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Old Jul 01, 2012, 11:19 PM
IntegrityHndywrk is offline
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IHW Heli Division
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United States, FL, Palm Coast
Joined Mar 2012
8,602 Posts
Experimental Durability Mod for D05CS Main Gear and Gear Cap

Experimental Durability Mod for D05 Custom "S" Main Gear and Gear Cap

Okay. So the problem with the main gear is that after boring the shaft hole bigger the bottom hub becomes much weaker. I usually explode the bottom gear hub, where the mounting pin is, WAY before i strip the gear off lately. I also pressed my motor pinion tighter against the main gear. This might have something to do with why it does not slip out and grind as easy anymore. But i am only speculating. In reality this is probably putting more strain on things like the gear's pin.

So since my current main gear has a wobble in it anyway from a crooked bore drilled though it. I decided to go ahead and experiment with adding some sold material too the main gear. When i removed the old gear I decided to inspect under the gear cap as well. BIG SURPRISE! (sarcastic) The nipple on the gear cap had been worn down again in just the few short flights between my frame swap/rebuild and now. Maybe 20 total. I cleaned the aluminum shavings i found stuck under there and came up with a little mod that should help with this wear on the gear cap. But i'll get back to that in a minute. For now lets get back to the main gear's hub.

This was my first attempt at adding solid material to the main gear. I was a bit worried about causing balance issues and making the gear wobble. Since this gear already wobbled pretty badly because i rushed drilling it out it was the perfect candidate for this little experiment. I basically covered the gear hub in CA once it was installed. Then dumped baking soda on it. The CA turns the baking soda into a solid hard plastic like material. It's not pretty and i'm sure it adds a gram or 2 to the over all weight of the gear. I'm also sure the weight is not balanced symmetrically. But since it's so close to the center i don't think it will be an issue. I sure am glad i only have to look at it when i put a new pack on, lol. I might color it in with sharpie marker or something. (pictures below)

Okay now for the Gear cap mod. The problem is that pitch pumps or any binding with the swash add pressure to the now weakened metal gear cap. Between the spinning motion and these squeezing forces being applied by the swash. It does not take long for the gear cap's nipple to sheer off. Once it does there will then be play on the main shaft which could cause response issues in pitch changes and making pitch pumps slower, things like that. I was using travadj to limit my swash from binding at the extremes. I don't think i like that method any longer. I did have some binding on the swash at the top with the rotor head when the cyclic was moved. Plus using travadj seemed to maybe slow the servos down too? Maybe not, but I now use the pitch curve to limit binding at the extremes. That seems to work better for me. So on the 2801 i now use a pitch curve to limit binding. Something more like (approx) 50 - 50 - 50 - 70 - 90 in normal and in Stunt mode i use something like 15 - 35 - 50 - 65 - 90 or 15 - 30 - 55 - 70 - 90. The point is the first and last pitch points on the 2801-pro get limited to limit swash movement at those extremes. Binding just wears everything out, not just your gear cap. Servos and other parts included.

So the solution I came up with to a longer life on the gear cap is quite simple. Go to a hardware store or bolt supply store would be better. Get some tiny washers that have about the same inner diameter as the nipple on the gear cap. I unfortunately did not measure mine but rather just took it with me on my search and physically compared it with the washers. I just happened to have some in my workshop that were perfect! They are approx. 1mm thick and almost the same size as the bearing. The ID matched the nipple just great. I will report back here later in an edit how this works out in the long run.

See pictures for more details.
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Last edited by IntegrityHndywrk; Jul 09, 2012 at 05:37 AM.
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