Mini 1st Gen Gimbal Calibration Question

[IntoTheSun]

Hello all, my 1st post here
I’m new to drones and learning to fly this little beast, all’s well so far, no crashes yet
I’ve had my first Gimbal Motor Overload while flying, probably due to faster flying lately, recovered that situation just fine…
But - now I am more aware of the health & operation of the gimbal.
My question is - upon observing the gimbal calibration at power up, I notice that it taps the flat surface the drone is on - when it does the roll compensation movement part of the calibration. Is this normal? Does the Mini just want to find out where the surface is, or just make sure it’s there haha?
The calibration seems to complete and the gimbal operates as it should, surprises me that it taps the surface it’s on though…

 

[old man mavic]

the MM is very low to the ground ,its best to have some sort of landing gear extension to raise it up i have the one that clips to the underside of the body there are many different sorts out there

 

[Deleted member 103366]

I suggest you check your observations.
I have just manually rolled two gimbals to their limit of travel whilst the drone being tested was sat on a hardback book. There was perhaps 1mm of clearance, not a lot I admit but clearance all the same. I also booted both drones and again there was clearance.
If your observations are correct then either the gimbal is hanging low or the front arms are sitting high or the surface on which the drone is sitting is not flat.

With regards to the gimbal, the assembly is suspended from 4 rubber dampers, it is not unusual for one of these to be displaced in a crash.
One end of each damper fits over a lug on the gimbal assembly's frame and into a 'groove' on that lug,
The drone end of each damper fits into and through a hole in the drone body, this end seems to be the one more likely to be displaced, There are several videos on you tube showing their reconnection, watch more than one, some repairers are a bit rough for my taste,

The rear dampers are easily reattached WITHOUT dismantling the drone. BUT I think it would be difficult to reattach the front dampers WITHOUT removing the drone's top cover, this is due to what looks to be very awkward access 'from below'.

If a damper needs replaced DO NOT use tweezers etc. with sharp ends, I fear they might puncture and then tear the damper.

 

[IntoTheSun]

the MM is very low to the ground ,its best to have some sort of landing gear extension to raise it up i have the one that clips to the underside of the body there are many different sorts out there

Ok thanks, I’ll look into some leg extenders or one of those sled type setups, I may make my own & see if I can make something lighter and more aerodynamic…

 

[IntoTheSun]

I suggest you check your observations.
I have just manually rolled two gimbals to their limit of travel whilst the drone being tested was sat on a hardback book. There was perhaps 1mm of clearance, not a lot I admit but clearance all the same. I also booted both drones and again there was clearance.
If your observations are correct then either the gimbal is hanging low or the front arms are sitting high or the surface on which the drone is sitting is not flat.

With regards to the gimbal, the assembly is suspended from 4 rubber dampers, it is not unusual for one of these to be displaced in a crash.
One end of each damper fits over a lug on the gimbal assembly's frame and into a 'groove' on that lug,
The drone end of each damper fits into and through a hole in the drone body, this end seems to be the one more likely to be displaced, There are several videos on you tube showing their reconnection, watch more than one, some repairers are a bit rough for my taste,

The rear dampers are easily reattached WITHOUT dismantling the drone. BUT I think it would be difficult to reattach the front dampers WITHOUT removing the drone's top cover, this is due to what looks to be very awkward access 'from below'.

If a damper needs replaced DO NOT use tweezers etc. with sharp ends, I fear they might puncture and then tear the damper.

Ok thanks. I haven’t crashed it but I did buy it used. It looks pristine new but it still could have crashed…

So I did indeed check my observations:
My flat surface is dead flat.
I do not see any displacement in the front legs - though I don’t think I could spot 1mm or 2mm of legs sitting high or low. The underbelly at the center frontmost clears the surface by appx 1.75mm. As Old Man Mavic said - these do sit very low…
Another several power up calibration observations - the gimbal audibly taps the surface the drone is on during calibration. 1mm of lift under the front legs is needed for the gimbal to not audibly tap the surface. I put a penny under each front leg (appx 1.25mm) and the gimbal just barely clears.

I took a closer look at the 4 mounting points. The four damper nubs appear to not be displaced and all appear to be mounted correctly in the frame, and none are torn. As you said the two at the front top are kinda difficult to spot but appear to be mounted correctly.
Those 4 gimbal mounts may very well be sagging down and not supporting the gimbal like when they were new. I don’t have another Mini to compare but IMO I think the gimbal should sit 2mm higher -and forward - of how it currently sits on a flat level surface.

I’m comfortable working on it and may replace the dampers, maybe, if not oh well, it still works and is a decent starter drone to learn on.

I have decided that the next (and more high end) drone I buy will be new and from an authorized reseller…now that I understand how delicate the gimbal is I will want a new drone for my next one - I take very good care of my things - and will want one that hasn’t been thru who knows what…

In the meantime these little devils sure are fun, and useful, I recently realized it’s a great way to examine my roof after a wicked storm haha…

 

[Deleted member 103366]

These may be of some use.
The "lead in"s shown on the spare dampers are presumably cut off once the damper is fitted, the photo is from an ebay advert.
The front damper photo is of a damaged gimbal ( both rear frame legs broken off) and the gimbal was most likely NOT in the 'correct' position when that photo was taken but it shows, adequately, how things connect.

Using your penny idea as a feeler gauge, the clearance between my drone's body (some where around the on/off button) and the book is between 0.8mm (go) and 1.4mm (no go). Just in case it makes a difference that was with the battery installed.
That suggests your drone itself is not sitting "low".

 

[IntoTheSun]

These may be of some use.
The "lead in"s shown on the spare dampers are presumably cut off once the damper is fitted, the photo is from an ebay advert.
The front damper photo is of a damaged gimbal ( both rear frame legs broken off) and the gimbal was most likely NOT in the 'correct' position when that photo was taken but it shows, adequately, how things connect.

Using your penny idea as a feeler gauge, the clearance between my drone's body (some where around the on/off button) and the book is between 0.8mm (go) and 1.4mm (no go). Just in case it makes a difference that was with the battery installed.
That suggests your drone itself is not sitting "low".

Ok thanks, good to know my MM sits normally, & thx for the photos, helpful.

I have ordered some PGY leg extenders and also a PGY camera hood (curious if this can be used with lens filters attached)(also curious how well it works on sun flare).

I have also ordered a set of new gimbal damper mounts - it looks to me as well that the OEM lead-ins of the dampers are cut off after the install (perhaps to save a fraction of a gram? or maybe interfere with gimbal movement?) but I will leave mine intact if they don’t interfere with gimbal movement - they should be a simple install process:
1) Remove the 4 screws holding the top cover on.
2) Carefully pry off the top cover.
3) Replace each damper mount one at a time.
4) (Optionally) Clip the damper mount lead-ins.
5) Replace the top cover.

I expect to receive all and do the install by next weekend Oct 16/17.

On the camera hood I plan to shoot videos while panning 360 across a low evening sun to see when sun flare presents - with & without the hood…

TBC

 

[Deleted member 103366]

Once you remove the top cover photograph the inside of the drone and save the photos, ditto photograph anything you remove BEFORE you remove it. (so you have a record of how thing fit together,)

I am not certain about "one at a time" of 3), to me that implies insitu and that may make fitting the dampers over the lugs on the arms of the gimbal's frame awkward. It might be better to first detach all 4 dampers from the drone then replace each damper on the gimbal.
Note there are protrusions in the top and bottom? of the 'groove' of the lugs, these protruaions mate with holes in the damper rubber, make sure they are mated.
There are two cables running to the gimbal from the drone, a flat ribbon cable and a round stranded cable. The ribbon cable is, I think, easily torn. It was torn on the crashed drone that I opened and looking at adverts for crashed minis on ebay I noted it was torn in quite a few of those adverts.
From memory it is, at the gimbal end, fairly east to disconnect it from the gimbal. I think I would be inclined to disconnect the ribbon cable before trying to replace the damper rubbers. It is a relative BEEP BEEP to disconnect it at the other end, besides which other bits of the cable run elsewhere and are stuck down.

When I was examining the crashed mini I did not have to worry about the above as the ribbon cable was already torn and both rear arms of the gimbal frame were broken so I simply disconnected both front dampers from the drone and then did what ever I wanted to do.

Before replacing the damper rubbers I would however check to see if the original dampers look stretched or deformed when compared to the new ones. If not look for other damage that could be the cause of the problem.

BE AWARE the gimbal assembly is electronically paired with a board or boards in the drone and if the pairing is broken repairing them is not a DIY job SO HANDLE the gimbal with CARE.

Do not let your prying tools penetrate deeply into the drone and have a GOOD look at MANY youtube videos to note the postion of the clips etc. that hold the top cover.

 

[IntoTheSun]

In short - if your gimbal doesn’t sit correctly or seems too loose - replace the gimbal damper mounts - note though that to remove the top cover and do this you will have to cut or remove or destroy the tiny warranty sticker that is attached to both the top cover and the body - inside the battery compartment - and therefore void any warranty. This procedure is primarily for no warranty Mini’s.

The full - Ok- I performed the gimbal damper mount replacements today and:

1. It resolved the issue (and topic of this thread) where - during power up gimbal calibration - the gimbal would tap the flat surface the Mini sits on - as the gimbal now sits a little higher - the movement that used to cause contact with the surface now clears by appx .5mm
2. I found the replacement process quite easy and inexpensive.
3. The (apparently) original and 1.5 year old gimbal damper mounts were permanently deformed and weaker (but not torn or damaged) and just old looking - these apparently have a limited lifespan and should be replaced periodically as regular maintenance.
4. Inside the covers in the gimbal area was in places fine (but abrasive to gimbal movement!) dust stuck to the insides of the covers. It only took very gentle air pressure to carefully blow out and clean out the insides of the covers and gimbal (extra special caution and gentleness on the gimbal!).
5. Being the first time I’ve opened up a Mini, the total time was less than an hour - next time it will take less than 1/2 hour to complete.

I went by my [previously posted] steps with the exception that instead of replacing one damper at a time, I removed and replaced the two on one side (one top and one bottom) onto the gimbal arms, then remounted them in the body, then the same for the other side. This procedure had two benefits:

1. The gimbal had enough movement to allow easy access to both mounts on one side by moving the gimbal ~gently~ as needed.
2. The remaining two dampers that were still in place held the gimbal assembly well enough to not strain the delicate cables attached to the gimbal assembly.
3. I did not cut the damper leads after installation as they are not in the way, and my scale did not register a difference in weight old vs new - the scale may not be accurate enough to show differences to the (I’m guessing) hundredths of a gram. BUT - if someone wants to make sure they don’t add weight and have to register then the leads could be cut after install. I’m going to register my Mini anyways so I didn’t worry about the leads.

I took pics of:

1. The tools I used (yes I use old guitar picks as spudger tools)(the quarter is for size reference)..
2. The old and new dampers - showing the old ones deformity. Pictured are the extra set of new dampers I bought.
3. The old dampers still in one side (right in the pic) and the new on the left to show how they sit differently and how the old ones were pleading for replacement. Kinda hard to see in the pic maybe…

 

[Deleted member 103366]

That's an interesting post. The comparison of the old and new dampers in very useful thank you.

 

[Deleted member 103366]

I am left wondering what caused the deformation, was the drone stored with the gimbal cover fitted and was the camera correctly seated within that cover?
I have a mini that was activated in November 2019 (2nd hand) and its gimbal still misses the book, its gimbal might be slightly lower than 'my own' mini (May 2020) but if so its not much lower/

 

[IntoTheSun]

Well…the Fly app says the drone was activated 545 days ago - I bought the kit on eBay about a month ago so don’t know it’s history over the past 1-1/2 years.
What I do know is that all components looked brand new, no nicks, scratches, signs of use, including the box.
The gimbal cover was on and the gimbal was situated correctly inside the cover - when I opened the box and initially took everything out.
I haven’t crashed it, I fly carefully and within my capabilities while I practice daily and slowly become a better pilot.
So the answer to that question is a mystery, perhaps at some point it was stored for some time with the camera not sitting in the gimbal cover correctly? Dunno…
But…no worries for me as the fix was easy and inexpensive