel itself and a gasket inboard of the springs to center it.

Very interesting. I'm a software engineer and have written clock algorithms for user interfaces, so definitely right up my street! Thank you Marc :-)

If there ever was a question if you are or not an engineer all went away with this episode. Very interesting presentation, I would not have wondered on my own but now I know.

Wow that is interesting. I always wondered why the low numbers on the date window were bigger than the larger numbers.

Love the way you think Mark! And it makes perfect sense, you're left handed! Great tutorial, thanks.

tell me you're an engineer without telling me you're an engineer lol

I always assumed the 3 and 4 o clock movements were the same. Just in different cases. Thanks

Always wondered about that, thanks for the explanation

That was a wonderful bit of OCD, Marc! I, for one, loved it. That's the kind of information I will never forget once I assimilate it. Perhaps you could answer another question that has been bothering me for quite a while now- What is the terminal velocity of an unladen Swallow?

Oh I wish I had a mathematical mind.when you explain it it makes sense but I could never figure that out like you did with such ease.

Us that own a 7002 and an SKX are familiar with the 4.00/3.45 crown thing! They still both get called the 4.00 o'clock though!

I love "Watch Nerd" videos. It proves to me that I am in a "community" of people who share an interest. I guess my high school teacher was right; I will need math later in my life.

We have been lied to!!! The 5 Seiko principles are probably a lie too 😭😭 I don't know how to live anymore

Thanks Mark, I enjoyed that learning.

Thanks Mark - you have totally messed up my OCD now I know my beloved SKX007J is imprecise by design - the excuse I needed to swap it for a 63MAS :)

Another knowledge gained. Thanks Marc...

My old school 7002 diver has a true 4 o'clock crown. They changed it with the skx line and everyone started calling it a 3:45 crown.

For the first 2 minutes of the video I just went what the hell is Mark talking about. And then it hit me. And then I was like oh my God that is awesome. Mark, you're such a nerd. And such a watch enthusiast. And that's why we love buying from your brand.

This was awesome.. feeds my engineering brain.

There are 30 deg between hour markers, so each degree represents 2 minutes past the hour. So 23 deg past three is 46 minutes past three.

Hey Marc, at least the case is not too late, the crown is just a little bit before 4 o'clock, better than right on time.

This is the exact reason why I have not purchased any of the recent ‘affordable’ Seiko Willard reissues … the crown is not at 4! Peter Korea made a great video on this a year (or so) ago. The original 6105-8110 had its crown at the 4 marker, yet Seiko persists in not doing so on their cheaper reissue models. Why? I cannot explain. Until then, I wear my Turtles, a Steeldive and Smiths homages. Thanks for another great video, Marc.

That was fun, ok next calculation, the Jacob & Co. Astronomia Tourbillon. That would be extra fun.

Great vid Mark. Now, I can sleep tonight.

4 o clock is an 18.5 minute past movement. That's how I mount the dial when modding using these movements.

I'm glad I'm no longer OCD now that age had has caught up. The reason I like the four o'clock position is that it keeps the crown out of the way. I wonder how many crowns get ripped off Tanks and Santos. ALSO, some high end watches have the dates off the 3 o'clock or 6 o'clock

From one engineer to another, thoroughly enjoyable geek out!

Seiko's divers that came before the SKX had the crown at a true 4 o'clock position, the 7002, 6309 & 6105 etc. Not sure why this changed with the SKX, but I also have a Daini made 7019-6010 from 1970 which has the crown at 3:45 like the SKX!

That was a rabbit hole I did not need to go down. 😳

Muc off does OK but probably not strong enough? But is good anyway as you can spray it on brakes etc. My engine on 50yr old bmw r60 came up well when I first used it. But we.re not talking shiny. 😊

Just to confuse things, the 6105 8009 has a true 4 o'clock crown as does the NH powered, near clone that appeared recently.

This is how it is when you’ve got an engineering background: you won’t rest until you figure it out. 🤔🧐🤓 😉

If anyone doubted that you were an engineer before selling watches their doubts are gone now!!! 😆

It's 3:45ish. I do movement swaps for SKXs and clients were always asking if I could get an NH36 into a 7002 case. You can't because the 7002 is ACTUALLY a 4 o'clock crown and the day wheel will be off.

So this only applies if the dial has day/date window. If you have a dial with only a day window you can use the movement in a 3 o’clock or a 4 o’clock crown.

Just cost cutting at the minute scale by the watch company, saves them from having to print both day and date wheels for a true 4:00 position, simply mass produce cases with the slightly off 4:00 crown position to use the same date wheel in both positions. My Orient Triton handled the 4:00 crown by placing the date window at 4:00 and not having a day of week indicator.

Loved it! Thanks!!

The 34627 crown. As always, amazing video, thank you sir 👏👏👏

Hahaha I've been eyeing my islander this morning and saw your notification about the 4 o'clock position and I can't unsee this

Arithmetic always gave me agida. I have a MA in history, but have to take my shoes and socks off to add up to 20.

I never thought about this before, but it would surely bother me too if I had. Thank you for both introducing me to and solving the conundrum simultaneously. 😆

As a modder this video answered some nagging questions for me. Cheers Marc.

The 7548’s, 6309’s etc etc are true 4 o’clock crowns. The later watches from IIRC the 7002 cases onwards (incl the SKX’s) are about 19 mins past

I enjoyed the episode, but I'm a nerd so I'm going to enjoy anything with math. 😊

learned this when i was ordering a NH36 movement for a build - had only two version listed - crown at 3 or at 3.8

Thanks for the great explanation! My brain hasn’t worked that hard in a long time. Lol Have a great day! 👍🏻👍🏻🇺🇸

Thanks mark. Very informative. I've recently purchased the parts to do my first build. A Seiko Samurai with a 3oclock crown and for the life of me I couldn't work out why there is a difference between the 3 and 4 o'clock movements. You have answered my question. Thanks. Keep up the good work. I also have a keen eye on the build as well. Cheers.

From now on I will refer to it as the 3:46 crown lol Great video!

Can also find the minutes by dividing 360 by 113.23 ,which gives you 3.179 , Then divide 60 by 3.179 = minutes

You're not crazy Marc ! Bright? Yes

Talk about seikos with the crown at 4 o'clock too. 62mas reissue is not 3.8, it's 4 o'clock. Most vendors just look the other way. Us modders need clarity.

I've noticed that my Seiko 5 Actus 6106 from 1970 has a four o' clock crown, but the 5s and my SKX with 7s26 has the ~3:46 placement.

Next, Mark explains the effects of Heisenberg's Uncertainty Principle on Seiko rehaut alignment... 😏

Spoken like a true engineer 👍

You just really re-defined what it means to be OCD in my mind. With that said, this was interesting.

I did the same but using a maneuvering board and the watch itself as a ship at sea.12 is relative north 3=90% 6=180% ect.. and I concur 113.46 relative from the 12 o'clock.

Dang! And I have been looking in down on mine for 20+yrs

That's EXACTLY the kind of stuff I use to go and sleep :-). Thanks Marc for this funny one. I actually realized my SKX009 crown was not at 4 a few days ago...

Nice! I'm not a math whiz but you made it understandable.

if in doubt find out. That's why you started & run Long Island Watches. If you really love what you do you'll never work a day in your life. YOU JUST PROVED IT!!!!!!!!!!!

What drives an engineer to distraction every day of their life…? They never stop asking themselves the question…WHY?

Great vid ,cool info thank u Marc

The 6309’s were the ones that had a true 4’oclock crown.

Love this

Date wheel reusability is also the reason almost all 4:30 date windows in Seikos are at 4:33.

Marc you just blew my mind! I don’t understand a dang thing you just did

Welp, that's enough math for me for today! Wait, who am I kidding? That's enough math for me for the rest of the year! Thanks Marc...I think.

Does this mean, that I can replace a dial on a 4 o'clock movement with a 3 o'clock date only dial and it will fit just fine?

I have an old Seiko diver from 1982 where the crown is placed exactly outside the 4 o'clock position. How can I find a new NH36 atomatic movement who will fit in this old case. Great video thanks for sharing.

Brilliant.

Interesting. Thanks.

Thank you for showing the math that was really cool I'm not good at math so it's kind of exciting that I can understand this

Staples has to pay for this, period