Archive for the 'Art' Category

MakerSlide Camera Slider Control Program

There has been a ton of interest in camera slider applications for MakerSlide.  A while ago I decided to make a very simple reference design for a motorized slider.  This design only required fabrication of one part.  The rest of the parts are existing components.  The part can be made on a laser cutter, router or even by hand.  There are no tight tolerances and you can use the MakerSlide carriage as a template for drilling some of the holes.  I can sell a complete slider system including motor for less than $120 for a 1 meter setup.  It would only be $10 for each addition meter.  The longest I can ship is 2.5 meters, but I stock the material in 4.5 meter lengths if you can figure out how t0 get it.

I don’t know much at all about this type of camera work so I did not see all this interest coming.  Several people approached me about buying my prototypes and I have sold several of them.  Most of them asked me how to control the motor.  I come from a CNC background so most of my demonstrations were done using CNC software like Mach3, EMC2 or even GRBL.  This has few issues.  The first is many photographers have no knowledge of CNC or G-Code.   The second is the solution is way overkill in cost and complexity for a single axis machine.  The third issue is portability.  This will probably be used in the field where a PC is impractical and power may be unavailable.

I decided to make an Arduino based controller.  Arduinos are good because they are cheap, small and easy to program.  They also use very little power.  I wrote a similar controller for the PIC processor a long time ago and borrowed the basic algorithm from that.  The method used could work for multi-axis machines if you want to steal the code.  The Arduino is. using my Stepper Shield.  I have just one driver installed and in another “slot” I have a bread boarded switch.  The stepper shield is nice because it can act as a mother board for many future features.

MakerSlide: Camera Slider Control Program 2011 CC-A-SA

0 = Set Current Location as 0
S = Stop now!
D = Disable Motor
E = Enable Motor
H = Home (Move to 0)
M = Move to ..(M Dest Speed Accel)
J = Jog until stopped ('J 1' for forward, 'J -1' for reverse, 'J' to stop )
I = Info (show current parameters)
G = Go (start program)
P = Show Program
C = Clear Program
L = Edit Line.  Format: L Line# Dest Speed Accel)  Ex: L 0 2000 3000 1500
      Use 0 for destination and speed to indicate end of program
      Use 0 for speed to indicate a pause.  Dest is pause in milliseconds
R = Set Max Speed
A = Set Max Accel
V = SaVe to EEPROM
? = Redisplay this menu

The controller uses a menu driven interface via the USB connection.  The easiest way to talk to it is though the Arduino IDE serial monitor.  That allows a free, common interface between PC, Apple and Linux,  but most serial terminals would work.  The commands currently work in the unit of stepper motors steps.  It could be easily converted to a real world unit, but at this time it is just easier to use the same unit that the motors use.  My system has 4000 steps per inch.  That makes for a very smooth system.  Extremely slow rates are possible.  It can go 1 step per second at 4000 steps per inch, so it could take well over and hour to go an inch.  You could hack the code to easily drop this by many orders of magnitude.  Each move can have its own speed and acceleration to fine turn the affect you want.

It has several commands to interactively move the carriage around.  This would probably be done to setup the system before the actual “shot”.  These include Move, Home (go to zero), Jog and Zero (define current location as zero).  You can also create a move program.  This allows you to define a couple dozen moves that run sequentially.    These can either be moves or dwells (pauses).  Once the program is entered it can be saved.  This allows you to pre-program the device before you take it in the field.

At power up the motor disables.  This allows you to slide the carriage by hand.  This is handy if you don’t have a PC to do it in the field.  As soon as you make any move or run a program the motors enable.

How it works (programmers only)

The controller uses a timer to run an interrupt function at a regular interval.  The default is 40,000 times per second, but that be be tweaked by changing one program line.  The interrupt function determines if a step should be taken.  If you want to move at 20 steps per second, you allow the interrupt to run (40000/20) or 2000 times before the step is taken.  A counter in the interrupt counts up until it is time to step.  By varying the count on the fly you can create smooth acceleration.  All the math required to smoothly accelerate could limit the interrupt rate, so  the calculation are done once, before the move occurs.  Inside the interrupt is all simple integer counting and a few tests.

 

Source code (Arduino 1.0)

 

 

 

Wiki Page on Slider

Wiki Page on Software

 

Buy one here at the MakerSlider Store

Future Plans

I have several features I want to add.

Drawbacks

Stepper motors draw a lot of power.  I was running my NEMA 17 at 11V and 0.1 amps.  You need a decent battery of 2000-3000 mAH to do a multi-hour run.  Steppers are also notoriously loud.  The camera will  pick up the noise if the mic is close the the motor like on the camera itself.   The motors I have are way over kill and running at less than 10% of their rated current.  I have some NEMA 14 motors on order.  Servo (not hobby servo) motors would be a lot quieter but and lower power, but are more complicated and might require gearing down.

Comments: feel free to comment below or on this forum thread.

Videos



Open Source Rotational Engraving Adapter (Part 1)

This is the new buildlog.net open source rotational adapter for laser engraving.  This allows you to engrave on a round surface.  This design uses a friction drive method to rotate the workpiece.  This has the advantage of keeping a consistent surface resolution regardless of diameter.  This was designed to be 1000 steps/inch resolution.  The length was sized to fit the 2.x laser, but you could easily scale it up to much longer or shorter.  One design goal was absolute minimum height.  This allows Z challenged engravers to be able to do some rotational engraving

The main feature of the design is the the two drive wheels.  These serve several functions.  They hold the rubber o-rings used to provide traction on the work piece.  They have built in MXL drive pulleys and they have a spacer to ride directly on the bearings.  These were 3D printed at Ponoko.  With 3D printing, complexity is free.   This encourages you to make the part do as many jobs as possible.  I was initially concerned about the strength of these, but they turned out to be quite strong.  I can probably reduce the material to take some cost out.  I used the basic, cheapest, white flexible material.  I was impressed with the detail level the material was able to hold.  The belt fit perfectly.

I started the design using convensional design techniques and off the shelf parts because I was concerned about the 3D printed part cost.  I soon realized that it was going to take 3-4 separate parts to do the job of one 3D printed part.  The cost was quickly getting close to even.  The convensional parts were also starting to look a little mismatched.  While I am a form follows function, type of designer, I am a big fan of a clean design.
Once I started playing with the 3D printed part approach, I quickly decided that was the route to take.  It was fun knowing that increaing the details on the part has no affect on the cost and in some cases actually reduces the cost.  The spokes and radiuses retain the strength, reduce the material and I think add a retro mechanical design asthetic.  Dealing with a single supplier, with a fast turn around and no minimum order, was very nice.
I have done 3D printing from other vendors, but decided to give Ponoko a try on this part.  Since this is an open source project, their online tools would allow others to easily order parts.

At the other end of the assembly are the idler wheels.  These also are Ponoko 3D printed items.  They have bearings that press on each side.  This allows them to roll freely with virtually no wobble.  One idler has a flange on it.  This acts as an end stop to the workpiece.  It prevents it from “walking” while it is spinning.  The stepper motor pulley serves the same function on the other end.  This end is highly adjustable.  There are three positions the wheels can be placed in.  The plate can slide on the extrusions and you can flip it over.  While all the adjustments are manual, they only take a few seconds to do.

Below is a video of some testing I did.  I was trying to test a variety of shapes to see how they performed.  In actual use the speed is very slow, because the the laser is primarily rastering along the length of the workpiece and this adapter just advances it a faction of millimeter at a time.

They all performed quite well.  The only item that did not test well was a roll of duct tape (not shown).  It was not very round so it wobbled a bit.  It also has a sticky edge so it did not ride against the stops real well.  The screwdriver at the end is an interesting example.  While it did spin smoothly, it shows that if the image is not going to be at the same diameter as the drive area, some image scaling will be required before engraving.  The bit is only 1/8″ diameter!

The design will be open source.  There are a few tweaks to make before I release the drawings and 3D files.  I may sell a complete kit for this.  I estimate it will cost less than $100 with motor and extrusions included.  I have not tested it in my laser yet.  I don’t have the time right now, so I am going to have another 2.x laser owner do that for me….stay tuned for part 2.

Items Shown in video

  • Drumstick
  • Beer Bottle
  • Odd Shaped Oil Can (remove oil before lasering)
  • Wine Glass
  • Tiny Screwdriver

 Assembly Instructions

3D CAD file (STEP)

Hacking the EggBot for Lasers?

Egg-bot

This little product from egg-bot.com has been showing up all over the web lately.  It is primarily designed for coloring eggs and other small sphere-ish items.  For the simplicity of it, it does a fantastic job and produces some amazing results.

Eggbot-Objects

With the recent discussion thread on the buildlog.net DIY laser forum about making an open source rotarty attachment for lasers, this has a whole new appeal.  There are even some discussions on the eggBot FAQ about using this for lasers.

On the Egg-bot website, they down play the suitability of it and mention safety issues.  To be fair, it is not really too suitable to laser use because of the size limits (1.25-4.25″ Dia and 6.25 max. long) and the special interface.  The cost of $195 is also a little high, but that is due to the included controller and pen motors, etc.  But lets get past all that and assume we have one and we want to hack it for lasers.

The first thing that comes to mind is dumbing it down to a simple rotary attachment to run inside the laser.  This would be rather simple.  Lets say you want to engrave a 1 inch square logo on a little 1.5″ diameter anodized flashlight.  First you would strip it down to just the basic mechanism and the rotary stepper motor.  The controller and pen controls are not used.  You would then plug the stepper motor directly into your Y axis stepper driver.  Be sure to dail down the current to what the Egg-bot stepper can handle.  You now need to create your logo image.  The image will be 1 inch tall, but the width needs to be stretched/squashed to fit the work piece.  Since linear surface motion is dependant on the diameter of the item, a little calculation needs to be done.
Say you have a 200step/rev stepper, a 10 microstep driver and a 1000dpi laser controller.  Your new resolution will be (Motor Res * Driver Res) /  (Dia * PI).  In this case (200 * 10) / (1.5 * 3.14159) =  424.4 dpi.  Your laser thinks 1000 steps will go an inch, but in reality it is going to go (1000/424.4 = 2.36) inches.  The solution is to make squash the image narrower by that amount, so your image is 1000 pixels high by 424.4 wide.  That is it. 424.4 dpi is probably a decent enough resolution for a logo, but that is going to drop quickly with as the diameter gets bigger.  If your stepper driver can increase the resolution, that will help.
Laser Cut Egg

image credit: http://dnashopper.com

The second hack the comes to mind is letting the EggBot control things.  It has a controller capable of running two small steppers.  Hook the laser’s X axis up to the EggBot controller and let it do the work.  That might work, but it would require some serious hacking to get the laser enable to work right.  The pen control is probably the candidate to do this.  You might even be able to just hook up a push button that clicks when the pen is in the drawing position.  I think a really low power level on the laser would be needed.
EiBotBoard
The third hack might ditch the whole rotarty thing and keep just the controller.  Actually you can buy the controller on it’s own from Evil Mad Science (out of stock for a while).  I’ll bet you could hack the open source software to make it become the complete laser controller.  It has two built in stepper drivers, a USB connection, a voltage regulator and a whole lot of other useful things.  I am sure you could get it to be a cutter controller and you might be able to get it to do some simple engraving.  The data transfer of the image data might be tricky with limited memory, but it is probably doable.  It has hobby servo drivers which might be a good source for PWM power control.

I would love to get one for the pure hacking fun of the project, but I don’t have the time right now.  If someone has a laser, has the hacking cred to tackle a project like this, I might consider a donation to the project.

Slicer – Google Sketchup Plugin

Slicer3 is a new plugin for Google Sketchup from TIG.  It allows you to slice an object into pieces that can be cut and re-assembled into the part drawn in Sketchup.  This would be great for a laser cutter.

In high school I did several architectural models and cutting the terrain was fun (for a while), but always very time consuming.  This tool would have saved me many hours of cutting and one nasty cut to my index finger.

Here are some images from the Google Sketchup blog that show some terrain being sliced in 3 different ways.

I decided to try a simpler example.  This is a little project box, that I might cut out of Acrylic or foam board.  If you subtract the time spend on screen shots and writing the steps, it probably took about 3 minutes to do.  Here was my process. Continue reading ‘Slicer – Google Sketchup Plugin’

Hand Made?

Hand Made Volleyball Line Winder

I play a lot of sand volleyball in the summer.  I used to have a plastic winder for my volleyball boundary lines.  It was in really bad shape because I tried to use it as a water ski rope and handle a while back.  Anyway, someone was sort of laughing at the condition of it a few weeks back.  On my bike ride home I decided it would be fun to make an over the top complicated one out of wood.

The next week I displayed my new creation and someone said, “Wow, look at Bart’s cool hand crafted line winder”.    I accepted the compliment, but wondered about that term: hand crafted.  I, of course designed it in CAD, cut it out on my CNC router and cleaned it up with a bunch of other power tools.  Was it really hand crafted?   What does that term mean these days? Continue reading ‘Hand Made?’

PVC – Update

Formufit - PVC fitting

FORMUFIT

I saw couple of thing on various blogs regarding PVC lately.  I think every general purpose maker has made something out of PVC at some point.  It has a lot of desirable qualities.  It is cheap, easy to find, and very easy to work with.  It is relatively strong and can hold a lot of pressure.  I have made a plastic bottle launcher, a paper rocket launcher and even a crude trebuchet for a scouting contest.

The first new PVC item I saw was these FORMUFIT PVC fittings.  They are aimed squarely at the maker side of PVC usage.  All of the parts are smooth, glossy, tapered, high quality parts without any of the annoying printing. labels or bumps.  Some of the nice features are interior detents so you have a consistent stop point so your project will come out square.  There are also slip tees.  The tee section on these are not a tight fit to the pipe so it creates hinge.  (This would have been real handy on the trebuchet).  The other part that fit in this category are the table cap (attaches legs to table), caster base and internal pipe coupling.

They also have pre-made Google Sketchup and MS Visio parts ready to design with.

PVC Table Cap

Formufit - PVC Table Cap

Continue reading ‘PVC – Update’

Full color 3-D viewing Stand For iPad

iPad 3D Viewer

Thomas Kumlehn of Pixel Partner sent me a nice email regarding the iPad Chair.  He did a roughly similar Instructable to mine on an iPad 3-D viewer.  This is another laser cut flat-pack iPad holder, but this holds the iPad in the perfect location for viewing stereoscopic 3D images and video.  He uses a readily available lens the redirects your vision to over under pairs.  The iPads portrait mode works very well for this.

I remember as a child, a friend had a vintage side by side stereo viewer with a bunch of black and white pictures for it.  I remember how amazed I was by them.

He has files available for cutting on his web site.

Continue reading ‘Full color 3-D viewing Stand For iPad’

The iPad Chair

iPad Chair

I am working on a fun, geeky project and I needed a little stand for an iPad.  I am not a real fan of the Apple company, but my wife got this though work and it will be perfect for my project.  I love this flat-pack style of construction and I was inspired by my recent post on SketchChair.  So I decided to make a little chair as my stand.

I started out by downloading the SketchChair software.  I was able to create a lot of cool chairs, but I could never get exactly what I wanted.  The software is a great concept, but it was not quite ready for what I needed.  I switched over to my 3D CAD package (Pro/E).  I stole a lot of the construction techniques in SketchChair, but modeled it in exact scale in Pro/E.  The design only uses four distinct pieces: 2 Sides, 2 Center Pieces, 6 Slats and 1 rear leg brace.

iPad Chair Mode

I exported the the drawing of the pieces via DXF (DXF Is here) to my Vectric Aspire CAM program.  Here I duplicated the parts to what I needed and used the nesting feature to fill the cardboard size I had.  Normally I would restrain the amount of rotation allowed to keep a consistent grain direction, but this time I let it rotate any any angle (screen says 45deg, but I actually used 5deg).  I wanted the finished product to look sort of cattywampus.

Continue reading ‘The iPad Chair’

Laser Cut Vinyl Record – Bad Idea?

Laser Cut Vinyl Record

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.

Continue reading ‘Laser Cut Vinyl Record – Bad Idea?’

Laser Cut Lamps

Laser Cut Lamp Curious Customs

I saw this over at Boing Boing.  They are by Curious Custom and are for sale in the Makers Market.  It is a really nice example of laser cut wood.  Unfortunately, I don’t think my laser is quite up to this thickness.  I live in a Bungalo with American Craftsman / Arts and Crafts style furnishings.  This would fit in just fine.  They are a good price at only about $30 USD.

Continue reading ‘Laser Cut Lamps’