On vacation till 4th of April

Hello,
I will be on vacation till the 4th of April and I will not have internet connection. Out of the "real world" for around 5 day!
Take care! 

Dive watches

Here you are three pictures of the same dive. The first picture is my dive computer, an Uwatec Aladin prime, the second picture is a Timex Helix and the third one a Casio SNK-200.

As you can see the mesurements of the three devices are very close. I wore the Uwatec and the Casio and my buddy the Helix.

It's nice to see that my two cheap back ups give the same values as my real dive computer. The two devices I wore only have a depth difference of 20cm!! and 1 minute of total dive time!

The Helix had around 4 more minutes of dive time because my buddy was more time underwater (I use to breath more than her)

I still don't have more dives to compare the tree devices but this first exam was passed with flying colors!

Design Tip - 8

This design tip is the first one about the friction design. Parts that have to move one over the other need a good design in order to get a smooth movement.
If the use of PTFE or PTFE filled material is not possible for cost reasons, and the use of POM is not possible because the parts have high aesthetics requirements (as explained on Design Tip - 7), the design of the friction areas is even more important.
This first tip is about to avoid 'surface to surface' friction areas. The attached sketch is simplified to a flat surface but it also applies to not flat surfaces (even more critical); the movement of the part is normal to the computer screen.
It is impossible to get a perfect flat surface (tolerances exist!), so it is also impossible to get two flat surfaces, if we want to move an not perfect flat surface over another not perfect flat surface we don't know what will be the friction area, so the friction area is out of control. 3D shaped surfaces are more difficult. An out of control friction area means that the movement could be smooth or not, the friction force could be high or low, etc.).
In order to have a controlled friction area, a 'surface to point' or 'surface to line' area has to be defined. The second sketch shows this kind of friction combination. It is a section cut so it could be any of the 2 friction systems. The friction "ares" will be points on the first system and lines on the second system. They are controlled surface areas with low friction force.
The second sketch also has a another tip included in the design. The "flat" surface has 2 slots, so the friction area is in the slot and not on the main surface of the part. The part slot will be a "bump" on the mold. This king of "bump" is very easy to polish. Friction surfaces have to be polished but it is not necessary to polish the entire part, so with this small tip we are helping to have a more robust mold. Apart of the polishing, the defined friction surface is very easy to modify. If after first Tool Try Out we realize the movement is not correct, the surface could be adjusted easily. My suggestion is to leave a small gap on the design in order to be able to modify the mold in a cheaper way (steel safe, no weld required).

Design Tip - 0

This Design Tip do not has number because it is not a tip. It is a question. 
Why is so difficult to find a good plastic part design forum where to share our experiences?
It is quite easy to find general and not so general information about plastic part design guidelines, but sometimes you have a particular problem that any guideline seems to solve. Then the experience of other people could be the solution. But, where are the people?
I'm not planning to open a forum here (at least not now). First of all I will need a good number of users to have the chance to be a useful forum. A forum with one or two posts per day is not the way to solve the things. The other point is I've never create a forum but I think this won't be a big deal, nowadays there are pretty good solutions for non expert admins.
If you are interested on this plastic part design forum just leave a comment. If you know a good forum, please also leave a comment, maybe I did not search properly (this should be the problem, I could not accept that there is not any good plastic part design forum on the net).

Timex Helix - Dive watch

I own this watch from time ago but never did a review (mini-review) of it. I think I have to. It is a digital watch with scuba diving functions. Not a diver shaped watch but a diver at the end.

The watch is quite big. It is much bigger than the Casio DW-280, and that Casio is not a tinny F91w.

The screen is quite big, it has 4 information lines. The main line has large and easy to read digits, the secondary line has smaller but big enough digits and the upper and lower lines have smaller digits.

It has the basic functions such as time, alarm, stopwatch and timer. To select the functions the crown has to be turned when in standard position. Quite original for a digital watch. Pressing down the crown the typical Indiglo illumination from Timex is activated. The crown also has two pull out positions for adjustments and to recalling saved data.

In the lower part of the watch there is a lock button that blocks the button and crown functions. It is a useful function to avoid accidental actuation during diving.

Apart of the basic functions, this watch has two dive modes. The Dive Track and the Dive Chrono. The Dive Track seems more useful, it gives you the current depth, the temperature, the diving time and the hour. After the dive you can recall the diving time, the max depth and the temperature (I think it is the min. temp.)

The Dive Chrono mode is quite strange, dives are considered 'segments' and the watch adds the diving times depending on the watch configuration. I think it is a kind of freedive mode but not so successful. The watch logs the last 20 segments (dive time and max depth), it also logs the surface time. I've never used this mode.

The watch could be set up in Metric or Imperial modes.

The band quality is quite high taking into account the price of the watch and the many functions it offers.

I've not deeply used the watch, it only has two dives. One is shown on the picture, max. depth of 10m and around 1h of dive time. The second dive was a little bit deeper (around 15m) but shorter. The watch worked perfectly and gave same measurements as my dive computer (Uwatec Prime).

It is quite curious that the watch is rated water resistant 50m! So suitable for swimming, white water rafting, no snorkeling water related work, and fishing... but it is able to measure the depth!

The hilarious user manual could be downloaded here:

http://www.scribd.com/doc/28993166/Timex-Helix

 I hope I will use it deeper this summer; I will try to understand the Dive Chrono mode and see if it is useful for freedive.

In my opinion it is a very nice watch for diving or snorkeling. It is a toy not a dive computer, so I will never suggest to use it as a primary depth meter. It also seems to be a good present for child but be careful with it, to try to go deeper is a VERY dangerous game. Remember freedive is not a game it could be a HIGH RISK sport if you don't follow the rules.

Vostock Amphibia

Is really Vostok near to close?
The website is not working for some days.
Not more Amphibias & Komandirskies? :(
Hopefully there are a lot of this watches at ebay or at Meranom, this last shop is directly linked from the non working Vostok web site. As could be seen the picture is from Meranom.
We'll see what happens with the most known Russian watch factory.

Casio SUF-110

Here you are some pictures of my "new" Casio SUF-110.

It is a 90s Surfing timer watch from Casio, it is using the module 942 and I'm looking for the instructions of this watch. Anyone can send me a copy?

This watch came in better condition than the DW-280 of a previous post. Just a simple clean of the watch, battery replacement and gasket greasing was enough to give a second life to this nice vintage watch.

The only problem of the watch were 2 scratches on the screen. One was big but not deep while the other is small but deep. To remove not deep scratches is quite easy using the correct product. I'm using Xerapol for this repairs. The deep scratches need a big polish of the screen, using a fine water sand paper before the Xerapol. I did not try to remove the deep scratch, in my opinion the watch looks nice (could you see the scratch?).  

William Trubridge in Dahab arch

This is not scuba diving, but this video from William  Trubridge is a must see.

More information about this apnea ET in his website.

Design Tip - 7

The resin selection is a really important part of any plastic part design. There are some selection criteria easy to find on Internet but as usually there is not a formula to apply.

In my opinion the thing to check is the experience. It doesn't mater if you don't have enough experience on the part you are designing. It should be people around you with experience on it. So ask the people! Look for the more experienced people in the company, it doesn't matter if they don't work on the design department. Quality, injection, purchasing, process are departments with an important knowledge of resin problems and solutions (maybe they don't know why, but the 'why' is our job).

Sometimes you have to design a part for a completely new application for your company, so you are not able to find information about the right material to be used. Then you have to use other ways, ask Google is one of the easiest ways, look into plastic design forums, look for blogs (why not alti-depth), and of course take a look to your competitors. If you don't have competitors you are so lucky... unfortunately I've always had competitors :(.

In order to compare material properties you need the material data sheet. Sometimes it is difficult to find the data sheets from the resin makers (why? I've never understood why! they should be the most interested on we choose their resins! Well... maybe they focus their efforts on the Purchase department :( ). You can use Campus, a good tool but you also have to download the information from the resin makers (not all resin makers have the Campus ata to be donloades). I know they have now an online version of campus, but I've never use it so I could not talk about it. I use Ides (The PlasticWeb), it is a web site with a large amount resin data sheets ready to be downloaded. Easy to search, a lot of information about UE and US resins (important if you are designing parts for both markets), free registration, etc. There are other sites with good database such as MatWeb, but I'm happy with Ides.

I use to design/review parts that have movement, so friction is important. The use of POM for these applications is a good start, the main issue of POM on my applications is the bad aesthetics properties of this material. Then sometimes we are not able to use POM, but we need to move the parts. It is not a good idea to use the same material on both parts so, if there are aestheticas requirements the use of ABS and PC could be a solution. You'll never get the smoothness of a POM part, so take care on the design of the friction areas and part shapes in order to improve the movement. In summary, if there is friction: POM if possible, do not use the same material in both parts and take care on your design. There are better materials than POM for friction but usually more expensive, PTFE (Teflon) is a very nice material for friction applications, you can also find PAs (nylon) filled with PTFE, a very good but expensive blend. On my current job PTFE is never used for cost reasons :(

Other applications such as chrome plating, limits a lot the possible resins to be used. I've never used other resins than ABS or ABS/PC for chrome plated parts. And not any grade of that materials, most resin makers have special grades for chrome plating.

On other applications I worked with, the cost was one of the most important requirement, so PP and PE were widely used.

As you can see, every application, finish, requirement is limiting the possible resin choose, so list your requirements and choose the resin that could fulfill most of them or the most important ones. 

Any questions on resin selection? Post a comment. I have experience on few applications but maybe another blogger could help you.

Seiko watch date calculator

This link is a must have for all SEIKO lovers. It is the Seiko Watch Production Date Calculator.
It is the easiest way to know the year of production of your watch. Very useful if you are looking for vintage Seikos on ebay :)

Casio JP100W

The Casio JP100W is another interesting Casio watch I have. 
It is able to measure the heart rate by puting the finger on the sensor. 
It is a nice gadget watch from the end of 80s. The manual could be downloaded at Scribd.
This watch is for sale, as some other watches I have. I'm trying to direct my watch collection to water related watches. Watches for diving, snorkeling, surfing or any other water use. 
If you are interested to buy this watch or any other from my collection (not the water related ones :) ), send me an email or post a comment.

Design Tip - 6

Another easy but useful tip. 

When a rotation axis is made half by half, it is easy to have flashes and small miss-adjustments at the parting line. The small flashes or bad adjustments could create an extra friction to the movement and the part will not rotate smoothly.

In order to minimize this issue the round axis could be slightly cut by both sides to have the parting line on a flat (not round) area. The axis working area will be smaller but smooth and small flashes will not affect to the movement.

The second sketch shows the cut axis. The sketch cut is bigger than necessary, it is only to show the design modification. A flat wall of 0.5 to 1 mm is OK on my applications but as explained on the Design Tip - 5, you can not take the number and apply them to your design. You should understand the concept and apply it to your design.

Remember, never apply formulas on plastic part design. Take the concept and apply it to your design.

Design Tip - 5

Today's design tip will talk about the snaps. This won't be the only snap tip, the snap design is difficult enough to have a single blog. 

The first tip about the snaps will be a "silly tip". I said it is a silly tip, but should be not so silly taking into account I've seen these mistakes more than 2 or 3 times this year on the parts I reviewed.

The first point is the hole dimension. The hole dimension has to be big enough to admit the snap deflection when assembling the part. On the attached picture, the dimension 'b' has to be bigger than the dimension 'a'. How much bigger? it depends on the size of your parts and the tolerances you are working with. On the applications I work b = a + 0.5mm is more than enough, but don't take this formula as 'The Truth', understand the concept and apply it to your design.

The second issue is easier. It is important to add a chamfer on the assembly side, it will help the assembly process. Using the same angle on the snap and on the hole is the best combination.

The last point is the parting line of the hole. This point was already commented on the 2nd Design Tip. It is very important to think about the mold, and define the part design to have a robust tool.

Casio DW-280 cleaning

Cleaning a "new" watch.


I bought this Casio DW-280 from ebay and arrived some days ago.
The watch came VERY dirt! I don't know how anyone can keep the watches so dirt. It is so easy to clean up the watch... let me show the cleaning process of this watch.
First thing is to disassembly the watch. In this case I've disassembled all the watch except the buttons (too much work for today). Then put all the parts into hot water with some cleaning product. I use a very good Spanish product KH-7.
Dont' worry! the module was not inside the water :) I left the module and the gasket out of the water. The module 1000 manual could be found on Casio's web site.
After some minutes inside the water and adding some soap, brush the watch. I use an old toothbrush, I think all the people use toothbrushes to clean their watches.
After brushing is time to dry. Some minutes over a dry tissue and then a final hand dry with the tissue or some clean and dry fabric. Take care with the moisture and dust inside the housing. To clean any water mark or dust spot inside the watch, it is necessary to disassembly again the watch.
After drying, the module has to be assembled again. It is important to put some silicone grease to the gasket, it helps to seal the back cover of the watch. Very important if you want to use the watch underwater. It is also important to add grease to the button gaskets, but as said before, too much work for today.
Close the watch!
The watch is clean and ready to be worn!

Design Tip - 4

Today the design tip is not really a tip. It is an invitation to all of you to share your experiences and questions.

So if you have problems designing a plastic part, you can post your questions here and I will try to help you. Of course if any bloger is able to answer the question feel free to comment the post. 

If you are not able to post pictures on the comments (I really don't know if it possible or not) , you can link an Image Shack or something like this or send me the picture and question I will post a new post with your question and pics.

Casio G-Shock test

Are the G-Shocks from Casio the hardest watches in the World?
I really don't know by the test videos are gorgeous!

More videos at Casio G-Shock web site

Design Tip - 3

Wall thickness.

This is one of the easiest issues, at least easiest in theory. As most of plastic part design documentation say, the walls have to be as uniform as possible.

If it's so easy why we have a lot of problems with the wall thickness? The point is that a lot of plastic part could not be done using a constant wall thickness. In my opinion there are two main reasons, one is the part function, sometimes to give the desired function to a part we have to use different wall thickness; the second reason is that sink marks are not accepted in most of our parts, so we need to make thiner walls to avoid the marks.

My suggestion is to try to use uniform walls where possible but if wall thickness needs to be changed try to use smooth thickness changes (not sharp changes). Try to minimize the changes. Try to add recesses in the not visible areas to keep the thickness uniform (if you are lucky and your part has not visible areas). Finally use the thinnest thickness possible (cost reduction is a must nowadays).

If you really need big thickness differences, you are not able to make smooth changes and it is not possible to add recesses on the b-side of the part, be careful! Your part will warp, will be difficult to fill & pack and it is probable you will have marks (sink marks, flow marks and others). In this case try to think on a different design to fulfill the specification, try to think if you are able to split the part in 2 or if you are able to give some of the function of the part to any of the surrounding parts.

Casio SUF-110 and DW-280 arrived!

Casio SUF-110 and DW-280 arrived!
Pics and review soon

Casio ARW-320

Unfortunately my Casio ARW-320 is still not here. 
The watch is quite important in Casio's history, it has the honor to be on the Casio milestiones.
I have the manual, so I'm able to check all the functions but still not able to push buttons. 
If you like this watch ans this watch style, you must visit the digital watch libarary, a very nice site with a lot of information of vintage digital watches. There are also some forums where to learn about watches, I'm following the nerd watch forum and the Digital Watch Forum. Almost any question on LCD and LED watches will be answered there.

Scuba diving

One of my hobbies is scuba diving. I'm starting on this sport, I only have the Open Water certification.
My last dives were in Dominican Republic during Christmas. It is nice to dive on a 27ºC water, when your in your country the water is at 10ºC.
The picture is from the first wreck I've ever seen. I hope after summer I will be able to post more wreck pics.
Very nice dive with Caribbean Divers!

Redirecting watch collection

I'm trying to direct my watch collection to water related watches. I'm not only talking about diver watches, I'm talking about watches designed to be used in (or under) the water.
An example of what I call "water related watch" is the Casio SNK-200 I talked about some posts ago. It is a LCD watch with a depth sensor, so you are able to monitor the depth. This is not the only depth sensor watch I have, I also have a Timex Helix and an Uwatec dive computer (not a watch).
At this point I'm trying to sell some of my not-water related watches, to be able to buy more water related ones. I will post some comments of the watches I want to sell, so if anyone is interested just post a comment.

Design Tip - 2

Let’s talk about fillets.

Some people say fillets have to be added to all edges of a plastic part. This sentence is not 100% correct, it is necessary to add fillets to most of the edges but not everywhere.

The picture shows a hole on a plastic part. The hole could have fillets at both sides or just at one side of the hole.

The first and second sketches show a hole with fillets at both sides, from the CAD point of view it is a small difference but from the mold point of view things are so different. To have fillets at both sides means the parting line has to be placed at the middle of the hole, the mould will be difficult to construct and to adjust. The third sketch shows a hole with only one fillet. The parting line could be placed at the not filleted edge, so the mould construction and adjustment will be easier. Easy and robust moulds are necessary to have good quality parts.

Before to add fillets everywhere, we have to think how it will affect the mould and if it is really necessary. In some parts only one of the sides is visible, so it is not necessary to add fillets at both sides. In other cases, the fillet (or chamfer) is done to help the assembly of another part, but usually the other part is only assembled by one of the sides, so again not so necessary to add fillets at both sides. Unfortunately sometimes it is a must to add fillets at both sides and the molds become more difficult, but if possible has to be avoided.

Fillets YES but NOT EVERYWHERE

Casio SNK-200

This is one of my favorite watches, the Casio SNK-200. 
It seems a plain digital watch but it has a depth sensor. It gives you the current depth, the max. depth and the diving/snorkeling time. 
After your dive your are able to recall the max. depth, the average depth and the total dive time.
The production of this watch was started beginning of 90's and the retail price was around 130USD. It has two SR927W/SG7 batteries, easy to change by removing the 4 screws of the back plate.
It is not easy to get one of these watches in an acceptable status, most of them were destroyed by young people or hardly used by spearfishing people.
This one is a quite strange model, it is the SNK-200, not the more usual SNK-100. I really don't know the differences between these two models, the screen is different (10 bar instead of 100m) but the SNK-100 manual I have has the same features I can find on my SNK-200.
That's all! I hope this summer I will be able to test the watch.

Design Tip - 1

This tip is based on a recent experience in one of my current projects. It is about Autodesk® Moldflow® Insight and sink marks but not only on Moldflow it could be extrapoled to other software tools.

Some days ago one of my colleagues told me there won't be sink marks on a part he is currently designing because Moldflow says it. 

Nice sentence!

We have to use Moldflow or any other software as a tool to help us to improve our designs, but the software itself is not able to say anything, and hopefully the computers are not smart enough to tell us things without our interaction.

Never use a single information as "The Truth". Ask people with more experience than you, go to the injection plant and ask the workers, they are injecting the parts you designed 8 hours a day (at least). So they know a lot about the possible problems your new design could have.

Coming back to my personal experience, I think the part will have sink marks, even the software "says" no. Other people with more experience than the designer and more experience than me, also thought there will be sink marks. So why to be more confident on a software than on some tenths of years of experience? To run a good simulation is not easy, if the software operator is not skilled enough, the results could be far of the reality, even if the operator has a lot of experience using the software we can have results not according to the real part. We have to use the results as a simulation of the reality, not the reality itself.

I have other bad experiences with Autodesk Moldflow Insight but I still think it is a very useful tool, if well used.

Remember use your brain, use your experience, use your colleague experience and use the tools but do not use only one of these.

Design Tip - 0

On this section I will try to post some tips of plastic part design. I've been working designing plastic parts for a long time so I have some experiences that can help people to improve their designs.

I also want to learn from other people reading their comments or trying to answer their questions. So feel free to comment, ask or correct!

I'm used to design small plastic parts for automotive market, working for several UE and US brands. Actually I'm working on motorbike helmet industry, so I'm applying my knowledge to a less developed industry and learning about fiber (never stop learning!).

I hope this section of the blog could help you.

Casio watches on the way

Watches I'm waiting for:

3 watches are on the way. Two from Deutschland and one from the UK.

The 3 watches are Casio. One SUF-100, at least this is what it seems from the ebayer picture, the second one is a DW-280 and the third one an ARW-320.

I've been looking for an ARW-320 for some time. It has a pressure sensor, close to some actual G-Shocks and Pathfinders. Thhe main functions are an altimeter, a depthmeter (alti-depth) and a barometer. A lot of functions for a watch launched to the market on the 1989! Yes more than 20 years ago!

Here you are some pictures from the auctions let's see what arrives :)

I'll post more pictures as soon as I get them.

Presentation

Hi! I'm so new in this blog world and still don't know what I will say on it. My two main hobbies at this time are Scuba diving and Watches, so I think I will explain some of my experiences on these subjects.

I'm working with plastic parts for a long time, mainly focused on the design of the parts, so probably I will also post some tips about it.
Comments, questions & corrections will be always welcomed on this blog.

Hello world

Hello World!