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DRIVEN REVIEW WORDS Dean Berry PHOTOS Walter Sidas PAINT Chewy Graphics
Robotronic Scalpel - Mini Carpet Cutter
As the 1/18-scale market is saturated with off-road vehicles, Robitronic decided to look at a road less traveled when they jumped into the micro racing scene.
The Scalpel,
a
1/18-scale pan
car—
with many of
the
same
features
found on
popular 1/12
racers like the
Associated
RC12L4—is sure to
make an instant
impact as it helps
a new
class
of racing
develop. When the
package
arrived
from
Axial Racing, the
importers of
the Scalpel, I
was like a kid on
Christmas
morning. A few hours
later the Scalpel
was
built
and
going from hand to
hand at my local
hobby shop, never touching the counter as everyone in
the shop wanted a look.
l
KIT
RTR
MICRO ELECTRIC ROAD RACER
AT A GLANCE
WHO MAKES IT: Robitronic
WHO IT’S FOR: Intermediate to advanced racer
HOW MUCH: $175
WHAT WE LIKED:
High quality parts and easy to build
Extremely adjustable
Same features as a competition 1/12-scale race car
Fun to drive
WHAT COULD BE IMPROVED:
Include metal pinion gears with a setscrew, not plastic push-on gears
T-Plate should be more durable
Less play in the steering arms
Include a servo saver (for the rookie racer)
THE BOTTOM LINE:
A very cool new class of racer with a
surprising level of
performance and
features
DETAILS, DETAILS DETAILS
The Scalpel’s graphite chassis accommodates four 2/3A cells. Nifty molded hold-down straps secure the cells. The rear suspension’s friction damper and oil-filled shock can also be seen.
A Hitec HS-81MG metal-geared micro servo steers our Scalpel via a pair of adjustable tie-rods.
A beautifully machined aluminum rear pod
mimics the design of 1/12-scale pan cars. A
370-sized motor comes in the kit.
Graphite front suspension arms feature adjustable damping springs. A molded thumbscrew is used to set the spring’s tension—no tools required.
An adjustable ball diff is incorporated into the Scalpel’s solid rear axle. Cone washers apply
pressure to the diff’s thrust bearing to set the diff’s tension.
Pre-mounted and trued foam tires come with the kit. Firmer rubber is used up front to make the car easier to drive, while soft rubber in back keeps the rear axle under your control.
The Scalpel's suspension is very sophisticated and adjustable. Individual upper and lower damper springs control the rear pod’s movement, and a single shock handles the pod’s forward and
backward motion.
"When the package arrived from Axial Racing, the importers of the Scalpel, I was like a kid on Christmas morning."
— Dean Berry
NEEDED TO COMPLETE
Novak Micro GT speed control
Spektrum micro receiver
Team Scream matched IB1400
battery pack Hitec HS-81MG steering
servo
Paragon Ground Effects tire
traction compound
WHAT YOU NEED TO KNOW
The Scalpel kit comes nicely packaged in nine separate bags labeled A through I. A clear Lexan body—to be custom
painted—is also included. The 20-page instruction manual is very easy to follow, as it guides you through each bag with clear illustrations.
The Scalpel comes with a 1.5mm graphite chassis. An upper stay is mounted above the T-plate in the center of the chassis to help eliminate some of the chassis flex. The rear of the chassis has four cutouts for the 2/3A battery, and the front of the
chassis is cut out where the steering servo mounts. Each of the 25 screw holes on the bottom of the chassis is countersunk for a smooth finish.
The rear of the Scalpel uses a T-plate-type suspension that attaches to a four-piece rear pod system. Upper and lower
friction plates supply damping. A center shock is used to
prevent sagging between the main chassis and rear pod.
The front suspension utilizes graphite A-arms with droop screws. The arms are mounted to the chassis by two ball ends with upper and lower O-rings. A spring on each arm—adjusted by a thumbscrew—allows you to set the stiffness of the front end to your track and driving style.
The Scalpel utilizes a direct-drive ball differential system. The differential rings are notched so they won’t slip during
acceleration. The thrust assembly and adjustment nut are
completely hidden behind the right rear wheel. While this makes it difficult to adjust, it helps keep the thrust bearing free of dirt and debris.
The included, clear Lexan GTP-style body fits super low on the Scalpel chassis, and it is designed to increase downforce and traction.
Robitronic refers to the rear foam tires as a red dot, or soft compound, and the front foam tires are considered a blue dot, or hard compound.
DIMENSIONS
SCALE: 1/18
LENGTH: 7.3 in. (185mm)
WIDTH: 4.5 in. (115mm)
WHEELBASE: 5 in. (129mm)
WEIGHT: About 11 oz. (312g)
TUNING OPTIONS
SUSPENSION
T-plate tweak via thumbscrews
Shock spring (rear)
Friction of rear damper plates
Front arm droop
Front spring and spring pre-load
DRIVETRAIN
Ball diff tension
TIPS
Prep the chassis by filing all the edges to help
prevent the graphite from splitting, and then put a coat of CA glue on all the edges to seal them.
The Scalpel does not come with a steering servo, so I used a Hitec HS-81MG. The servo mounted very easily, and I used the RA2014/5 servo horn to attach the threaded tie-rods to the steering knuckles.
While building the Scalpel I noticed an unusual amount of play between the steering arm and axle. After checking the Robitronic website (robitronic- usa.com), I found a six- page “Scalpel Tips ’n Tricks” sheet that not only addressed this, but gave some great building and setup advice. The sheet suggests you
thoroughly clean the steering arm and axle and reassemble them using red thread-lock.
The “Tips ’n Tricks” sheet suggests you use some diff grease under both friction plates to ensure smooth and consistent movement of the rear pod.
RECOMMENDED ACCESSORIES
Metal pinion gear with setscrew
Aluminum steering arms
XRAY M18 foam front bumper
COMPETITORS
BRP SC18 V2
PERFORMANCE SCORECARD
TEST VENUE: R/C Madness, Enfield, CT
SURFACE: Indoor Ozite carpet roadcourse
STEERING
Understeer Neutral Oversteer
COMMENTS: I found that fully coating the rear tires and just the inside of the front tires with Paragon Ground Effects tire traction compound worked well; this gave the Scalpel just enough steering, and kept it from feeling twitchy. “Responsive” is quite an understatement when it comes to the Scalpel. It took some getting used to for the first few laps, as once I got the feel for the car, and had the tweak properly adjusted, the Scalpel was running very smoothly and I was throwing down some quick and consistent laps.
BRAKING
Poor Fair Good Excellent
COMMENTS: Rear-wheel-drive cars are traditionally poor at braking, but thanks to the wide, blue-dot rear foam tires, I could really dip into the Novak Micro GT ESC’s brakes without causing the rear end to slide.
ACCELERATION
Poor Fair Good Excellent
COMMENTS: As it runs off only four cells, I did not expect the Scalpel to be all that quick with the stock motor, but I was pleasantly surprised after a few laps. Because the Scalpel is so light—it weighs less than a pound—it is very quick off the line and gets up to full speed in no time. Coming out of the corners, it snapped up to speed smoothly and quickly.
SUSPENSION
Poor Fair Good Excellent
COMMENTS: The front suspension works well, and is easily adjusted with droop screws or thumbscrews to increase tension on the front springs. The rear T-plate is a bit fragile, and the spring loaded center shock would operate more smoothly if it was damped somehow, like a micro VCS shock.
DURABILITY
Poor Fair Good Excellent
COMMENTS: You can’t go this fast and expect nothing to fail, but for the most part the Photon took all the punishment I threw at it and asked for more. I was very surprised that only a plastic right front C-hub broke after hitting a cement sidewalk at full speed. Replacing many of the plastic components with some of the aftermarket aluminum goodies that IRC has to offer would make the Photon almost indestructible.
THE LAST WORD
Robitronic has found a winner with the Scalpel. It is a blast to drive, easy to build and setup, and a simple design makes it a breeze to maintain.
Being one of the first 1/18-scale pan cars on the market, the Scalpel is sure to draw some serious attention from micro fans as well as 1/12-scale and sedan racers alike.
With the addition of a load of hop-ups from Robitronic (like red anodized damper disks, steering arms, brushless-motor pod-plate, front bumper, and a six-cell graphite chassis), the popularity of the Scalpel is sure to grow.