HS645MG explodes in the cold, X2??

[cogfounder]

I just blew 2 HS645MG servos out in the cold. Both WP'ed with wet tape.
But today was 32* in Buffalo, thats a heat wave for us this time of year!

I have run them in much colder weather so far (-9*F), yet today,
I lost two in a row. And I was being nice to them too...

OK, .. I was not whooping things too bad... no more than "normal".
And a lot less than I see others do with the same anyway..............

Does anyone think the inhearent moisture in that one plastic/nylon gear,
on the motor shaft (?), could have expanded/contracted it so much
as to explode things inside via repeated stress fractures???

The one servo is running like a winch now, 360 revolutions both ways?
The stop pin/tab on the metal final gear should prevent that , right???
Unless I busted the top half of the servo case, TWICE!!
Or did I spin the motor shaft gear flats, and thats what I hear spinning??

(sorry, looking for a few blind answers here, untill I open them up.
but still, there could be an answer somewhere within the ranks,
and this just now happened to me.)

I ran 45 minutes on a cheap Venom 3000mah NiMh out there,
before I got so cold I had to quit, but I have done that
many times these past years, with no issues,
and in much colder weather too.

I am absolutly sure my rigs did not hit anything hard enough
to pop the servo gears, because I ran them fine untill shut-down,
right up to the side door,
and then just put them in the basement tub to drain off,
before the needed serviceing for winter/water runs.

I guess I could post this in the electronics forum,
but I am running them in both my scx10's, and even my
ax10/Eclipse dedicated crawler build.

I figured I would start here, where I live,
and feel more comfortable about the people I ask for specific help.

Its why I bought the 645 mid-budget servos in the first place,
because it was, for its good and bad points, recommended here.

I just wonder if anyone has seen the same thing with these servos,
no matter the conditions? but more over, in extreeme cold??

FWIW, I am running an XR4 radio from RC4WD,
and think I can take advantage of a better "digital" servo now,
so am VERY open for suggestions about that option,
but it would be my first one, so many questions might follow?

And hey, at least I didnt start a "whats the best servo for my scx10" thread over all this.....

Dave












I have destroyed a mess of servos in my time,
but have never broken a stop post on a gear before.

[ThunderbirdJunkie]

You probably broke the centering peg inside the top of the case.

Have you ever had a windshield on a 1:1 break in the cold? I've had it happen on two cars...and the crack's pattern actually followed exactly where the defroster hit the windshield at the base.

Something similar could have happened. Things can work dandy for years and years, then suddenly a big crunch after years of use.

Hopefully you get it sorted out.

[cogfounder]

Oh Yeah,
I understand your anology, ThunderbirdJunkie.
Thats what I expect to see in there, too...
hard plastic shattered like glass.

But the servo got even colder than I did out there,
so I cant blame it for busting just to get back in the warm house...

Its a great budget servo, but I am stuck with this weather,
so I think its time to get serious about them,
and spend a few more bucks on better ones this time around.

Ill BE DAMNED if a few feet of snow is going to stop me, or my rigs!!!!

But to be honest, I dont know squat about these HT digital servos.

I cant help but think a 200 buck jobie with an alloy case
and all metal gears wouldnt warp itself into metal dust out here,
going in and out of the weather, the way the operator must.

Guess ill just have to etch/fab a 9v heating grid/blanket to keep
servos happy in sub zero temps, huh?
like the hot lines on a rear 1:1 windshield.

Anybody been around long enough to remember using
resistor wire off a real car battery to charge nicads in the late 70's?
(and to think, lipo batts scare me after doing that for years...LOL!)

Well, a bit of tungsten wire wound around a servo might do,
if the potential(s) math is right. Yes?

Might need a jacket for plastic cases, but metal ones should be fine.

Hummm... need to dig out my trusty T55......
(yeah, I am that old.. still got my slide-rule too)

[indiana mudcat]

Those servo's just have weak gears, it would have broke just as easy if it was 90 out. How much do you want to spend?

[cogfounder]

Well, Indiana Mudcat,

I figure a hundred bucks would be 3 steps up from where I am at now.

But I would have to get a Castle BEC for each rig also,
as I am running everything raw at this point
on all three of my Axial rigs, and my Venom Creeper too.

I am talking $480+ already,
so believe me, I am going to listen to what people say!

I have studied a bit about better servos here,
but I have to be honest, it is a big step for me,
and I dont think I understand about digital servos
enough to make a good choice on my own....

[ThunderbirdJunkie]

cogfounder...stupid question. Have you set the EPAs on your radio? If you do this, you're less likely to have similar breakages.

[cogfounder]

Yes, I have, and I was quite suprised by the amount I had to limit it too.
Didnt expext it to be so much, but the rigs turn very well.

I ran these servos for some time with zero issues,
one even last winter, and I feel I got my monies worth
out of them.

Its just time for me to look into something better.

Since the one 645 is already spinning,
it might be time to make a servo winch out of it LOL!
After I open it to see what actualy happened
and clean it out that is.

[devenaberger]

many people have said to use elec tape or silicone, it works, only until water works through to the adhesive, what you need to do if water is your problem is to get brush on electrical tape. it seals phenominally and is much easier to work with than thick silicone. dont be shy with it either you can use a lot, just make sure to go in layers to allow proper dry time for a truly water proof system.

now drop it in a pool and be suprised haha

[cogfounder]

I have actually done that with the wet tape to them already.

Thats why I havent opened it up yet.
I have it all over the servo and the wires going into the
radio box. I went a little heavy on it
so its going to be a job getting it all off without hurting something.

I couldnt find a small enough o-ring for behind the horn,
so I cut a thin piece of fuel tubeing and streached it over the spline.

I used a trick Gearstripper taught me, and rolled up a piece of
paper to put in the tubing. Helps a lot to make flat, even cuts.

Im pretty sure this is not a water issue tho.... he he