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Old 05-03-2008, 01:36 PM   #20 (permalink)
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Hey all, been a busy day doing things around the house and I still have a list as long as my arm!

A few general things before I reply to people's posts...

I had a further look through the gears whilst replacing them in order to test the servo plugged straight into the Rx and found that the inner most gear that provides the drive straight from the motor in the servos is stripped on the lower of the two parts of the gear. I assume this is the most common gear to strip as it is the one that rests against the bronze drive gear.

Annoyingly I was expected a delivery today of a couple of servo's for a twister 3D that are rumoured to fit (and provide essentially exactly the same spec as the e-flite servo, same torque, speed, size etc). The plan was to fit one of these and examine the gears in the other (they are dirt cheap so I'm not to concerned about them being top of the line). Though they might not be the best solution for the long term they give me the opportunity to play around with set up with a fully working bird.

Hey mupchu.

Originally Posted by mupchu View Post
The white stuff that looks like pva glue, is supposed to be grease for the gears. When I rebuilt my servo's I cleaned it up with alcohol (not that kind ), and used my own grease to lube them back up. White lithium grease is supposed to be prefered (at least that's what finless uses). I am a mountain biker so I happened to have some grease on hand that is plastic friendly so just used what I had.
I managed to sneak into a local car parts place whilst doing some shopping for the Mrs and picked up some spray white lithium grease to add to the parts kit!

Originally Posted by mupchu View Post
That said you gears look good on the tail, I would plug it directly into the RX and see if it works. You could have a problem with the gyro if the servo works in that channel. If the servo does not work it looks like it's a burnt out servo. When you look at the gyro, what mode is the gyro in for the tail servo (analog or digital). The stock servo is digital, but it cannot handle the output of the gyro, and should be run in analog mode.

You can get a spektrum DS75 and use it, similar spec's to the stock but the bonus is that the servo can be driven in digital mode. Also you might want to look into what the shops around you do keep in stock regularly, running a hitec hs55 or 56 would also work (those would both be analog).
Originally Posted by mupchu View Post
Put the servo back together before checking it, not sure if it would damage the gyro but it might damage teh servo itself as well.
It looks as though the inner most gear is stripped but when I get my test servo's this will be my next step if it doesn't work out of the box. I only found out when rebuilding the servo to follow your advice, All the gears spin from the servo arm in if this one is not added. No drive from the motor though obviously!!

I was looking at the Rx and it is a jumble of wires, which set should I remove if I need to test this, I assume one of the other servos?

The gyro is still in standard mode. In the future if I do an upgrade to a servo that can handle digital is the stock gyro OK?

Very few of the local model shops around here stock much in the way of parts at all. There is reasonable large number of shops outside the area that do online shopping and have reasonable postage rates and good stock levels of most things. Apparently though there is general shortage right now of some Blade parts and most shops seem to be waiting on order. Most said they would be back in stock in around 2 weeks though and all were helpful in discussing possible alternatives.

Originally Posted by mupchu View Post
I can definetly relate to not wanting to upgrade at this point. I would say though that a locked in tail will help you learn more than anything else though. The nice thing about heading hold gyro's is you can really focus on the cyclic controls, and you're tail should stay locked.
I have definately thought about this but it is a real toss up at the moment between that advantage and the disadvantage that I expect as a learner I will have certainly a few tail heavy landings and main blade related acidents too and as such may destroy a few sets!

How often do the servos themselves go rather than the gears? I think I ould happily keep a few sets of gears on hand but replacement servos in the next price band aren't particularly cheap. For now I'll get her up and running and hopefully that will teach me enough to be able to recognise the need to upgrade and also do the upgrade without to much issue!

Originally Posted by mupchu View Post
If you have not gotten a Sim already I would highly suggest it as a worth while investment. If nothing else if you get grounded by lack of parts it's a good way to keep your skills fresh. Also it's helped my feel much much more comfortable with the nose in orientation without racking up injury's and broken parts
Injuries!! Eek!

My PC is pretty much only fit for office type apps and cubasis but it does just run Clearview (I tried phoenix and just got the old BSOD). My sim cable came today and just about kept off the disapointment of my servos not arriving. I haven't had a chance to play with it yet with the Rx but have brought a projector home from work for real size flying practise when I get through this dang list (typing this on a break from domesti duties)!

Originally Posted by mupchu View Post
The tail rod looks fine from the pic, but when you get the tail servo working you should listen to see if the servo is making a lot of noise when trying to more the tail. The servo should not make a buzzing sound all the time or something is binding.
I'll look out for that. The elevator servo is making a buzzing sound as you describe so after the tail is done I will have to investigate that.

Thanks again for your reply. Have a good weekend.

Originally Posted by Twmaster View Post
I too am rebuilding a crashed B400 (see attached photo of the carnage). This was just a badly crashed airframe with motor but no electonics.

I'm finding it to be a fairly simple machine to work on and fairly inexpensive to buy parts for. It only took me a couple of hours to install everything the bird needed.

I've reassembled the bird and at present am programming my DX7 to work with her.

Second photo is the rebuilt bird with the head just sitting on the main shaft for the picture as I am in the process of leveling the swash.
Hey Twmaster! Looks like a sweet job you've done. First photo looks like nothing more than a kit! Nice work man. Is see you have changed the blades and is that a different canopy too? Looks a little more spacious than mine!

Good to hear it has been a good heli to work on as I expect this is going to absorb a good number of ours of my newb mind!

Originally Posted by Twmaster View Post
The part number for that Spektrum Digital 75 servo is DSP75 where the 'P' in the part number means programmable.
Originally Posted by Twmaster View Post
I've put Hitec HS-65HB servos on the collective and the Spektrum DSP75 on the tail set to 'tail' mode via programming box.
What does the programmable functions allow you to do (excuse me if this is a totally dumb question!)? The programming box you mention, I assume this is on the cost options list! Is it something I am going to need to invest in in the longer term?

Originally Posted by Twmaster View Post
I decided to go ahead and use these servos as they are easy to get gears for unlike the interglactic backorder the E-F DS75 servos are experiencing.
I can feel your pain on that one! It does also seem to appear that this upgrade is the standard choice for many experience B400 pilots so it is good to know when I get to that there will be plenty of people who have done it before!

Originally Posted by Twmaster View Post
Also, Ted, it sounds like the BEC is overloaded on that ESC. That would explain it getting hot just sitting there powered on. As others suggested you may have a defective servo (or two, or three....)
Could this be due to the potential binding and tail servo issues other people have mentioned?

Thanks for your reply Tw, enjoy flying that beautiful bird.

Originally Posted by notreallyme View Post
from what i am seeing you need to check if the servos are pluged into the correct channel, or it may be possible you have a mode 1 controller (euro version with thottle on the right stick) or someone that might have tried to set it up this way with a mode 2(thottle on the left stick). one more thought i know replacing gears in servos is the inexpensive way each time you crash but in the long run replacing with servos that "won't" strip when you crash is in the long run cheaper if you are going to replace later anyway. it will save all those stock gear sets/servos you buy while you are crashing/learning
Hi notreallyme. Throttle is definately on the left stick. I have adjusted the swash in the DX6i to the correct setting (is was on 90degree) and will take some new images of the movements this evening or tomorrow.

Regarding the gears, what servos are you running and what are the gears made of? What is the material most resistant to newb errors (I'm mostly thinking of tail blades digging in)?

Thanks for your reply man.

Take care all.

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