One of the worst jobs with the 2.x Open Source laser is the hardware kit. I hate counting out all the parts. Some of the part counts are like 150+. The MakerSlide reward kits have a lot of parts too for the wheels and spacers, etc.
I finally decided to get a part counting scale. Essentially what this scale does is weight things in part weight units. The scale has a resolution of 0.0001 lb. It can only weight up to 3.3lbs, but that is fine for what I do. You can get higher rated scales, but the resolution goes down. When weighing light things like nylon spacers, you need the resolution.
First you zero the scale with the container you want to use, then you go through a calibration routine. The scale tells you how many parts to load. It has a few options for this, but I generally use the 10 piece count. You then load the 10 pieces in and tell it when you are done. It then tells you if the scale has enough resolution to do the job with a “PASS” message.
You can then dump parts in and it tells you how many are in the container. You actually get quite good at estimating hand fulls, so you get quite close with the initial toss. You then know how many more you need.
I did not give a lot of in depth thought when choosing the MakerSlide extrusion length to purchase. I did not want a lot of waste, so I just bought the largest piece I could handle. I figured 6″-12″ average waste on each piece could be expected. The longer the piece, the less percentage that would be.
The manufacturing size limit was set by the anodizer who could only handle about 20 foot lengths. The limit on my end was about 15 feet. This was due to what I could realistically cut. My space is about 27 feet long, so if I put the saw in the middle I could cut most reasonable sizes with a 15 foot length.
When it came time to cut the material, the reward requests came in all over the map on length. On past projects I had used some simple logic to fit the pieces into the stock, but that was yielding some serious waste now. I dreaded the thought of 10-15% waste and little chunks lying all over the shop. I had heard about cut optimization software and decided to look into it.
It turns out that there is pretty well established math behind this. There is a good article on Wikipedia about it. It is generally called the Bin Packing problem. There are 1D (length, like my problem), 2D (area, like out of a sheet) and 3D (volume, like boxes in a container) problems that can be solved.
I tried a bunch of freeware, shareware and demo software. I was really impressed with the results. They did not always yield the same results, but generally agreed within about a percent. The choice came down to a flexibility and a few key features. I did not have the time to roll my own solution from free software libraries, but I knew I wanted to do some customizing. I decided to go with an Excel add on from Optimalon. The Excel format allowed a lot of quick macros and imports to be easily added.
The software allows you add in a number of stock lengths. This allows me to put in the standard raw lengths, but also some scraps that might be able to be used. You enter the cuts by length, quantity and ID. The ID can be used to determine what customer the part belongs to.
One feature I wanted was a way to label all the parts.
I have several Dymo label printers that I use extensively. I wanted to automatically print labels from the software. I found that Dymo had an SDK. The optimization software prints a cut table for each piece. I feed this table to an macro that uses the label printer.
This string of labels is now my cut list for each piece of stock. I print one string per piece of stock. A single persons parts are usually scattered among several pieces of stock, so this helps sort it out later.
So far the software works great. The more varied the lengths, the better it does. My target is in the upper 90′s for yield. So far I have found it does really well including some 100% utilizations where the last saw cut is less than the kerf of the blade. Here is a typical final cut piece.
The only drawback is that the cuts are optimized for material usage and not cutting efficiency, so you are often moving the saw stop on every cut. If I CNC the cutter, this will not be a problem and Excel can drive the cutter.
Everywhere I look these days I see a blog article about someone laser cutting old vinyl LPs. I think the first place I saw it was on the Make Magazine Blog. It seems like a great idea, especially if you choose an image that fits the record you are cutting. It also fits the recycle/upcycle trends.
I decided to give it a try. I had an old Zydeco LP on the Alligator records label. I found a simple alligator profile and decided to give it a try. I don’t remember the exact speed and power settings, but the material cut like butter with a nice clean edge. The only strange side effect was huge amounts of brown smoke. I had a decent assist nozzle, but my old evacuation blower was not the greatest.
I call my laser an open source design. What does that mean? Right now it means whatever I want it too. That is actually a bit of a pain because I am on my own own to define it. The route I chose was to adapt an existing license. Unfortunately there are hundreds, if you count all the variations. I chose the Creative Commons license even it does not directly address the special issues of open source hardware. but, it was configurable and had a nice logo.
Well things are about to take a big step forward in this area. There is an Open Hardware Summit coming September 23 in New York, right before the Maker Faire. They are working on creating a comprehensive definition of open source hardware. They have a draft definition here.
For the user of open source hardware, this could be helpful. Hardware by it’s nature is likely to require an initial investment. Unlike software, where you can usually easily evaluate it with little cost. Knowing a project conforms to a standardized definition might make you feel better about making that investment.
I saw this over at the Craft: Magazine Blog. It is an amazingly detailed cross stitch inspired pattern laser cut into stainless steel. It was done by Imogen Luddy, a London based textile designer. Unfortunately for us laser geeks, there are no details on how this was made, but I doubt it was on a 40W CO2 laser.
Using 16th Century Italian Lace as a starting point, this laser cut stainless steel table top subverts the notion of a traditional table covering.
Someone asked me what the tap drill size for an M6 x 1 is. “Easy 5mm…don’t you know the trick?”, I said. For a 75% engaged thread (most common) just subtract the pitch from the diameter. They had never heard of the trick. I asked around and nobody had heard of it. “Too bad it doesn’t work for inch sized taps” they said.
Actually it does, but you might need a calculator and you need to know your sizes. For #4-40, you need to know what the actual diameter of a #4 is (about 0.112″) then what is 40 TPI (0.025″). That equals about .087″. So that means about a #43 drill. Isn’t the inch system fun!
But a 3/8-16 is pretty easy. 3/8 – 1/16 = 5/16 drill.
I have seen rope or paracord used to hold thing together in this fashion before, but Yoav Yeches has really done a good job with his furniture.
I have always been fond of the look and feel of good quality climbing rope. This rope along with natural colored wood makes a good combination. I also like the non regular lines he took with the rope. Most of the other examples I have seen, and probably the way I would have done it, used very geometric patterns.
This looks like something anyone with a CNC router could easily do.
I found Kenneth Maxon’s, Max’s Little Robot Shop via CNC Cookbook. His work shows amazing design, mechanical wizardry and artistic flair. I have often said, “it is not worth doing unless you over do it”. He takes that concept to a new level. Each part it a true work of mechanical art.
He is currently working on a Sojourner (Mars Pathfinder) inspired robot to autonomously circumnavigate the block that he lives on.
Keep up the good work Max!
image from Kenneth Maxon http://www.users.qwest.net/~kmaxon/index.html
image from Kenneth Maxon http://www.users.qwest.net/~kmaxon/index.html
image from Kenneth Maxon http://www.users.qwest.net/~kmaxon/index.html
image from Kenneth Maxon http://www.users.qwest.net/~kmaxon/index.html
image from Kenneth Maxon http://www.users.qwest.net/~kmaxon/index.html
The European Solar Decathelon 2010 just concluded in Madrid, Spain this week. The Solar Decathelon is sponsored by the US department of energy and “challenges 20 collegiate teams to design, build, and operate solar-powered houses that are cost-effective, energy-efficient, and attractive.“ Virginia Tech won the top prize this year, but the FabLab House entry from the Institute for Advanced Architecture of Catalonia (IAAC) has generated a lot of Internet buzz because of it’s unique layout and styling. I was attracted to it for many reasons, but really got excited when I saw the laser they are used to build it.
image credit IAAC
image credit inhabitat.com
Here is a “making of” video.
Now for the laser “pron”.
The laser pictured here is a MultiCam 2000. It has a working area up to 168″ x 80″ and power up to 600watts. It can cut and engrave at 1200 dpi. They cut many of the parts off site using CNC. They claim the pre-fab house can be built in 15 days.
My next laser project is definately going to be a gantry style laser like this with the tube mounted on the gantry. I think it makes a lot of sense because it vastly simplifies the alignment because you remove one axis from the problem.
Well here we go….This is my first test blog entry. This is intended to be a companion blog to my buildlog.net web site and forum. It will focus on all thing laser cutter/engraver and to a lesser extent, CNC, fabrications and cool stuff people are building.
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