RoboBlade Prototype

I finally cut, tapped and mounted the components for my RoboBlade prototype. Basically it is made to slide into whatever robot chassis I like, be modular (there’s even room for power if I don’t want to get it from the main system), use message oriented middleware to talk to other subsystems, and run wire to the sensors or actuators as the case may be.

If you recall the square opening in the center of the plates I was building in my last post, that’s where wire as well as ventilation will go. And these boards – there will be several, one per subsystem – are intended to slide into the electronics section (that’s the middle).  Most of the sensors will then be mounted up above, or on the side.

More on all of that later. Today I just had about an hour so I took a piece of the Lexan that was already cut to size (albeit poorly), tapped some holes and mounted an Arduino, a blank perfboard and two blank mini breadboards.  I really wanted two perfboards on one side, but didn’t have time to cut the screws down to size. Since this is just a prototype anyway, I wasn’t worried about it. After all, nothing on this project yet has been measured or cut precisely; that’s part of the whole thing, to learn these new tools while I build my electronics and robotics fun.

Next up I need to stabilize the body and build the rails for these boards. Oh, and then build more boards, hook up sensors and power, etc.   More on all that later.

Here are some pics.

Sheet Metal Work This Weekend

Boy did I learn a lot this weekend!

I started out with this fantasy that I’d complete a nice-looking, cool robot body with … well, I’ll just show it to you when I have it done.  In the meantime, here’s what I was able to do this weekend.

I:

  • Use my air shears to cut a sacrificial piece of sheet metal.  Also drilled holes and then used a metal blade in my jigsaw to cut out the center piece.  These sheets are heavy, so I cut out another hole at one of the sides in order to see how much rigidity it retained.  Answer: A lot.  I can probably remove a lot more material and still have a strong and sturdy robot body.  Oh, and the size is about 13 inches square, with 135 degree angles cut for equidistant sides.  I really want (I think) an 18 inch footprint, but I’m working with what I have, and 13 inches is what I could get.  Frankly, it’s heavy and might just be fine.  I’m going with it for the moment.
  • Used a combination drill/tap/deburring bit in my drill to put some a threaded hole in a piece of Lexan (like plexiglass, but without the shattery parts).  I was surprised at how easily it worked!  Having never successfully used a tap before, the combination bit was really nice.
  • I used the same bit to tap threaded holes in the Lexan, a piece of aluminum and in the thick sheet metal.  It worked flawlessly each time.  I don’t know what the lifetime of the bit is, but I hope it will do a lot!
  • I used my handy-dandy thread checker tools to see what these billions of screws from the old copiers were.  Right now I’m using metric 3mm .5 pitch and 4mm .7 pitch and those bits were standard.  Since I have a ton of those screws, being able to tap into my material directly will a) save money on nuts, and b) look nicer, more professional.  I was really pleased with the result.
  • Having done a few experiments it was time to cut a template.  The template will be used to pattern the platforms for the 3 layers.  The first/bottom layer will be for batteries, the second/middle layer will be where the bulk of the electronic circuitry goes and the top layer will be where the majority of the sensors are mounted.  Trust me, in my mind it’s such a cool thing ;-)  Anyway, I measured and cut out the template and experienced some mild frustration along the way.  Mainly, all the tools I’d normally use to cut a straight line in wood were just not working.  The air shears don’t have a flat edge to keep along a clamped down straight-edge, so they allow me to move them around too much to keep a straight line.  My jigsaw, with a proper metal blade, would cut nice and straight for a few inches and then invariably start drifting right, away from the straight-edge.  For all my efforts I just couldn’t cut it to cut well and had to go back and trim repeatedly.  I finally decided that since this was a prototype anyway, non-perfect cuts would have to be acceptable.  I cut the rest of the edges by hand using the shears and those cuts where the cleanest of all.  (Later, on a run to the hardware store, I picked up a bit for my Dremel that says it will edge stainless steel.  That’s to be tested shortly.)
  • I cut out three of the platform sheets.  I had planned to run threaded rod vertically through the contraption, using washers and nuts to hold the platforms at highly-adjustable heights.  In the end it proved too unstable so I’m going to cut more sheet metal, bend 90 degree brackets and tap all of it so I can put together a solid core, then I’ll attach everything to that.  However, you’ll see that I drilled the holes through the plates and then put temporary bolts in to keep them all from moving.
  • At this point I drilled some more holes in the center and used the jigsaw to cut out the “wiring and ventilation shaft” hole through all three.  I was surprised when my jigsaw had zero difficulty, cutting through it like a soft piece of wood.  Nice jigsaw blade!
  • In the last photo, it’s hard to tell but what I’m doing is just testing that my mental model for the electronics will work.  I’ve got more of that Lexan and am cutting it into 3″ x 8″ strips.  Then I’ll tap them, put on spacers and secure components like Arduinos and Raspberry PIs and breadboards (only while prototyping, of course) and then finally, perfboard with my finished circuits.  The idea is to have different boards for different purposes and to have them slide in like blades in a blade server.

Admittedly my skills are currently weak, my materials aren’t what I’d prefer and what I see in my mind’s eye is waaay more cool that what I produce, but every journey starts with a single step and I had to start somewhere.  This is a hobby, after all, and I firmly believe that “the journey is better than the inn”.  This is a journey and I’m enjoying it immensely.

I’ve pulled a LOT of aluminum from these old computers and from heat sinks in the copiers.  Hopefully this year I’ll build a forge and cast aluminum from which I can machine sharp-looking machined parts for a truly awesome robot / electronics education platform.  Granted, that’s a lot of skills to learn, so the journey will be long.  But again, I sure am enjoying it!

First Turning on a Metal Lathe

Another tool I recently added to my shop is a small metal lathe.  I have plans for it but am still learning and I haven’t even finished doing the work to properly square it all up, but I figured I wouldn’t hurt it turning a small rod of aluminum.  I have watched enough videos on YouTube that I thought I could do a simple turning easily.

I was right, it worked pretty well.  The quality is pretty bad, as you can see from the photos, but on this one piece I was able to a) bore the center, b) do a facing cut, c) turn down the diameter of the entire length, and d) turn a divot (right term?).

It’s a long way from something usable but it was enjoyable anyway.  Every path to mastery starts with a single step!

Here are some images of the turned piece.

Bending Sheet Metal

When I started collecting all those broken copiers (for robot and electronics project parts) I also added a few tools to my shop.  Tool purchases are always easy to justify :-)

Anyway, one of them was an inexpensive metal bending brake.  Odd name, and basically it just lets you put a bend up to 90 degrees in a straight piece of metal.  The one I bought cost about $30 and it can only handle thin sheet metal or, if the metal is thicker, a smaller strip.

I performed a test shortly after buying it a couple months ago and I performed another test yesterday.  A month ago I bent a very pliable piece of sheet metal cut from an old desktop computer case.  Those are pretty thin, but yesterday I tried bending a piece from an old rackmount server case.  That ended up being some pretty tough stuff, and my bending brake was having nothing to do with it.  However, on my list of things to build/buy is 90 degree angle brackets.  I’d rather not buy them, having bought these tools in order to do as much fabrication as I can on my own.

So in a moment of inspiration I cut a thin strip of the heavy stuff, clamped it into the brake and Wa La! It bent easily.  I can bend the thinner metal by hand, so it wasn’t going to work as a angle bracket, but this stuff is solid and will hold things together well.

The images are of the thin metal in the brake before bending, the bent piece and then the angle bracket from the thicker stuff (yes, I have a gauge I can use to gauge the gauge of the metal, but it’s buried behind a mess of stuff).  Another cut on the longer side and I’ll have me a nice little, very strong bracket.

Couple that with now having some experience with a tap and die kit (coming in a future post) and it’ll look nice and professional.

 

Phone System Components

So I think I mentioned that I ended up with a phone system that was being tossed out.  Here’s what I ended up harvesting from it.

Battery backup system with batteries, power switch, 2 punch-down blocks, dozens of buttons and LEDs (surface mount), a dozen RJ-45 (?) cables and connectors (which will make wiring cleaner in some cases), speakers, microphones, DC power adapters (where the plug goes – PBC mount), typical PCB components – resistors, capacitors, etc., and some decent flat black plastic panels.

Here’s a pic of some of it.

Not too bad!

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More Parts & Ideas

I picked up another copy machine yesterday morning on the way in to work.  When I told the people giving it to me what we were doing with it, they also gave me an old phone system.  That means speakers, microphones, buttons and LEDs!

This morning I woke around 3 am with several ideas for opening panels.  These include options to open a ring of 8 panels at once via a single motor (think a hexagonal ring, 8 panels, all driven by a belt and 45 degree gear angles), vertical and horizontal belts, solenoids, panels that slide vertically, panels that slide from top to inside or bottom to inside, and plenty more.

After sketching these out on paper, I realize that it’s time to learn some open source CAD software.  I also decided that since one of the drivers for this whole endeavor is for my son’s mechanical engineering interests, we’re just going to go ahead and build prototypes of all of these different ideas.

Also in the mix is a launcher/ejector for a light saber (of course).  I have a few ideas on that, although some of them might be of the speed to make it more of an elevator than an ejector.  I decided that we’ll build each of those as well.  After all, if we aren’t experimenting with each of these ideas, we’re probably doing the whole “learning” thing wrong ;-)

I spent an hour or two last night watching YouTube videos on stepper motors.  I’m pulling several of these from the larger copy machines and am excited to start working with them.  Still in the “raw materials collection” mode, though.

A couple images from the notes this morning.  Now out to the freezing garage to pull things apart!

Bending Plastic & More Parts

The weather was fairly warm today so I opened the garage door and spent a good portion of the day taking apart the copiers we have so far.  You can see from the photos how much comes out of these.  In the beginning I saved almost everything, but with more material I find that I’m going to be able to be more selective.

One of my goals for the day was to bend some plastic.  I have a heat gun that I use for electronics shrink tubing.  I cut a flat piece of plastic from a larger, more involved one, and put it in a vise, then applied heat from the heat gun as I held the plastic in a curve.  For not having any form, I thought it turned out ok.  All I was trying to do was see what kind of options I had.  I think that once I have a form (probably wooden), I’ll be able to make pretty decent curves; consistent and professional looking.

My son was excited about this, since it means that a round Star Wars R2-type unit will be possible.  I’m excited because it probably means I can get good bends (without curves) if I do something octagonal.  I like the idea that I could have 2 or 3 of the sides all formed from one piece.  I think that will provide a more professional look.

We still have a long way to go, but this was a good next step. Later steps include building and using the forms, possibly with a vacuum attachment (we saw one of those at a Maker space), bending sheet metal, building bases and frames and such.

It’s time to start planning what we want in each of the robots and how we’re going to allocate space within them.

One of the other things that I enjoyed about today’s work was just how many different ways that hinges, actuators and levers were used.  I am learning a lot from tearing down these copiers, getting ideas on how to build things that I wouldn’t have had otherwise.  I am looking for good books on mechanical engineering and suspect these techniques would be covered there, but still it was fun to see.

I also pulled out several components that were unfamiliar.  I believe that there are some linear actuators that are magnetic, and there were some other parts I couldn’t identify.  Part of the fun is figuring out what those are and then coming up with a way to apply them.

All in all, still having fun!

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