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.
I have had a project going in the background to create a small, but strong and quiet spindle for small CNC routers. This is my second iteration of the design and I think it is close to what I want.
Frame
I started with an UHMW frame. This frame presses together then uses some hi-lo plastic screws to keep it together. UHMW is very stiff, but cuts well on a simple CNC router. I used a 1/8″ single flute end mill for all cuts. I try to ramp plunges wherever possible to limit the meterial that tries to climb the tool. It can all be cut from a sheet from one side with the exception of the pocket for the motor. This is needed to get enough shaft to come through. This pocket does not need close registration with the other so it is easy to flip it and run that side. The frame is rock solid. It feels like you could drive a car over it.
Spindle
The spindle shank was a key find off eBay. It has a ER11 collet which can handle a little larger then 1/4″ bits and there are plenty of cheap metric and inch collets available. The shank steps down to 8mm. This is great because the step can ride right on the lower bearing and cheap normal and angular contact 8mm bearings are available. I used an angular contact bearing on the bottom, and a normal bearing on the top. The top pulley installs with a spring washer to keep a 8-10 lb pre-load on the bearings to eliminate axial play. The bearings press fit into the end plates. The lower angular contact bearing takes the axial load from hard plunges. The axial bearing I found does not have a good seal on it, so I am a little worried about that. I am looking for a better bearing, but I might make my own seal that would seal to the spandle shaft. I might add a cover for the front and top.
Pulleys
I am currently using MXL belting which is rated for about 20k RPM, but at this diameter and length I think it can go a lot higher. I was planning to use multiple rubber o-rings, but that requires custom pulleys.
Size & Weight
The overall size is rather small at 90mm x 84mm x 82mm and total weight is 0.72 kgs. You mount it by tapping holes into back side. I will have a standard set of holes, but leave room for custom mounts.
Motors
It accepts a variety of motors. You can use univeral motors for small power tools. These will work on AC or DC and are good if you want to run it off 120/220VAC. You can also use RC hobby motors. These are available in brushed and brushless DC. A brushed 12VDC motor is cheap and the you can use a cheap PC power supply. I also test a water cooled brushless DC motor. This is the quietest option, but has the added cost of a speed controller. The motor shown will do over 30k RPM. I need to modify the top to give clearance for the water fittings. It can run for a few minutes before it gets hot, if you don’t load the motor too much. This motor can pull over 550 watts continuously. That is more than 2/3HP. I am hoping a simple PC cooling system will do the cooling.
Speed Control
The speed controller is controlled like a hobby servo. It uses pulses in the range of 1ms to 2ms to set the speed. You can program the controller though the servo interface to determine if you want reverse, etc. I decided to use an Arduino to control the speed. There is a servo library that makes it easy. I have the Arduino reading a pot them setting the speed accordingly. You program the controller by powering it up with the pulse input set to max speed. You then can set a few options like range and direction.
Next Steps
The next step is to find a way to do real world testing with it. I need a water cooling system and something to mount it to. The design will be released as open source.
I have been using a ShuttlePro as a pendant for years on my router. A pendant is basically a hand held remote control for your CNC. It allows you to control a set of functions right at the machine. I typically use it to zero the machine on the part, tweak the feedrate, start/pause/restart the job and do an e-stop.
The router’s pendant is starting to die. It has been through hell. I have dropped it about 10 times on the concrete floor. It has also seen a lot of oil and fine dust. A couple buttons are getting intermittent. I have the functions to working buttons, but I was getting worried it would stop working completely. I could not live without it, so wanted to get a replacement on order. I found a good deal on eBay ($54) and since they had several, I decided to get one for the laser as well.
The ShuttlePro was designed for video editing. One thing you do a lot in video editing is jogging the video forward and backward. Typically you want to race forward until you get close then slow down and even go frame by frame until you get to the desired spot. Sounds like CNC doesn’t it? It has three dedicated functions for this. Full speed forward and back via buttons, variable speed via a spring loaded jog dial and a frame by frame little detented rotator wheel. It also has a lot of redefinable buttons. These buttons have clear snap on caps, so you can add labels to them. I have a Corel and PDF template at the end of the post. Someone at the Mach3 forum dicovered this product and within days there was a plugin for it.
Setting it up is easy.
Download the ShuttlePro plugin from the Mach3 downloads page. Place the ShuttlePro.m3p file you download in a convenient place like your desktop. Double click on it. That will launch a program that registers it with Mach3. Plug in the ShuttlePro into your computer. It uses the built in Human Interface Driverss (HID) so you do not need to install a driver. It comes with some software to test it, but you must uninstall it before using Mach3. Start Mach3.
Use the config Plugins menu pick to open the
Make sure the plugin is enabled with a green check. Now click on the word config to the right of the plugin name.
That will bring up the screen above. Each button can be associated with any of many functions. My config is shown above. You probably want some keys across the top to select the current axis. I like to have the two buttons to the outside of the central wheels be rapid movement buttons. It is also handy to be able to lock the pendant so accidental button pushes do not screw up a run. I used the second button from the lower right. The rest are up to you and how you use your laser.
I got into a discussion at work about digital vs. dial vs. vernier calipers the other day. The discussion started because some of our aging eyes were having trouble reading some of the aging vernier calipers in the low light. There were some pretty strong opinions about which is best. We did manage to agree that the biggest contributors to accuracy were the quality of the caliper and the skill of the user.
I mentioned that, while I agreed with some of the arguments for mechanical calipers, I still liked the little tricks you could do with digital calipers. Some of the die hard mechanical caliper people did not know what I was talking about.
The ability to zero the caliper anywhere on the scale lets you do some neat tricks.
Distance Between Hole Centers – If you have two equal diameter holes and you want to measure the center to center distance, you can measure the diameter of the hole, zero the caliper then measure the outside edges of the hole. This will give you a good center to center dimension.
Shaft Clearance – Measure the shaft, zero the caliper and measure the hole.
You can easily figure out a few other clearance values you can do with the other modes of a caliper like the depth pin. Some people said they even use it as a simple math calculator by moving it to a value zeroing it, moving again, zero it, etc then rolling back to true zero for your answer (ignore minus sign).
I saw this post over at the Make Magazine Blog. This is an interesting method of containing the exhaust gas on a particularly nasty material. It basically puts the work in a box with an IR transparent window. The box has a fitting to suck out the fumes. It uses a polished silicon wafer as the laser window that was bought off eBay.
I probably would have put it in a Tupperware box, because the seal might be better and it is probably more resistant to the nasty fumes. I could have used this when I tried my vinyl record cutting.
Tim at Outguessing the machine has started an open source SMD pick and place project. So far he has a head design, some scripts for EMC2 and some preliminary optical testing done. He has uploaded the head to Thingiverse. It features a stepper driven head for aligning the parts and an aquarium vacuum pump for picking up parts. The head uses a standard Luer-Lock port for interchangeable needles.
It looks like there is a lot of work to go, but it is a good idea and he has a good start.
I stumble across this when reading a Machine Design magazine. This is a 2D scanner based on a camera that mounts on CNC mill. It can be used to reverse engineer parts.
It uses a Mach3 plugin to control the position. Knowing the exact position of the camera allows the software to create a very accurate 2D image of the parts. The exact scale of the image is also known.
The interesting thing is that there is a freeware version. There is a video on the web site that takes a $20 eBay pen cam and generates an image accurate to a few thousands of an inch. The software created a 400+ image composite image. The quality can go up quickly with even a cheap USB microscope cam. you can even use the unlicensed version of Mach3 because it does not run any G-Code.
I was at the Detroit Maker Faire over the weekend. It was quite a drive from Chicago, but well worth it. The place was full of 3D printers. Most of them were MakerBots and the others were mostly RepRaps (Darwins and Mendels). It is great to see MakerBot Industries having success with an open source product. I almost missed the actual MakerBot “booth”. It was tucked behind a a few bigger displays. They had a couple MakerBots printing away. They were printing a lot of coin bottle openers. They have a slot for a coin that catches on the bottle cap. …quick to print and a crowd pleaser.
Thingiverse
I spent some time chatting with them about all of the DIY digital fabrication going on with printers, CNC machines, lasers, etc. They mentioned that they had a project started to design and build a 3D scanner. It makes a lot of sense because easily getting things into 3D format helps the whole movement along. Below is a scan and print of Bre Pettis, one of the founders of MakerBot and Thingiverse.
Thingiverse
Thingiverse
When I got home I started to look into the Makerscan and 3D scanners in general. Unfortunately the MakerBot people are just getting started. They have a links page, a Google Group and a decent sense of direction and that is about it right now. The links page has a lot of good stuff. I have heard of the David Scanner for a long time. They have a complete kit.
I stumbled upon this while researching another post and thought this fit in with the “digital fabrication” theme of the blog. This is an auto measuring miter saw. What this means is you enter a dimension and a motorized stop moves out to the exact location for the cut. It also correctly deals with angled cuts. It works in decimal, factions, inch or metric. It stores up to 10 cut dimensions. See it at SawGear.com. Hook it up to a Cold Saw and it could be the ultimate extrusion cutting machine. Unfortunately, it is pretty pricey at over $2000.
I have a nice 12″ cabinet table saw. You can buy various after market fence options for it, but I thought you could make an awesome one using linear bearings. You could even rig it up with a lead screw and stepper motor. I thought of some great features for it. You could have it step in in regular increments for ripping sheet stock into strips. You could have it step in in regular increments to score the back of some stock for bending. You could have a feature where the fence would act as a measurement for the miter gauge. It would move out of the way right before the cut.
sawgear.com
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