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Old Jan 15, 2013, 02:23 AM
Specializing in RC since 1972
Temple, GA, USA
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Originally Posted by jonesy40001 View Post
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Originally Posted by kaptondave View Post
Using ACC Trim is the technically correct method and is easier to adjust, especially if both axis need trimming. That is the reason for it being there. Shimming is akin to using duct tape in lieu of a proper repair (IMO).
I strongly dissagree. Any airframe, fixed or rotory wing needs to be "straight and ballanced".
...
The original comments were about shimming the KK2 inside the airframe vs. shimming the calibration platform that the copter sits on while calibrating vs. adjusting the ACC trims in the KK2 SL menu.

The ACC trims were put there because mechanical shim adjustments are tedious and inaccurate.

Shimming is not an exact, repeatable process. You will never split hairs like consistently changing 1/4 degree difference in roll. You will never get it exactly the same twice with a standard bubble level. The landing gear will sit on a surface imperfection. The KK2 will shift due to vibration damping mount compression when shims are inserted, etc.

Changing the ACC trims is a repeatable process that can be dialed in without levels or rigs. It was put there for just this reason.

Build / repair your copter straight and true with a correct CG and with good level landing gear. Set it on something level and run the sensor calibration. From then on just trim the ACC trims. Works at the flying field or at home. Does not require what I would expect to be a difficult insertion of tiny shims, repeated several times till it flies straight. Does not require a level place and a level.
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Old Jan 15, 2013, 03:24 AM
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Australia, QLD, Meadowbrook
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Originally Posted by kaz1104 View Post
Loosing a blade is sort of flyable ... loosing a propeller on a quad ...is not !!
.
This I know first hand. I posted a vid some pages back.
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Old Jan 15, 2013, 03:37 AM
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Originally Posted by theothercliff View Post
The original comments were about shimming the KK2 inside the airframe vs. shimming the calibration platform that the copter sits on while calibrating vs. adjusting the ACC trims in the KK2 SL menu.

The ACC trims were put there because mechanical shim adjustments are tedious and inaccurate.

Shimming is not an exact, repeatable process. You will never split hairs like consistently changing 1/4 degree difference in roll. You will never get it exactly the same twice with a standard bubble level. The landing gear will sit on a surface imperfection. The KK2 will shift due to vibration damping mount compression when shims are inserted, etc.

Changing the ACC trims is a repeatable process that can be dialed in without levels or rigs. It was put there for just this reason.

Build / repair your copter straight and true with a correct CG and with good level landing gear. Set it on something level and run the sensor calibration. From then on just trim the ACC trims. Works at the flying field or at home. Does not require what I would expect to be a difficult insertion of tiny shims, repeated several times till it flies straight. Does not require a level place and a level.
This subject re-circulates in this thread over and over and people ask the same questions over and over and the same answers are given over and over. Most refer to placing shims or bits of paper, wood, metal or whatever under the landing gear to level the airframe. It was mentioned that one pilot placed shims between a motor and mount to correct the thrust line. Correct acc callibration is mostly a once only opperation. The kk2 it self does not need to be mounted level at all, and using the acc trim is a hit and miss process as the numbers are not representetive of actual angle.
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Old Jan 15, 2013, 08:54 AM
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Originally Posted by jonesy40001 View Post
I strongly dissagree. Any airframe, fixed or rotory wing needs to be "straight and ballanced". Remember you are not flying the FC, you are flying the airframe. "Tweeking" a multi rotor on a flat, level surface before callibrating the Acc is, IMO, by far the best way to ensure the airframe will hover flat and level in flight.

Pete.
I think you missed the point. I have posted previously that tuning a multi-rotor should start with a frame that is square and level. The discussion was about whether drift should be corrected by shimming or by tweaking ACC Trims. My position is to use ACC Trim.

+1 to what theothercliff posted.
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Old Jan 15, 2013, 09:11 AM
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Originally Posted by jonesy40001 View Post
Most refer to placing shims or bits of paper, wood, metal or whatever under the landing gear to level the airframe.
I can see no valid reason the airframe, with landing gear, should not be built level to start with. Since most designs are symmetrical it would be hard for them to be anything else. Once done the main platform should remain true. The landing gear takes a beating (at least mine does) and can get out of true but there is no need, within reasonable limits, to mechanically or electronically re-level after every hard landing.
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Old Jan 15, 2013, 09:44 AM
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It's funny that you two keep arguing, but the code is clear. Both way produce the identical effect when done. Some prefer to shim because it's a lot easier for them to grasp than the acc trim that is all.
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Old Jan 15, 2013, 10:34 AM
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United Kingdom, Bracknell
Joined Oct 2007
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Thanks all for reply's. Seemed it took a bit longer for it to dry out than I thought.
Yesterday, took ribbon cable out, dried it and put it back, still no joy.
Tried it today and all is well except for back light not lighting display up. Can live without that.
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Old Jan 15, 2013, 11:09 AM
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Originally Posted by brontide View Post
It's funny that you two keep arguing, but the code is clear. Both way produce the identical effect when done. Some prefer to shim because it's a lot easier for them to grasp than the acc trim that is all.
I am an engineer by profession and a craftsman. The concept of building a multicopter that is not square and level is foreign to me, akin to the concept of building a table with one leg shorter than the others. I know however that even well-built copters can drift and believe that the ACC Trims were included in the KK2 design specifically to correct that, and so use it that way. Granted the same result can be achieved by shimming. To me that is a duct tape approach but to each his own.
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Old Jan 15, 2013, 11:33 AM
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Originally Posted by David Parry View Post
Thanks all for reply's. Seemed it took a bit longer for it to dry out than I thought.
Yesterday, took ribbon cable out, dried it and put it back, still no joy.
Tried it today and all is well except for back light not lighting display up. Can live without that.
I went back and had a look at the picture of the board and it appears that there is a crack or scratch in the board just to the left of the LED. If there is a crack in the circuit board it might be the cause of the LED not lighting. Have a close look there with a magnifier or check with an ohm meter to see if that is the cause of it not working. Check from the stand off to the solder pad on the LED, both sides, then check the LED itself.
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Old Jan 15, 2013, 11:52 AM
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The KK2 is the bizz, flight controller and gimbal controller

SSG Gimbal Movie (3 min 47 sec)
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Old Jan 15, 2013, 01:27 PM
Specializing in RC since 1972
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Originally Posted by brontide View Post
It's funny that you two keep arguing, but the code is clear. Both way produce the identical effect when done. Some prefer to shim because it's a lot easier for them to grasp than the acc trim that is all.
The reason that I bring it up when it is mentioned is that I want to help newbies understand that you can painstakingly and less accurately add shims of some sort, or you can click a button to easily and accurately do the same thing.

Ever had to add both down thrust and right thrust in a motor? To have three washers of down and one of right you need 0 washers in the lower starboard corner, 1 washer in lower port corner, 3 washers in the upper starboard corner, and 4 washers in the upper port corner. Shimming the KK2 needs this kind of head scratching.

Change it with a shim: You try to handle it by layering different sizes or number of paper scraps because you want a very small change. Depending on your design, you take several minutes to remove the KK2, calculate your guess about how many shims to add in each direction (roll and pitch) add shims, and put the KK2 back in. If you decide that you want it back the way it was, you sometimes find out that removing a set of shims does not quite put you back where you were because you compress them more or less when you tighten the KK2 mounting. Adding another shim for roll may change the shim angle for pitch.

Change it with a button: It takes less than 10 seconds to change the number in the KK2 menu. Like it better the way it was? Change the number back and it flies exactly the same as it did before. Know you need a lot of roll and just a little pitch? Just add 3 clicks of roll this way and 1 click of pitch that way. Don't be scared of it, if you adjust it the wrong way, just go in the other direction like you would with shims.
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Old Jan 15, 2013, 01:45 PM
Specializing in RC since 1972
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Originally Posted by jonesy40001 View Post
This subject re-circulates in this thread over and over and people ask the same questions over and over and the same answers are given over and over.
I choose to try to help newbies know the best and easiest way to do things. Some might choose to say RTFM (page 1).

Quote:
Originally Posted by jonesy40001 View Post
Most refer to placing shims or bits of paper, wood, metal or whatever under the landing gear to level the airframe.
That would be an interesting poll! If true, it means that more than half of the people who use the KK2 could make things easier on themselves if they learned a different way of doing things.

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Originally Posted by jonesy40001 View Post
using the acc trim is a hit and miss process as the numbers are not representetive of actual angle.
Are paper shims calibrated in degrees now days? Adding and then removing additional shims does not always get you back exactly where you were (compressing several different layers of paper differently by tightening screws differently). Clicking 2 clicks of ACC roll trim and later putting the setting back where it was, does put it back where it was before.
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Old Jan 15, 2013, 01:58 PM
Specializing in RC since 1972
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Originally Posted by David Parry View Post
Thanks all for reply's. Seemed it took a bit longer for it to dry out than I thought.
Yesterday, took ribbon cable out, dried it and put it back, still no joy.
Tried it today and all is well except for back light not lighting display up. Can live without that.
That LED is one of the few things on the board that can be fixed. The LED is still OK, there is just a problem with a trace or a resistor.

I had a cell phone that came back to life like that. I recall that it got washed. I took it completely apart. A week later it still didn't work. A year later I happened to try it again and it was working.

If it is fresh water, just disassemble, blow it off, and let it air dry. Usually a day is enough, but it might take a week or a month if there are things you can't take apart.

If it is salt water, rinse it off well. If there are any components that cant't take water (potentiometers, barometric sensors, currently dry places where water might stay for a month) you need to be careful to not get those wet.

Salt water is corrosive (in the long term) and conductive. Don't power it on if there is salt on it. (Hard to do if you crashed into the ocean. ) Fresh water isn't usually that big a deal for battery powered items.
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Old Jan 15, 2013, 02:17 PM
Playing R/C lawn darts...
United States, WA, Marysville
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To aid in drying out electronics you can place the item in a sealed jar with some dry rice. Obviously don't bury it in the rice but just place it on top. After a couple of days the rice will have pulled all of the water out of the component. It have done this with an iPhone that fell into a puddle of water. Took about a week to get all of the water out of it. That phone is still working after two years.
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Old Jan 15, 2013, 02:34 PM
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Originally Posted by theothercliff View Post
The reason that I bring it up when it is mentioned is that I want to help newbies understand that you can painstakingly and less accurately add shims of some sort, or you can click a button to easily and accurately do the same thing.
The bad thing is that many newcomers to multirotors will buy without asking questions or doing some research first. A little research goes along way. Not every frame comes straight. Not every KK2 board will calibrate the same. What PID settings work on one frame will not work on another, etc. etc. etc.

The wheel just keeps spinning round and round and the thread keeps growing and growing.
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