Archive for the 'Prototyping' Category

DIY Jumper Wires

I love using these jumper wires for prototyping. They work great for breadboards and Arduino headers.

You can buy them all over the place including SparkFun.  They are available male/male, male/female and female/female in various lengths.

Sometimes you need to hook up something that already has wires attached. I got these pins and single pin housings from Pololu the other day.

I really like them.  The housing works for either male or female pins.  You can either manually crimp the pins with a needle nose pliers or use a real crimper.  The crimper works for both the male and female pins.

Here are the links to the parts.  If you know of other sources, please add them in the comments.

Male Pins

Female Pins

Single Pin Housing.

Crimpers

Proper use of a crimper is a learned skill.  You need to take the time to learn it.  I lend out my crimpers all the time.  Many people try to use their first attempt in project.  The pin falls off or does not have a connection.  They then give up and use pliers.  The bottom line is there is no better way to put the pin on than a proper set of crimpers.  This is how the professionals do it.  It only takes a few attempts to get it right.  Take the time.

One of the biggest mistakes newbies make is stripping too much insulation.  It is usually just a tiny amount and only the length of the wire barrel portion.  It is very important that the insulation barrel of the crimp grabs onto the insulation.  That is the thing that really holds the pin from being pulled off.

I always buy my crimpers from eBay where they are usually about 25% of retail.  Avoid generic or all purpose crimpers.  Try to get the manufacturers brand.

The crimpers I used are Ampmodu Mod 90418-1.  The can be found used on eBay for around $50.  Pololu suggests you can use this general purpose crimper.  I also have that crimper and it works better than anything you could do by hand, but is no where near as good as the real one.  The 90418-1 has a little “gate” thing that fits between the part the crimps on the insulation vs the part that crimps on the wire.  This allows it to crimp just right on each part and sets the depth of the inserted wire.  It also has two different wire size ranges.You can see this gate in the picture as the shiny bit with the square cuts.

 

 

Pololu Compatible Relay Driver


I just got my production boards for my Pololu compatible relay driver. This is a little plug in module that can be used to drive off board relays. It uses the signals that are normally used for step and direction to control two relays with the voltage that is normally used to power motors.

Pololu stepper drivers are great little items.  They are inexpensive and very easy to use.  You only need a step and direction signal to control them.  If you use them in sockets, as I show here, they are portable between projects and experiments.  If you accidentally smoke one, you only need to replace the single driver.

There are a lot of carrier boards for these.  There are Arduino shields and many other applications.  Often, it would be nice to be able to drive a larger external load like a spindle or blower.  You can then use the existing step and direction signals to drive the relays.  It uses the voltage normally used to drive the motors for the coil voltage.  The only wiring required is two wires to the relay.

I chose to put the relays off board because the real estate was pretty limited and I wanted to provide the voltage isolation for AC powered devices. I am also a big fan of DIN rail mounted relays. They are very reliable and inexpensive. They are easy to swap around and have some nice features. The relays shown have a LED indicator and also a manually test button that moves the contacts. The relays shown are about $10 each, including the DIN rail sockets.

I got the boards from Gold Phoenix in 2 sheets of 50. They were not cut out, only V scored. Fortunately I have access to a depanelizer at work and was able to easily separate them. I probably could have snapped them apart too. The depanelizer looks similar to this one. Two slowly spinning sharp disks chop them apart.

The boards have all the components required to drive the relay including a supression diode. I am using a pretty hefty transistor here, but you could substitute a smaller one.

Schematic (PDF)

Gerber Files

New 3D Printer For Sale

UP! Printer

There is a new additive thermo plastic printer for sale at PP3D.com.  They call it the UP! printer.  They are selling the first 100 units for $1500 USD, then the price goes up to $2990 USD.  They claim a 0.2mm resolution.  The models do look quite good.  There was a video, after the jump.

UP! Printer

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Arduino G-Code Stepper Controller

rStep Project

Reza Naima has been working on an Arduino G-Code Interpreter.  There have been a few other projects like the grbl projects and the rerap type machines have some g-code history to them.  Most of the project is being documented over at the rStep Google Group.

It is nice to see more and more open source G-Code interpreters for micro controllers out there.  In some projects this can free up the PC or at least reduce the need for expensive and or complicated CAM controllers like Mach3.  A quick look at the firmware shows it handles a decent sub set of  G-Code commands including arcs.

rStep Arduino G-code Controller

To see the video…. Continue reading ‘Arduino G-Code Stepper Controller’

Ink Jet 3D Printer

This looks like an interesting hack.  There are not a lot of details, but apparently there is some good information at the Yahoo DIY 3D Printing and Fabrication Group and at CandyFab.org.  It looks like a lot of work and the results are questionable, but if you’ve read any blogs here you know I never criticize people for showing early, but rough results.

It appears he uses paper sheets on the powdering tray to set the height of each pass.  Remove at sheet and the level moved down.  Great, simple, consistent idea.

See video after the jump.

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The Age of the Self Replicating Machine.

MC Escher - Drawing Hands

There is a saying amongst DIY CNC router builders that goes something like this… “You only need to build your first router good enough to build you second one“.  In my case that turned out to be true.

I built a wood, conduit and skate bearing Solsylva router.  I painstakingly layed out the various pieces using calipers, t-squares and compasses.  I cut them out using hand held tools like jigsaws and drills.  It worked remarkably well, but every time I routed out a perfect CAD drawn piece, I always thought “Gee, I wish I had this thing when I built the router“.

It wasn’t too long before I built my bigger, better, more accurate router.  I was able to use tougher materials, hold tighter tolerances and cut more exotic shapes.  It works much better.  A few months ago I finally pulled off all the good bits and Sawzall’ed the old one apart to get more room in the shop…a bitter sweet day.

Most of today’s designs develop inside a computer.  Resolution and accuracy are infinite in this realm.  We expect our fabrication machines to output similar accuracies, but how does one construct a machine with this accuracy with common (analog) tools.

Today’s open source machine are addressing this head on.  There is a big push towards self replication.  Struggle past the first one and the rest will be easy.  It is not just an accidental bonus it is initial design requirement.  It is a lot more work, but I think it builds the strong communities behind these projects that help insure their success.

Here are three examples of self replicating machines…

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D.I.Y. Selective Laser Sintering – Update

SLS Printer XY Stage

Update. Peter is still working on his SLS project.  He is experimenting with a new fully laser-cuttable x/y stage.  He is catching some flack for the ideas in some blog comment sections like hackaday.  Obviously there is some refinement needed for accuracy, backlash, etc, but I applaud his efforts.  I am sure some of his ideas will find their way into the final design and we will all benefit from it for this and other projects.

If he was just building a device for his own use, it would probably be easier and cheaper to use conventional materials, slides and gears, but he is clearing spending a lot of time to design something the budget conscious maker can afford.

Many people put similar questions to me on the design of the open source “self replicating” laser cutter.  I have redesigned and rebuilt constantly to lower the costs, tools and skills required to build it.  I swapped out very robust milled aluminum parts with laser cut Acrylic ones to prove they would work.

His most recent changes area aimed at removing the “shearing/binding issues” from the previous iteration.  He is using Kapton tape (Polyimide-film) to reduce friction and using a four gear contact point.

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Rotational Molder

rotational Molder

I saw this rotational molder a while back on several blogs (Ponoko, Core77, designboom).  Rotational molding is typically used to make large hollow plastic parts.  They make anything from kayaks to gas tanks.  The molds are very simple hollow cavities, that split into at least 2 pieces.

A specific amount of material is placed inside and the mold is heated.  When the material is in a liquid state.  The mold starts to rotate in 3 dimensions so the material evenly coats all the walls.  The material in allowed to harden and the mold is split apart.  You now have a seamless hollow plastic part.  It has a parting line, or flashing, but the part is essentially seamless.

This machine is a beautiful example of flat-pack design.  There is very little waste material.  This version ditches the heating step and uses cold set resin.  They recommend a two part resin called ‘Easy flow 120′.  It is available at Mouldlife.  It comes with a sample mold and you are on your own for the next one.  It looks like the mold was vacuum formed.

It is called My First Rotational Moulder and is available for purchase at StudioMyFirst

(I guess they spell molding differently over there?)

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