Money Shooting Tool.

Are you a boat or home owner?  Do you wish paying your bills was more fun?  Do you have stacks of cash sitting around just taking up space?  Well this is the project for you!  Over the next month we will be designing version 2 of the Rain Maker.  It’s a tool that you load with cash and then launch at about the speed most of my project eat cash lately.  Version 2 you ask?  That’s right most of the longer projects we model in class take me several attempts to get right.  Here is a link so you can see it in action. 

https://www.instagram.com/p/CYP6pMlIizE/

The first draft lets me work out the ideas and see if I can get a working prototype.   In this case I knew I wanted to try over molding like our favorite tool company here in Milwaukee and I was not sure if my cash accelerator device would work.  About a hundred hours of printing later I can tell you it does and I learned a lot of do’s and don’t when over molding on 3d printed parts.  I do really like the feel of the urathane rubber in my hand and it is so much fun to see money shooting our the front of the tool.  This is going to be a fun one so join us Mondays @ 7pm or watch the series on YouTube.

 

Weekend Project: Wine Rack

Last weekend I made a 60 bottle wine rack from some 1″ pine.  I sized it to fit on a counter top in my basement, under the upper cabinets. I was pretty happy with the design of a somewhat smaller Belgian beer rack I made in the past, so I copied some of its basic style. I really like the strong vertical lines of this design, as it contrasts with the strong horizontals of most wine racks.Wine_Rack_Assembled4

With the compound miter saw and table saw, I transformed three 6′ long pine 1″ x 12″ boards into the necessary 150 pieces! The rack holds 60 bottles, so I cut 120 10″ x 9/16″ x 3/4″ pieces. These are connected to 26 uprights that measure 18.1″ x 3/4″ x 1.5″, which are connected to 4 horizontals that are 52″ x 3/4″ x 1.5″.  Note that a spacing of 3.1″ is sufficient for wine bottles, but 3.35″ is the minimum for most champagne bottles.  The 3.35″ width also holds half bottles and just barely holds 12 oz beer bottles.  Also note that for strength reasons, the 10″ long pieces need to be cut along the grain, not across it.  Here are all the pieces, just before I nailed them together:

Wine_Rack_Parts2

It took about 1.5 hours to cut the pieces, and 1.5 hours to assemble them. Note that I used a nail gun and 1″ long, 18 gauge nails for most connections, except the uprights to horizontals, where I used 2″ long nails.  Check out the completed wine rack, made from $25 of wood and nails, in use!

Wine_Rack_Full2

Laser Cut Cocktail Recipe Coasters!

Years back, I used to throw a lot of cocktail parties.  Between myself and two good friends, we owned five cocktail shakers and 35+ martini glasses.  During the parties, we’d typically be the only three people shaking martinis for all the guests.  Though that’s awesome, it also means we missed out on much of the socializing and mingling during each party.
blog21In preparation for a recent birthday party, the solution came to me: Use Lasers!  So, I laser cut ten coaster-sized pieces of basswood and then laser engraved my twelve favorite Martini and Champagne cocktail recipes on them.  I also cut stands for them that had a laser engraved “best practices” guide for shaking Martinis – you know, the things that bartenders are typically too busy to do for you: Chill your glass before pouring your drink into it, shaking your drink until it is sufficiently cold, etc.  The drinks have recipes that taste better than what most bartenders will make for you, because they include things like an amount of lemon or lime that they’re too busy to squeeze into your drink.
blog22The party was an even more awesome experience for me, because I wasn’t only shaking drinks all night.   It was also even more awesome for the guests, as they found that great cocktails are super easy to make!  And who doesn’t like to make things? blog26 Also, the carbonated Gin & No tonic is real crowd pleaser!  See my previous post about home carbonation for more info, and note that all types of inappropriate things can be carbonated:  Gin, Ardbeg Corryvreckan, grapes, etc!

How To Laser Cut Really Big Halftone Photos

Wanting to up the ante a bit after having the Makerspace laser cutter chop out hundreds of city blocks to form a big map of MKE, I decided to laser cut a  24” by 18” halftone image!  As it required the laser cutter to carve 10368 circles out of an off-yellow piece of 98 Lb paper, the cutting took 1.3 hours and produced quite a bit of confetti.  I’ll display this with a purple (rather than black) paper behind the off-yellow laser cut paper.  In person there is an interesting transition from an abstract purple/yellow shape into a black and white image as one moves further away from the image.  You may even want to sit back from your monitor to improve the “image quality.”

Laser_Cut_Halftone_Image_color2

Check out this video of the laser cutter in the middle of cutting 10000 circles!  Note the mysterious logic employed by the laser cutter to determine the order of its cuts.

I imported a photo into GIMP, and desaturated it to produce a black and white image.  After bumping up the contrast and darkening it slightly to nearly saturate the darkest areas (and avoid any totally white areas), I brought it into Inkscape.  Inkscape can create halftones in a two step, manual process.  The first step is to draw an 8 pixel by 8 pixel circle in the upper left corner of the 1133×720 pixel image, and select Edit->Clone-> Create Tiled Clones.  To create a rectangular grid of halftone dots whose sizes are set by the color of the image below, use these settings:

Rectangular_array

From a quick test cut of a particularly dark area, I found that I needed to add an offset between each row and each column to account for the kerf of the laser.  I.e. the laser beam has a cutting width that is wider than that of the line, and so in the darkest areas of the photo the halftone dots overlapped, causing a large section of the paper to fully detach. That led me to make this test strip with 11 shades of grayscale, evenly spaced between pure black and white.  I laser cut this test strip with various offset distances between the rows and columns in order to arrive at the optimal 10% extra offset between adjacent rows and columns shown in the above settings. Note also that the smallest size circles may not even be exported from Inkscape due to their infinitesimal dimensions (i.e. if you export as a .pdf).  The minimum gap between circles with 42% speed and 100% power on an 1133 pixel wide image blown up to 24″ is 0.79 pixels, which is 0.017″.

test_tripApplying these same settings to the image created a 128 by 81 array of circles, for a grand total of 10368 vector objects.  In my first trial run last weekend, I found that sending this much data to our 60 Watt Universal Laser takes 5 minutes and results in a print error I noticed only after hitting start!  After 1.3 hours of vector cutting, I found that a few of the rows and columns were shifted a bit from their intended location.  It’s not clear whether this had to do with the print error, or if the paper moved slightly during the cutting process.

In order to improve the second version (shown at top), I chose to move away from the rectangular grid of halftone dots – recall that Kays and London teach that hexagonal close packing is for champions.  The reason to abandon the rectangular spacing is to improve the dynamic range (i.e. to make the blacks blacker).  For example, rectangular grids of circles pack at an “efficiency” of Pi/4, which is 79%, whereas hexagonal close packing results in a pi/6*sqrt(3) packing, or 91%.  That means that the darkest sections of the image will be darker, as more of the light colored “front” piece of paper can be cut away.  See the image below, and note that the hexagonal pattern does indeed appear darker.

rectangular_vs_hexagonal2

It turns out that Inkscape doesn’t easily permit this.  I ended up spending an hour or two fiddling with the column and row offset settings using my 11 black/white tone test strip to find settings that gave the hexagonal offset with the closest, even hexagonal spacing between adjacent circles.  The following settings worked great for an 8 by 8 dot on the darkest square of the test strip:

hex_arrayI test cut this yesterday, sending ¼ of the data at a time to the laser to avoid printing errors. However, part way through the cutting, cut-out paper circles stuck to the long air assist nozzle of the laser head (ironically) hit a washer I was using to weigh down the paper to prevent movement while cutting. The paper shifted by about 1mm, which was enough to make some adjacent halftone dots overlap and cause others to have a visibly wider spacing.

In the process of cutting that photo, Shane happened by and mentioned that vector cutting 10368 objects may be just as fast as the typically-very-slow raster cutting time.  With three clicks, I turned off the vector outline of the halftone dots, and selected a fill color.  After test cutting a row, I found that he was right.  Check out the difference between raster  (100% speed, 100% power) and vector (42% speed, 100% power) in the darkest section of the image – the area with the closest spaced circles:

vector_vs_raster2

The vector halftone dots are perfectly circular, though the edges are a bit rough.  Some of them have a very small border and so are a bit fragile.  The raster halftone dots are not very circular, but the edges are very smooth and the boarders are slightly wider.  I chose to raster cut the 24″ x 18″ image, and found that the raster cutting time of 1.4 hours was nearly equal to the 1.3 hour vector cutting time.

Note that many programs can create halftones, though often the results will not be suitable for laser cutter use:

halftone_error

The next step is to laser cut this image into wood.  Also, Inkscape will let you draw any shape to create tiled clones from – so please do share photos of any halftone images you create with star shapes!