Kagama Any good servo replacements for Kagama 4 (UK) - Cheaper but good?

[shortround9191]

Looks to have good speed metal housed esp the cap where it’s important. For the price don’t think it’s a bad give a shot servo

 

[Atomic Skull]

I've looked to see if anyone sells them retail, but sadly - they don't in the UK, it seems.


If you live in the US, Promodeler servos look like a decent option, provided you spec one that works off BEC.

Yeah they do not sell retail if they did the servos would cost over twice what they do. You're basically paying wholesale price.

Just add a bank of capacitors to pick up the slack during amp spikes. Or a supercapacitor backup guard would also work. People also say they have just run them off a BEC but the stall torque will be a bit lower than spec that way. The thing is this goes for ANY servo with that kind of torque output (40kg-cm or higher) not just these ones. With servos that strong the BEC voltage will sag when the servo comes under load especially during the initial split second current spike.

 

[Horatio]

How about this?

https://himodel.com/radios/Corona_BL2068HV_88g_60kg_Large_Torque_All_Metal_Servo.html

https://himodel.com/radios/Corona_BL1029HV_82g_50kg_Large_Torque_All_Metal_Servo.html

Can't say what the internal wiring is like like as Corona fills the space where the logic board and wiring is with potting compound so that the hot section is entombed in an immovable block of epoxy. EDIT: It's silicone potting not epoxy potting.

EDIT found the picture from this RCG thread: https://www.rcgroups.com/forums/showthread.php?3994193-Corona-BL1029HV-servo-50KG-Sneak-Peak

View attachment 9404

These look pretty good and are well protected!

And they're low cost, low risk to try them.

Back to Promodeler....

Reading through the Promodeler shipping blurb, I noticed they offered 'Orbital' - via Space X - for $50 million. So they obviously have a GSOH.

There are so many choices now, people are basically opting between the cheapest, disposable unheard of servos, or much more costly, higher performance branded servos.

Most modern servos, with hall effect pots and precision metal gears, brushless motors etc should have good speed, torque and be brilliant at centering.

Back in the day - I was hugely impressed by HiTec servos. For the money, there was nothing better and they were durable, backed with the best, quibble free warranty.

Now, I'm all about Protek 170 SBL/TBL servos and AGF 81's.

The latest edition is this 16kg, 0.05 sec/60° low profile servo - the A62BHS, installed into this Losi 22X-4 Elite.

These are available here in Blighty for £72 retail and AGF sell them for about $80, which is even better - roughly $10 cheaper. To clarify, I have no experience with this servo yet. It's a few grams heavier than offerings by KO, Tekin etc. But compared to the venerable Tekin T-120 - the AGF matches or exceeds it's specification - and is £50 cheaper!! Has to be worth a go, right?

 

[Atomic Skull]

These AFRC servos look good (both are the same just the color is different)

https://www.aliexpress.us/item/3256803938229325.html
https://www.aliexpress.us/item/3256804019114985.html

As I said earlier AFRC are actually made by AGFRC as you can see in this teardown I did of their 760us helicopter rudder servo:

https://www.rcgroups.com/forums/showthread.php?4689835-AFRC-D3623HBH-S-tail-servo-teardown

These are clearly made in the same factory as the AGFRC servos. If they are knockoffs then they are extremely good quality ones and someone spent a lot of unnecesary time and effort duplicating internal details nobody is likely to see. I tend to think that they would not waste time and money on that and Occam's razor is that they are just OEM AGFRC servos.

 

[Atomic Skull]

I have heard good things about GX / Yipin servos. Supposedly the same programmer and app that works on AGF servos will work on them or so I have heard on RCG (not confirmed). They DO NOT appear to be actual AGF servos like AFRC as you can see in the first video the internal PCB is different, though the soldering appears competent at least. At the end of the day they are cheap servos though and the AFRC seem to be the "king" of budget servos given they are actually made by AGF.

 

[Atomic Skull]

This one appears to be the same thing as the AK70 but in a different shell with a plastic top and helical gears. The AK70 used to be $40 but it got popular and they doubled the price so this could be a good alternative. They are also available on Amazon with overnight Prime shipping.

https://www.aliexpress.us/item/3256807801013037.html

I have read that they are realistically 58kg-cm which is still very good for the price. Speed is 0.09sec at 8.4v according to the specs.

 

[Atomic Skull]

Found a video of it:

Note how the wires exist the case, they filled the case with silicone potting compound and left out the strain relief and had the lead come straight out of the block of silicone through a hole in the side of the case. Now take a close look at that and compare with the Corona brushless servo:

Kagama Post in thread 'Any good servo replacements for Kagama 4 (UK) - Cheaper but good?'

May 25, 2025

How about this?

https://himodel.com/radios/Corona_BL2068HV_88g_60kg_Large_Torque_All_Metal_Servo.html

https://himodel.com/radios/Corona_BL1029HV_82g_50kg_Large_Torque_All_Metal_Servo.html

Can't say what the internal wiring is like like as Corona fills the space where the logic board and wiring is with potting compound so that the hot section is entombed in an immovable block of epoxy. EDIT: It's silicone potting not epoxy potting.

EDIT found the picture from this RCG thread: https://www.rcgroups.com/forums/showthread.php?3994193-Corona-BL1029HV-servo-50KG-Sneak-Peak...

• Atomic Skull

• 

Looks exactly the same including the two indentations above and below the lead. Either Corona are making these for GX / Yipin or GX / Yipin are making the brushless Corona servos.

Whatever the case these servos should be about as waterproof as a servo can get.

 

[Atomic Skull]

Ok so, I was completely wrong about the GX3270BLS servo, it's not potted, that plug for the servo wire is just that, a hard plastic plug. I can't imagine that it's cheaper than a rubber strain relief. That said it seems pretty good quality for a $40 servo. Nothing egregious like the $35 PTK servos that had horrifyingly poor internal soldering with melted insulation and wires soldered to the tops of through holes when they didn't have enough land area to be reliably soldered that way.

The soldering on the internal leads appears pretty good and the PCB uses through holes for the wire to board soldering joints, but no electronics silicone goop applied to them to protect against vibration (I have corrected that). The bottom of the gearbox is a plastic bit that sits on top of the center so getting at the wires is relatively simple just pop that piece out.

The gears are indeed all helical, and it has 5 ball bearings, two for the main output gear, two for the midgear and one under the "wedding cake" gear. I'm not convinced that the extra micro ball bearings are better than solid brass bushings and pins in this application though.
Haven't actually tested it yet, I'll run it on a tester for an hour later and give it a good burn in before putting it into service.

EDIT: running it on a tester now, comparing to another 0.9 sec servo the claimed speed seems accurate. It is also very quiet and the gear train is smooth. I cleaned out all the stock grease are replaced it with Super Lube though the grease that came with it seemed fine, if a little thin. I prefer Super Lube because you can leave it sitting for years and it won't evaporate or harden.

This thing is strong I am completely unable to move the servo arm off it's position in the slightest by hand.

 

[Atomic Skull]

Ok so this servo will not fit in a Corally servo mount without modding it, the servo is 21mm wide and 40.6mm long and it is impossible to get it in without destroying the wire. So I cut the front of the servo mount so that the servo can be installed from the side rather than from the top.

The servo is also a bit too tall and had to be moved up so I used the grommets and an extra washer under them. I could not use the eyelets because they were 2.5mm ID and the grommets are a very hard and stiff rubber that will not fit a 3mm eyelet.

 

[Atomic Skull]

Yipin servo is working great in my Asuga so far but I can't really recommend it due to the modifications to the servo mount needed to get it to fit and definitely not for a 1/10 scale it's way overkill for that. More trouble than it's worth for most, I did it because it was a fun project. Also I added a 14000uf cap pack to the receiver, not sure if that was necessary but it seemed like a good idea. I just rolled my own from some Nichocon 4700us 16V caps I had laying around and a section of Hansen Hobbies 0.1" PCB strip. One lead goes to the receiver and the other to the fan (because the fan used to go to the extra port on the receiver)

 

[Atomic Skull]

Further update, the servo survived having the servo arm BENT and the plastic link ripped out of the turnbuckle