NELSON CNC Adjustable Spline™ Servo Wheels

Made in the USA

We are pleased to announce a new addition to our line of radio control linkage products. The NELSON Adjustable Spline™ aluminum servo wheel. This unit is designed to be used with our large selection of single and double aluminum servo arms and can be used by itself with the use of ball link fittings. The wheel is the same size as a standard JR plastic wheel. Our servo wheels are available for JR, Airtronics, Hitec, and Futaba servos.

NELSON Adjustable Spline servo wheel provides a perfect fit to metal spline servos. Designed to be used with our large selection of single and double servo arms.

Adjustable Spline JR servo wheel installed on our DSA250 2 1/2" double servo arm. Note slit cut into flange and clamping screw which provides clamping action.

Plastic servo arms and wheels are still commonly used for all types of models including 40% aerobatic aircraft, jets, and large scale models. However, there is a valid argument or need for the use of metal servo arms and wheels with the newer 35% and larger aerobatic aircraft.

Engines for the 35% to 45% aerobatic aircraft are getting lighter and more powerful. The aircraft designs are constantly being improved.  New maneuvers are being performed that where unheard of only a couple of years ago. Servos are bigger and more powerful. All of these considerations put a greater load on the control system and linkages. Our new servo wheel design provides for new additional mechanical security for these aircraft.

JR Digital servo with our DSA300 3" double arm attached. No modification necessary to servo for installation.

We recommend the use of the standard nylon servo arms and wheels with 33% and smaller aerobatic aircraft and jets with under 20 pounds of thrust. Aircraft that are larger we suggest the use of our Adjustable Spline servo wheels.

Most of the after-market metal servo arms and wheels don’t always fit the servo spline properly. Some fit OK, but many times the metal arms and wheels are too tight or too loose a fit. Once you get a tight fitting metal arm or wheel installed, you may not remove it again without damaging the servo. The loose fitting units can be secured better with the use of a locking compound such as Loctite™, but then it may be difficult to remove the arm or wheel from the servo due to the Loctite™.

The wide range of fitness of the after-market metal arms and wheels are not necessarily caused by errors by the manufacture during machining, but due to the manufacturing tolerance of the metal spline produced by the servo manufacture. Properly CNC machined, the tolerance of the machining the arm or wheel spline can be made to very exact dimensions. In the past the fit was not a problem because the intended design of the servo is to attach a plastic arm or wheel to the servo’s spline.

Bottom view of SSA125 servo arm fastened to an Adjustable Spline servo wheel attached to a JR servo.  Note clamping screw.

The splines of plastic arms and wheels are made slightly undersize. They can easily be forced onto the servo’s spline resulting in a perfect fit. Metal arms and wheels cannot be forced on if the servo’s spline is slightly oversize.

What we have designed is a CNC machined 6061T-6 aluminum servo wheel that has a unique spline that is actually clamped to the servo’s spline. There is a slit in the servo wheel and a machined flange on the bottom of the wheel. A 2-56 socket head cap screw and miniature elastic stop nut are used to squeeze the unit onto the servo’s spline. Only a small amount of movement of the clamping action firmly attaches the wheel to the servo’s spline. This assures a perfect fit regardless of any oversize or undersize dimensions of the servo spline.

Adjustable Spline servo wheel used as a stand alone servo wheel shown with a RCL77 Ball link.

This clamping action eliminates any possible play or movement of the servo wheel when attached to the servo’s spline. The attachment of the wheel to the spline is so strong that it is difficult to remove our servo wheel from the servo. We still have the normal attachment of the wheel to the spline with a screw going through the wheel into the center of the spline’s shaft. Now we have a double locking system to hold the wheel to the servo’s spline thus increasing the safety of the wheel/servo attachment system.

Another problem solved with our Adjustable Spline servo wheel is the elimination of the metal arm or wheel wearing or getting looser over time. Vibration can cause other arms and wheels to wear when they are not properly attached to the servo’s spline.

Our Adjustable Spline servo wheel is available for the JR, Futaba, and standard Hitec servos with standard spline's. The JR unit can also be used on Airtronics and the Hitec digital servos. We recommend using our servo wheels with any servo with metal servo splines.

_________________________________________________________

Use of our Adjustable Spline Servo Wheels on JR8611 servos. Posted 11/14/04

Have recently received two reports that our JR Adjustable Spline Servo Wheels do not fit JR8611 servos. Seems that JR8611 servos can have now have two different size metal splines. Our JR servo wheels fit the JR8611 servos when they were first released. Problem seems to be with the more recently manufactured JR8611 servos. The Hangar 9 metal servo wheels and arms also don't fit the later JR8611 servo splines. Technical support was called at Horizons and the technician said the metal servo splines are all the same and there is no such problem!!!!!!

At the moment, there appears that there is no way for the customer to know, without testing, what size 8611 servo spline he has. There is no separate part number for the old type or new style JR8611 servos. Suggest that the customer take a metal servo arm or wheel that is or was used on a JR8411 servo. See if that arm or wheel fits the JR8611 servo. If it fits, great. use our Adjustable Spline Servo Wheels. If it doesn't fit, then at the moment, we cannot offer an Adjustable Spline Servo Wheel for the later series JR8611 servos.

_________________________________________________________________

Over 50 different types, styles, and sizes of heavy duty 1/16” thick 2024T-3 aluminum single and double servo arms are available that can be directly attached to our Adjustable Spline™ servo wheel. Other manufactures only have a limited selection of metal servo arms. We can also easily create custom sizes at no extra charge to the customer. The new servo arms are added to our catalog when customers order new sizes. A separate servo arm catalog showing full size dimensions of our range of single and double servo arms, and our bellcrank selection is available for $2.00.

ADJUSTABLE SPLINE™
SERVO WHEEL DIMENSIONS
Diameter: .993 in.

Thickness of wheel: .080 in.
Thickness of hub: .246 in.
Linkage attach hole dia: .083” (for 2-56 screw)
Outer attach hole spacing: .830 in.
Inner attach hole spacing: .711 in.
Weight w/cap screw & nut: 1.4 oz.

Adjustable Spline Servo Wheels
ITEM NO.	DESCRIPTION	QTY. PKG.	PRICE	ORD. QTY.	ADD TO CART
SW100JR	JR/AIRTRONICS/HITEC	1	$7.95
SW200FT	FUTABA	1	$7.95
SW300HT	HITEC ANALOG TYPE	1	$7.95

Revised 3/24/04

NELSON Adjustable Spline Servo Wheels are available from

NELSON Hobby Direct or from hobby dealers.