Hacking Amazing Soldering Features into the Already Great Weller WMRP

Weller, the German soldering tools manufacturer, has a nice range of micro soldering irons (pencils) designated as the WMRP series. These are 12V, 40 W or 55W units with a 3 second heat up time, and allow quick tip exchange without needing any tools. [FlyGlas] built a neat soldering station / controller for the WMRP series based around an ATMega microcontroller running Arduino.

It’s packed with most of the features you see in a professional rig.

  • low offset op amp for soldering tip temperature measurement with type c thermocouple
  • cold junction compensation using the PTC (KTY82-210) included in the WMRP soldering pencil
  • input voltage measurement
  • soldering pencil current measurement
  • recognizing if the soldering pencil rests in the stand (–> standby)
  • 3 buttons to save and recall temperature values
  • rotary encoder to set soldering temperature
  • illuminated 16×2 character LCD module
  • USB for debugging and firmware update
  • 4mm safety socket for +12V power input and a protective earth socket for connection to ESD protection

WMRP_controller_02A PWM signal from the microcontroller controls the load current using a MOSFET. Load current is measured using a Hall Effect-Based Linear Current Sensor – ACS712. The corresponding linear output voltage is buffered and slightly amplified using AD8552 zero drift, single supply, RRIO Dual Op Amp before being sent to the microcontroller ADC input. To ensure ADC measurements are accurate and stable, a low noise precision voltage reference – ADR392 is used. Another precision resistive voltage divider allows input voltage measurement. The supply input has over-current and reverse voltage protection. A set of buttons and a rotary encoder are connected to the microcontroller to allow settings and adjustments. An analog section measures the thermocouple voltage from the soldering pencil as well as the stand-by switch status. The handle has an embedded reed switch that is activated by a magnet in the support stand which puts it into stand-by mode. Another analog section performs cold junction compensation using the PTC sensor within the soldering pencil.

The Git repo contains the initial Arduino code which is still a work in progress. While the hardware source files are not available, the repo does have the pdf’s, gerbers and BOM list, if you want to take a shot at building it. Check a demo video after the break. Thanks [Martin] for sending in the tip.

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Adding PID Control To A Non-Adjustable Iron

Do remember your first soldering iron? We do. It plugged into the wall, and had no way to adjust the temperature. Most people call these kind of irons “fire starters.” Not only are they potentially unsafe (mainly because of the inadequate stand they come with) they can be hard to use, slow to heat up, and you never know what temperature you are soldering at.

[Mike Doughty] wondered if you could hack a cheap iron to be temperature controlled. He began by taking apart an iron, and adding a K-type thermocouple to the mica heating element with the help of a fiberglass sleeve. After a few tries at fitting and finding the right placement for the thermocouple, he then reassembled the iron, and attached everything to an off-the-shelf industrial PID controller.

Not one to trust that everything was working, [Mike] began to test the iron. He used a Hakko FG-100 soldering iron tip thermometer to measure the “real” temperature of tip, and compared it to the value the K-type thermocouple was reporting it to be. The results were fairly impressive (as seen in the video after the break). Only about 10 degrees out. Not too shabby.

He concluded that although it did work, it wasn’t a replacement for a high quality soldering station. We suspect the real problem with this idea is that the mica heating element is way to slow to respond to any thermal load that the tip is given (but then neither did the unmodified iron.) If you’re interested in hacking together your own soldering station, you might be interested in the open source soldering iron driver.

[via Dangerousprototypes]

Continue reading “Adding PID Control To A Non-Adjustable Iron”

DIY Thermal Insert Press

You might not know what a threaded insert is, but chances are you’ve seen one before. Threaded inserts are small metal (typically brass) inserts that are pressed into plastic to give a strong point of attachment for bolts and screws. These inserts are a huge step up from screwing or bolting directly into tapped plastic holes since the brass threads are very strong compared to the plastic. The only major downside to these inserts is that the press to install them is incredibly expensive. Thankfully, [Alex Rich] came up with a cheap solution: a modified soldering iron mounted to an Arbor press.

Commercial threaded insert presses typically use ultrasonic welding or heat welding to fuse inserts with plastic. [Alex] chose the simple route and went with heat welding, which (as you might imagine) is way simpler than ultrasonic welding. To provide the heat, [Alex] mounted a 100W Weller soldering iron to the press, which he says handles the impact with no problem. Unfortunately the copper tips of the Weller just wouldn’t hold up to the impact, so [Alex] made his own tips out of some brass he turned on a lathe.

If, like most people, you don’t have the capability of making injection-molded cases, let alone an Arbor press on hand, you’re not out of luck! Using this same technique people have successfully added thermal inserts to 3d-printed parts using a soldering iron and much smaller DIY presses. Have any ideas on how you could use thermal inserts in your 3d prints? Let us know in the comments.

A New Handle For An Old Soldering Station

About 20 years ago, [Simon] spent a few week’s pay on a soldering station, a Micron W/2172. It served him well for the past few decades, but lately he hasn’t been able to find a supply of new tips for it. The Micron went into a cupboard and he upgraded to a newer Hakko soldering station.

The old Micron was still sitting in the cupboard when [Simon] realized both stations use a 24V supply for the heater, and you can buy replacement Hakko handle for a few bucks. Having two soldering stations would be handy, so [Simon] set out to convert the old Micron station to accept Hakko handles.

The only technical challenge for this modification was to figure out how the old circuit board in the Micron would read the thermistor  in the new handle. The original circuit used a dual op-amp, with one side used to amplify the thermocouple and the other to compare it to the temperature set point. After measuring the set point and a bit of Excel, [Simon] had a small circuit board that would replace the old op-amp. After that it was only a matter of wiring the new handle into the old station, calibrating the temperature settings, and enjoying the utility of two soldering stations.

Homemade Soldering Stations for Cheapy Irons

Homemade Soldering Station for cheap Soldering Irons

Everyone reading this post has had a cheap pencil-style soldering irons that plug straight into the wall at some point in their lives. Even if you’ve upgraded to a professional soldering station, you probably have one of these cheapy irons kicking around that are slow to heat up to an unknown temperature. [Pantelis] thought he could fix the latter problem with his Homemade Soldering Station for those basic soldering irons.

Since the intent of the soldering station was to control the temperature of the iron [Pantelis] had to figure out a way to sense the temperature. He did this by strapping a thermocouple to the iron near the tip. The wires were run back through the handle and then along the power cord.

Homemade Soldering Station for cheap Soldering Irons

Both the stock iron plug and the thermocouple leads plug into a box put together specifically for this project. In the photo you’ll notice the LCD screen that displays both the target and actual temperatures. The linear potentiometer below the LCD screen is used to set the target temperature. The LED to the right alerts the operator that the iron is heating up and when it is at temperature and read to go.

Although there isn’t a lot of schematic or part list information, [Pantelis] did do a good job photo documenting his build. Check it out, it’s worth a gander.

Solderdoodle is an Open Source, USB Rechargable Soldering Iron

solderdoodle

Battery powered soldering irons are nothing new, but what about a soldering iron that can recharge via USB? [Solarcycle] realized that it might be handy to be able to recharge a portable soldering iron using such a ubiquitous connector and power source, so he developed the Solderdoodle.

The core component of the Solderdoodle is a Weller BP645 Soldering Iron. The heating element is removed from the Weller and placed into a custom case. The case is designed to be 3d printed. The STL files for the case are available if you want to make your own.

The Solderdoodle does away with large, disposable batteries and replaces them with a lithium ion battery pack. The battery contains no built-in protection circuitry in order to save space. Instead, this circuit is added later. [Solarcycle] appears to be using a circuit of his own design. The schematic and Gerber’s are available on his website.

The Instructable walks through all of the steps to build one of these yourself if you are so inclined. If you don’t have the spare time, you can fund the project’s Kickstarter and pre-order a production model. It’s always great to see a new commercial product with an open design.

[via Reddit]

Fail of the Week: Oil Expeller and Hasty PCB Layout

fotw-oil-extractor-hasty-pcb-layout

This Fail of the Week is a twofer. On the left we have an attempt to heat the output of an oil expeller. After a bountiful crop of sunflower seeds [Mark] picked up the oil expeller to make is own cooking oil. He tried to use the soldering gun as a heat source but after just a couple of minutes of on-time it melted the soldering iron’s plastic case. He’s looking for an alternate heat source but we wonder why he can’t just ditch the plastic and bolt this to a heat sink?

To the right is the product of hasty PCB layout. [Andrew] needed a USB to GPIO converter to use with his Android stick. He had built several of these before, etching the PCBs himself. But now he didn’t have the time to do his own etching and figured he could lay out a revision of the board and have it fabbed. Turns out this isn’t the time saver he had hoped. Problems with the location of silk screen labels aren’t a huge deal, but the ‘V’ in the board where his USB connector is located blocked any cable he tried to plug in. A bit of cutting solved that but he also had to deal with spring terminals whose leads wouldn’t fit the diameter of holes drilled in the board. We always print out the Gerbers and compare the footprints to our parts before submitting to the fab house. But we’re not sure we would have caught the USB cable clearance issue doing it that way. What checklists do you use before submitting your own boards?


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.