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How to balance the new 1345T quick release props...

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Glad to hear I got your explanation right, Joe, and thanks for clearing things up once again. lol

Btw, thanks as well for your input, Editor. : )

Hope this all helps you out, Jon.
 
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Glad to hear I got your explanation right, Joe, and thanks for clearing things up once again. lol

Btw, thanks as well for your input, Editor. : )

Hope this all helps you out, Jon.


You are very welcome and thank you for your input, Skynet1
I'm also glad the editor chimed in to strengthen the importance of safety.

I'll try to get that video done in a couple of days.

Joe
 
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Hi Joe,

thank you for your comprehensive reply; all extremely useful information.

If you do have the time to make an instructional video on dynamic balancing that would be
fantastic and may even give me the balls to try it (observing closely all of yours and Ed's safety advice),
and hoping I don't lose said balls in the process! I agree that dynamic would definitely be the most thorough method.
I don't have a workshop so would it have to be done on the dining room table. It's only an Ikea one so I don't mind
if I have to drill holes in it for strappage. I usually have a table cloth on it anyway and i'm not married so job done.

Nearly all of the hobby type shops you mention have all but dried up in my part of the world, probably down to
the proliferation of on-line sellers with such competitive pricing available now. Hey ho.

I will also have a look at your supplier for the motor hubs although i'm sure there must be a company in the UK
that can supply them. I'll have a good look.

Keep up the good work, and thanks again to all for trying to get this one sorted.

Jon
 
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You're very welcome, Jon!

Happy to know that my long writeups are useful. :)

I have an eye doctor appointment this morning and plan to start filming when I get back from that.
I'll show the setup along with the steps involved to balance one prop, then all ya have to do is repeat the same steps for balancing the other three, or however many you have to balance (spare props if you have them).

Mine will be done on a folding picnic table in my dining room as well so you don't need a shop to do this. My shop is a real mess right now.
One other thing to keep in mind, these Inspires don't put out that much lift with just one prop so there's no real worries about it lifting the table. Just make sure it's securely strapped down.

Thanks again and hopefully I'll have a video up by this afternoon (eastern USA time).

Be back soon.

Joe
 
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Out of curiosity, if there's conclusion that motors by themselves can be out of balance, what's to prevent the 'other three' motors from inducing some vibration into the system when trying to dynamically balance the forth motor/prop combination? I can see this becoming an iterative process.

I suppose it's possible that the magnitude of vibration incidence from three prop-less motors is orders of magnitude less than the prop'd motor. I just don't know.
 
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Out of curiosity, if there's conclusion that motors by themselves can be out of balance, what's to prevent the 'other three' motors from inducing some vibration into the system when trying to dynamically balance the forth motor/prop combination? I can see this becoming an iterative process.

I suppose it's possible that the magnitude of vibration incidence from three prop-less motors is orders of magnitude less than the prop'd motor. I just don't know.
I think you may have just answered your own question, Rush :)

Seriously, you are right. It has everything to do with the huge difference in the levels of magnitude between propless motors and one with a prop on it.
There are things like what moment the weight is at that have to be considered. In other words, a slight amount of weight near the hub wouldn't be very noticeable while that same amount of weight at the end of one of the blades will be very noticeable.
The motors have no choice but to have a small moment since the motors aren't large in diameter.

We're on the same page. :)

One thing that Jon may have to do while using a 45mm lens even after doing an "As close to Perfect Balancing job as possible" is to experiment with different dampers. Damper durometer has a lot to do with what frequency and what amplitude the vibration is at. Dampers are designed to dampen certain ranges of vibration frequencies and amplitudes. Using the wrong dampers can keep a fella from ever getting it right.

Well, my break is over for now. I'm working on an instructional video on dynamic balancing and need to finish it up.

Thanks, Rush!! :)

Joe
 
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Thanks Joe, nothing new there ... Moment arms, harmonics, momentums, etc. it just occurred to me that the prop in question really wasn't isolated from the rest of the system.

Not sure how I'm going to move forward yet. Not excited about taking my hubs off and on, and I don't think you can buy hubs for the new motors and QR props yet. I only see the adapters in the store.

Mirror system is not a bad route. It's the trial and error part to determine which half of the prop to tune that frustrates the process. If I could buy hubs, I'd go that route. With that not possible, I may try live balancing.
 
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Thanks Joe, nothing new there ... Moment arms, harmonics, momentums, etc. it just occurred to me that the prop in question really wasn't isolated from the rest of the system.

Not sure how I'm going to move forward yet. Not excited about taking my hubs off and on, and I don't think you can buy hubs for the new motors and QR props yet. I only see the adapters in the store.

Mirror system is not a bad route. It's the trial and error part to determine which half of the prop to tune that frustrates the process. If I could buy hubs, I'd go that route. With that not possible, I may try live balancing.
I understand completely.
Looks like they would have hubs available for purchase but that's DJI for ya I guess. :)

I've been working on an instructional video showing how the frustration part is at least reduced.
Problem is, I'm not used to being on the "Other" side of the lens. Lol :-O
Time for take three tomorrow.

At least it shows my presentation flawsI. I need to work on to work on that part (a lot) Lol
 
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Hey fellas,

I managed to finish the video but there's a problem I didn't count on.

I've always balanced my S800 and S1000 using the dynamic method (at least ever since I discovered that the static method wasn't good enough for those models) and has never been a problem but I can put those in full manual mode which means it doesn't use Atti or GPS.
In manual mode, you fly them with full control from the transmitter (no assistance from the flight controller at all). You can even do a flip with them as long as you have enough altitude for recovery while in manual mode (not sure why you would want to but you can).

I found out the hard way that these Inspires are a much different story. I didn't think it would be a problem except for not having precise control over the throttle range.
When I throttle it up, it goes full speed and when I bring it back to mid stick it goes idle since it never left the ground.
I disabled the VPS system and put in Atti Mode before doing the balance but the computer is still looking for it to gain altitude before it will throttle back to the normal speed for hovering and for descending or ascending. It will try as hard as it needs to to gain altitude and since it's not, it goes to full throttle.

During my last spool up, it actually hung in the full throttle position even when I brought it back to mid stick, the only time it slowed down was when I brought the throttle all the way down and even then it took much longer than normal to shut down. For a couple of seconds, I thought I was going to have to shut the battery off to get the motors to shut down.
It did throw the IMU way out of calibration. Luckily, it did do OK after I did the full IMU calibration.
After a lengthy discussion with DJI Tech Support about what happened, they confirmed that its not a good idea since the Inspire is actually tilting the wrong way.
In a high wind flight, the Inspire will tilt into the wind but in this case it's tilting the wrong way and causing the gyro and accelerometers to work against the computer's algorithms.
It may do this for a second or less in an actual flight but certainly not for an extended period of time like it is when performing a dynamic balance.
All it needs is a second or less to cycle through the PID Loops three times (each loop being less in amplitude from the previous loop and it only takes about 1/4 of a second or so to go through a single loop). The programmed algorithms tell those PID Loops how to react in normal flight as well as when a high gust of wind is encountered.
The only way to prevent this is to have the Inspire strapped down very tight and then it picks up resonance from the table which defeats the purpose and gives you a false reading in the reflected laser beam so either way, it's not good.

I figured it was flighting the IMU the first time I balanced mine but it never caused the IMU to lose it's calibration and hang at full throttle............until this time.

So, I no longer recommend using the dynamic method for balancing the Inspire props.
I sincerely apologize for promoting the dynamic method! I was wrong to do that but it was an honest mistake.
It worked and still does if you have a multirotor that has a fully manual mode such as the S800, S900 and S1000 Etc.

I do have good news though!! :)

DJI has done away with the conversion hub kit that was made just for the original Inspire 1. Now they are all the same. That same hub WILL work on the V2 and the Pro Model. It will work on all Inspire 1 series now.

While on the phone with DJI, we discussed that issue and they made it clear that the new hubs are made for all Inspires now.
If you'll go to DJI's website, click on the link for the STORE (big blue link at the top), then scroll down to the Inspire 1 Pro or the V2.0 model (either one), click on that, then scroll down to RECOMMENDED ACCESSORIES bar, look for a little blue link (named MORE) to the right and just above the accessories bar, click on that and it will take you to a page for the accessories, scroll down to the seventh line, the hubs are the first one on the left and it IS now made for the V2 and the Pro models as well as the original Inspire 1 series. Order just one kit cause it has one CW and one CCW complete hub set in that kit.
With this new hub set, you can accurately static balance your props if you use EJH's adapter rod.
That's it, now there is a reliable solution to static balance the 1345T props without having to remove your own hubs.

Unfortunately, I still can't find anyone willing to 3D print my design. It doesn't matter to me, I just want everyone to be able to balance their props!

BTW, Mark (the editor) was more right about the need to hold the Inspire from moving at all!! Thanks, Mark!!

One other thing you can do, is to put your Inspire into a hover and tilt your camera up to the point where you can see the props while in flight. Do a 360° rotation of the camera while having it pointed at the props. Shoot it at 60fps, then put that footage into your editing software and slow it down to 40% of it's original speed to see if there is any movement in the arms or to see if the gimbal is bouncing around (or at least moving back and forth). With the camera being that close to the props and arms, you'll notice if the camera is static or if it's moving around. This needs to be done on a calm day or the wind may cause the gimbal to move.

I've uploaded a video that I shot of my S800 after I static balanced three props and dynamic balanced the other three props. The three props that were static balanced caused the arms to flex, the others did not flex.
Keep in mind that the S800 was notorious for having arms that would flex so those props HAD to be PERFECTLY balanced to keep the arms from flexing.
The S800 EVO arms are much stronger and flex much less. The dynamic balancing method for those multirotors is much different than it is for the Inspire.

Also keep in mind that the Inspire arms themselves won't flex, however, the arms aren't fixed solid into the "T" shaped pieces that the arms are held by. There is a little play there and it will show up in a video that's been slowed down. You have to slow it down to see it. Viewing it at the normal speed is just too fast to see the movement.
I filmed my first Inspire before balancing the props to see if it was noticeable and it was. After balancing the props, there was no movement.
I didn't keep the video though, at the time it was taking up much needed external hard drive space so I deleted it.
I will film it again next time I get a set of props that need to be balanced. I'll film it again before and after balancing the props and keep the video next time.

I suggest that you film the props after a balance job just to make sure it's as balanced as it should be but that's up to you of course.

Jon,
You may have a hard time getting your 45mm lens to be really smooth. The reason I say this is because at that focal length, any tiny movements will be magnified and I'm not sure that even a set of different durometer dampers will take care of it. It may take something along the lines of the Z15 gimbal to hold a lens steady at that focal length but I could very well be wrong. You may just have to experiment with it.

Here's a link to the 1345T prop hubs for the Inspire 1, Inspire 1 V2 and the Inspire 1 Pro: Buy Inspire 1 Series - 1345T Propeller Installation Kit | DJI Store
Order it from DJI though cause if you order it from someone else, it may be one of the early conversion kits. It has the same part number, go figure!

Here's the link to the video of my S800 filming the props while in flight:

P.S. I did verify that the likelihood of actually damaging the IMU is very, very slim unless you do it a bunch of times but in my humble opinion it's not worth the risk.
Again, if I had known that the IMU would have been at risk, I not only would not have suggested it to you guys but I would have never done it myself.
I was worried about it so I sent mine in to be checked. I just got it back (very quick turnaround too) and they confirmed that no damage was done but it was suggested to not use the dynamic method again.
I asked if DJI was going to come up with a balancing tool for the 1345T props but they said that there were no plans for it at this time (at least as far as the tech guy knew).

Again, my sincere apologies to everyone!! It's been a learning experience for all of us with these odd shaped prop hubs.

At least now we know we can order a direct replacement hub for the V2 and the Pro models.
It would have nice if DJI had made some type of an announcement about that part. I guess they have a lot on their plates eh?

I wish I had figured this out before spending the time to make the video that isn't any good to anyone, but that's OK. At least nobody did any damage that I'm aware of.

Sincerely,

Joe
 
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Hey fellas,


Hi Joe,

thank you for the update and sorry you had to go to all that trouble only to come across such an insurmountable problem.
Rest assured your efforts and posts are very much appreciated. You've already helped me a huge amount in understanding
the technicalities and importance of prop balancing and the fact that you've actually attempted this is invaluable knowledge.

I've just ordered an EJH rod for the 1345T although there may be problems with a permit for shipping to UK addresses. We'll see.
I also followed your instructions for the 1345T Prop installation kit from the DJI site, (not from other vendor). I ordered the kit that
was 6 rows down and 3 in as it may be different on the US DJI site, not sure.

Regarding the 45mm Olympus lens i'm using... I've done some tests and it's actually pretty good, i'm only getting un-usable wobble
when flying in a breezey wind and it seems worse when lowering throttle to track down. I still need to do more tests over the next few
days but really looking forward to giving the static balancing a go when I have the tools. Once done i'll film them like you said to look
for any play around airframe connections.

Cheers,

Jon
 
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Sorry all, don't know why it came out all italic and in that grey box. Hope you managed to see my post anyway Joe.

Cheers,

Jon
 
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Sorry all, don't know why it came out all italic and in that grey box. Hope you managed to see my post anyway Joe.

Cheers,

Jon
Yes, I was able to read it fine, all I had to do was expand it to read the entire message and thanks for the response.

The DJI Tech guy guided me to the prop hubs on their website and said which line, etc. so it being in a different place on yours must be the difference between UK and US websites as you said.

I'm happy to know that you are getting good results with the 45mm lens except for in wind and when descending. I can see where the wind and descending would be an issue.
I've seen my X3 and X5 cameras move around in wind but it's not noticeable since the subject is at a distance and the focal length is no more than 20mm on mine.
I tend to think that the slight movement in the arms where it attaches to the "T" helps to keep vibrations from reaching the main frame to a point but I'm sure there's a limit.
I'm wondering if your 45mm lens still wobbles at very slow descents and in calm wind?
Have you tried using slightly stiffer dampers with the 45mm lens? Just curious.

It sure seems like they would make it easier for people in the UK to order from the US. That's been a real problem for many years!

When I was filming the instructional video for dynamic balancing, I went back and read my notes. I used a piece of wax paper to hold the prop over when I done the sanding, the idea was to capture the material removed from the prop and weigh it (some was imbedded in the 600 grit sandpaper but very little). After weighing the dust, the most I ever had to sand off was about 2 grains which is only about 1/12th of a gram. That's pretty minor in my opinion. 4 out of 16 props were less than 1 grain. To me that means that the stock props are pretty close as is.

I applied a very thin coat of wax to make the props slick again to reduce drag where it had been sanded, I applied wax to the bottom of both blades evenly to keep it in balance. That worked pretty good.
The drag on the side where it's sanded does cause that blade to track slightly higher than the other blade. I'm still splitting hairs by being so particular about it. Maybe even a little overboard, I don't know if all this is paying off but I'd like to think it is.
The DJI Tech guy seemed to think all I've done is a good idea (except for the part of using the dynamic method). He said he's seen earlier Inspires come in that needed new IMUs because they weren't working right anymore. He seems to feel that minor vibrations over time are the culprit.

I told my friend Mike at the hobby shop that does dynamic balancing for his customers about this so he quit offering it but he suggested setting up a CW and CCW motor with ESCs controlled by a standard PWM controller like a servo match box so it wouldn't be connected to the Inspire anymore. That way he could accurately control the motor speed through the entire range without it going to full throttle by itself. Then set them up on a permanent test bench so he could continue to perform dynamic balancing for his customers.
It makes sense to me but it would be a lot of cost and work for the average Inspire owner just to balance his or her own props. With him providing that service, it would be worth the expense and trouble.
He has 3 or 4 crashed Inspires at his shop that he could use to put most of it together but would still need to buy the motors, hubs and ESCs.

I still feel really bad about suggesting that people use the dynamic method until a better static method could be used. If the Inspires had a manual mode, it would work great but they don't have that option. Even in Atti mode, it's still trying to gain altitude and go full throttle. It won't try to tilt itself into the wind like in GPS mode since it will drift with the wind in Atti Mode, but it's still not good.

At least now they use the same prop locking hubs for the entire Inspire 1 series.

Thanks again, Jon

Best wishes,

Joe
 
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So to balance the 1345Ts I have to remove the hub from the motor?? No one makes a device to use that does not require that step. I'm awful nervous about going around removing hubs...
It's just 2 small screws and the hub comes off!
JE
 
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ejh is not showing that he has got any for sale, how is everyone getting on with the balancing of 1345t props?
 
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I ended my balance problems by switching to 14" t-motor carbon fiber props. I still had to do some balancing on them but it was a piece of cake compared to the stock props, hubs, special rods... I also changed to a simple magnetic balancer and throwed the Du Bro balancer in the trash.

Never heard before that someone used after market dampeners on inspire and 45mm lens, is there a discussion thread somewhere?
 

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