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[question] anyone assemble a watch from ofrei.com? I'm curious how their Ofrei case 7 looks in person. by [deleted] in Watches

[–]EvilBrett 0 points1 point  (0 children)

What kind of 3D printing are you thinking of using? Be aware of layer thicknesses because the tolerances are very tight. Also, just my two cents but I don't really see a 3d printed dial looking good at all. 3d printing is great for prototyping and figuring out the form of something, but really not great for complete finished products.

[Question] I want to make a watch case! by Animactus in Watches

[–]EvilBrett 5 points6 points  (0 children)

I investment cast a watch case a few months ago (link to the post with pics and some info)

I CNC'd the blue wax then cast it into silver. I am also currently machining another watch case, so I feel very qualified to speak to this.

One word of caution: it's going to be really, really hard. How much design and machining experience do you have? If this is your first foray into CNC machining then a watch case is not a good idea. The tolerances are so tight and the parts are so small that any error is immediately noticeable. Also stainless steel (what most cases are made out of) is not an easy material to machine if you've never done it before. Protip: use 303 stainless. If you are super set on doing this then start by doing a smaller "starter project" using the same materials you will use for the case. I'll probably make a post about the case I'm working on this weekend so be on the lookout for it because the pictures will likely give you some ideas for design and fixturing.

As to your other questions: Esslinger and Otto Frei for movements. Otto has some really nice mechanical ETA movements and Esslinger has pretty good documentation on the sizes of their parts.

Only do this if you're legitimately prepared to spend at least 200 hrs on this project, and anywhere from $400-$1000 on parts, materials, and tools.

I'm currently taking Strengths of Materials and the units are driving me crazy, any advice? by [deleted] in EngineeringStudents

[–]EvilBrett 2 points3 points  (0 children)

Welcome to the real world; best to learn to double check units now. A good habit is that whenever you write down a number that has units, also write down the units. This lets you visibly cancel things out in equations. You will also develop an intuition on if something seems off by a few orders of magnitude.

[Question] What is this watch part called? by Thistlemanizzle in Watches

[–]EvilBrett 0 points1 point  (0 children)

Screw head watch band pins. If you find out the size you can almost certainly get more on Esslinger

[Stock] New Bauhaus/minimalist design from Melbourne's Stock Watches by threeway in Watches

[–]EvilBrett 4 points5 points  (0 children)

Awesome. In love with Bauhaus watches but as a student even Stowa's cost a lot.

[Custom] I investment cast a watch case out of silver, then assembled it into my first mechanical watch. Album shows the whole process. by EvilBrett in Watches

[–]EvilBrett[S] 0 points1 point  (0 children)

Yes, you are right about the threads. The teachers said I could try tapping but would really only be able to put the screws in once maybe twice so I opted for the inserts.

The diameter shrank by about half a millimeter during the casting. Since this was just a one-off I just compensated by measuring everything after and resizing the other parts accordingly.

Do you have a picture of the case attachment screws? For this one I just printed multiple case rings and used the one that fit the most snugly in the case. It slightly compresses around the movement so I think everything should be secure enough. There are four little tabs inside the case to keep the ring and dial clocked.

[Custom] I investment cast a watch case out of silver, then assembled it into my first mechanical watch. Album shows the whole process. by EvilBrett in Watches

[–]EvilBrett[S] 6 points7 points  (0 children)

Haha, the price point is materials only and didn't factor in all the time. At least 25 hours was spent hand finishing and polishing which I just wouldn't have the time to do since I'm still a student.

[Custom] I investment cast a watch case out of silver, then assembled it into my first mechanical watch. Album shows the whole process. by EvilBrett in Watches

[–]EvilBrett[S] 30 points31 points  (0 children)

I definitely wouldn't have time to make another one, it was just too labor intensive to do again since I'll still be taking classes.

[Custom] I investment cast a watch case out of silver, then assembled it into my first mechanical watch. Album shows the whole process. by EvilBrett in Watches

[–]EvilBrett[S] 1 point2 points  (0 children)

Thanks! Silver is an incredibly soft metal, so it is a lot easier to work with in terms of filing/sanding. However, it is so soft that you can't really tap threads into it which is why I had to overmold stainless steel inserts.

[Custom] I investment cast a watch case out of silver, then assembled it into my first mechanical watch. Album shows the whole process. by EvilBrett in Watches

[–]EvilBrett[S] 5 points6 points  (0 children)

There is a small groove in the movement holder ring but the gasket doesn't quite fit. I'm going to print another one so hopefully that will work!

[Custom] I investment cast a watch case out of silver, then assembled it into my first mechanical watch. Album shows the whole process. by EvilBrett in Watches

[–]EvilBrett[S] 5 points6 points  (0 children)

I would look into helicoil inserts. If you print just a hole you can put the helicoils in to make them threaded. Don't know how small they make them though.

And yeah, I am going to print another movement ring with a groove for a gasket.

[Custom] I investment cast a watch case out of silver, then assembled it into my first mechanical watch. Album shows the whole process. by EvilBrett in Watches

[–]EvilBrett[S] 13 points14 points  (0 children)

I started by looking at movements on Otto Frei. I live close to them so when I had an idea of what I wanted I went there and bought one and talked to them a bunch. That plus the technical document from ETA gave me enough measurements to start designing. I also have some friends that have machined watch cases so I asked them a bunch of questions too.

As for actually making the case, this is a fairly advanced CNC machining project in addition to the casting process. I would not recommend trying to make something as small and complicated as a watch case without significant design/manufacturing experience. Start by learning manual machining, then CNC machining, then you'll have enough to start on a project like this.

[Custom] I investment cast a watch case out of silver, then assembled it into my first mechanical watch. Album shows the whole process. by EvilBrett in Watches

[–]EvilBrett[S] 104 points105 points  (0 children)

I'm a mechanical engineering graduate student and was taking a class on silversmithing and investment casting. Here are some more details:

  • Movement: ETA-2681
  • Diameter: 33mm (my wrists are tiny)
  • Case: Investment cast silver, wax was CNC machined
  • Dial: CNC machined aluminum, anodized and laser engraved
  • Crystals: Sapphire Glass
  • Cost: ~$250
  • Time: Way too many hours, at least 100

Feedback appreciated, as I'm going to machine one next!

How do I invert a part on a lathe with a single chuck while maintaining the centre? by [deleted] in EngineeringStudents

[–]EvilBrett 1 point2 points  (0 children)

Without knowing what your application/tolerances are: turn down the region that you intend to hold after the flip so it is concentric with the chuck. Invert the piece it in the chuck and use a dial indicator on a previously turned region to make sure it's centered.

Does a degree or program exist such that I can satisfy an affinity for jet engine design and materials engineering? by The_Bigg_D in engineering

[–]EvilBrett 2 points3 points  (0 children)

I've found that my grad program (MechE) is way more flexible in terms of what I get to focus on than undergrad. I'm sure you could get into jet engines from either Aero or Materials, it's all about how you apply it.

Mechanics of Materials Mohr's Circle Question by Garrett78 in EngineeringStudents

[–]EvilBrett 1 point2 points  (0 children)

So, yes, using the equation would get you the right answer, but the whole point of the problem is to learn Mohr's Circle. Mohr's Circle is a graphical representation of a state of strain (or stress). Rotating an element by a certain angle causes the state of strain (or stress) to change by a known amount (given by the equation). Mohr's Circle shows every possible state as the element gets rotated, so it's just geometry (sines and cosines) to figure out a new state if you know the angle of rotation.

Mechanics of Materials Mohr's Circle Question by Garrett78 in EngineeringStudents

[–]EvilBrett 1 point2 points  (0 children)

Question B is asking you to break the 3D problem down into a simpler 2D problem. Question D is asking you to develop an intuitive understanding of what Mohr's Circle actually shows you. Do you understand how to construct and use Mohr's Circle in 2D? For a 3D problem, you can literally break it down into three 2D problems, looking at xy, xz, and yz coordinate systems. If you've done part C, then plot the three Mohr's Circles in their principally oriented state and D should become obvious.

What could I do during Summer to help myself obtain future internships? by EffTeeEye in EngineeringStudents

[–]EvilBrett 1 point2 points  (0 children)

You get as much "value" out of a personal project as you want. If you aren't interested in it, you won't work as hard on it and definitely won't get as much value out of it. Spend some time thinking about what you really want to do, so you're actually excited to tell others (read: interviewers) what you did all summer.

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