Am i missing something ???

I just found this on AliExpress:
￡360.82 | DIY 6DOF-Rotary-Stewart-Motion-Simulator 220V 750W AC Servomotor White Driver and Helical Planetary Reduction Motor 50:1
https://a.aliexpress.com/_EyWUqxs

Does it seem a bit cheap to you guys

It’s misleading. Common trick for some sellers on Ali. I think this is for 3 motors and gearboxes shipping is another $450 USD. if you actually select 6DOF the total is much more than what you see.

It seems to be only the motors and gearboxes. A 750w motor (no gearbox) is $100-$150 shipped. It may be a fair price for what you get but the listing is designed to be misleading.

Ali is mostly a bunch of merchants that do what they want. Some are fair and clear others are not. So read everything especially what’s in the box. If it doesn’t tell you what’s in the box you might not get what you expect.

If you select 3DOF and "with gearbox" the price including shipping is >$2000. So It's not really cheap.

I've tested several of the chinese servos and would recommend theese: https://de.aliexpress.com/item/1005008720824516.html (select 750W incremental 17 Bit) They are around $155 per unit including shipping.

Gearboxes are also ~$150. I'd recommend helical gear with low backlash (<5arcmin) from Stepperonline, for example. So for §2000 you get 6 servos, 6 drivers, 6 gearboxes and all required cables.

Yes, @Aerosmith is right — these servos are okay, but there are some important notes:

I tested a 1kW A6 servo with brake. The A5 series might be similar, but it would be great if someone could confirm this.

The A6 has an internal air cooler, which is not silent — a potential deal-breaker depending on your setup. On the plus side, there's no whining noise like you get from the black AASD drivers.

However, you’ll need to wire your own connection cables. They use a DB44 connector, and there are no ready-made cables available for Thanos, Motion4Sim, or the Knaufinator board.

Another thing to note: in position mode, they don’t provide a torque signal. So you’ll need to rely on the internal homing methods.

That said, the price is excellent.

i have a pcb for the A6 for testing which i can share if needed for the aasd layout but there are still some difficulties

Yes, the A5 driver also has a fan which runs at full RPM as soon as the servo is enabled. I use a closed cabinet so I don't really hear them. If the fan noise is a problem for anybody he could replace the fans with lower noise types or simply remove them. The heatsinks don't get hot unless you put really high load on the motors.

There is a torque signal available but not in the default settings. You need to program one of the outputs to code 18 "ToqReach".

And yes, you are correct, you can't use one-on-one DB25 cables to connect to Thanos or Motion4Sim controllers. There is a DB44HD cable supplied but the other end is open and you have to solder a DB25 connector manually, there.

I've made adaptor PCBs to fit the A5 pinout to the layout of my own motion controller which uses RJ45 cables. But I think it would be no big deal to make something similar for the standard DB25 pinout of the AASD servos.

Ahh very interesting, the A6 are confirmed from factory not to support the torque signal (17 for output here) in position mode , thats pitty for rotary rig users where torgue is a really good way to home.. . i also invested hours to get it working before asking factory

Ugh, so they support a torque output but it doesn't work in position mode? That's tough. I have to check this again with the A5 drivers, too. I thought we could rely on the documentation... I should be more careful before recommending chinese products.