LulzBot… Soon!

LulzBot

LulzBot is know for producing and selling open source 3D printers, and in the spirit of open source, they do their best to give back to the community. In the past they’ve helped make Slic3r better, and more recently they’ve done a printer giveaway to hackerspaces… and yes, we’ve been chosen!

We are one of the LulzBot Hackerspace Giveaway 2014 Winners, and we’re pretty excited about it!

We (as a space) acquired a 1st gen MakerBot Replicator (the one with the wooden frame) and it’s served us well (ok, we never quite got the second extruder working, and it was down for repairs more than a few months last year.) Anyway, the MakerBot has been our best 3D printer to date, but with a LulzBot TAZ on the way, we’re really hoping to up our 3D game to include bigger and better prints, and hopefully explore new materials like Nylon, wood, and NinjaFlex. Being fans of open source ourselves (a makerspace is all about sharing!) it’ll be great to have a high-quality printer for our members as well as events like the Milwaukee 3D Printing Meetup.

Once we get the TAZ in and up and running, we’ll share the results. Thanks again, LulzBot!

Table Saw Guard

guard04

 

This started out as an experiment, but it’s working well enough that I might as well call it permanent.

Our table saw came with a blade guard that was attached to a splitter, and every time someone moved the guard, they’d bend the splitter out of position, so it didn’t line up with the blade. Instead of bending it back, people would just remove the guard and put it in some random place where we couldn’t find it, so a lot of the time we were using the saw without a guard.

Over-arm type guards are available, but some people have built their own, so I decided to give it a try. The Lexan sides and the spacers between them were cut out on the CNC router. Everything else was sized to fit the saw. (It’s made for a 10″ blade, but for some reason we have an 8″ blade on the saw right now.) A giant washer acts as a counterweight (it weighs about a pound).

I thought we’d have to fabricate a cantilevered arm from welded steel, or maybe some of the carbon fiber tubing that’s laying around. But first I built a prototype out of 2x4s, and it worked well enough that I decided to leave it that way (I replaced the two clamps with nuts and bolts after the picture was taken.)

splitter02

 

The new splitter was cut from 16 gauge sheet steel on the vertical bandsaw in the metal shop, then filed to fit, and bent with a pair of pliers to line up with the blade. It has slots in the bottom, so it can be removed by loosening the bolts with a 10mm wrench (for certain kinds of cuts that it would interfere with, such as dados). Since it’s not attached to the guard, it doesn’t get bent as easily as the original one.

For more info (including DXF files), see the wiki page:

http://wiki.milwaukeemakerspace.org/projects/guard

Gothic Arch Room Divider is Finished (Sort of….)

Sanctuary and More 102Silversark put together an amazing fashion show on Friday to showcase pieces she made inspired by church architecture and her trip to the Netherlands. This is something I cooked up for a background piece for the show.

The design work took several months and the actual creation of the piece took about a week, working 12-16 hours a day.  The frame is made from CNC routed aspen (thanks, Jason H.!) which is a rather “fuzzy” wood and required two days to hand finish, including the use of a set of needles files to smooth out the inset edges.

The acrylic panels were hand-stained with Gallery Glass stain and simulated liquid leading. They’re not quite finished yet, but I plan to complete the staining within the next week.

I’ll also be using this as a backdrop for various events including the Sustainability Summit coming up as well as the Concinnity sci-fi/gaming convention on April 5th. Additionally, this might be making its way to Embellishments in the Grand Avenue Mall for a window decoration.

I can’t wait to make another one!

SnakeBite Extruder Works!

I repaired the Budaschnozzle hot-end over the weekend and bolted the SnakeBite extruder to it and then to MegaMax and tested it last night.  There’s plenty of tuning to do, but the first print looks promising:

 

Start of SnakeBite’s first print

 

More of SnakeBite’s first print

 

Not too pretty but it shows promise.

Not too pretty but it shows promise.

3D Printable Thermal Enclosure For 3D Printer

Well, OK, not the whole enclosure, just the parts that hold it together.

MegaMax can print big stuff but he’s had problems with large prints delaminating.  The answer seems to be enclosing the printer to keep the prints warm while printing.  I designed this box and 3D printable parts to hold it together so that I can take the box apart easily to work on MegaMax or move him to other locations and put it back together when I’m done.  The box is 38″ D x 28″ H x 32″ W.

box door open

 

 

 

 

 

 

 

 

 

 

box door closed

 

 

 

 

 

 

 

 

 

 

 

 

 

The box is made of 1″ PIR foam with corners suitably notched to accommodate the printed parts.  MegaMax has a 450 Watt heater in the printbed so the box gets super-toasty inside.  I suspect it gets a little too toasty but haven’t made any measurements yet.  I’ll soon be moving the electronics out of the box.  I didn’t do anything to seal the seams in the box because it doesn’t seem to be necessary.  I did tape the edges of some of the foam boards with clear packing tape to prevent damage.

Design and stl files are available at http://www.thingiverse.com/thing:269586

Camera Accessory Mounting System

CAMS pieces

Those who know me know that besides being cheap (hey, it’s part of being a maker and being DIY) I tend to use cameras a lot. Well, on occasion camera related things break, or I’ll need a part that doesn’t exist yet, or exists, but it too expensive, or isn’t designed right, or whatever.

All of the issues mentioned above lead me to create “CAMS” the “Camera Accessory Mounting System”, which will be a modular system that allows me to mount things to cameras, and mount cameras to things.

The connecting pieces of CAMS are 3D printed, and design is happening in OpenSCAD. The other parts of CAMS consists of standard 1/4″ hardware, nuts, bolts, screws, etc. There are also knobs that fit onto the nuts to allow for easy finger tightening.

CAMS Arm

There’s a wiki page for CAMS, which doesn’t have a ton of info yet, but you can also check out blog post #1 and blog post #2 about the arm.

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!