Questions of Equipment and capabilities.

[Samantha Blakely]

Dear All,

I was directed to your group by a friend when I was enquiring about buying or renting equipment to work on PCBs. Specifically I am after a hot air rework station for working on PCBs.

I was wondering if you guys have one, and if so what the cost would be for joining your group as a regular user of your maker space.

Other than a hot air rework station do you guys happen to have a pcb reflow oven or a hotplate?

Thank you for you help.

Regards,

Samantha Blakely

[Kris]

Hi Samantha,

Yes we do have one, and a (small) pcb reflow oven.

Come and check us out on a Tuesday evening or Saturday.

First visit is free, more info and pricing is here

www.robodino.org

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[Samantha Blakely]

Hi Kris,

Thanks for the information. I will be there on a weekend within the next 2 weeks; hopefully. I can't wait to meet you guys.

Regards,

Samantha Blakely

[Madox]

Hi,

Kris has answered your question on what's available at the space; you'd find that small hot plates are extremely cheap on places like AliExpress and works quite well with low temperature solders.

Though of course, the value of visiting the space is probably getting feedback/advice on your PCB :)

[Samantha Blakely]

Hi,

I am not a fan of low temperature solder alloys based on bismuth, and indium. In my experience they tend to make brittle and weak joints that are not suitably stable over time. I would prefer the traditional SN/PB alloy or PB free SN based alloys. The cheaper stuff from ali express is not suitable in my opinion. I would rather pay more for a superior product that will keep working well for the next 10 years.

As for feed back on PCB design that would be great. Do you guys have experienced PCB design engineers in the group? I would love to meet them. I have some limited experience in PCB design and am currently having my project's PCB manufactured in china, but I don't have a lot of experience in SMD soldering by hand, and that is why I am looking for a reflow oven. 

[Madox]

Don't disagree on the solder.  What's wrong with the cheaper stuff, most are actually very capable ... [hides in mild shame of giant collection of AliExpress stuff at home]

I do have a pricier teeny tiny hotplate though, I'm literally using it now for probably a very unintended purpose... Wonder if anyone (other than Gav) can guess what this is....

I'm not an expert but there are others who may choose to reveal themselves :)  But I am curious, could you tell what you're making?  Is it for hobby purposes or...?

[Samantha Blakely]

The cheaper equipment on alibaba tends not to conform to the expected or published specification. Summary: Cheap and nasty. I would rather pay the cost required to get equipment that works as advertised. 

In the past I have wasted too much of my life fixing cheap chinese crap. These days I am all too happy to buy good tools/equipment that just works. I would rather not waste time diagnosing cheap chinese junk. If you put an hourly rate on your own time (perhaps $20 / hour) you typically find that it is cheaper to pay the premium for the equipment that works than fiddle with the Chinese junk.

As for what I am building. I am building a distributed weather and data acquisition system. It is solar powered bluetooth mesh of devices that measure environmental, and terrain data. Basically a live measure of soil health (moisture, temperature, carbon/nitrogen content etc), solar intensity, and wind intensity. It is a hobby project, at the moment, that I am doing with a friend who is a farmer but it could be commercialised at some point if everything works well. I have no plans for commercialisation but things could change.

FYI: the picture you have uploaded has not rendered at all.

[Andrew Larkin]

Samantha, what platform are you using for the project?

You might want to explore OpenThread as an alternative to Bluetooth mesh. The reason is your application is likely to be low bandwidth so you can trade the high datarate of Bluetooth for much longer range. OpenThread sits on 802.15.4 (like Zigbee). Platforms like Nordic and ST can support both BLE and OT.

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[Samantha Blakely]

Hi Andrew,

I have already designed the PCBs with plans of using a UBLOX BMD300 BLE radio and the PCB is already in production. The components have also been purchased. So unless a alternative radio can be found that has OpenThread support that has the same form factor, footprint, and pin outs I will have to stick to the bluetooth for now. Having said that, the BMD300 is based on the nordic nRF52832 which does not support thread but there are other SOCs in the same family that have thread support. I might look to see if there is drop in replacement that I could use for the next iteration if there is one.

I had not heard of OpenThread before. I will have do some reading about it this weekend. Thanks for the info :)

Samantha

[Kean Maizels]

Hi Samantha,

 

I’ve designed a handful of PCBs using the ublox BMD-300 modules.  If you check the BMD-340 docs, you will find that a minor change to the PCB footprint allows using either BMD-300 or 340 and then you can upgrade from the nRF52832 to nRF52840.  Not an exact drop-in replacement, but only minor schematic, PCB, and firmware changes required as long as you don’t need access to the extra I/Os.

 

I don’t know very much about OpenThread, but I did some work a few years ago with Bluetooth Mesh before it went through a major refactor around Zephyr.  These days I’m working with Wirepas Mesh although another team now do the firmware development.  Wirepas runs on the same hardware but requires licensing (well officially Bluetooth does as well for commercial use).

 

I’ve assembled a couple of hundred PCBs in-house using the ublox BMD-300, and more recently a few with BMD-340.  I run a couple of PnPs and reflow ovens (a T-962A now mostly replaced by a RF-A350 aka ZB-3530HL) and use Loctite GC-10 paste.  The LGA footprint is quite easy to work with as long as you use good paste and have good stencilling technique.  I only had a couple of soldering failures in the early days and none in the last couple of years.

 

Happy to chat if you need any assistance.  Just drop me an email.

 

Kean

 

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[Jenna Nelson]

Just to divert on this thread because it occurred to me:

Re:alibaba/aliexpress- I don't think I'm actually disagreeing, but I've placed just under 500 orders with Aliexpress and regretted few of them. I totally agree that for tools you've got be careful, they are often super dodgy knockoffs or crep. My "favourite" trick is ordering something and realising on delivery that it's about half the size you'd expect it to be: well played evil vendor, well played.

But it's really good for componentry. I wouldn't buy most of my components, raw stock, small items from anywhere else. GT2 timing pulley and belt, LM317 voltage regulators, R8 coletts, NEMA 23 stepper motors, flex couplers, connectors, solder tip refresher, RasPi heatsinks, ball bearings, bannna plug terminals, connection wire, shielded audio cable, ferrite core toroidal thingies, R8 three jaw chuck, hex socket head screw kits (in M3, MN4, M5, M6, M8), a CNC pendant, spring dowel tension pins, thrust and axial bearings, neodymium magnets, ... that's just reading fro my orders from 2012 onwards. I believe the only order that hasn't arrived was a high power laser I was hoping to use for etching work, but it was intercepted by Australian customs.

The stuff that has been crap tends to be high consumer demand where if the deal looks too good to be true: it is. Fake USB sticks where they've faked the firmware, to Smanatha's point more "expensive" tools that are actually quite shoddy, cheap USB power adapters that have so much noise they are unusable.

Actualy it's amazing how much of the stuff from almost 10 years ago I still know exactly where it is and in quite a few cases have used on the last 7 days! Epoxy resin colourants, ESP modules, M* bolts, milling cutters, a high speed water cooled spindle that I've been holding onto for 7 years!, and so on. 

I'm dialling in what Temu is good for at the moment. It's just another drop shipper and again, it's crap for a lot of stuff, but just fine for other things. Raw materials, components, etc all seem fine. Magnetic adhesive white board, silicone mats to put in kitchen cupboards, laundry hamper, M* bolts because I ran through my supplies- all good. The little art satchel thing- I didn't check the scale properly and it's crap. Oh the "Jangklife" compact electric screw driver for like $8? Terrible! But gold! Like amaziningly good for $8 but still really terrible- I've had several people prefer to use it *because* its so low power and light!, and the name alone is worth the price. 4,084 reviews and I honestly believe they are real.

Anyway, I agree with Samantha that for bigger items: caveat emptor, expect someone is working out how to screw you. And for the smaller stuff, you still want to be careful, but I've easily got, like 475 out of 500 orders that were exactly what I wanted for a ridiculously better price than in Australia. (Final example- all the DETA/Arlec smart stuff can be bought for about 1/2 to 1/3rd the price from Aliexpress because it's all rebadged Chinese stuff, and the "Grid Connect" app is a reskinned version of the Tuya Smart App. And Grid Connect is many versions old and much shitter by comparison. You can just use Tuya Smart on all your DETA/Arlec stuff and it Just Works. All the light switches in my apartment, most of the light bulbs came from AliExpress).

Jenna

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[Madox]

Oops on the silly picture :) Here it is again ...