Tangent Audio

In a big push to get the Pelican luggage attached to the bike before a trip to the Delaware Water Gap, I spent a lot of evenings and a couple weekends frantically trying to finish a workable design and get it prototyped.  As mentioned in the last post, I had what seemed like a workable puck design all sorted out, but the more complex latching/locking component still needed work.

I wasn’t sure at first if I was going to design it such that the Givi rack needed to be modified, perhaps with a different catch component.  In the end, I decided the more interesting challenge was to make it work with an unmodified rack, and also felt this would make a better end product.  So, I set off with this goal, and spent a couple of days trying out different design ideas on paper, and eventually refined them into CAD models.

The approach I ended up with would require a significant hole to be cut in the Pelican cases, for the end of the catch to poke into the case.  I could have avoided this, at the cost of making the bike wider when it had luggage mounted.  I deemed this an acceptable tradeoff, and knew I could solve the case breech with some clever gasketing and another machined plastic part.  I ran out of time to complete this part before the trip, but with some mis-use of thick plastic sheeting and gaffer tape, I came up with a quick fix that worked fine for the trip.

Working out a locking mechanism was also a bit of a challenge, but in the end I came up with an acceptable approach which seems like it will be secure enough for the application.  Unfortunately, I also ran out of time to actually fabricate the locking mechanisms before the trip I had planned, so I used a cable lock and padlocks to keep the cases secure to the bike.  In the near future I will complete the locking mechanism.

Above is a video showing the simple process for attaching and removing the case.  Ultimately, the design ended up being quite solid, and survived an 800 mile shakedown trip with no issues to speak of at all, aside from the inconvenience of not being able to lock them up easily.  It’s not out of the question to improve the strength of the setup even further in the future with a metal backer plate, to be installed inside of the Pelican case.  It’s fairly rigid as it is, using just the durable plastic of the case as support, but it may not survive multiple drops of the bike onto the cases.

My little EX500 bike is a bit cramped for me.  One of the worst problems is that my wrists, especially my throttle wrist, have been going numb even after only short rides.  I thought it would be worth trying some handlebar risers to bring the grips a bit closer to me, and improve the angle between my wrist and the bar.  There are some commercially available risers for the EX, but given that I have a CNC machine and a penchant for making things more difficult than they need to be, I thought I’d try making my own.

The basic idea of the commercial risers seemed sane enough, so I figured I’d just copy them.  The only real trick was measuring up one of the flanges on the handlebar, which I did a couple of weeks ago on a cool and rainy Saturday morning.  With a bit of guesswork and a few 1:1 printouts, I was able to zero in on a close match to the OEM handlebar flange, and I knew I was on my way.  After staring at the CAD for a short while, I determined I would go one step further and do a bit of a custom twist, and add tabs to hold a small “dashboard” for a GPS mount or other possibly for accessories like a Powerlet plug.

I ordered a couple of large chunks of 2024 aluminum bar stock (1.5″ x 3.5″ x 10″) off of eBay for a pretty good price, tracked down the longer M8-1.25mm bolts I would need to replace the stock bolts in the handlebars (I used 50mm length), and picked up a new 3/8″ 3 flute endmill with a 1.5″ cut length so I could actually mill the thick stock.  With all of the materials in hand, and the prospect of a bunch of motorcycling coming up this weekend, I figured I’d push to try to get the risers fabricated in an evening, and was successful, barring a couple of recoverable hiccups.

This project is the first when I really made use of the new Tormach tooling system that I bought with all of my leftover nickels and dimes a couple months ago.  I didn’t do anything super fancy, but the main part of the machining did have one tool change.  Had I done all of the drilling by CNC instead of manually, I would have done several more tool changes.  The major lesson learned is that the drawbar really needs to be tight, much tighter than is typically required for a normal R8 collet.  This is the second instance where I’ve had the tool get loose in the Tormach collet and dive into the workpiece.  Thankfully it was during contouring, and I was able to recover, though I did lose precision on the part because I had to re-zero it.  The corollary lesson is that I need to more diligently create and use a zero touchoff point for X and Y so in case of having to re-zero I can get closer than I did this time.

The third major area is improving my fixturing techniques.  I lose some amount of precision when I bolted the workpiece down to the fixture plate that I made.  I simply was not able to get it to line up with the original drill positions as closely as I wanted.  I think the cheap Chinese 5/16″ bolts I was using were all bent and forcing the workpiece this way and that, not allowing me to properly align it with the soft hammer and dial indicator.

All in all, it was a low precision part so none of the mistakes/problems really mattered.  And, as you can see by the photos, it fit perfectly fine despite the troubles.  In fact, it was one of the easiest fitups I’ve done – no problems whatsoever mounting the risers on the motorcycle this morning.

Next up is to measure and design the crossbar “dashboard” plate which will mount between the two tabs that protrude.  There will be some careful balancing of where that plate falls, to make sure I still have enough room for the ignition key.

12►

I recently got a motorcycle, and since I have a CNC milling machine, there’s plenty of excuse to try my hand at making some farkles for the bike.  My girlfriend also happens to ride a V-Strom DL-650, and needed a kickstand plate so her side stand wouldn’t sink into the dirt where she parks her moto.

Add a little bit of CAD/CAM time, a bad ‘Strom pun, and a couple hours with the CNC machine, and you get what you see here.

I have a few other projects in the works for my motorcycle, mostly in the name of making it more comfortable and safer to ride.  I’m a tall guy, and my little EX500 is a bit cramped for me.  So, I’m working on a design for some handlebar risers, and also some mirror extensions so I don’t have to keep ducking my elbows in to see who is behind me.  More on that as the projects evolve.  The materials are on order and CAD/CAM work is underway…

I quite literally turned a mountain of spare change (65lbs worth, to be exact) that I had been collecting for ten years into a slightly less heavy pile of metal and granite, and purchased a Tormach CNC Tooling kit.  This will allow me to set up all of my tooling ahead of time and pre-measure the heights offline.  Using the touch tool I can then safely touch off the Z height of my work, and the varying heights of the other tools and holders are automagically accounted for.  This means significantly less hassle when running programs which use multiple tools, as the tool changes are now very quick (under 30 seconds), and I will no longer have to split up my programs into multiple parts and re-touch for every new tool.

I plan to put together a video showing how this all works at some point, since it is not terribly well documented out in the world from what I can tell.  My first experiments last night look promising, and after some optimizations I think I’ll be ready to show how I’ve got it working.

In the mean time, here are some photos of the Tormach tool holders and some of my tooling.

I’ve been knee-deep in USB and LCD hacking, playing around some concepts for a control pendant for my CNC mill.  It was a good excuse to exercise my rusty skills on the EZ-USB microcontroller, which I haven’t used in years, but was the basis for many projects from the past.

The first experiments were to make a generic HID (Human Interface Device) input/output device, connected to some buttons and LEDs on the evaluation board that I was using.  By using hidcomp, a nice plugin for EMC2, I was fairly quickly able to tie some buttons to jog controls on my mill with some rudimentary speed controls.  This will form the most basic functionality for my pendant, which will have a couple of these nice Happ subminiature joysticks.

Once that was working, I wanted to try to get the LCD functionality in hidcomp to work, so I could output EMC2 info like axis positions onto a display.  The first hurdle, which easily chewed up many hours, was trying to get HID Feature Reports to work with the EZ-USB framework.  Feature Reports are a way for HID devices and the host to exchange configuration information.  In this particular case, the hidcomp package expected to receive a feature report indicating the size of the LCD.  After a lot of digging into the HID documentation and the HID usage tables combined with some critical modifications to the EZ-USB framework, I finally had success convincing the hidconfig program to see my device as having an LCD.

Next step was to find a suitable display to hack onto the EZ-USB board.  A couple of years back, I picked up a cheap display from SparkFun for another project, which I never got around to working on.  So, it sat in a box for a couple of years, and I thought it would be a good idea to dust it off and put it to use.   I had many other displays that I considered, but various constraints like required supply voltages, different logic levels, etc., conspired against them.

The display is serially interfaced, basically a 9-bit version of SPI. I figured the best first step was to just throw it on some I/O pins on the EZ-USB and bit-bang it.  In fairly short order, I was able to port one of the pieces of sample code from SparkFun and get the display painting the screen in different colors.  The down side to the bit-banging is that it’s extremely slow.  Unfortunately, the 8051 microcontroller in the EZ-USB does not have any hardware-assisted 9-bit SPI-like mode.  The closest it has is an 8-bit mode, known as “serial port mode 0.”  After much brainstorming, I could not come up with a practical, workable way to use the 8-bit mode to my advantage.  After giving up on that approach, I decided if I re-ordered my I/O usage I could optimize bit-banging as much as possible.  Using the bit-accessible I/O, I knew I’d save a lot of instructions for things like strobing the clock line.  I kept the data pin on a non-bit port at the highest bit, so I could simply left shift the data through the port for each phase of the bit-banging.  If I end up using one or more of these displays on my final pendant design, I may end up using a CPLD to create a hardware 9-bit shift register to further optimize driving this display, as even with my optimizations it’s a bit sluggish.

Anyway, here it is, with a simple configuration set up from hidconfig to have it show X, Y, Z axis positions, their homing status, and some system run status.

Before…

After…

My friend Dan built the electronics for a temperature controller for his electric smoker.  I figured since I have the CNC mill, it was a moral imperative for me to do some nice enclosure work for him to make the project look slick.  Dan admitted his initial attempts at the case work with a Dremel tool were lacking somewhat, so about a month back he passed the guts over to me so I could have a go at it.  It took a few attempts to come up with a design I was satisfied with and execute it well enough to consider it done, but I chalk all of that up to gaining experience on the machine.   I was pleased to finally be able to present the finished product to him last night!

The electronics originally fit into a waterproof PVC Carlon box.  The lid had been previously attacked with a Dremel, but I figured if I cut out a large window and made an insert for it, we could salvage it as well as end up with a nifty look.  So, I started out by CNC milling out a roughly 4.7″ square from the lid.  I then made a clear polycarbonate insert, just slightly smaller by about 0.010″, so it would slip fit inside and stay in place with a flange.  The polycarbonate insert received some decorative milling on the front panel, and some functional drilling on the rear panel to provide mounting and a place for the knob to pass through.  The insert also got an engraving treatment with some text using the new high speed spindle mount that I built last week.  Since getting engraving working well, I had tried a few experiments of back painting engraved text.  I did the same for the Smoke-O-Tron, using some water-based Rust-Oleum hobby paint.  I made sure the see-through LCD window was well masked off with the original paper that came with the polycarbonate as well as some supplemental electrical tape.  I sanded the back of the insert, avoiding the LCD window, with 220 grit in my random orbit sander, and applied a couple of coats of black spray paint.

The main electronics consists of the main PCB and a small character LCD.  After one misguided attempt of doing blind tapped holes in the clear insert (ugly and visible), I came up with the much cleaner “mezzanine” approach.  This is often done in front panel work in devices, especially when varying heights have to be accounted for.  The particular scheme I chose allowed a completely clean front panel look with no visible screws.  The electronics mount to both sides of a small polycarbonate plate, and the plate itself is mounted to the PVC enclosure by way of some custom-length standoffs.  The standoffs also serve to sandwich the front panel PVC insert in place.

I also made a quick shaft adapter/extender for the encoder wheel, which adapts from 6mm to .250″ and provides a long enough shaft extension that passes through the mezzanine, front panel insert, and into the knob.

All in all, I’m fairly pleased with the end product.  It looks slick, and I have learned a few new techniques for future projects.  As usual, here is a video which details the making of the enclosure, and a bunch of pictures as well.

12►

I’ve been working for the last week or so on a mount to hold an auxiliary high speed spindle on my mill.  I chose a Proxxon Micromot 50/EF tool, which is a fairly slim 12V handheld rotary tool (think Dremel).  I wanted something powerful enough to do high speed engraving, but probably not a lot more.  The tool spins at 20,000 RPM unloaded, which is literally 10X faster than what my X3 mill spindle spins at.  The general rule with cutting tools is that you need higher RPMs when the tool diameter shrinks, and the engraving cutters are ridiculously small.

I wanted to use the opportunity to try out some new techniques and make the part “the right way.”  I knew I wanted to try making a fixture for the part, and I wanted to pay extra attention to speeds and feeds and shoot for a nice finish on the part.  It took one attempt with taking cuts that were too aggressive to dial back and fine tune the feed and depth-of-cut (DOC).  The second attempt turned out much better, and I attained a nearly mirror finish on the vertical surfaces, along with a much happier sounding tool.  I used a mix of MDI (manual commanding of the machine, e.g. ‘go to X=1.0 Y=0.175′), manual drilling with the quill, a facing wizard program to face off the aluminum stock, and CAD/CAM to design and generate G-Code for the bracket.

I put together a video that shows many of the steps of the process for making the part, with a quick bit at the end showing the high speed spindle doing some engraving.

I still need to drill and tap for the clamp screw, but the fit was tight enough to run the engraving without it.

Here are several photos of the process, too.

Did an engraving test tonight with some new engraving bits that I got from this eBay seller.  Decent results, though I am plagued by the X3′s slow spindle speeds.  I tried an experiment of painting the engraved text and then backspraying the entire piece with flat black, to see the text through the 1/4″ polycarbonate.  It looks pretty decent – kind of a classic look, but still better (and less hokey) than anything I’ve produced on my own so far.  The closest I’ve come is printing text on a laser printer, carefully cutting it out and using a Sharpie to color the edges, and sandwiching it between a front panel and a piece of clear plastic.

This is an experimental run for my friend Dan’s “Smoke-O-Tron” temperature controller that he designed and built for his meat smoker.  I am doing a little bit of enclosure work for him to make it look snazzy, and work on my own CNC mill enclosure-making chops at the same time.

After more work than I anticipated making the Y homing sensor mounting block and making a bracket and sensor setup for the Z axis, tearing down half of the machine, rewiring, adjusting/loc-titing/rebolting, circuit hacking, and other general tomfoolery, the machine has functional homing capability!

I ended up using the second block I had made when I machined the X block on Friday night.  It needed slight modification to work for Y, as the mounting holes were slightly different.  I unfortunately crushed one of the sensors discovering this (there’s no visibility to sensor when it’s installed).  The Z bracket was fairly straightforward, and I came up with a slightly simpler scheme than the ProMiCA version.

With all three axes installed, it came time to get them wired up to the control PC to test them out.  This proved to be a royal pain in the neck, and I had to construct some filtering/cleanup circuitry to eliminate some really bad noise.  The issue seemed to be that the ‘on’ level of the sensors I used was giving me around 1.4 volts output, and with the stepper drivers turned on, they were spewing out enough noise to bump the inputs over the TTL threshold.  I tried a few combinations of filtering caps and pullups/pulldowns, but nothing helped.  I finally had success with a simple RC filter on the input to a Schmitt triggered inverter (74LS14) that I happened to have kicking around from prehistoric times.  Seriously, that particular chip probably dates from my high school robotics hacking days, so it’s doing its ilk proud in my CNC.

Here is the final result, after EMC2 was configured properly for homing:

And here are some photos of the process:

Unfortunately, back in October, I discovered that my level of conversion kit for my mill did not include the hardware for home sensors for each axis.  Everything was there, but for a few small brackets and mounting blocks, and the actual optical sensors themselves.  I asked whether the company would simply send me the CAD drawings for those small parts, but they wouldn’t for intellectual property reasons.  I suppose it’s fair, but still frustrating.

So, since then, I’ve been manually homing the machine.  It’s annoying, and has to be done each time I start it up.  I figured I would be a pain in the neck at best to add the homing sensors for the X and Y axes, since I needed the machine apart to conveniently get in to take measurements, yet I needed it together to know where the “fingers” of the interrupters landed exactly.  Not to mention, I needed the machine together to actually machine the parts!

Since getting the shop set back up, I’ve been trying to think about and tackle a lot of little projects to get things operating better.  I’ve been working on designing my own electronics breakout board (more in a later post), and I’d just included the homing sensors.  Needing a break from schematic/PCB work, I decided tonight would be a good night to start tackling the homing sensor mounting.

I could just reach up into the X endcap enough to take some rough measurements of the bolt spacing.  After a couple of test holes in a scrap piece, I determined the proper spacing of the mounting.  I then experimentally determined where the “finger” intercepts the optical interrupter.  Doing some old-school PAD (paper-aided design), I quickly sketched up what I needed.  I rough cut up a piece of nylon and went to town on it, running the mill in a mix of manual jog mode and simple G-Code commands.  It’s a lot like manual milling with a DRO, just easier and faster.  Once I get my pendant built, I think it’s going to be a very enjoyable way to work.

The mount fits perfectly on the X axis.  I was hoping it would also work for the Y, but the spacing appears to be different, so I’ll have to make a new block for that next.