Author Archives: Ian

Dirty Cables price increases and lead times

via Dangerous Prototypes

DirtyPCBs

Its really hard to convince Huaqiangbei market suppliers to cooperate on a project until you can prove value by making a bunch of orders. Our approach is to guestimate a price at DirtyPCBs, send through a few months of orders, and then ask if they’d like to cooperate with us. Generally this will open doors to closer integration like getting full price lists.

After a few months of running Dirty Cables we looked at our overall order history. On 75% of orders we lost anywhere from $5 to $500. This was totally expected and part of convincing suppliers to give us full pricing details.

Our current supplier makes outstanding cables, but getting a quote is still like pulling teeth and takes ages. They also seem completely uninterested in providing a full price list. We’re in the market today shopping for a new supplier, but in the meantime prices on most connectors have been doubled or more based estimates from the first few months of data. It would also be fair to say lead time is currently 10-20 days, more on large or complicated orders.

Since a lot of the loss/expense is in the low volume orders of 100 cables, we need to compensate with bigger discounts on high volume orders. Connector prices are easy to update in the back end, but volume discounts require a site update that will come towards the beginning of next week. If you’re placing a large order and think the price is too high, please contact us for a more accurate quote.

DIRTY CABLES: Cheap custom cables available now

via Dangerous Prototypes

DirtyPCBs

Dirty Cables is a drag and drop cable builder that gives you access to cheap custom cable services from China. Build a custom cable, get an instant quote, and checkout. Your custom cables should ship in 3 to 7 work days.

Huaqiangbei is full of cheap custom cable vendors with a big pile of samples on their booth. We tried to put the pile online so you can get cheap cables without making a trip to China!

cable-pile-2

We excavated the cable sample piles to see which connectors are common, cheap and readily available in the Chinese market. We bought bundles of everything and identified 17 common cable-to-cable and cable-to-board connector families to add to Dirty Cables. Read more about the different cable families here.

Cables are probably best understood by touching them yourself, so we put together a Dirty Cables Sample Kit that includes examples of each cable and connector. The kit is available in the store for $9.95.

In the coming weeks we’ll document a few more common and cheap connectors that didn’t quite fit in the first sample kit:

  • Crimp terminals: ring and spade ( M3/3.2mm, M4/4.2mm, M5/5.2mm, M6/6.2mm), two-part blades (2.8mm, 4.8mm, 6.3mm)
  • Coaxial power connectors (5.5×2.1mm, various)
  • LED strip connectors (3528/8mm, 5050/10mm, etc)

Dirty Cables is highly experimental. If pricing seems way off, if you find bugs, or if we’re missing your favorite connectors, please give us a shout in the comments or through the contact form.

DIRTY CABLES: Cheap custom cables available now

via Dangerous Prototypes

DirtyPCBs

Dirty Cables is a drag and drop cable builder that gives you access to cheap custom cable services from China. Build a custom cable, get an instant quote, and checkout. Your custom cables should ship in 3 to 7 work days.

Huaqiangbei is full of cheap custom cable vendors with a big pile of samples on their booth. We tried to put the pile online so you can get cheap cables without making a trip to China!

cable-pile-2

We excavated the cable sample piles to see which connectors are common, cheap and readily available in the Chinese market. We bought bundles of everything and identified 17 common cable-to-cable and cable-to-board connector families to add to Dirty Cables. Read more about the different cable families here.

Cables are probably best understood by touching them yourself, so we put together a Dirty Cables Sample Kit that includes examples of each cable and connector. The kit is available in the store for $9.95.

In the coming weeks we’ll document a few more common and cheap connectors that didn’t quite fit in the first sample kit:

  • Crimp terminals: ring and spade ( M3/3.2mm, M4/4.2mm, M5/5.2mm, M6/6.2mm), two-part blades (2.8mm, 4.8mm, 6.3mm)
  • Coaxial power connectors (5.5×2.1mm, various)
  • LED strip connectors (3528/8mm, 5050/10mm, etc)

Dirty Cables is highly experimental. If pricing seems way off, if you find bugs, or if we’re missing your favorite connectors, please give us a shout in the comments or through the contact form.

How Scotty made his own iPhone in China

via Dangerous Prototypes

Over the past two months we’ve been super excited to follow Scotty’s adventure recycling/refurbishing an iPhone 6S in the used cell phone market just south of Huaqiangbei, Shenzhen, China. Scotty finds all the bits and pieces from various sellers and then follows the iFixit instructions, backwards, to build his own recycled franken-phone.

Despite living in the market and running six hacker camps, it was still not clear to us exactly what goes on in the used cell phone markets. This video blows that open and exposes the brisk trade in recycled iPhone parts here in Shenzhen.

Along with This is Not Rocket Science, Scotty also took us on a three day phone recycling expedition earlier this month. Watch his channel for more videos and clips soon!

CHINA STUFF: Email that works…

via Dangerous Prototypes

mail-dp

Working from China is a constant reminder that the location of internet services is super important. North America and Europe are just a few internet hops from our servers in Hetzner’s carbon neutral, green energy data center in Germany. From China, however, we’re often routed out through Beijing to San Jose, then to New York, London, Amsterdam, and finally Frankfurt. On a good day we can do that with only 2-3% packet loss.

Back in the good old days Gmail’s imap service worked perfectly even though Google was blocked, but eventually email was blocked too. At that point we added a managed mail server at Hetzner in Germany. Despite having our own non-blocked mail server, Hetzner’s data centers are unreachable during peak periods of the day because of peering agreements, congestion, geolocation, and a million other factors not worth arguing about.

The image above is a WinMTR report, a combination of ping and traceroute that helps locate network problems. 219.* is where we exit on China Unicom’s cable in Beijing and connect at San Jose, California. Nearly 50% packet loss, average ping time of 482ms. This is better than normal because San Jose connected directly to Frankfurt when this test was taken, instead of the more typical New York-> London-> Amsterdam route.

So how bad is it exactly? 5 tries to send a simple text email without attachments. “Failed to save draft, try again?” prompts every few seconds. Ability to see mail subject headers, but not download the message text. Want to send or receive an attachment? Better schedule that for late at night or first thing in the morning.

International bandwidth from China

There are three cable landings in China: Beijing, Shanghai, and Guangzhou. Each is dominated by one of the three state-owned ISPs. China Unicom (our provider) is big in the north with international traffic routing through Beijing and around 1TB/s bandwidth. China Telecom is big in the south (e.g. Shenzhen area) with around 2.5TB/s of bandwidth through Guangzhou. There are also a lot of bit players like Great Wall and TopWay that have city and regional backbones that eventually dump onto the major state-owned ISP infrastructure.

Part of our problem is using a northern ISP (Unicom) in the south. All of our traffic is routed to Beijing before leaving China. While we can see Hong Kong from the office and can walk there in about 15 minutes, connections to Hong Kong websites are routed up to Beijing and back for a 3000km+ journey. This isn’t our choice, Unicom has a monopoly in our Huaqiangbei office and nothing else is available.

This was intended to be an epic post using MTR to analyze the optimal routes and geographical locations to stash internet services with the best chance to be reachable from China. That idea bombed because nearly everything changed dramatically day to day. A test from yesterday is different than a test today, which will probably be different than a test tomorrow. Follow below for tests of several major email providers and their accessibility from China.

Rackspace Business Email is a disaster from China

rackspace

Over the past few months we tested a lot of email services. Rackspace is a well respected company with business email hosting for $2 per box per month. Signup from China triggered a review, so we had to call support to complete the order. The Rackspace rep volunteered that they have constant complaints from users in China, not something you want to hear. The MTR report shows why, routing to their imap server is a disaster (30% loss, 361ms average ping).

Microsoft Office365 email works great from China, but is itself a disaster

office365

Probably the most distressing part of daily life in China is using Microsoft’s Bing search engine. It’s a terrible search engine, but it’s always super fast within China. You might even find what you’re looking for if you skip directly to the third page of results, link number 5…

Microsoft’s Office365 imap mail service also works very well inside China, and at $4 per box per month it isn’t very expensive. The MTR report suggests Microsoft is running a server in Hong Kong that connects directly to China Unicom (219.*). The service is fast (21ms ping) and very accessible (very few lost packets).

(Un)fortunately Microsoft’s automatic email migration tool sprayed crap all over the place. Their suggestion was to hire an authorized partner for support. After a while all the subscription plans, conditions, and lack of support started to seem quite sleazy. We canceled when mail migration failed and they demanded 1 year commitments for each test account to help debug it.

ABCHK.net is our email hero

abchk

ABCHK.net is a hosting and email provider located in Hong Kong that specializes in email service for Mainland China. We were super skeptical that we could get a stable connection to Hong Kong, but they provided a test account that blew everyone away. 10 meg attachments? Uploaded and sent in seconds. It works perfectly at all times of the day, and the MTR report shows a direct, clean route to the imap server. No packets to destination lost, 31ms average ping.

For less than $7/month we get five mail boxes and 100GB of storage. Real people answered emails and handled the mail migration from our old server in Germany. After a month we are still extremely thrilled to be able to use email “normally” from inside China. Attachments upload and download super fast, and the server is always 100% reachable.

This applies to Unicom only!

Tests were done on commercial and residential China Unicom 100Mbps fiber connections. China Unicom is not the optimal ISP for Shenzhen though. It makes more sense to be on China Telecom with 2.5x more international bandwidth exiting just an hour north in Guangzhou. In the office Unicom has a monopoly, but we had a Telecom connection installed at home and will run the tests again on Telecom in a few days. Anecdotal evidence from other Telecom users doesn’t seem particularly promising though.

Admittedly this is all niche info, but it was hard won and seemed worth sharing here. At the very least someone in a similar situation might find this on Google. Or on Bing, page 3, result 5.

How to measure laser cut length or time?

via Dangerous Prototypes

800px-Laser_cutting_snowfla

To price laser cutting online we need to extract two pieces of info from uploaded design files. The area of a box surrounding the design, called the bounding box, is the amount of material needed. The length of all the cuts in the design can be used as a rough estimate of the cutting time consumed. Here’s where we’re at…

A dirty cheap laser cut service has been “coming very soon” for far too long. We planned to take SVG files and use a friend’s script to measure the bounding box and cut lengths. Unfortunately we never found a laser cut supplier willing to take low volume/high-mix orders and provide all the pricing info to give instant quotes.

Last week a comment at Hack a Day mentioned that dirty laser cutting is taking forever. Surprised by the interest, we asked around and found some willing suppliers. However, these suppliers only accept dxf, dwg, pdf, eps, and ps formats. SVG won’t do. Now we have a supplier but no way to give instant online quotes.

Conversion

Converting to and from SVG is plagued with wrecked arcs and curves. Potential customer dissatisfaction factor is super high. Absolutely not reliable enough for a commercial service or even for pricing.

Extracting info from CAD programs

Inkscape loads all the above formats, but we were not able to extract total path length from the command line or the shell interface. Autocad.io is an online version of AutoCAD that might be able to provide the design stats and a nice rendering, but if the API is slow or busy are customers supposed to wait minutes for their quotes?

A couple CAD programs seemed promising, but eventually we couldn’t find anything that runs on Linux and can extract the stats we need via the command line.

Measuring scripts

The script that measures PCBs in our store and at DirtyPCBs combines a bit of gerber code knowledge with some math to crank out basic stats without ever loading a CAD program. A small script to extract path length and bounding box size from dxf is very doable after a quick thumb through the spec, however nothing seems to exist online.

The learning curve to implement the dxf format and the debug time to perfect it puts this in the labor of love category. It would be a blast if we really wanted to do it, but since it’s standing in the way of a dirt cheap service that will likely never turn a profit (laser cutting is cheap and common…) there’s no resources to dedicate to writing our own.

Create g-code and simulate the cut

G-code is a popular way to control CNC mills and 3D printers. A CAM processor (yes, like the one in Cadsoft Eagle) combines information about the machine, such as cut speed, with the path in the design file to create a series of cutting steps or instructions. G-code is accepted universally, much like gerber files.

Lots of existing scripts convert dxf/pdf/eps/ps files to g-code. Once the design is in g-code there are several programs that simulate the cut and estimate the cut time (or filament used, etc). This seems like the proper way to do it. As a bonus, it lays the framework to calculate cut time and difficulty for a future DirtyCNC and DirtyInjectionMolding service.

This is as far as we’ve gotten. A dozen Python scripts on github look promising, but nothing directly outputs the info we need without a bit of hacking. We’ll continue to knock together a solution in the next few days.

Please shout out in the comments if you have thoughts on any of these methods or experience with any tool chains that might work. Help us get laser cutting online and we’ll reward you with – what else – free laser cutting service!

Image source: Adam Dingley CC BY SA