Why Workshop 88 Rocks

I just had another experience Thursday evening reminding me why makerspaces are so great. I needed a very custom spring, but didn’t know how to make it. (It was to remove backlash in the gearbox of a stepper motor driving a robot to play a Theremin, but that doesn’t matter.)

I had the stepper in my hand – since it’s always easier to discuss something concrete – and asked member Bill if he knew anything about making springs. He did, but not the kind I needed. We talked about mandrels and springback, and threw out ideas about how to design a form to wind what I needed.

And then he pulled some music wire from a cabinet and started bending it by hand into very roughly what we thought we needed. That physical strawman let us pull and twist and point and talk about which direction the forces were acting and how to anchor it and how a spring like that really works. After a delightful session of technical banter, I had a LOT more insight into the spring I needed plus the eye-opener that I could just make it by hand! I grabbed some wire and a pair of pliers, and in 15 minutes had a spring that did exactly what I needed.

A fun technical discussion and exploration with a friend, and going from a show-stopper problem to a perfect solution for a few pennies’ worth of materials – it doesn’t get much better than that. And that’s why we hang out at makerspaces.

The project I needed the spring for is another great, if darker example of what happens at the space. An old lonely, dusty Theremin has lived in the back room for years, and I brought it out to see if I could make it work. It had just started to play its first eerie notes, and I was showing it to whoever wandered by, when somebody – a visitor, whose name I don’t recall – said “It would be neat to have a robot play it.” Whoa. That would be so frickin’ cool that even though I needed a new project like I needed a hole in the head, the Theremin playing robot was off and running. Here’s a clip of it playing a scale a couple of weeks later.

I bet lots of makerspaces have stories of whole projects that started by somebody musing “Wouldn’t it be cool if…”.  I guess we’re all suckers for that. 🙂

Prusa i3 MK2S 3D printer kit assembly time lapse videos

Prusa i3 MK2S 3D printer kit assembly time lapse videos

If you’ve ever wanted to see someone assemble a 3D printer from the ground up, I’ve captured every detail, sped it up, and set it to music just for you:

Link to 300x time lapse video (longer, more detail, different background music):
20170323 GoPro Prusa i3 MK2 assembly and print (300x time lapse)

The videos were captured using a GoPro Hero 3 Black in time lapse mode taking a wide angle high definition image every 5 seconds to a 64GB micro SD card.  The camera was mounted to a tripod using parts printed on the Replicator 2 and powered using a USB hub.  The resulting 30fps HD videos were created at 400% and 200% speed respectively.

History…

In 2012 I bought a MakerBot Replicator 2 for my father, which he graciously offered to keep at my house (he’s absolutely the BEST sharer).  He has since moved to a larger house and in December 2016 we happily moved the 3D printer to it’s new and rightful home in his shop where it has been getting good use making parts for an interesting capacitive network antenna power coupling project, and lots of little toys for the grand kids.  It was a great turn-key printer, able to easily slice and print models with its simple intuitive software.  Unfortunately without a heated bed and with limited head temperature it could only print using PLA. This left me without convenient access to a 3D printer, but gave me the opportunity to expand my 3D printing horizons.  I’d been considering buying one for a while, but finally I needed to make a decision.

The search…

For me, selecting a new 3D printer was as difficult as buying a new car.  There are a lot of decisions to make: Cartesian or delta? Retail, kit, or clone? Open or closed source? Which hotend? Cooling fans? Heated bed? Which materials (PLA, ABS, PETG, Nylon…)? What software can be used? and the biggie… How much do I want to spend?

I started my search with the usual “top 10” lists and “3D printer” roundup articles.

# 1 in All3DP top 10 in 2017
(All3DP is totally worth subscribing to by the way)
#1 in Make Magazine 2017 3D printer comparison
Make Magazine review:
Toms 3D review:
If you are interested in 3D printing and are not familiar with Tom, you should be, check out TOM’s 3D  website for some of the best, balanced, scientific reviews and comparisons of 3D printing components, printers, and filaments:
Tom‘s YouTube Channel:
Tom is also a moderator on Google+‘s fantastic 3D Printing group:

I didn’t have to look for very long before one machine started to tick all my boxes:

  • Open Source
  • Kit (and assembled versions available)
  • Cartesian
  • Auto mesh bed leveling
  • Part cooling fan (for PLA)
  • Heated bed (for ABS and other materials)
  • Multi-material
  • Multi-slicer,
  • Affordable
  • … and as an added bonus it has a 4 color upgrade coming later this year.

The Prusa i3 MK2

The machine…

The Prusa i3 MK2 is the latest printer designed by RepRap legend Josef Prusa, and the one at the top of the 2017 best 3D printers lists all over.  If you are not familiar with RepRap (http://reprap.org/) , it is a community of hardware and software makers who have been advancing open source 3D printing for the last couple of decades.  The basic concept behind RepRap is to create a machine capable of creating copies, or improved copies, of itself.  We all have that community to thank for democratizing and popularizing 3D printing to the point where fused filament 3D printing became commercially viable for the public (that, and a couple patents expiring).

Josef has been at the heart of two of the most popular recent open source 3D printer designs: the Mendel, and the Prusa (his namesake), each model undergoing several successful iterations and improvements.  In 2009 Josef Prusa opened shop and began selling printers and kits.  Today, true to his RepRap roots the latest machine, the Prusa i3 MK2 is used to print parts for customers printers in Prusa Research’s “build farm”.

Josef Prusa in Prusa Research’s build farm where Prusa printers are printing Prusa printers.

If you’d like to know more about the printer check out the Prusa website.

The wait…

I was going to order it over Christmas break 2016 but was waffling. I wasn’t sure if the printer was getting too much hype, or if I should get a dedicated dual head printer, or if I should just grab a turn-key printer like a Taz from a local store.  That delay would cost me a lot of time.  I eventually committed to ordering the Prusa i3 Mk2 kit in late January for a whopping $773 (USD) including shipping, an extraordinarily modest price.  Due to high demand and limited supply capacity for parts like the custom heated bed, I would have to wait 3 months.  This was not a surprise, Prusa was very clear about the lead time for their printers.  I received the printer late March.

The assembly…

By now I hope you have watched the assembly video(s).  I could have ordered the printer fully assembled and calibrated for an extra $200 (and extra lead time) but part of the reason I wanted an open source printer is to easily modify and improve it, and for that reason I wanted to know each nut and bolt personally.  It took roughly 8 hours, 5 good beers, 3 cats, and a dog (all featured in the videos) to assemble, test, and calibrate the machine.  The tree frog took 3 1/2 hours to print.  I had already read all the assembly instructions while waiting for the printer, and learned a LOT from watching Tom’s 6 part series about building the cheapest possible clone of the Prusa i3 MK2. (16 1/2 hours of interactive YouTube live streams!!! The clone was eventually named “Dolly” by someone in chat for the first cloned sheep of the same name)

  1. Prusa i3 MK2 live assembly: p1, Y-axis
  2. Prusa i3 MK2 3D printer clone live assembly: p2, X & Z Motion
  3. Prusa i3 MK2 3D printer clone live assembly: p3, X & Y Motion
  4. Prusa i3 MK2 3D printer clone live assembly: p4, Wiring and Printbed (mechanics finished!)
  5. Prusa i3 MK2 3D printer clone live assembly: p5, Electronics and Firmware!
  6. Prusa i3 MK2 3D printer clone live assembly: p6, final setup and first print!

If you decide to get the Prusa i3 MK2 kit or assemble a clone, here are some tips…

  • When there is a captured nut, POUND that nut into place before assembling the parts!!! Both Tom and I had the upper nut from the part cooling fan come loose and bounce around inside assembled parts for tens of minutes before carefully getting it seated.
  • Read ahead.  There are a few steps that provide instruction regarding previous steps like “but don’t over tighten”, or other things that may be should have been said in advance.
  • Look at all the pictures and stay organized.  The instructions are done VERY well in the “Ikea” style.  There are many details that you can only get from the pictures.
  • Be careful to use the correct length/size fasteners, rods, etc.
  • Review each step when done to make sure you didn’t skip or overlook anything.

The quality…

The print quality is amazing.

I haven’t had a lot of time to print many models yet but the resolution and quality of the first PLA print of the tree frog are far and away better than anything I’ve seen before.  It’s only 50mm wide but the surface is so smooth from the .5mm layer height, and the underside is flawless due to the part cooling fan.  The details in the eyes, nostrils, and hips are impressive too.  I’ve also printed a Raspberry Pi case, camera mount, (for OctoPi) and computer stand mounts in ABS.  I’ll be printing some drone parts soon in PETG and ABS, and bought some Nylon to play with.  I’ve tried Slic3r and Cura model slicing software used to convert models to g-code files for 3D printing.  I  preferring Slic3r which was provided by Prusa pre-optimized for this printer, but they are both very good tools.  Stay tuned to blog.workshop88.com for more of 3D printed projects in the future.

Finally, on the topic of Dolly, and a home made clone…

Even though I just bought, assembled, and am still coming up to speed on my fantastic new printer, the idea of building a clone for 1/4-1/3 the price (somewhere in the $250 range) has me and several friends on the verge of starting a group clone build.

Thanks!

Thanks to Kevin Meinert of subatomicglue for letting me use his awesome music in the videos.  If you would like to hear more, visit www.subatomicglue.com.

If you’re interested in building a Prusa or another 3D printer, or a clone, or discussing 3D printing, check out Workshop 88 on Google groups, Slack, or come by our weekly open house any Thursday night after 6:30pm.  Details can be found here.

D. Scott Williamson
Compulsively creative

Maker of CamBam supports Workshop 88 makerspace!

HexRay supports Workshop 88 with a complimentary
CamBam site license & member discount!

Workshop 88 would like to extend a big thank you to HexRay for supporting the our CNC efforts by allowing us unlimited use of CamBam on club Windows and Linux computers plus a discount on CamBam to Workshop 88 members.

For more information about CamBam, check out their website: http://www.cambam.info/

From the website:

CamBam is an application to create CAM files (gcode) from CAD source files or its own internal geometry editor. CamBam has many users worldwide, from CNC hobbyists to professional machinists and engineers.
CamBam currently supports the following:

  • Reading from and writing to 2D DXF files.
  • 2.5D profiling machine operations with auto-tab support
  • 2.5D pocketing operations with auto island detection
  • Drilling (Normal,Peck,Spiral Milling and Custom Scripts)
  • Engraving
  • True Type Font (TTF) text manipulation and outline (glyph) extraction.
  • Conversion of bitmaps to heightmaps
  • 3D geometry import from STL, 3DS and RAW files
  • 3D waterline and scanline machining operations
  • Extendable through user written plugins and scripts

Be sure to check out their CamBam bundles with Mach 3 controller and CutViewer too.  Personally, I purchased the full CamBam + Mach 3 + CutViewer bundle; I couldn’t beat the price and I’ve been happy with them to this day.

As if that wasn’t good enough: “Unlicensed CamBam installations will continue to work after the 40 evaluation uses are up and allow editing drawings and viewing toolpaths.  However, g-code output is limited to 1000 lines, so another option is for people to work on designs at home, then bring them in to the group’s licensed computers to generate g-code.”

This level of support from HexRay is fantastic and something Workshop 88 greatly appreciates!


I have been using CamBam as my go-to CAD-CAM software for many years, to see a sampling of the kinds of things it can do, take a peek at some of my personal CamBam projects:

3D vacuum forming mask mold master for independent movie

Utility shelf for beverages and keys

Wall artwork – Wooden V

Engraved Bahr family crest

Atari Adventure engraved sign

Philosophy Custom Guitars engraved sign

Working miniature TV

Halftone portrait

Stay tuned to see CamBam powered Workshop 88 CNC projects!

…and on behalf of Workshop 88:

THANK YOU Andy @ HexRay!

If you’d like to find out more about Workshop 88, please contact us:
http://blog.workshop88.com/interact-with-us/ or stop by our weekly open house any Thursday evening after 6:30pm.

D. Scott Williamson
Compulsively Creative

3D Printing PLA on a flexible metal build plate

3D Printing PLA on a flexible metal build plate

By D. Scott Williamson

I love 3D printing.  I’ve designed and printed hundreds of models on the Replicator 2 and have developed many useful skills and techniques. The Replicator 2 has a non heated polycarbonate build plate with MakerBot emblems laser cut into one side and the other side is frosted.

I don’t care for having the MakerBot logo in relief on the bottom of my prints so I print on the frosted side of the platform.

These are rafts but I don’t like having the MakerBot logo embossed on my work.

This worked well for hundreds of prints but eventually, scraping the prints off the platform smoothed the rough surface and parts started sticking harder and harder to the build plate.  Ultimately they stuck so hard that the force required to get a spatula or razor under a part started cutting grooves into the build plate.

Two of the most common 3D printing problems are related first layer adhesion to the build platform…

If the first layer does not bond well enough it can result in corners lifting especially for broad parts on unheated platforms.  In the worst cases the part breaks completely free from the platform partway through a print leading to a stringy mess, wasted time and filament, and in rare cases the PLA can stick to and damage the insulation on the print head.

Catastrophe! Lifted corner, parts broke free, filament everywhere, and damaged thermal insulation on the print head.

If the first layer bonds too well to the build platform the part or platform may be damaged when removing the part.  When using blue tape, it may not be possible to completely remove the tape from the part.

I started using blue painters tape and Aqua Net hairspray on the build plate.  I found this combination to work well with PLA, though I’m not sure how necessary the hairspray is.  The problems are that the tape is damaged when removing most prints so needs to be reapplied frequently and can be difficult or impossible to remove from the bottom of finished parts.

Blue tape stuck to part.

Sometimes it’s impossible to remove all the tape residue.

Blue tape doesn’t last long and requires sticky messy maintenance.

I considered a heated build plate, and glass or metal build plates when the idea occurred to me to try to use a flexible metal build plate. I conducted several experiments using a cable chain model that is challenging to print due to fine detail and thin parts that need to bond well in the first layer.

Experiments

Experiment #1: Aluminum flashing with 2 coats of hairspray dried with heat gun and held by binder clips

First I tried aluminum flashing with hairspray.

  1. Measured and cut the aluminum on a paper cutter and nibbler to perfectly fit the build plate

    Aluminum flashing on roll with Replicator 2 build plate

    Rough cut aluminum.  Use gloves, sheet metal is sharp.

    Cut aluminum to size on the paper cutter.

  2. Rolled flat

    Thin sheet aluminum was curled and needed to be flattened.

    Rolling the thin rolled sheet aluminum flat with pipe on foam.  A towel could have also been used underneath the material.

  3. Cleaned with alcohol to remove oils/grease

    Cleaned the sheet aluminum with ammonia and alcohol.

  4. Coated one side with a thin film of hairspray, let it dry, and applied a thicker coat of hairspray

    Two coats of Aqua Net hairspray applied.

  5. Dried the hairspray with heat gun

    Used heat gun to rapidly dry the hairspray.

  6. Clipped aluminum to build plate with binder clips at the edge

    Aluminum plate clamped to build platform.  (The clip in the upper right corner is about to get knocked off.)

  7. Leveled the build plate to account for the thickness of the aluminum plate
  8. Printed a test

    The PLA bonded weakly to the platform and the parts detached easily in the second layer.

    The upper right and lower left clamps had to be moved because the print head knocked them off.

The nozzle interfered with some of the clips and knocked them off.  The PLA did not adhere to the build plate.  Failure.

Experiment #2: Aluminum flashing with wet hair spray and binder clips

Aluminum flashing with wet hairspray yielded the same results.  Failure.

Experiment #3: Aluminum flashing with glue stick held by clips

Using the back side of the same build plate I used a generous layer of glue stick.

  1. Using the back of the cut aluminum plate from Experiment #1
  2. Coated the plate with glue stick
  3. Clipped aluminum to build plate with binder clips at the edge where the nozzle would be less likely to interfere with them

The PLA adhered wonderfully and the print turned out great.
When done I removed the aluminum plate and was able to remove the print by bending the plate – Success!
But the aluminum does not lay flat and the part left dimples in soft thin aluminum plate before letting go.  I need a stronger material.

Experiment #4: Steel sheet with glue stick held by clips

I scrounged around and found a stiffer steel plate salvaged from a magnetic children’s book many years ago.  I did not try to cut the steel plate to fit the platform because I don’t have a shear and did not want to dull my paper cutter cutting steel.  I can cut the steel on the metal shear at Workshop 88.

  1. Using paper towels, I cleaned the steel plate with ammonia to be sure to remove oil or grease, then with alcohol, and finally with tap water
  2. Coated the plate with glue stick
  3. Clipped steel plate to build plate with binder clips at the edge where the nozzle would not interfere with them
  4. Leveled the build plate to account for the difference in thickness between the aluminum and steel plate
  5. Printed another test

The print turned out great!

But the plastic clips that hold the build plate to the printer are raised causing the plate to be irregular and warped and not flat against the polycarbonate platform beneath it.

If you remove a print by flexing the steel it pops right off but it is still possible to dimple the steel this way.  The dimples can easily be gently pounded out with a broad hammer with the steel on a flexible surface like a neoprene mouse mat or a towel.  Parts firmly attached to the steel are easily removed using a spatula and/or a razor so dimpling turned out to be a non-issue.

Experiment #5: Steel sheet with glue stick held by magnetic sheet

To get the platform to lay flat on the platform I attached a sheet of flexible rubbery plastic “refrigerator magnet” material originally intended to be a furnace vent cover to the platform with double sided tape.

  1. Cut magnet to size
  2. Attached magnet to build plate using double sided tape and pressed it flat using a rubber roller
  3. Aligned the steel plate with the platform and when laid flat the magnet holds it firmly and flat
  4. Leveled the build plate to account for the additional thickness of the magnet layer
  5. Coated the plate with glue stick
  6. Printed another test

Best results yet!

Excellent first layer adhesion with fine detail.

The build plate is flat and level, firmly attached to the platform in the center without using clips which makes it very easy to insert into and remove the plate from the printer.  The finish on the bottom of every part is smooth and shiny, far better even than when printing with a raft.

Even though others reported using a coating of glue stick up to a dozen times, I found reused glue stick not to adhere well.  Adding layers of glue builds up, so every couple of prints I wipe the plate down with a wet paper towel before adding a new layer.

I’ve added alignment markings to the build plate to help install the plate consistently, to help center parts, and to help apply glue only where it’s needed for each print.

 Examples:

Markings help guide application of glue and placement of parts in MakerWare software.

Printed right where expected, with a beautiful first layer and finish quality on the bottom without a raft.

Extremely challenging pinhole lens print

This pinhole lens is .2mm thick and each hole is printed separately with 2 shells then the rest is filled in, if any pop off the build plate it will stick to the hot end and gather the rest into a blob of plastic.

This folding phone/tablet stand (http://www.thingiverse.com/thing:692523) is a favorite model in my house.  It’s a hinged phone/tablet stand that prints fully assembled. If you look carefully you can see that there is some slight curling. The plastic is pulling upward at the corners and even though it has not detached from the build plate it is deflecting it slightly up off the magnet.

The finish quality of the base is comparable to printing on glass.

Not every print has been perfect though, this is another phone/tablet stand that started to curl. The print head caught one corner and moved the entire build plate on the magnet. You can see it continued to print offset before I stopped it. It is impressive that it moved the whole build plate without detaching from the platform. I was able to reprint this model successfully. Only a heated bed or chamber can really prevent this issue entirely, but a stronger magnet may require more force to move.

Future work

  • Cut the build plate(s) to size on the shear at Workshop 88. The build plate is still larger than the platform and must bend to go over at least one of the platform holding clips.
  • Cover the entire platform with magnetic material.  The current magnetic material does not cover the entire platform, it is what I had on hand.
  • Find stronger magnets.  The print quality is wonderful but it is still possible for corners of large parts to lift the platform off the magnetic base while staying attached to the platform.
  • After I started printing on steel I found PRINTinZ’s flexible build plates.  I haven’t used them but check them out! http://www.printinz.com/printinz-3d-printer-plates/

Thanks for reading, and good luck with your 3D prints!

D. Scott Williamson
Compulsively Creative

Animatronic owls

3338

Workshop 88 member Anna Gillespie created a series of animatronic owls for an event at the public library where she works. The owls were controlled with arduinos using servo motors and a wav shield for the sound of the owl hoot.  Some of the owls turned their heads and some of them flapped their wings in addition to hooting. This was a great project to watch from start to finish; thanks, Anna, for sharing with us!

CAD CAM tutorial

CAD CAM tutorial
by D.  Scott Williamson

This tutorial will show you how to use Computer Aided Design and Computer Aided Manufacturing or CAD CAM tools to create and preview a Gcode file of the Workshop 88 logo that can be run in a 3 axis CNC Mill.

Background

There are 5 main types of machine operations

  1. Engrave (follow path): The tool tip will follow the 3D path provided.
  2. Profile: The tool edge will follow either the inside or outside contour of a path down to the specified depth.
  3. Pocket: The tool will remove all the material within a contour down to the specified depth.
  4. Drill: A drill routine will be executed at each point location.  Drill routines come in 2 flavors:
    1. “Peck” used with drill bits, drills to successively deeper depths liftig the bit out of the work regularly to clear chips from the flutes.
    2. “Spiral” used with endmills that are a smaller diameter than the finished hole.
  5. 3D relief: The tool tip will remove material above a 3D surface usually specified in a 3D model or a 2D height map image.  There are two main modes:
    1. “Waterline” similar to inverted pocket operations where bulk material is efficiently removed outside the 3D model to a number of stepped depths resembling waterline in a topological map.  Typically used in a first pass with a large roughing bit to remove the bulk of the material.
    2. “Raster” moves the tip of the bit smoothly over the model in a raster pattern.

Gcode is a “numerically controlled programming language” which is why a Gcode file extension is typically .nc.  It is a human and machine readable text file.  You will rarely if ever need to look at or edit the Gcode.

Overview

This tutorial will demonstrate Engrave, Profile, and Pocket operations, which are the most popular.

There are 4 steps to this tutorial:

  1. Create a .svg file containing paths needed for machine operations
  2. Create machine operations
  3. Export Gcode
  4. Simulate, visualize and validate

Continue reading

T-Kit 1380 Kit Build: Part 2

Today, I’ll be continuing my 80m transceiver build that I started in T-Kit 1380 Kit Build: Part 1.

At the end of the last post, the board looked like this:

The full board

The full board

Today I’ll be moving on to the VFO section of the board.  A VFO, or variable frequency oscillator, is the circuit that allows you to tune a radio.  This particular VFO is based on a Collpits oscillator, and can tune over a 50-70 kHz range centered on a frequency determined by the component values.  The frequency range shown in the image may seem a bit strange.  This transceiver can be built to cover that 50-70 kHz range somewhere near 3.5 MHz to about 3.75 MHz.  The short explanation is that the frequency we’re interested in is shifted by the frequency of the VFO to an intermediate frequency of 8 MHz, where we can do filtering and amplification at a single fixed frequency.  Since a lot of circuit characteristics are frequency-dependent, performance is much better if the components can be selected for just one frequency.

schematic

The majority of the components are supplied with the kit, so their values are fixed.  One of them, an inductor, I had to wind myself.  Since this phase required quite a few components, I decided I’d lay them out before I started.

components

Rather than start building immediately, I decided to wind the inductor first, so I could get that out of the way.  The instructions specified 28 turns of the green #28 enameled wire on the red toroid core.  I had to count the turns several times to be sure.

inductor

The inductance of the coil is dependent on a lot of things, including the material the core is made of, the diameter of the core, the number of windings, and the spacing between the windings.  Later on in the build, I tweak the range covered by the transceiver by adjusting the coil spacing.

phase-2-complete

From this point on, it was simply a matter of stuffing the board and soldering, as per the instructions.  The one thing I would have changed was the process for doing initial testing of the inductor.  They have you tack a couple leads to the pads you’re going to use, and then tack the inductor to those.  Unless your inductor is wildly off, you’re not going to be rewinding it, so I would have skipped that step and just soldered it in directly at the beginning.

The testing of phase 2 was relatively simple, because I’m using a frequency counter.  I just hooked up the frequency counter, and adjusted the spacing of the turns on the coil I mentioned before until the VFO covered the range between 4.470 MHz and 4.391 MHz.

I’ll talk more about it in the next post about the transmit mixer and filter, but that provides an actual range of 3.530 MHz to 3.609 MHz.  This includes the QRP CW calling frequency at 3.560 as well as W1AW’s code practice sessions transmitted on 3.5815.  It does not include the main CW DX window between 3.500 and 3.525 MHz, but I’m still working on getting my Amateur Extra license, so I’m not authorized for that part of the band anyway.

 

T-Kit 1380 Kit Build: Part 1

I won a T-Kit 1380 80m 3 watt CW transceiver kit at the WCRA Hamfest back in 2014, and it’s been sitting on my bench unopened since then.  I didn’t have my license at the time, but I got my General license about a week later. I decided that this summer was a good time to start building it. Here’s a link to one you can pick up if you’re interested : http://www.rkrdesignsllc.com/-13/

I have quite a lot of kit-building experience, but most of it is digital electronics, so this is probably the most complex kit I’ve ever built, both in number of components and circuit complexity.

If you’re not familiar with amateur radio, this kit will let you transmit and receive on the 80m band (between 3.5 and 3.75 MHz) using CW (morse code).

1380 Manual

The schematics in the manual are a bit low-res, but the instructions for assembly are very good.  My biggest complaint with the manual so far is that errata are supplied as a stack of papers inside the manual.  Some of them referenced parts this kit doesn’t use, so it was a bit of a chore to go through and update the instructions and update the steps by hand.

The assembly process is documented in phases, with testing procedures at the end of each phase.

Phase 1 is construction of the DC input circuitry as well as the keying circuit.  The keying circuit is connected to the code key, and disables the receive circuitry while transmitting.  Here’s the diagram for phase 1.

Phase 1 schematic

Phase 1 schematic

Here’s the board as assembled:

Phase 1 assembled

Phase 1 assembled

This is a pretty densely packed board, and the silkscreen suffers for it.  The manual gives pretty decent drawings of the section of the board each phase is concerned with, and this helps quite a lot.  You can usually locate a component by finding a nearby component you’ve already installed, or one whose silkscreen isn’t broken up by a pad.

Once this phase was assembled, there was a short test procedure to verify that it is operating correctly.  Essentially, I had to apply 12v to the 12v input, and then verify that R13 (the resistor in the center of the board, just between the two beige ceramic capacitors) read 0v while the key wires were disconnected (the white and black wires just under ‘J1’), and 12v while they were touched together.

I misread the directions and it took me a while to figure out what I was doing wrong (I was measuring voltage drop across the resistor, not between the resistor terminal and ground), but in the end, everything checked out.

The full board

The full board

As you can see, there’s quite a lot of work still to do, so come back next time, when I move on to assembly and testing of the VFO section!

Surface-Mounted LEDs for LEGO & LED Inventing Camp

PlacingParts0270Rachel and Jim made up some very skinny surface mount LED/resistor strips that fit between Lego posts for a STEM camp Rachel is running.

A simple pattern was etched on flexible copperclad Kapton film, using vinyl from the vinyl cutter as resist.  Solder paste blobs and the tiny 0805 components were hand placed, ReadyToSlice0273then reflow soldered on the hot plate.  Here are some ready to be sliced apart.  The resulting glowing Gummi bears were a big hit with the kids!

EllaHead180514Campers beta-tested Rachel’s Conducty Inventing Kit during a week-long Spring Break camp at Moore Toys and Gadgets in Wheaton. They built circuits Cooper134906581directly on LEGO baseplates using conductive tape and components designed to fit between the LEGO studs. Kids lit up everything from Minecraft torches to outdoor campfires made of LEGO. Here, Cooper and Ella show off their creations.  The Conducty LED Inventing Kit will be launching on Kickstarter later this Spring.