Cheap Chinese Servos

HOW DO THEY STACK UP?

For a long time there was a very limited choice of servo brands.

Futaba, JR and Hitec were the main servo manufacturers and although their offerings have always been of excellent quality, the prices have also been quite high.

And then the Chinese started making servos that they now sell under a wide number of different brands.

But are they any good?

When a single faulty servo can cause a very expensive crash, is it really worth trying to save a few dollars by purchasing a cheap servo from an unknown manufacturer?

Testing servos

Over coming months I'll be testing an increasing number of different Chinese-made servos of all types and brands.

Right now I'm building a test-rig that will automatically plot speeds, accuracy, centering, overshoot, torque, current-draw and other important aspects of a servo's performance.

But in the meantime, I've rounded up a few good and bad examples.

The Good

I've had very good success with the following servos:

• Hextronic HXT900 (cheap, powerful light)
• Scanner RC servos (powerful light, reliable)
• Vigor VS2 (very cheap and good value)

I'll be posting more in-depth reviews of these little gems shortly.

The Bad

Perhaps the worst servos I've ever had the misfortune to waste my money on are the TowerPro MG995 hi-torque metal-geared servos you often see advertised on eBay and various online model shops.

These are an extremely heavy servo with poor accuracy, massive amounts of over-shoot, highly variable centering and low levels of reliability. While I might be prepared to risk one on an old model truck or buggy, I most certainly would not dare to use one on a model airplane.

And despite what some of the ads claim, these are not coreless servos. In fact one of the reasons they perform so poorly is that they use a heavy 3-pole motor that has lots of inertia.

An updated version of this servo (marketed as the Toward Pro MG996R) is quite a bit better in its accuracy and centering but, because it uses the same cheap parts, still can't be considered a servo worth trusting an expensive model to.

The Rest

Right now I have a desk littered with servos of all sizes, shapes and brands so the testing task ahead of me is somewhat onerous -- but stay tuned because I'll gradually work my way through all the options and provide a detailed report on my findings.

Summary

Yes, the Chinese are getting their act together when it comes to making servos that can rival the big names but be very careful, there are some awfully bad designs out there and others that are quite badly assembled.

Those on the "What's Good" list can be purchased with some degree of certainty that they'll provide good service but if you're thinking of buying an unknown brand, be very careful.