Ideas for improvements on the Open Source Disc Shooter

Here are some of the ideas I’ve been kicking around:

  • A magazine1 that you clip in the front of the shooter.  When you clip it in it should depress a spring, or more likely, tension a rubber band.  When you press the button clipping the magazine in, it could actually eject the empty magazine.  That would be sweet.
  • Lower profile.  In looking at insides of the Tracer Guns, it looks like the only reason for the bulky barrels over a long thin slot is so the toy looks more like an actual gun.  I’d rather have an optimal design that uses minimal plastic than something that looks like a gun.
  • A variety of discs for maximum aerodynamics.  In the designs uploaded to Thingiverse I included 18 variations on a disc.  Perhaps some will fly or spin better than others.
  • Rubber band powered mechanism.  Rubber bands are easier to find, cut to size, and replace than metal springs.  It could also lead to a more compact design.

I’m sure other ideas will come to me.  I just wanted to jot them all down before I forget them.

Now that I have my chess set complete, it would be pretty cool to have a working OSDS prototype before Botacon.

  1. Hey, Dave, happy??? []
November 29, 2010 | Comments Closed

It was called a “Tracer Gun”

Tracer Gun from

Tracer Gun from

Despite my best efforts I could not locate an image on the interwebs for the kind of disc shooter I remember playing with as a kid.   Finally after much googling, I found a picture and the actual name of the type of toy.   Apparently they were known as “Tracer Guns” and were produced circa the 1960’s through 1990’s.  (Image of a Tracer Gun at right from  Whenever I searched for these online I only found references to larger disc guns that shot larger foam discs from cylinder mounted on top.

A variation I had not seen as a kid, but desperately wanted, was disc shooter that had a removable and re-loadable clip.  In the pictures to the right you’ll see a grove about halfway down the barrel, just above a protuberance.  That protuberance would house about 20-25 discs depending upon the gun you had.  In order to load/reload the gun you would have to slip each disc under the firing pin one at a time.

Once I discovered the name of this type of toy, Wikipedia filled in the rest.  They had some pictures of a tracer gun which had been taken apart to expose the insides.  The best part is the gun depicted has a clip loading mechanism!

Having taken apart the non-clip version as a kid, I recall it having a similar metal spring as a source of power. 1  I believe the rubber band on the trigger is merely to keep it in place.  The protuberance on the non-clip version and the clip on the clip version of the toys both contain springs for advancing the next disc into place.

To be clear, I am not looking to duplicate, copy, or replicate this toy.  I don’t want that toy.  Rather, I would love to print a toy of my own, or a collaborative, design that will shoot harmless plastic discs.

Tracer Gun, clip removed - from Wikipedia

Tracer Gun, clip removed – from Wikipedia

Tracer Gun, exposed - from Wikipedia

Tracer Gun, exposed – from Wikipedia

  1. They were quite breakable, unfortunately. []

Help with the Disc Shooter?

The other day I sketched up a concept of a disc shooter – the style that used to be available in grocery store aisles at about my eye level.  Strangely enough I noticed over time they moved them lower and lower on the shelves until they stopped carrying them entirely.

In any case, I’d really like to print out an open source version of a disc shooter.  I was figuring that since we’re such good friends and all, you’d be willing to help out.  I’ve already gotten the ball rolling and posted my work designing the various components.

I realize this is a frivolous use of your time, but wouldn’t it be cool to be all “pew pew!” and then I’d be all “pew pew pew!” 1

  1. I want to print mine in clear PLA so I can see the bits inside working and the discs in fluorescent red so they’re easier to find. []
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How awesome is this photo?

The Most Interesting Men In The World

I’m surprise the universe didn’t explode. Old Spice Man and The Most Interesting Man in the World?!

November 24, 2010 | Comments Closed

Time? What time do you think we have?

The hours grow short until Botacon Zero.

I am determined to have a fully printed chess set before Botacon so that I can play12 at least one game.  I’ve been tracking my heat/speed/etc settings in PLA but it is a time consuming process.  It just holds its heat so long that small lower layers stay molten and gooey too long.  The only reasonable option that I can foresee is dialing in my settings for PLA so that it prints at slightly cooler temperatures and far more slowly than I am printing right now.  However, between work, blogging, holidays, and other sundry obligations I don’t think I’m going to have time to fully dial in my MakerBot for printing small parts in PLA.

I spent most of my free time this weekend cranking out parts.  I printed up two more key fobs, all the non-pawn pieces for the second half of the chess set, and a really large number of experiments/tests/proofs of concept/nascent ideas.

PLA, and I can’t believe I’m actually saying this, has been a lot of fun.  I get to run a robot making things, mostly toys or toy components, that smells like cotton candy, without warping.  The downside, as I’ve mentioned above, is that it doesn’t work nearly as well for small parts.  Last night I printed the tallest objects I’ve ever attempted – a 10cm cylinder and another 10cm model. 3

This is the long way of saying…  I’m bringing a printed chess set to Botacon.  The clear PLA side may be droopy and melty looking, but by god you’ll see it there.  I’ve actually got way more than enough melty looking pawns to call this set done. 4  I’ll probably just come back and print the clear pieces again once I get PLA dialed in. 5

  1. And, by play, I mean lose graciously. []
  2. And, by graciously, I mean to say that upon not winning I will smash every piece to bits and yell something along the lines of “I MADE YOU!!!  WHY WILL YOU NOT DO MY BIDDING AND STRIKE HIM DOWN!?!” []
  3. I’ll upload it shortly. []
  4. So, maybe I am? []
  5. If that happens []
November 22, 2010 | Comments Closed

What would you charge?

I know some people use their MakerBots as small scale rapid prototyping services.  What I don’t know is what or how they charge for providing these services.  Obviously, there’s a cost associated with the plastic, electricity, wear and tear, failed prints, etc. 1 Setting aside the intrinsic value of what you have produced 2 , what’s a reasonable way to set the price of an object printed on a MakerBot?

I can think of several ways to look at this:

  • Resource cost. $0.04 per cubic centimeter, of pure cost in terms of just MakerBot ABS/PLA.  Electricity is probably around $0.02 per hour of print time.  The laptop connected to the MakerBot is capable of multitasking, so there’s no real opportunity cost there.
  • Shapeways. Their gray ABS is $2.50/cc.  They also have a white nylon polymide for $1.50/cc with a $1.50 start up charge.  Their colored prints are made with a plastic powder that is relatively fragile.  At $2.50/cc and assuming it takes 4.5 minutes to print 1cc, this comes to $0.56/minute.3
  • Ponoko. Their UV curable resin is $2.76/cc and their white nylon polymide is $0.80/cc. 4 Their colored prints are made with a plastic powder that is relatively fragile.  At a MakerBot’s printing speed, $2.76/cc comes to $0.61/minute.
  • Metrix:Create. They charge $0.50 per actual minute of build time.  However, Metrix:Create members get 20% discounts and anything printed from Thingiverse gets a 20% discount.  Without any associated discounts and assuming we print at the same speed, this comes to $2.25/cc.

I believe transparency makes for a better customer experience.  That way a customer can see right up front what they may be spending, avoiding “sticker shock.”  It is probably a lot easier for the average customer to estimate the volume of a digital design than it is for them to guesstimate how long my printer would take to print such a thing.

What metric and pricing structure do you use to charge for your printing services?  Do you go by volume, weight, plastic used, machine time, or something else entirely?

  1. It takes about 4.5 minutes to print one cubic centimeter of ABS or PLA.  This is a rough average of several different types of settings, but assumes a roughly 0.36mm layer thickness. []
  2. Pretending 19cc of a puzzle cube is worth exactly 19cc of a toy rocket, window latch, or plastic part that will fix the international space station. []
  3. This is more of an analogy to a MakerBot’s printing speed than an actual assumption of the printing capabilities at Shapeways. []
  4. There are discounts for their “prime” members. []


I spent WAY too long this morning working on a post here…  got ready to hit print…  and was told by WordPress the post no longer existed.  Even better?  Every post and page on the entire site was gone.  Even better?  MySQL said the posts table had crashed.

I use a plugin that backs up this website regularly, so it wouldn’t have been tragic – just painful.  However the post I spent the morning working on was totally gone.  I was able to repair the posts table using the MySQL repair function, but that post was GONE.

That sucks.

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Vincent, here I come!

The DeYoung museum in San Francisco has a special exhibit of Post-Impressionistic Painters on loan from the Musée d’Orsay in France.  I’m taking the day off work tomorrow to go check it out.  I know I’m not alone in saying Van Gogh is my favorite painter of all time.  More than any other painter, Van Gogh’s works speak to me of the wonder in the world around us.

I mentioned recently how much I loved a recent episode of Doctor Who entitled “Vincent and the Doctor.” 1  Well, someone uploaded a clip and sped up the audio.  It makes for disorienting listening, but the brilliant monologue from Bill Nighy as Dr. Black, a museum curator, answering the question, “Where do you think Van Gogh rates in the history of art?”  Just tune in at 1:52 for his response.2

Amusing side note, the DeYoung has a list of things prohibited at the exhibit:

  • No strollers or baby-carrying backpacks are allowed in the exhibition.
  • Tickets do not allow for re-entry into the exhibition; there are no restrooms located inside the exhibition galleries.
  • Sketching, photography, videotaping, and cell-phone cameras are not allowed in the exhibition.

Can you imagine?  No sketching while standing in front of the most inspirational works of art in all the world?!  :(

  1. That episode of Doctor Who may just stay on my DVR until it’s drives rot to pieces. []
  2. Well… um… big question, but, to me Van Gogh is the finest painter in the world.  Certainly the most popular, great painter of all time.  The most beloved, his command of color most magnificent.  He transformed the pain of his tormented life into ecstatic beauty.  Pain is easy to portray.  But to use your passion and pain to portray the ecstasy and joy and magnificence of our world? No one had ever done it before.  Perhaps no one ever will again.  To my mind, that strange, wild man who roamed the fields of Provenance was not only the world’s greatest artist, but also one of the greatest men who ever lived. []