| << return to blog entries
2010-03-30 07:08:22 (4546 views) This is a report of our day at the factory yesterday. A preview: waterproofing works 99%, the surprise was a total challenge but it has been basically fixed, all's great!!
Let's go with order. First let's get some breakfast at the bus station.
Nah, pass on that... doesn't look too healthy!!
In western societies, ads read "buy! buy! buy!" - here it's all about "culture" and civilization. Apparently culture can transform an industrial town with perennial fogs into the Australian gold coast. But it has the side effect of mirroring all the ad background pictures! :)
As you can see from the above picture, in case of emergency escape routes are followed diligently. When in panic, run: in any and all directions! :)
Ok, seriously... Jason's in Europe doing some better paying business, but we had his assistant Sonia with us. Just to break the ice in the taxi we asked her if she'd been briefed on the day's mission. We absolutely didn't expect her to know because (a) Jason's away and (b) we had a few different things that we wanted to accomplish. Amazingly though she said oh yeah, let's see, 1. make the o-ring softer, 2. enlarge the screw holes and 3. work on the rubber overmold for the surprise.
Holy... nicely done! You don't usually get this level of follow up here... All right, so we went to KFC first to grab a bite... carefully avoiding Pizza Hut (yuck!)
We sat down with Sonia and the two top guns here at the rubber factory. One is actually the big boss...
The softer o-rings came out of the machines very quickly and we were able to verify that these work a lot better. Though there wasn't much water around so we postponed that test.
We went right on to the surprise. This is a total headache. We were on it for over 6 hours. The big boss was about to give up. We had rubber going into the mechanical parts and messing up everything. Tried to close the holes with glue, but no luck. Then tried the soldering iron and molten solder. That worked. Rubber was no longer getting in. But the parts were still not working. In the end it was determined that the pressure was too high. So we tweaked and tweaked. Switched to a rubber with a lower melting point. This needed a longer "cooking" so part production went up to requiring 5 minutes a piece.
Nothing seemed to work and Mr Tang the big boss started complaining that it was a headache and was about to give up. Fortunately we didn't let him, and kept insisting on trying a combination of things and proceeding very scientifically by dissecting parts and figuring out what went wrong at each trial.
In the end, by the scientific method, were victorious!! We actively instructed personnel on what to do, and how to proceed. Their intuitions about what was going wrong were not correct. However they did help us for a whole day (despite our modest contribution to their earnings) - so we're very grateful and enthusiastic about having their help.
This would NOT have been possible had we not moved to China and come here personally to fix things up. So at least we know this was the right move.
Out of all of this a disturbingly biological looking defective piece came out. Just a curiosity - not important!
Already exhausted, we further abused of Sonia by having her drive us to the other factory where they enlarged the DreamLover 2000 screw holes with a huge machine. We went to 2.6mm then 2.7 - finally the screws went in smoothly.
In the evening, back home after a very intense day, we went straight for the sink, screwed in the unit tightly with the new, softer O-ring, plugged all the grommet holes and waited. Five minutes in water, splashes, and shower jets - then dried the outside and opened. NOT A DROP!!! This is complete success for the o-ring waterproofing...
Some items remain to be fixed.
- The grommets leak by a very very tiny amount, they are reducing the size of their hole as we write this.
- The surprise overmold still has a small issue: the cable melting point. Before with the higher melting point rubber the cable was melting entirely. Now it is unaffected with the result that the rubber overmold doesn't stick to the cable (which is needed for proper waterproofing). So we're shopping for cables with a melting point of about 210C (neoprene melts at 250C, we may have to go with this if nothing else comes up). The point here is that the molded plastic must adhere to the cable, and to do this the cable must start to melt on its surface. Seems like our everyday cables and connectors (USB, Mouse, Power supply) are actually quite sophisticated thingies!
What are the next steps for waterproofing?
- Find neoprene cable to test the final overmold settings (temperature etc)
- reduce grommet hole sizes and make them softer. Make sure cable can slide through but no water will leak
We're almost there. Please have patience.
No idea it was going to be this complex!
Comments
Post new comment
 |
Buy this book: Kitchen Chinese by Ann Mah and be a bit adventurous.
Molds look good. Interested in the proper temperature of the rubber and wire coating melting point.