Differences

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--- builds:invisible_jet [2018/10/17 09:19]
prysk
+++ builds:invisible_jet [2019/01/27 14:22] (current)
prysk
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-{{ :builds:41963357_235173833828348_7156935104630095872_n.jpg |600}}Some media:
+{{ :builds:41963357_235173833828348_7156935104630095872_n.jpg |600}}
+Some media:
 Playlist of Kart POV
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 For 2018, the team consisted of myself, my friends Amanda and Max, and my brother David. We started on the kart right after the FRC and Battlebots seasons wrapped up (RIP Brutus). The only thing that changed for 2018 was the theme: we decided to build Wonder Woman's Invisible Jet plane. I think we're going all in on the airplane theme, expect an airplane themed cart every season from now on! (suggestions always appreciated).
+{{:builds:36064318_10214351866922867_3464131023917285376_n.png?600|}}
+Final Conceptual stage before assembly.
+{{:builds:42603568_562654254153672_245132166042746880_n.jpg?600|}}
+As it sat in the pit at Maker Faire NY
 **Construction**
-So for the **frame**, it's 1x1" 1/16" wall steel box tubing. Super standard stuff, dirt cheap from suppliers and super easy to work with. It's all MIG flux core wire welded with an Eastwood MIG (love that thing), and the angle design is heavily inspired from RUGreasy and FUBAR (2 IIRC).
+So for the **frame**, it's 1x1" 1/16" wall steel box tubing. Super standard stuff, dirt cheap from suppliers and super easy to work with. It's all MIG flux core wire welded with an Eastwood MIG (love that thing), and the angle design is heavily inspired from RUGreasy and FUBAR (2 if I remember correctly).
 Initial frame construction:
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 {{:builds:40574319_288468855316187_3801298291799359488_n.jpg?600|}}
-We originally planned to use this as the frame, however with some highly precise "standing on the frame and bouncing up and down" testing, we determined there to be way too much flex in the long 1x1 runs. That necessitated a bit of a fix:
+We originally planned to use this as the frame, however with some highly precise "standing on the frame and bouncing up and down" testing [inset slo-mo], we determined there to be way too much flex in the long 1x1 runs. That necessitated a bit of a fix:
 {{:builds:41302211_400232730510643_3690914728894267392_n.jpg?600|}}
@@ Line 46: / Line 56: @@
 The **steering** was a part of the kart that I put a bunch of thought into, but having never designed any sort of steering system, there's only so much one can learn without taking a college course in it. I ended up using the Red Shirts/Big Orange Truck design for the steering, which uses a couple of ball joints, thrust washers, shoulder bolts, and a milled plate to greatly simplify the steering process. Definitely contact Matt Hagan if you'd like the design, it saved me a lot of headache. [[https://www.instagram.com/p/BlS3mPQljOp/?taken-by=phil.rysk|Here is a video/animation of the steering set up.]]
+We used a BMI bowtie steering wheel, a piece of conduit as the column, running through two Markforged bushings to a BMI double arm Pittman arm. Using some tie rods that I has saved from a dumpster, it made a crude, albeit effective steering setup. See the **upgrades** section for recent changes.
 **Powertrain** was something I had to do on my own. [[http://www.etotheipiplusone.net/?p=4187|Charles had done a teardown of the motor]] but it still hasn't been too widely used. The gearbox you see in the photo is a bench test setup that got kind of...used...on the kart. We weren't sure if two of those motors would cooperate chained together in a gearbox, [[https://www.instagram.com/p/BkWNiZuhesn/?taken-by=phil.rysk|so we needed to do some testing.]]. It ended up working fairly well with cheap e-bike controllers, at least at lower speeds. These motors top out at around 6000rpm, and the path right now is 10t sprocket -> 16t and then a centrifugal clutch with a 12t -> 60t output. It works fairly well, the clutch is there to try to maximize off the line power seeing that sensorless brushless motors have that issue.
@@ Line 55: / Line 67: @@
 The **electrical** aspect of the powertrain was quite simple. We had to modify the e-bike controllers a bit to the low voltage cutoff of the leaf cells, but that was somewhat simple. For our first event, we wanted to keep the electrical as simple as possible, and it held together quite well through the entire event.
-The **body** is SUPER COOL and I'd love for Amanda to write about it
+The **body work** is SUPER COOL and I'd love for Amanda to write about it
 **Event Reports**
+__**New York Maker Faire, 2018!**__
+NYMF '18 being the first race of this kart's history, I wasn't hoping for much, but really was hoping for some reliability. Some initial thoughts:
+  * Have a list of stuff that's being brought up, prepare the week before
+  * Corner pits are bad, I hate having a $100 welding jacket walk. Get there earlier on Friday
+  * **Always bring a welder**
+  * Battlebots are hard to move
+  * Better bumpers on the front (not .5" plywood)
+  * HF tires suck badly enough that they pop in the second test lap
+  * Body work that's sturdy enough to be used to get in or out of the kart is nice
+  * No 3d printed parts in critical systems
+  * Steering is a bit loose, though it works well
+  * Ground clearance: ugh
+  * Going 15mph in something you built is both fun and terrifying
+  * Worry about all the things breaking, not just the steering, or the frame
+The biggest issue we ran in to was that the gearbox was still the bench test prototype: the gearbox plates were 1/8" 6061, and the jack shaft bearing blocks were Markforged plastic.[[https://www.youtube.com/watch?v=WXhJ0nLqzSs|This led to multiple chain issues and ended with a bearing block melting into a bearing.]]
+Otherwise, the components and systems I was most concerned about performed spectacularly. The electronics were rock solid, though the cheap e-bike controller seemed to have trouble getting out of the "1st" electrical gear
+The steering also kept together quite well, and after the event when I did a teardown, there was a lot less wear than I originally thought there would be.
 **Upgrades, changes, and future stuff**
+__**September 29-30**__
+Gearbox work. Replaced the Markforged plastic bearing blocks with CNC'd aluminum blocks, and a longer output shaft. Immediate improvement, much less flex in output. With properly spaced output shaft, no longer have issues with bolts coming out.[[https://www.youtube.com/watch?v=5VCEGFOLO5A|Noticeable difference in testing.]]
+{{:builds:42796945_1180676058750765_3239628900057219072_n.jpg?600 |}}
+{{:builds:42833646_255946574998243_5609846614270148608_n.jpg?600|}}
+__**October 6-7**__
+Steering work. Replaced column with solid shaft. Replaced Markforged bushings with oil-infused brass bushings. Took apart and inspected/greased/oiled all the components. New shoulder bolts for the tie rod ends that go into the knuckles, to limit steering slop/play. Additionally, 10" slicks installed. Better ground clearance, though skids a lot in the school hallways. Will have to test on asphalt.[[https://www.youtube.com/watch?v=y08IqKmj6aQ|Noticeable improvement in steering.]]
+{{:builds:43480485_889522587919447_6198155575025467392_n.jpg?600|}}{{:builds:43299324_164731067784911_2039308020407599104_n.jpg?600|}}{{:builds:43467035_1861453097266179_8918564869351931904_n.jpg?600|}}
+__**October 13-14**__
+New VESC's came in. Replaced the e-bike controllers, additional noticeable difference. Regenerative braking is a nice plus to have: I like being able to let off the accelerator pedal and get quickly to a desired speed. Blew the fuse after turning regeneration on though, will have to install a diode to protect the fuse from the back current. The acceleration is brutal though. Will need better brakes as well. Neat-ified the wiring. More power poles, but much better run: less chance of catching fire or coming apart. [[https://www.youtube.com/watch?v=d1wQODyQTKQ|Noticeable improvement in testing.]]
+{{:builds:43951962_314718855974771_727734620069560320_n.jpg?600|}}{{:builds:44027586_281460745828650_2761882284515655680_n.jpg?600|}}
+(This is how David gets to work in the morning)
+__**October 20-21**__
+No work
+__**October 27-28**__
+Replaced the centrifugal clutch with a straight sprocket: wanted to get some testing in on difference between a centrifugal clutch and a direct connection. There's a lot more cogging than we'd like, but this might be due to not having the controller parameters right.
+In testing, we also came across another issue: mainly that we forgot to put a ground lead in the CAN cable between controllers, and the back EMF from one managed to blow the CAN chips on both up when trying to manually push it backwards. New controller chips have been ordered, and a ground lead has been installed. This is also a good excuse for me to just make the heatsink I've been planning for the VESC's for 3 weeks now.
+{{:builds:img_8156.jpeg?600|}}
+__**November 3-4**__
+No Work
+__**November 10-11**__
+Finally got the motor controllers fixed and back in. Took the time to make the heatsink, it seems to be working nicely! Going to have to figure out a better retention method, a bit of VHB tape right now to hold it down for testing.
+{{:builds:img_8259.jpeg?600|}}
+{{:builds:img_8264.jpeg?600|}}
+{{:builds:img_8266.jpeg?600|}}
+__**November 17-18**__
+No Work
+__**November 24-25**__
+New body concept and design work
+__**December 1-2**__
+More concept and design work with some bodywork manufacturing starting
+__**Build on hold until end of FRC season**__
+Good luck to all the teams!
+{{:builds:kart_2018_hopefully_not_broken_v11.png?600|}}

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