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.

I must have angered the mechanical gods recently.  Flat tire last night right near my house, rolled the car back into my driveway… This morning, got up early to change my tires to my summer tires (long overdue), and the head sheared right off of one of the security lug bolts, leaving the tire stuck.

Now that the machine is here, I decided to do a small project to start my way up the learning curve.  For a while I’ve been planning to build a camera mount for our rallycross car so that we can capture some footage of our events.  I happened to spy a neat design on  someone’s car at a recent event – it clamped to the headrest posts and extended towards the center of the car to provide a spot for the camera.  It looked easy enough to copy and modify to suit my needs, and it occurred to me that it would be a fun project to get my feet wet on the new machine.

Digging through the “useful materials” scrap bin I’ve been building up over the years, I found a big chunk of nylon which would be well-suited to clamping blocks, and some aluminum C channel.  I designed on-the-fly and I think I’ve got a decent start.  Still need to work on a simple articulated camera mount and probably re-doing one of the clamp blocks which bore the brunt of my rookie machining mistakes.

I did a test fit-up in the two cars it was designed to fit (the clamps are adjustable) and it seems to be quite stable.  Should hold a camera quite steadily, subject to the stability of the seat itself.  Hopefully it’ll help to produce some watchable video!

Overall I’m finding that I really enjoy machining.  The precision of the machine is quite a revelation.  Until now I had done all of my half-ass mechanical work using pretty low end stuff like drill presses, hack saws, files, and a lot of eyeballing and rough measurements.  To have basically produced a small assembly actually using math and counting on the measurement capabilites of the machine and to have it work and turn out well is really quite a thrill.  That much of it turned out within good tolerances (+/- .001 in many cases) gives me hope for when I actually get good at it.

Using the machine manually is a bit of a chore, especially keeping track of turns of the dial.  However, it does give me a basis of appreciation for what it will be like when the machine is under CNC and I can run it in semi-manual mode with a pendant.  In essence, much of the tedious wheel-jockeying should be reduced.  Shuttling the bed to a particular coordinate where I want to perform a milling or drilling operation will be as easy as typing it in.  Executing simple stuff like milling channels, pockets, circles, etc., will all be fairly easy.  And that’s all before it gets really fancy with CAM software, taking CAD drawings and churning out parts with hopefully ever-decreasing tedious tasks.  The future looks bright!