project-image

PSIcle sensor: Measure tire pressure with your phone!

Created by Rover Development

Measures your bike's tire pressure with your phone. Spot check pressure before rides, after fixing flats, or fine-tune on the trail.

Latest Updates from Our Project:

Functional LP prototype sensors
about 1 month ago – Wed, Nov 02, 2022 at 01:16:07 AM

Hi everyone.  We know it's been a long time, but we've been back and forth between the two suppliers trying to solve the issues.  As the title says, we have a design that should work for LP sensors, but the HP sensors are going to take a bit more work.  We currently don't plan to ship LP sensors until the HP sensors are working as well.  We will let you know if that changes.

In the past several months, we've spoken to both molding vendors, component vendors, and a molding consultant.  We've made several changes to the internal design to improve the issues, and we had to have new parts manufactured and run through the production process.  We have made functional LP sensors that hold up to 60 psi before they start to leak, but the design goal is 150 psi for the HP sensors.  We should be able to achieve that with some more iterations.  The external appearance and specifications should be largely unchanged.

We're being really conscientious about not overspending on the process.  This means we're doing small batches of parts and iterating the design.  We also are modifying and reusing the prototype molds for each new attempt.  Each batch needs to be sent back to us for functional and destructive testing, and this iteration and testing obviously takes a while.  It's possible that we could run out of funds, but the methodical (and slow) iterating and testing is helping to reduce the chances of that.  That's why the updates are trickling out so slowly.

We'd estimate that we have one more round of prototype mold changes, and then some testing and on to the production mold.  This will probably take about three months, but we'll send out an update once the prototype mold is successfully producing HP sensors along with plans to scale up production.

Sensor seal achieved!
5 months ago – Sat, Jul 09, 2022 at 05:56:21 PM

Thanks for your patience.  Progress was slow for a long time after the last update but there's a sudden flurry of activity in the past two weeks so it's time for an update.

As you recall, there were two molders we were working with.  Molder A was the original one, and even after two different molds, they couldn't achieve an airtight seal between the mold material and the tube extension, so we started looking for a backup molder.  We found one and they guaranteed they would be able to make the parts seal.  We were cautiously hopeful.

Molder B wanted to see the parts before they would start on the mold.  This got us back into Covid delays.  Molder B is in mainland China, and they had some shutdowns going on.  It took about a month for our shipment to arrive.  Generally it takes only four days.  

It took two weeks to go the last few hundred miles

After Molder B received our parts, they said it would take 60-70 days for the mold to be made.  More delays!  However, they must have either started that lead time before they received the parts, or it was simpler than they anticipated, because we received test parts a couple weeks ago.   We were thrilled to find they have a strong, airtight seal, and they seem very durable.

We're not totally done yet though, because a little bit of rubber is leaking into the sensor element and damaging it.  So the sensor still reads, but the pressure and temperature data is wrong.  This should be much easier to fix than the seal issue was - we just have to tighten the gap a bit between the circuit board and the tube.  The molder is working on testing this now.  We expect to have final prototypes within about two weeks.

After that, we'll have to order the final extensions and start molding and shipping.  Hopefully we don't have more shipping delays, but even if we do, the major product risk seems to be resolved, so after we solve the last minor issue we're on to production!  Thanks for your patience!

Circuit boards complete and threaded extensions
8 months ago – Sat, Apr 16, 2022 at 11:07:23 PM

Hi Everyone.  We've had another month of delays and frustration, but the major milestone since the last update was the completion and receipt of all the circuit boards.  There were numerous delays in both the build and shipping due the entire city of Shenzhen, China being shut down, but we finally received them, and they look and work great.  This is a huge milestone passed on the road to delivery of the units.

We also received some new extensions that we believe may help address the sealing issues.  The new extensions have threads all the way down the body, as shown below.  These threads will provide more surface area for the rubber to adhere to and should improve the sealing.  The last mold trials only had leakage along the smooth body of the original extension, so the zig zag of the threads should help address this.

These extension tubes were also extremely delayed due to the shutdowns in Shenzhen, so we were just able to ship the tubes and circuit boards to the molders this week.  It's a really difficult time to make anything in China with citywide shutdowns affecting numerous different cities.

Due to the delays in receiving the circuit boards and extensions, there have been no new mold trials since last month.  We are working with both molders to define their mold trial schedule for the new molds and will provide an update as soon as we can.  We apologize for all the delays and rest assured, we are just as frustrated as you.  We are pushing forward as hard as we can despite the odds and we are making progress bit by bit.  Thank you for your patience.

Molding and other updates
9 months ago – Sat, Feb 26, 2022 at 10:33:15 PM

Hello everyone.  A lot of activity this month, but we will still be waiting a while to see the ultimate results.

The Taiwan molder was not able to make leak free assemblies before Lunar New Year, so we started talking to the US molder and quickly ran into an issue.  We originally had them quote a higher quantity, so when we went back with the final quantity purchased by the campaign they were not able to make the parts cost effectively.  Essentially, their costs, which were already much higher than the overseas molders, were much higher than expected at lower quantity and we couldn't make the order work.  They did agree to serve as a paid consultant to help us to get good units molded, so we may use their expertise after all.

When Lunar New Year ended, we got into deeper discussions with the molder, and they have requested some modifications that they believe, and we agree, will make the design much easier to seal.  The design changes add about 1 gram of rubber to the overall weight.  This additional weight is not ideal, but shouldn't pose any major issues with bike wheel balance, even at high speeds.  Plus, it's the lowest risk path to getting parts, so we opted to do this, at least for now.  We just paid for this new mold and we should see results in about 4 weeks.  This will still be a prototype mold because it can only make one part at a time, and parts take a long time to make with this molding technique.  To get the unit cost down, a production mold would need to be made afterwards if this mold works.  An image of the revised design is below.

To further reduce risk, we reached out to over a dozen other overseas molders and found one that has promised us a money-back guarantee that they can make the units.   A potential major advantage of their design is that it will inject liquid plastic into the mold.  The previous vendor used solid preforms that get squished when the mold closes.  Although this is a standard way to make tire valves, it has been difficult to get this process to work well with our circuit board.  Closing the mold first and then injecting liquid plastic may be significantly simpler.   Another major advantage is that each mold cycle is faster, so if this first mold works, it will serve as a production mold - there is no need to make a different production mold.  We also expect results in about 4 weeks on this.

If the molds still don't seal, we plan work with one or both vendors to apply epoxy to the units to seal the sensors before they go into the mold.  This is what we've done for all the prototypes and it works really well, but it is very time consuming to apply.  Epoxy would work, but would add a lot of labor so we don't want to have to go to that unless we can't get the molding to work.

The circuit boards are in process and should be done on about March 7th.  At that point, we can send some to the vendors to have on hand when they begin their mold trials.

The apps are ready, though the iOS app won't go up on the app store until we're able to send some hardware to Apple for them to evaluate.  This will happen after we get some good parts off the molds.

In spite of the extra mold costs, we're doing ok with funding and we should be able to fill all the orders with one of the molding methods above.  This has obviously gone on much longer than we originally said, but the learning curve for the molder has been so much longer than we expected, especially given the fact that we had prior experience with them.  Thanks for your patience!

6 month update
11 months ago – Thu, Jan 20, 2022 at 04:01:09 AM

Hello all.  We've had some good progress this month and I think we're basically one minor breakthrough away from manufacturing and shipping.

First, there's been some progress in the molding.  The molder has managed to seal the molding material around the extension and created a leak free seal.  This is a big accomplishment because the leaks around the tube were previously quite bad.

At this point the molder is having some issues in preventing the circuit board from moving during the molding process.  The circuit board moves and breaks through the rubber surface, causing a new leak point.  This type of issue is why we built a prototype mold before a production mold.  We've already discovered several things we will change in the production mold to make the sensors easier to make.  In the meantime, we may just make the rubber material thicker in the area shown in the small picture below to seal any leaks even if the circuit board moves during prototype molding.  It's easier to make material thicker because to do that you remove steel or aluminum from the mold.  Removing mold material is a lot easier than trying to add it back in.  This is often called "steel safe" in the molding industry, and it will allow us to quickly change the design for further leak improvements and tests, if necessary.

This month we managed to find a vendor who was willing to make less than 2000 aluminum extension tubes for testing, and we purchased 100 of them.  They looked great and went straight to the molder in Taiwan for the mold trials described above.  We're ready to order the balance of the units needed after we finalize a molding process.  The lead time on these extension tubes is about two weeks.

We also decided to place the order for all the circuit boards, since we currently feel that it is unlikely that changes will be needed on the circuit board.   All of the components were shipped to China for the circuit board assembly.  The circuit boards should be complete by the end of Feb.  By then, we should know who is molding them and the circuit boards can go into molding.

Which brings us to the last point for the update.  We've given the Taiwan molder until Feb 1st to make leak free assemblies and send them to us.  If they are unable to do it, we will start working with the US-based molder.  This ultimatum seems to have paid off already as they were able to create a seal around the tube where they had not been able to before.  If they keep making progress, we should have the first leak free samples soon.  If not, we'll be starting up with the US-based molder in Feb.  Although they are a lot more expensive, they have more experience and it will be far easier for us to communicate with them and visit their facility.  One way or another we'll get this done.  Your patience is very much appreciated!