Archive for January, 2011

Makerbot Lighting Build

Thursday, January 27th, 2011

One of the things that's a nice addition to any Makerbot is internal lighting.  I know I've held a lamp up to my bot more than a couple times to get a better look at what was happening at the nozzle.  MakerBot Industries had a lighting kit earlier on and latter added strip lighting.  These strips come with adhesive backing and can bee hooked directly to a 12 Volt supply for power.  Unfortunately, they don't come with much in terms of instructions for use, and they're permanent nature makes them less than ideal for people constantly upgrading or modifying their bots.

Using the LED strips as a starting point, I decided to make a modular lighting solution for my Cupcake CNC that I could swap to a Thing-o-Matic if I decided to upgrade.  I created a few mounting plates that I could attach sections of my strip of LEDs to that I could also wrap my wiring through and could easily be attached and removed from my bot.  One plate attached to the underside of the Z-stage, and two others that are mounted at the top of the bot's build chamber.  You can grab the design files and a detailed BOM for this project here.  I'll cover the construction of the Z-stage assembly here, as it's a little more involved than the top assemblies and works on both the Cupcake CNC and the Thing-o-Matic.

All plates are laser etched/cut from 0.06" thick sheets of PETG (kits are available here with all the parts needed to assemble and mount the lights).  PETG is great for this application because it's crystal clear like the acrylic the Z-stage is made out of but it's nowhere near as brittle.  Below are some pics of the Z-stage plate before and after removing the protective film after laser cutting.  The outlines that are etched on the plate show where the individual strips of LEDs go.

You'll need to cut four 2 inch long strips and one 4 inch long strip off of the end of your LED strip.  Do not just cut these strips from anywhere in the length of the strip! The strip is actually divided up into groups of 3 LEDs in series with a small current limiting resistor in the middle.  You'll need to cut the strip where one circuit ends and another begins.  There will be a set of exposed copper pads clearly labeled + and - where this occurs.  Cut in between these sets of pads leaving a set of exposed copper pads on each side of the cut strip (the white dashed line in the center of the picture below).

Once you've got the strips cut, get out your soldering iron and add a blob of solder to the exposed copper pads at both ends of each strip.

Next, remove the protective backing on the strips and attach them to the  mounting plate.  The outlines should make placement easy.  Don't worry about strip orientation.

Before going much further, let's assemble the power connector.  I opted for the simple solution and just used two 0.1" male headers for my power connector (This will eventually connect up to one of the 3-1/2" floppy power connectors on your ATX power supply) and some black and red 18 gauge wire twisted together with a hand drill for my power cable.  If you picked up a kit from me, you'll have some nice 2 conductor Red/Black wire to wire everything up with.  I removed less than 1/8" of shielding from the ends of my power wires and tinned them (applied a bit of solder) and tinned the 0.1" headers a bit too.  I used 1/8" heat shrink on each conductor, and if you want to do this as well, make sure you place it on the wire before proceeding to the next step.

Next, solder the power wires to the header.  If you've already applied solder the the header pins and the wire you should be able to simply touch them together and apply a little heat with the soldering iron to mate them.  Do not hold the header while soldering the wires on!  Also, make sure to solder the power wires to the shorter side of the header if there is one.  Polarity doesn't matter at this point.  It should look something like this when done:

Next shrink wrap the wires if so desired.  I used a small length of 1/4" shrink wrap over the whole thing:

Now we can cut our power cable to length.  I cut mine to 24 inches and had plenty of slack.  Size it up on your bot if you're unsure how long you'll need to cut it to make it from your Z-stage to your power supply with a little slack for movement.

Next we need to finish up wiring the lights on the mounting plate.  For this I used some nicer 2-conductor color coded red/black wire.  Use the same technique of tinning the wires before mating them with the solder blobs you put down previously.  If you do it right you should only have to touch each connection only briefly with your soldering iron to make the connection.  Pay attention to the polarity of your connections when connecting the strips together.  Positive and negative connections should be clearly labeled with + and - on the silkscreen of the strips.  Positive connections go to positive and negative connections go to negative.   As long as each individual strip has one positive connection and one negative connection they should light.

Next we need to connect up power.  You'll notice that there are pairs of oval holes on the edges of the mounting plate.  These are for power wiring.  You'll want to fish the power wires in one of these paired holes and out the other:

This should help prevent damage to your lights if something accidentally yanks on the power cable.  Next solder the power wires to the positive and negative pads on one of the LED strips.  When you're done it should look something like this (again, if you picked up a kit you'll have red/black zip cord rather than the twisted pair pictured):

At this point you'll want to inspect your work, making sure you don't have any bridged connections or positive pads connected to negative pads.  If everything checks out, it's time to test it out.  Power up your bot and find a free 3-1/2" floppy power connector.  If you've followed the standard wiring scheme of red being positive and black negative, you'll want to plug your header into the the power plug with yellow (+12V) matching up to red as shown below.

If everything is connected up correctly, you should see everything light up immediately:

Constriction of the two top light plates is almost exactly the same as the Z-stage plate but you'll want to adjust the length of the power wire you give each.  The right top plate was relatively close to the power connector I was going to plug it into so I left it fairly short:

While I left about 2 feet of wire on the left top plate because I ran the wire for it across the front of the bot.  Pay attention to where you will be running the power wires for each of these plates and make sure you don't cut their cords short!

Now the only thing left to do is attach it to your bot.   The two top light plates attach easily with 2-M5x15 bolts each.  I ran the wire for the left right light plate out of the hole on the back right of the bot.  The right top light's power wire I ran through the M5 holes on either side of idler pulleys in the front of the bot and out the front right hole on the top of the bot:

Next you'll want to install the Z-axis plate.  This plate is attached using the M5 bolts that hold your extruder to the Z-axis.  Remove the bolts holding your extruder in place, slide in the plate, then re-bolt down your extruder.  I added a third M5 bolt to hold the plate down that is installed just behind the extruder in one of the mounting holes that would be used to attach the pen plotter accessory.  Make sure you install the bolt with the cap side down (like the rest of the extruder bolts) if you choose to install this third bolt.  Lastly, check to make sure nothing is sticking down past the nozzle on your extruder so nothing can snag on your parts as they're being built!

I used some clear tape to tack down the power wires to the Z-stage and make sure they don't interfere with the operation of the machine.

That's it.  Plug everything in, flip the power switch on your supply and the motherboard and proclaim "Let there be light!"

Here's some more pics with just the top lights on:

And just the Z-stage lights on:

Quick Projects – Build a Simple Vinyl Roll Floor Rack

Monday, January 3rd, 2011

I recently acquired a vinyl cutter that came with a reasonable cache of sign making supplies.  These supplies included several 24" and 15" rolls of vinyl that I had no easy way of storing, so I made a quick rack to store most of them (the alternative was buying a $50-60 wall rack I had to mount that only held 16 rolls or a $200 floor rack).  I played with the idea of making racks that would work with some cheap gondola shelving I picked up, but in the end I opted for a simple floor rack because it was easier, and significantly cheaper, to build.

Materials

  • 16 M3x40 bolts - Perfect length for spanning  2 sheets of 1/4" material using 1" spacers
  • 16 1" Spacers - I had some around for stacking PCBs on my Makerbot
  • 16 M3 nuts - I've got a lot M3 hardware because of Makerbot projects
  • Rubber feet hardware - Picked up at Home Depot for $2
  • 3-12"x18" Sheets of MDF - Available at Home Depot in 4'x2' sheets for about $6
  • 15' 1" Schedule 40 PVC electrical conduit - About $2-3 for a 10' section
  • Wood Glue

Construction

First you'll need to cut/drill your parts out.  Get the design files and a more detailed BOM from the Thingaverse page for the rack here.  I cut out all these parts out of 1/4" MDF on my laser cutter, but you could easily just use a hand drill and a hole saw to make them.

Bottom MDF Sheet

Top MDF Sheet

Cover MDF Sheet

Next you'll want to cut your conduit into sections.  You can make quick, clean (but not always straight) cuts with a pvc pipe cutting tool, pictured below.  I used 1" schedule 40 electrical conduit, which is a little under 1-1/3" in diameter in 12" sections.  You could probably get away with shorter sections and conserve a little conduit.

After that's done, start assembling everything.  Install the feet and assemble the top and bottom pieces with your M3x40 bolts and 1" spaces.

Next you'll install the cover, which will prevent the bolt heads from damaging the ends of the vinyl rolls.  Use a couple conduit sections to make sure everything's aligned correctly then glue it to the top layer and clamp it down.

Now all you have to do is wait until the glue dries, remove the clamps, install the rest of the conduit sections and you're done.

Quick Inkscape Tutorial – Perspective Transforms

Sunday, January 2nd, 2011

Let me start out by saying that far as open source software goes, Inkscape is definitely on my top 5 list and there a number of things that Inkscape can do that other proprietary vector graphics programs can't.   That said, I've used a few other proprietary vector graphics programs before and it seems like there are some nice features missing or buggy in Inkscape in its current state.  In many cases, you can get around the limitations of Inkscape and get the effects you want, you  just have to work a little harder than you would have in other software packages to get there.

I ran into one of these cases recently while trying to make a quick set of paths to use with my vinyl cutter to make a sticker for my laptop.  I used standard path operations to create a sensor tower warning symbol, but then I ran into trouble when I wanted to perform a perspective transformation.  Some other vector graphics packages roll this functionality into a "free-transformation" tool that allows you move each of the points of the bounding box of the currently selected objects and some separate this transform into its own tool/operation.

A quick Google search returned a number of videos showing how to perform a perspective transform, but it seems the functionality and path to it has changed over time.  After figuring everything out I also found this good post on all the pitfalls of perspective transformations here.   Basically, the old path for the perspective transformation was "Effects>Modify Path>Perspective" and it is now found under "Extensions>Modify Path>Perspective"  and it will only work if the paths you will be applying the transform to follow some strict guidelines.  Basically as of Inkscape 0.48.0 r9654 you'll need to make sure that:

  1. All elements you are going to transform must be paths.  No text objects, no bitmaps, no rectangles or other shapes, just paths.  If you've got any shapes amongst the paths you will be transforming you can convert them to paths by selecting them and got to "Path>Object to Path".
  2. All elements you are going to transform need to be grouped or in a combined path.  I was able to use nested groupings without issues but if your results are not as expected you may have to remove nested groups.
  3. You must define a "target shape" to determine the bounds of the transform that is a 4-sided polygon who's points are drawn clockwise starting from the bottom left corner.  Drawing the points in any other way will result in odd behavior.  All sides must be straight lines, no curves.
  4. You must select both the paths you will be transforming and the target shape by selecting your paths first then shift-clicking your target shape second.

After you've done all this, go to "Extensions>Modify Path>Perspective" and everything should work as expected.  In addition to being able to use nested groupings, I was able to assign transformations to individual paths and get predictable results, so some of the issues with the perspective extension may have been fixed recently.