One of the things about standard servos that has always bugged me is the crappy means provided to mechanically fasten the servo to whatever it is you want to control. Those little plastic tabs, frankly, suck. Zip ties, foam tape, everything sucks. Ever since I first built an RC car as a kid, I’ve been plauged by flimsy servo attachment. I would be hard pressed to come up with a worse design.
So I’m somewhat interested in the Hitec Robot specific servos, HSR-8498HB & HSR-5498SG, as they seem to have a built in hole pattern that allows for reasonably stiff mechanical connection.
Why don’t I see more stuff made with these? Is it because nobody wants to make the linkages and whatnot to take advantage of this system, or am I the only one who cares about the lack of stiffness inherent in the standard servo design? Is there some drawback to these particular servos that I can’t see (I’ve never seen one in real life).
It almost makes me want to machine custom casings for standard servos, but that seems like overkill.
while many servos have (tabs that suck) 'they, along with other ranges of grate servo manufactures, are putting there time into engineering the servos to be better. many people i know dont choose the type of servo because of the tabs but for the speed/power etc, (main feature of the servo).
this is an excellent point and i would prob take this up with the manufactures. better or like you say built-in hole patterns are really good but LM would have a nightmare if these tabs get replaced by hole patterns. (SES)
yeah!
i would agree it would be over-kill but interesting. and also may give you new ideas for new RC designs!!??
The tabs will probably be there forever. There are too many companies providing things that use servos that the tabs work perfectly fine with for the manufacturers to abandon them.
Our Servo Erector Set makes very strong assemblies using the tabs, so I guess I don’t understand the problem you are having with them.
We may be designing a series of brackets for the 8498 servo next year.
The tabs work well enough for RC cars and spitfires, I suppose. I have had problems in the past where tabs broke off or just didn’t provide a good enough bearing surface to prevent the servos from wobbling a little as they move. It’s just general sloppiness that doesn’t have to be there.
I don’t want to blow this out of proportion - just wondering out loud. I’m beginning to think that I’m just a tad on the picky side when it comes to the mechanicals. I’m looking forward to your new brackets - they sound like a huge step in the right direction.
Unless someone can give me a good reason not to, I think I’ll be home brewing some “brackets” for 8498 servos myself in the not too distant future.
One question - will the case plates with the triangular hole pattern that come with the 8498 fit on the 5498?
The mounting tabs on a standard hobby servo are designed for vibration isolation. Consider the vast majority of applications have servos sitting in a tray a few inches away from a 2-cycle internal combustion engine bolted firmly to the frame, whether it’s an r/c airplane, car, or boat. Normal attachment has a rubber gromet in each of the 4 holes and then a screw with an non-threaded shank and wide head is bolted to the servo tray. If you bolt the servo rigidly to the tray without the gromets you get all this nasty coupling of vibration between the output pushrod and the gear train and the servo wears out at a seriously accelerated rate. The mounting technique works very well when used as intended.
As the market for hobby servo applications expands beyond the original uses you will see new case designs introduced. consider the dynamixel AX-12 and it’s cousins (used with the bioloid system) as an example, as well the obvious 8498 which I believe is actually marketed AS a robot servo. I doubt it would last very long installed for R/E/T control in an ic r/c airplane.
Excellent point on the vibration. I hope that you’re right that newer specialty servos will evolve with more rigid mounting systems. Of course, by then, we’ll be using lawn mower engines to power the bots…
