Cheap servos versus expensive ones

[Tmcfarland]

I have been using emax servos in my gliders. They seem to work fine. Just wondering if I jumped up to the 50$-60$ price range would I notice much of a difference in performance and reliability. Thanks for any info.

 

[Doc J]

I have been using emax servos in my gliders. They seem to work fine. Just wondering if I jumped up to the 50$-60$ price range would I notice much of a difference in performance and reliability. Thanks for any info.

Hi Tim, as you have noticed, many new servos have recently become available in every price range, and I have tested many of them, which is why I feel qualified to answer this.

Let us take a look:

Makers like MKS hold the high ground (sorry), while other companies like KST are close behind in spec and reliability but mostly much lower in price. Other companies like GWS and Kingmax are popular for high-end GPS models but don't sell well in the USA.

When this glut of new servos came to the market, many people in the USA tested them, and it's probably true that they didn't perform well, mainly in internal tolerance and reliability. Bad test results, "Rubbish", "Unreliable" etc., became keywords. Even to this day, people remember this. But I think if many of them switched their brains on again, forgot any bias from original tests and realized that if those same servo manufacturers didn't improve, then they'd be out of business. It might be a good idea to re-test some of the new versions from companies that failed previously.

I have asked several testers to re-test, but no—they all hark back to the original dismal results from years ago, completely or intentionally forgetting that progress may have been made in the intervening time and wailing that they don't want to waste their valuable dollar-encrusted time.

Perhaps the problem is that there are just too many servo manufacturers around these days and not enough information to make a solid choice for something that suits you unless you just think screw it and get your chequebook out.

I'm sure if you bought Servo A (like MKS) as a high-priced component, you'd get great results in performance, reliability, and lifetime, and if you bought Servo B (like KST), you'd get damn good results, too. It would be practically impossible to tell the difference except by asking your bank manager.

One company to look out for and whose products I have tested extensively and found to be very high quality is GDW. I don't know if these are sold in the USA yet, but they have exceptional performance - easily up there with the 'big boys'. So you might wonder why you haven't seen them so much. Well, they are an OEM manufacturer for some of those same 'big boys' who have done business this way for years and have not needed to market their own products. In fact, it's only in recent years that they have sought to sell as their own brand.

Another good one is Kingmax, whose products were almost laughed out of the market by the wise testers. Trust me, those GPS guys with those five—or ten-thousand-dollar models will not use rubbish.

There are also new kids on the block, like Chasen, who seem to be well-regarded. But knowing the business as I do, I might be tempted to think that they have a large sponsorship budget rather than any clear and present advantages.

For a total solution, especially for IDS installs, Tomas Liu Studios is probably the Rolls Royce and yet not diabolically expensive. I have known Tomas Liu for over 30 years, and I know that he does. He is a maestro. I can only describe his products as "Spun by the light of a diamond", which is what my teacher told me I'd have to achieve in finishes in the Aerospace industry.

If somebody asked me directly what I thought was the best for an individual servo I'd say:

MKS - KST - GDW - Kingmax is in order of cost AND performance/reliability.

For a total servo/frame/arm/horn solution and incredibly well-made parts? Tomas Liu, without a doubt.

Cheers,

Doc.

 

[Tmcfarland]

Hi Tim, as you have noticed, many new servos have recently become available in every price range, and I have tested many of them, which is why I feel qualified to answer this.

Let us take a look:

Makers like MKS hold the high ground (sorry), while other companies like KST are close behind in spec and reliability but mostly much lower in price. Other companies like GWS and Kingmax are popular for high-end GPS models but don't sell well in the USA.

When this glut of new servos came to the market, many people in the USA tested them, and it's probably true that they didn't perform well, mainly in internal tolerance and reliability. Bad test results, "Rubbish", "Unreliable" etc., became keywords. Even to this day, people remember this. But I think if many of them switched their brains on again, forgot any bias from original tests and realized that if those same servo manufacturers didn't improve, then they'd be out of business. It might be a good idea to re-test some of the new versions from companies that failed previously.

I have asked several testers to re-test, but no—they all hark back to the original dismal results from years ago, completely or intentionally forgetting that progress may have been made in the intervening time and wailing that they don't want to waste their valuable dollar-encrusted time.

Perhaps the problem is that there are just too many servo manufacturers around these days and not enough information to make a solid choice for something that suits you unless you just think screw it and get your chequebook out.

I'm sure if you bought Servo A (like MKS) as a high-priced component, you'd get great results in performance, reliability, and lifetime, and if you bought Servo B (like KST), you'd get damn good results, too. It would be practically impossible to tell the difference except by asking your bank manager.

One company to look out for and whose products I have tested extensively and found to be very high quality is GDW. I don't know if these are sold in the USA yet, but they have exceptional performance - easily up there with the 'big boys'. So you might wonder why you haven't seen them so much. Well, they are an OEM manufacturer for some of those same 'big boys' who have done business this way for years and have not needed to market their own products. In fact, it's only in recent years that they have sought to sell as their own brand.

Another good one is Kingmax, whose products were almost laughed out of the market by the wise testers. Trust me, those GPS guys with those five—or ten-thousand-dollar models will not use rubbish.

There are also new kids on the block, like Chasen, who seem to be well-regarded. But knowing the business as I do, I might be tempted to think that they have a large sponsorship budget rather than any clear and present advantages.

For a total solution, especially for IDS installs, Tomas Liu Studios is probably the Rolls Royce and yet not diabolically expensive. I have known Tomas Liu for over 30 years, and I know that he does. He is a maestro. I can only describe his products as "Spun by the light of a diamond", which is what my teacher told me I'd have to achieve in finishes in the Aerospace industry.

If somebody asked me directly what I thought was the best for an individual servo I'd say:

MKS - KST - GDW - Kingmax is in order of cost AND performance/reliability.

For a total servo/frame/arm/horn solution and incredibly well-made parts? Tomas Liu, without a doubt.

Cheers,

Doc.

Thank you for all the info.

 

[Wayne]

Tim,

Let's add to the equation a bit. At least this is what I do. I do not have bottomless pockets, if we all did, this conversation would not exist.

If I have an airframe that I think might get something from the higher quality servos, then I will use a top quality servo in it.

My next step down is going to be a high quality budget minded servo. Emax, PowerHD, Orbit, etc.

About the only time I will use a 9 gram cheap-o servo is in a 3D printed model, or similar foamy. A more accurate servo just is not going to help one of these airframes.

For me the top brand are: MKS, KST (CHA is KST), Frsky (Yes Frsky makes some pretty dang awesome servos.)
Mid Grade servos are most anything else we sell that is over $8.
Low Grade are the servos we offer less that $8.

I love Emax servos. Don't think one has ever let me down!

 

[Tmcfarland]

Tim,

Let's add to the equation a bit. At least this is what I do. I do not have bottomless pockets, if we all did, this conversation would not exist.

If I have an airframe that I think might get something from the higher quality servos, then I will use a top quality servo in it.

My next step down is going to be a high quality budget minded servo. Emax, PowerHD, Orbit, etc.

About the only time I will use a 9 gram cheap-o servo is in a 3D printed model, or similar foamy. A more accurate servo just is not going to help one of these airframes.

For me the top brand are: MKS, KST (CHA is KST), Frsky (Yes Frsky makes some pretty dang awesome servos.)
Mid Grade servos are most anything else we sell that is over $8.
Low Grade are the servos we offer less that $8.

I love Emax servos. Don't think one has ever let me down!

Thank you. So far my emax servos have been fine. When I move to a Carbon F5J $$$. The I think I would go the extra mile.

 

[JustinMader]

+1 for Kingmax. I've had multiple Emax servos die, both in the air and on the bench, so I don't mess with those anymore. I also beat the hell out of my planes, so my note is more about durability.

When I was looking to ditch Emax, I discovered Kingmax and AGFrc, both of which are in all my currently flying foamies. Both have been great. Kingmax are a little less expensive, but AGFrc can be found on AMZN, which is great for people like me with a lack of patience.

Once I started messing with composite aircraft, I've stuck to KST. Only had one questionable one thus far (was considerably more noisy than any other), but I do like the programming card for setting endpoints pre-radio/FC.

 

[Doc J]

+1 for Kingmax. I've had multiple Emax servos die, both in the air and on the bench, so I don't mess with those anymore. I also beat the hell out of my planes, so my note is more about durability.

When I was looking to ditch Emax, I discovered Kingmax and AGFrc, both of which are in all my currently flying foamies. Both have been great. Kingmax are a little less expensive, but AGFrc can be found on AMZN, which is great for people like me with a lack of patience.

Once I started messing with composite aircraft, I've stuck to KST. Only had one questionable one thus far (was considerably more noisy than any other), but I do like the programming card for setting endpoints pre-radio/FC.

Hi Justin,

I have also tested AGFrc. I liked their programming card, but I had 1 out of 4 (wing) servos fail on a 24-hour continuous load test. They apparently fixed the problem (Badly worn output gears) by upgrading the gear material, but I have not tested any since because I have been busy with other stuff. Re AGFrc: I suspect the problem has gone away as the Chinese bunch are very quick to initiate design changes. Also, I should mention that my standard testing on the test samples is pretty severe.

Wayne has mentioned FrSky, but I have not tested any of them yet, and I have not tried to find out who actually manufactures them.

You are pretty safe with KST Chaservo - they were among the first servos I tested and - shone. In fact, on all my tests, I could find no practical or important difference between KST and MKS with their published specs - bar the price.

Kingmax and GDW passed all my tests with flying colours, including the dreaded 24-hour (5 kg or more loading, depending on the servo spec) load tests and the 10-minute overloading tests. There was no accumulated slop or apparent wear and no loss of accuracy. Electrical tests were also very stable over the 24-hour test period.

No wonder the GPS guys like Kingmax. Now, at least one well-known flyer that normally flies Kingmax is trying GDW.

Cheers,

Doc.

 

[Red]

Hi Justin,

I have also tested AGFrc. I liked their programming card, but I had 1 out of 4 (wing) servos fail on a 24-hour continuous load test. They apparently fixed the problem (Badly worn output gears) by upgrading the gear material, but I have not tested any since because I have been busy with other stuff. Re AGFrc: I suspect the problem has gone away as the Chinese bunch are very quick to initiate design changes. Also, I should mention that my standard testing on the test samples is pretty severe.

Wayne has mentioned FrSky, but I have not tested any of them yet, and I have not tried to find out who actually manufactures them.

You are pretty safe with KST Chaservo - they were among the first servos I tested and - shone. In fact, on all my tests, I could find no practical or important difference between KST and MKS with their published specs - bar the price.

Kingmax and GDW passed all my tests with flying colours, including the dreaded 24-hour (5 kg or more loading, depending on the servo spec) load tests and the 10-minute overloading tests. There was no accumulated slop or apparent wear and no loss of accuracy. Electrical tests were also very stable over the 24-hour test period.

No wonder the GPS guys like Kingmax. Now, at least one well-known flyer that normally flies Kingmax is trying GDW.

Cheers,

Doc.

I'm flying FrSky servos in the Tocatta, and GDW in the Alpenbrise. Both working great so far.