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Sep 05, 2017, 11:42 PM
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Lynxman's Avatar
Build Log

MKUltra - A 3D Printable 4WD 1:10 scale buggy


I present "MKUltra", my second 4WD buggy design.

The initial design is finished, and I have started printing parts for my new car. I am trying to develop a modern 4WD buggy that can compete with other modern buggies. I have no delusions about being able to design better cars than the likes of Associated, Xray or Schumacher, but I hope it will be a lot more capable than my old design, the Lynx.

It features fully ball raced steering linkages and front spindles, ball bearing diffs, belt drive front and rear, and room for standard "shorty" lipo packs, with easy access to the battery. There should be plenty of room for the electronics, with particular thought made to the location of the ESC, motor and battery cluster. It has been designed specifically for printability and strength using PLA. CV axles from BSR BZ-44, FTX Vantage or Quanum Vandal can be used, though I haven't tested all variations yet.
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Sep 06, 2017, 08:49 PM
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Lynxman's Avatar
The prototype is taking shape. I tried printing a belt from elastomer, and it actually looks like it can work with mild motors. I will have to try running one in a car. I don't have the balls and discs I need for making the ball bearing diffs so I might make fixed spools instead initially until I get the parts I need.

Looking forward to designing the body.
Sep 07, 2017, 02:43 PM
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The belt layout fits perfectly. Both battery and motor can be removed easily. I had to make a slight cutout to the left motor mount to get the motor in and out without loosening anything. I also had to change to a different front belt idler to make room for the steering link, but it's perfect now. The steering action is super smooth, sturdy and slop free.
Sep 07, 2017, 03:09 PM
head designer at TEAM-D DESIGN
dogoman's Avatar
Wow I really like the new design! It's sleek!
Sep 08, 2017, 10:53 AM
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Access to the diffs i s easy. Both front and rear top frames swing up after removing some screws. Visible right behind the battery in this photo is the screws for the rear belt tensioner It's a screw that pushes the idler up to increase tension. Work well.

The photo shows fixed camber and tie rods. I don't have suitable turnbuckes yet so I just printed these to assemble the car.

I need softer springs. The stock springs on these china-shocks are too hard. I will probably try the big bore shocks from my BSR BZ-222 buggy.
Sep 08, 2017, 05:59 PM
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I made some adapters to use big bore springs on the shocks. Works great. The spur and pinion are printed too. 48dp is barely printable with a 0,4mm nozzle.

The car weighs 1340 g without a body, so it's underweight for 4WD 1:10 class buggies. Some brass ballast low in the chassis would take care of that.

The car is designed to use aftermarket wheels and stay within the regulation dimensions. I will print some wheels too, just for the sake of having printed as much as possible. The wheels in the photos are the stock wheels that come with the BSR BZ-222 buggy.
Last edited by Lynxman; Sep 08, 2017 at 06:48 PM.
Sep 09, 2017, 01:15 AM
head designer at TEAM-D DESIGN
dogoman's Avatar
I'm simply amazed at how great your designs are! They keep getting better and better! If only I could get my printer to work right
Sep 09, 2017, 01:24 AM
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Lynxman's Avatar
What's the problem with it?

I made gear diffs now to use while waiting for the balls and steel washers to get here for the ball diffs. They seem to work fine and hol up to punches on my living romo carpet. I don't want to drive it in my yard until I have a body to protect the insides. I'll shoot a video of it on asphalt later today.
Sep 09, 2017, 03:06 AM
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Next up is widening the rear track. It's only about 235 mm now and I want it to be 245 mm. The wheels in the video below have weird offset which makes it look even worse than it is.

Here's a video of the prototype without a body. It's incredibly quiet. That's one of the reasons why I love belt drives. The chassis, steering components and suspension feel very strong and stiff to the touch and I think it will be durable. The car is able to turn very tightly, which is one of the requirements I had since I have a tight track. It is incredibly agile, as is evident in the short video. It has 3D printed 48dp spur and pinion and a 13.5t sensored brushless motor.
MKUltra - A new printable 1:10 4WD buggy (2 min 3 sec)
Last edited by Lynxman; Sep 09, 2017 at 04:15 AM.
Sep 09, 2017, 06:09 AM
Fan of just about anything RC
SoloProFan's Avatar
I'm a big fan of belt drive. And your design seems to run well. I do think it will be more silent with a metal pinion and non-printed spur. When comparing to the sound of my Lazer ZX-5 (not even belt drive) or Optima Mid, both are even more silent.
Sep 09, 2017, 06:28 AM
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My Cat XLS is also quiet.

I bought some 1/8 scale shocks my mistake. Maybe I have to try a bigger buggy later on.
Sep 09, 2017, 07:40 AM
Fan of just about anything RC
SoloProFan's Avatar
Quote:
Originally Posted by Lynxman
My Cat XLS is also quiet.

I bought some 1/8 scale shocks my mistake. Maybe I have to try a bigger buggy later on.

I believe you did that on purpose, your subconscience already wanted to design a 1/8, and made you make this "mistake"


Btw, you don't happen to have a Lazer ZX-5 near you, so you can design and print a gear cover, to finally be rid of small rocks getting in the pinion/spur? https://www.rcgroups.com/forums/show...sho-Lazer-ZX-5
Sep 09, 2017, 08:03 AM
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I don't think so. I know someone who has a vintage ZX-R.
Sep 09, 2017, 08:50 AM
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Quote:
Originally Posted by Lynxman
I don't think so. I know someone who has a vintage ZX-R.

ZX-R is different, belt drive. The ZX-5 is a later design, fully gear drive, but almost as silent as belt. At least, when no grains of sand etc are trapped in the spur...
Sep 09, 2017, 10:18 AM
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Lynxman's Avatar
Yeah I know. I am most familiar with old cars.

Another thing I like about belt drive is the lack of a rolling torque reaction since the motor is transversally mounted.


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