Robotronic Scalpel - Mini Carpet Cutter

DRIVEN REVIEW WORDS Dean Berry PHOTOS Walter Sidas PAINT Chewy Graphics

		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.

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Links

Hitec RCD Inc.,
www.hitecrcd.com,
(858) 748-6948

Novak Electronics Inc., www.teamnovak.com,
(949) 833-8873

Paragon Racing,
(952) 442-6364

Robitronic,
distributed by Axial, www.axialracing.com,
(949) 600-8642

Spektrum, distributed by Horizon Hobby, www.spektrumrc.com,
(217) 352-1913

Team Scream,
www.teamscreamcellmatching.com,
(978) 337-0429