I've just bought a Zagi 480 si. I bought Hitec HS 81 micro servos under
recommendation. However, the pre-moulded holes in the zagi seem to be for
standard servos; the holes are too big and too deep for the micro servos.
The instructions in the box recommend standard servos. Does anyone know, is
it possible to use the micro servo (which are listed as an option on the
zagi website) and if so can anyone recommend a good way to secure the micro
servos in the oversize holes? A little difficult to explain exactly, but I
assume there are lots of these zagis about so I banking someone must have
come across the same issue.
Ted shuffled out of his cave and grunted these great (and sometimes not
so great) words of knowledge:
The HS-81 are fine.
As for the oversize holes, measure how much LONGER the opening for the
servo is than the HS-81. Get some BASSWOOD of the appropriate size (if
you need to it is ok to CA a couple of pieces together to get the
correct thickness ) and CA a piece in ONE END of the servo opening.
Then mark and drill pilot holes (I use a 1/16" dia drill bit ) for the
You are better off with basswood rather than balsa - less chance of the
servo screws pulling out.
So who recommended the HS-81s? At least you now know that that party
is not a reliable info source. I have a Zagi 60 in which the HS-81s are
standard. The servo wells are a tight fit for the servos; nothing
holding them in but friction and the mylar tape covering. So you might
stuff the dervo wells with pieces of scrap EPP foam and be OK.
However, the gear train in the HS-81 is kind of brittle (ask me how I
know). If you're going to do aerobatics close to terra firma you might
be better off with larger or MG servos. ;^)
Davey Boy wrote:
I will harmonize with the others here. I have these servos in
my Zagi and my Trick Razor. They are a tight press fit. I shimmed
with balsa and it is all held in place by compression against the
foam...and tape patches over the top.
I figured I would watch them and if they loosened, I would
respond to that. They've stayed tight and I do some pretty mean
outside loops with both models and I fly the Razor upside down more
than the Zagi right side up.
I also figure that in a really bad prang, the foam would act
as "servo savers." Maybe.
I am also using the cheapo $20 electronic mixers in both Zagi
and Razor with just regular xmitters. I preferred doing this than
messing with my one cheapo computer radio.
Good luck. (Yes, it is strange to throw a Zagi that way but
| I've just bought a Zagi 480 si. I bought Hitec HS 81 micro servos under
The HS-81MG servos are better -- they'll survive a lot more crashes.
The MG means `metal gears'.
If you need a slightly bigger/stronger servo, the HS-85MG is a good
The HS-81s you have aren't really micro servos anyways -- they're more
mini. But they're probably fine for your plane, as long as you don't
(As for how to mount them, that's already been answered.)
Hitec has had `karbonite' gears for a while now, and I've been very
happy with them, and yet to have any of them strip on me. But I don't
think they're available on the HS-81MG sized servos yet.
I'll go ahead and use the HS 81s cause I already have them. If I crash and
strip them I can replace them with something stronger next time. I'll
probably use polystyrene and Bass wood to wedge them in and use the covering
tape to hold them down. I read an article once about using insulation
expanding foam for fixing servos into oversize holes (buy it in a tin, spray
it under/around the servo in the hole, it expands, sets and your're done).
Trouble is you only get one go at it, if it goes wrong your're buggered.
Don't think I'll risk that.
Thanks for the replies; I'll keep checking in case you have any other
| I read an article once about using insulation expanding foam for
| fixing servos into oversize holes (buy it in a tin, spray it
| under/around the servo in the hole, it expands, sets and your're
You wrap the servo in a plastic bag (like from a grocery store) very
close to the servo and it creates a very nice little pocket for the
servo to sit in, and it's held in with tape. (You remove the bag once
it's all dried.)
You can do the same with epoxy too, but epoxy weighs more, which can
be signifigant if you need lots of it.
It's a good idea.
| Trouble is you only get one go at it, if it goes wrong your're
Not true -- you can cut out the bad foam and try again if something