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JakeRobb

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About JakeRobb

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  1. I’m coming along on the parallelogram steering. I have something halfway mocked up that seems like it’s going to work! I used some spare bits of thin aluminum plate and shaped them with a disc grinder. Just a few details to work out: The turnbuckles are a bit too long — significant toe-in at their shortest setting — and they’re a bit too bulky at the end. If anybody knows a good place to shop for turnbuckles that actually lets you filter by the key dimensions and end fittings, that would be really helpful! I need to make a piece that links the two sides, and I need to make a mechanism to connect to the servo. Once I have a setup that works, I’m going to re-fab the whole thing with bearings — right now it’s just through holes with screws and nuts. It’s a little sloppy, but suitable for a proof of concept! Also, the oversize tires I ordered showed up. They are substantially bigger than I expected, but they fit with no interference. I honestly kinda love how it looks with these on. Hilarious in an aggressive sort of way. So, with those tires on, I had to play a little — even with no steering. So, once again, I hooked up the battery, powered it on, pointed the wheels straight, and goosed it. There’s still enough torque and traction to pull a wheelie from a stop on carpet! I didn’t stay in it, so I don’t know if it can still flip itself over. Ignoring the inevitable heat issues that will come from this combo, I’m pretty sure this setup will be an absolute rollover king, and I’m kinda thinking about a wider set of tires for the front, too.
  2. You got me excited there for a sec, but those are all dual-axis sticks. I want a left stick that only moves up and down, and a right stick that only moves left and right. The 3GR-2.4 is perfect. I paid too much to have it shipped from Germany (because that was literally the only one I could find), but it is exactly what I wanted! I really like all of the digital tuning options — for example it can limit the rate of change on either channel so that I don’t accelerate or steer too abruptly.
  3. I’m sticking with solid for now at least. Will decide if I want to put the effort in on an IRS once I have the steering conquered. The two minutes of run time I had before disaster struck was very promising: with spike tires, it was good fun in my yard and gravel driveway, and wicked fast on asphalt. I didn’t have any issues controlling it, but obviously two minutes is not a large enough sample size! I’m still waiting to see if I have heat issues. Probably. We’ll burn that bridge when we get to it, as my dad likes to say. I ordered a set of those larger tires, as well as a couple others in more normal sizes but different tread patterns to try. Looking for something with a good balance of acceleration, top speed, traction, and heat that is reasonably well suited to both grass and pavement. I’ll report back when I know more!
  4. I'm looking at your picture, and I can't figure out what you have beneath the pivot. I assumed it was just a couple of ball screws to attach to the turnbuckle. No? Okay. What bearing do you have in there? 1150? Any particular reason you went with that? My setup would be distributing load across two bearings, so it seems reasonable that I could go smaller.
  5. Okay, let's talk about steering. If you are still following my thread, you might know that I got things working enough for a test drive, but completely ravaged the steering in the process -- and that my hopes for a more robust setup did not work. Specifically, I bought this upgrade kit for a Traxxas Slash in hopes that I could fit it. No such luck! I like what you've done with steering, but I'd like to try to take it a bit farther. Here's what I'd hope to change relative to your Ultra G design: Switch sides on the arm that goes from the pivot to the servo. My huge LiPo's wires would interfere with yours as it crosses over the body. (It sounds like you did this on Ultra Hornet already, to clear the driver.) Introduce some parallelogram geometry, with the sides matching the length of the steering arms as closely as possible. Try to get points where the tie rods connect to the parallelogram to be as close to the lower A-arm pivot points as possible. The point of #2 and #3 would be to minimize bump steer. I don't have a good CAD system, but here's a relatively crude drawing (Ultra G on the left, my proposal on the right): One thing I'm curious about on yours is the size of the central pivot. Did you use that size for strength? On your setup, the lower control arm pivot point is much farther outboard than on mine, so this might work out better for me than for you. You could move things outboard, but I don't think that would leave enough room for articulation. Regardless, I think it would be a slight improvement on your setup. What do you think? Any chance you'd help me turn this into a real design and figure out how to bring it to life? I'm hopeful that it has enough articulation without the sides of the parallelogram hitting each other. I also like that the lateral connecting bar between them will offset the tie rods down a tiny bit, bringing them closer to parallel with the lower A arms.
  6. Thanks. I looked up the Scorpion wheel, and it says it's just a friction mount; not 12mm and not the like hub on my Hornet (does that have a more specific name?) either. Is that what you have? What hub surface do you use? Any specific tricks to mate it up? Any issues with slippage? You said that the BZ would have too much power and it would be unmanageable. Tire diameter is an effective way to manipulate gear ratios; a larger tire would mean less torque at the contact patch. You'd get more top speed and less tire slip under acceleration. Seems like a good trade, so why not? Endbell is the end of the motor where the connections come out, right? Sorry, I'm still learning some RC-specific terminology. Yeah, but it wouldn't be the (Super) Hornet of my childhood memories, so it's not the same. That's why I'm willing to spend relatively stupid amounts of money on this. If I'm buying something new, I'm going all out -- definitely 4WD, maybe bigger scale, 4S or more, brushless....
  7. Okay, so the parts I ordered for the steering came Saturday. They are either not going to work or they’re going to require more modification than I was hoping. I haven’t decided yet. I knew when I ordered that it was questionable. So anyway, the steering was the only thing holding up a proper test drive, so yesterday I decided to put it together with the stock steering setup, but using the Hyperion micro servo. Had to cobble the mounts, and I had to use a non-servo-saver horn since I can’t seem to find a servo saver with A15T splines. It worked, ish. Had to extend the toe links as far as they would go to get a remotely reasonable toe angle. Max steering angle to the right was pretty limited, but it was functional enough to try it out. Anyway, this was about 5pm; light was fading. So I grabbed my girls (solo parenting today), got them suited up for cold (it was about 28F here today), and out we went. I hopped it around in the grass for a bit, then up to the road (residential dead end, no traffic) for some speed runs. Holy badword, it’s FAST! Just a guess — 28-30mph? No idea. I made sure the kids knew to stay out of the street, and I sent it zooming down the road maybe 200 yards, which felt like it took two seconds. Turned it around for a high-speed flyby and sent it. Meanwhile my four-year-old daughter had decided she wants to make a “tunnel” for the car with her legs and has gone into the street and made a wide stance. As the car is approaching at max speed, she says “dad, drive it through this tunnel!” Which, by the time the sound reaches my ears and I process it, the car has already slammed into her foot. As I turn my head, I see her, in the middle of the road, get flipped off her feet like a cartoon. Thankfully, she was wearing thick winter boots, a thick hat, and leather mittens, so injuries were limited to a minor nosebleed. I had my other daughter gather up the car, and we all went inside to take care of the kid. I’m pretty sure the car hit her tire-first, because the servo horn snapped off, and one of the tie rods stripped itself out of the ball end. So, back at square one on the steering. 😅 It was a ton of fun for about two minutes!!
  8. Cool, thanks for the explanation. More travel is something I’d prioritize; most other aspects are tunable. You mentioned the Thundershot’s open diff; isn’t the MR’s ball diff also open? I don’t have any experience with ball diffs, although from what I understand, I guess if you have the ability to adjust clamping force of the thrust washers against the balls, you could create a bias, but if I’m thinking about this right, that would create the opposite of the desired behavior — preventing slip at low torque and allowing it at high torque, rather than the other way around. The only diff tuning lever I’ve heard about in RC is the viscosity of the diff fluid, and AFAIK that’s applicable to both ball diffs and gear diffs.
  9. I might like that. Not yet ready to pull the trigger; I want to get the steering sorted and then enjoy it as-is for a bit before I decide whether I want to spend more time and money on that — so don’t go to the effort on my account just yet! If I did decide to do it: I care less about which conversion is easier and more about other characteristics. Is one or the other lighter? Offer more travel? More adjustability? Better geometry? Look better? More durable? Etc. I’ve been away from the hobby for a seriously long time, so I’m not familiar with the Thundershot or the Manta Ray — and I’m not even super clear about what’s different between a Hornet, Super Hornet, Grasshopper, GH2, or any of the other similar buggies. I’ve never used Shapeways before, nor done any sort of 3D printing. I did a tiny bit of CAD like 20 years ago, but nothing like SolidWorks. I’d love to learn to use it someday! I just checked and you can get a “maker” license for $99/year, which is pretty palatable for me.
  10. To be fair, about half of that budget was on the Futaba 3GR-2.4G transmitter, which is everything I hoped it would be. Also: with a functional radio set and ESC, I finally got a chance to try it out a little -- still no steering, but I pointed the tires straight and goosed the throttle, indoors on carpet. Holy cow! It wheelied so hard it flipped over. 🤣
  11. Oh, I forgot to ask: what software do you use to model your parts?
  12. Fabulous! I’m finding my own way through some upgrades to a Super Hornet; somebody pointed me to this thread. I am focusing on the front for now; started with a Project CRP front suspension conversion. I have to build my own steering setup because I modified things to make room for a giant 8000MaH 2S LiPo and now the steering servo doesn’t fit in the standard location. I have a plan and some parts on the way, but I’m just guessing what’s going to work! As of today, I have everything but the steering functional — including a 2.4GHz radio set with a dual stick Futaba controller (I despise pistol-grip controllers) and an ESC. Once I have the front sorted, I am interested in an IRS conversion like you’ve done. The parts lists are much appreciated! It seems like you have the front-end and rear-end stuff mixed together though, which will be fun to pick through when the time comes.
  13. Right now I have a fresh set of these: https://a.co/d/9axXH97 I’ll probably try something like these next: https://a.co/d/8T3S7pb (I have a set of 12mm hub adapters on hand.) They’re larger diameter and much better suited to a mixture of on- and off-road use. My front tires are the same style as the rears. I’d like to find something better for those too. Any suggestions?
  14. I don’t know if you noticed, but I’ve spent like $600 on this project. I’m way beyond sensible! At this point my objective is to make it ridiculous. My daughter will probably paint the body shell pink and purple with sparkly unicorns or something, which totally fits the plan. If I wreck it, oh well — most likely I’d still be able to use the motor and all the electronics on something else that can handle it better. If I find that you’re right about the BZ having too much power, I’d probably just find a larger-diameter tire to increase the effective gear ratio. Or maybe at that point I’d scrap the whole thing and buy an 8S X-Maxx! (Although then I think I’d be forced back to pistol-grip controller land, so perhaps not! 🤮)
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