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

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#81
I started second-guessing my last tests because so many people chimed in that they had trouble with their props being out of balance and I seemed to have 12 that were perfect. I found that I made a critical mistake when using the laser technique. I had my drone tied down too tightly against REALLY compressed foam. I believe that I tied it so tight that it dampened the vibration too much.

SO, (and I feel like I was back in a college physics lab), I got a nice thick piece of foam and tied the drone loosely enough that it didn't move more than an 1/2 inch or so when I engaged the motors. As Joe said, just so it barely compresses the foam. Doing it that way, I had vertical lines everywhere!!! (Still no horizontal or C-shaped patterns though). With twelve props using trial and error and with my lack of experience, it would have taken me hours with trial and error to get them all balanced.

The EJH rod just came in the mail, so I used that. It was no hassle at all taking out two screws on each hub. 11 of the 12 props I owned needed a little sanding and 2 of them needed a lot.

So then I retested each prop on the laser table and the dot patterns were spot-on. I didn't find any out of balance after balancing with the EJH rod.

My conclusions:
1. If you have a new DJI prop, it is probably out of balance.
2. Both techniques are very effective for finding unbalanced props.
2. The EJH rod is easy to use as you simply remove the hub, attach the rod and start balancing. In addition to the rod, I would recommend a good prop balancer. Purchasing the rod and the balancer cost me more than using the laser technique.
3. The "Joe Technique" requires a laser pointer, a reflective surface, a way to attach the reflector, a vise for the laser, a nice piece of foam, a way to tie down the bird, and a good location to work. (You want the laser to reflect a good distance away so you can see the vertical lines easier). All of these materials (except initially for the foam) were in my shop already. This will help detect if your motor is out of balance as well if your prop needs work. And this technique is much cooler. You get to play with a laser and it does not involve cats.
 
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#82
Good afternoon, :)

I managed to complete the calculations for the density of the prop material and was able to get a good idea of the density of the materials used for 3D printing. I based the design modification on the data from those calculations (modification of gray52's design). I hope I chose the right 3D printing material for my calculations. According to research and calculations, the size to weight ratio of the 3D plastic is heavier than the size to weight ratio of the prop material. The 1345T props are very light weight.
I don't have a straight carbon fiber version of the 1345T prop and there may be a difference in weight there. If some pilots use straight carbon fiber props, we may need a different adapter, or, it could be that this one will be close enough (depending on the weight difference).
Could anyone with a 1345T straight carbon fiber prop weigh the two versions of props (Carbon fiber reinforced 1345T prop weight - vs. - Straight carbon fiber 1345T prop weight?)
It would be much appreciated!

I've read where some pilots feel that the stock prop outperforms the straight carbon fiber props but I don't know how accurate that info is. One pilot said that he gets more flight time with the stock props as well as better overall performance. My associates also have the stock props like myself.

Again, we should make a prototype and test it before going any further.

This drawing is for the CCW prop. Once we know the weight ratio is correct (by testing it), I can draw the one for the CW props (that one will be easy, all I have to do is reverse which side the tapered, flat sided part comes out on with the round part that slides onto the standard balancing rod that comes with the "Dubro" balancing tool). The hole in the prop adapter is deep enough to insure it's centered and held in place accurately.
I plan to install a rod in each adapter (one for CW and the other for CCW) and just leave them on. I already know we can order as many replacement rods for the Dubro balancing kits as we want. The part number is DUB959
If I have this right, most 3D printing is done using STL files. Exporting this drawing from my CAD software in STL isn't a problem at all. I can export it in STL, then share it on GrabCad so gray52 or whoever happens to be the one to print it, will have direct access to the file for download (Or, I can share it with my online CAD account for collaborating so it's private).

I had to go about this a little different from what I originally had in mind.
I thought of the smallest diameter of the prop hub as though it were the main hub, then I started thinking of the added sections of the largest diameter of the hub as added weight. Once I done that, all I had to do was add weight to the disc itself to counteract the added weight of the outer portion of the prop hub. This approach just made it easier to figure out.
Keep in mind that a portion of the motor housing counterweight is meant to counterbalance the added weight portion of the prop. The motor housing counterbalance also accounts for the small portion of the locking tabs that fit into the notches on the prop. The rest of the motor housing counterweight is for the remaining weight of the locking tabs and locking hub "that aren't part of the prop balance".

I realize that the weight is actually already in the prop now but part of it is closer to the center of the prop hub and part of it is farther away from the center of the prop hub.
This causes an imbalance due to the moment of where that weight is at.
I'll give you an example of what I mean by "Moment" if you don't already know:
If you take a standard airplane prop and you add 1/10th of an ounce to one side of the prop but you add it very close to the center of the prop, there will be little effect on the balance.
Now, take that same 1/10 of an ounce and add it to the tip of the prop (as far away from the center as you can get it), suddenly, you will notice a LARGE effect on the balance.
It's kind of like a seesaw that kids use at a playground. If you have a 50 lb child on one end and a 150 lb adult on the other end, it won't work. But, if the 150 lb adult moves just close enough to the center of the seesaw, the "Effective" weight is now the same on each side of the seesaw.
In other words, the "moment" is the distance from the center or pivot point of an object to where the weight is placed.
Concrete vibrators use a perfectly round disc but they cut away weight from one side to cause the motor to vibrate at a high speed, the farther the weight is from the shaft on one side, the harder it will vibrate, the closer the weight is to the shaft on one side, the less it will vibrate. It will still vibrate at the same speed but not as hard or violent if the weight is closer to the shaft. I think you get the idea by now (if not at the beginning;)).
This is the entire principle behind this very simple design modification. Yes, it does require a fair amount of complex calculations but the design and concept itself is still simple in nature.

Personally, l like having the disc for the prop to press up against. This will prevent damage to the prop by not allowing the prop to move sideways on the part that goes up into the prop. Sideways movement could spread the sides of the hole apart (which would make it bigger than it should be by stretching it out). The taper in the prop hub hole helps a lot. Not hard to draw in CAD either.

Another thing we need to test is how snug the prop balancing adapter fits into the prop hub. It needs to fit "just" snug enough to hold it in place while balancing but not so tight that it would spread the sides of the hole apart.

Below are some photos of the design in CAD. I captured the photos using a screen snipping tool so you all can see what it will look like.
The gray part is a drawing of the center hub of a 1345T CCW prop without the blades, in all other aspects, it's exactly the same with the exception of a slight amount of athletics. I didn't want to spend too much time making a perfect looking prop hub in CAD. I can also round off the sharp corners on the balancing adapter just a bit so they aren't so sharp. This is a fairly rough drawing but it is the right size down to within .001" tolerance.

If these can be printed in white and red, (white for CCW and red for CW), it would help a lot when it comes to attaching a prop to be balanced.

Let me know what you think.

I'll ask gray52 to have a look as well.

Thanks! :)

Joe

Prop Balancing Adapter - Expleded View.JPG Prop Balancing Adapter.JPG Prop Balancing Adapter - Top View.JPG Prop Balancing Adapter - Side View.JPG
 
Joined
Feb 13, 2016
Messages
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Age
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#83
I started second-guessing my last tests because so many people chimed in that they had trouble with their props being out of balance and I seemed to have 12 that were perfect. I found that I made a critical mistake when using the laser technique. I had my drone tied down too tightly against REALLY compressed foam. I believe that I tied it so tight that it dampened the vibration too much.

SO, (and I feel like I was back in a college physics lab), I got a nice thick piece of foam and tied the drone loosely enough that it didn't move more than an 1/2 inch or so when I engaged the motors. As Joe said, just so it barely compresses the foam. Doing it that way, I had vertical lines everywhere!!! (Still no horizontal or C-shaped patterns though). With twelve props using trial and error and with my lack of experience, it would have taken me hours with trial and error to get them all balanced.

The EJH rod just came in the mail, so I used that. It was no hassle at all taking out two screws on each hub. 11 of the 12 props I owned needed a little sanding and 2 of them needed a lot.

So then I retested each prop on the laser table and the dot patterns were spot-on. I didn't find any out of balance after balancing with the EJH rod.

My conclusions:
1. If you have a new DJI prop, it is probably out of balance.
2. Both techniques are very effective for finding unbalanced props.
2. The EJH rod is easy to use as you simply remove the hub, attach the rod and start balancing. In addition to the rod, I would recommend a good prop balancer. Purchasing the rod and the balancer cost me more than using the laser technique.
3. The "Joe Technique" requires a laser pointer, a reflective surface, a way to attach the reflector, a vise for the laser, a nice piece of foam, a way to tie down the bird, and a good location to work. (You want the laser to reflect a good distance away so you can see the vertical lines easier). All of these materials (except initially for the foam) were in my shop already. This will help detect if your motor is out of balance as well if your prop needs work. And this technique is much cooler. You get to play with a laser and it does not involve cats.

Lol, I got a kick out of the last part of your post about playing with lasers and it not involving cats. I used to have a lot of fun with lasers and getting the cat to chase it :)

I wonder about just buying an extra set of CW and CCW locking hubs to have on hand to static balance your props using EJ's balancing tool? I think they are only like $10 or $11 each.
That way you wouldn't have to remove the hubs from your Inspire motors when you want to balance a new set of props.
With time, these props will wear out and get a little sloppy so I imagine we will have to buy new props from time to time. Not a bad thing to me, they aren't very expensive ($20 for 4?).
We may even have to replace the locking hubs from time to time as well? (due to wear over time).

I had mentioned earlier that using the laser method could be a good way to troubleshoot in case they still seem to vibrate after doing a static balance. I still feel that way.

I balanced a friends Inspire props last night with EJ's tool, then tested the results with the laser and found only one that didn't pass (out of eight). It turned out to be part prop and part motor imbalance but mostly motor (one of the fine balancing compound dots or blobs had come out of the motor housing).
I spooled the motors up without the props and we could feel the higher level of vibration on that one motor where the compound had come out. I was hoping it would be obvious if the motor was in fact out of balance and it was obvious.
I just bought some balancing compound yesterday from an electric motor shop that rebuilds motors. I took my Inspire with me and showed it to them, they knew immediately which kind of compound to use for that application, luckily they had some in stock. It's a two part epoxy and very sticky!
I installed the compound last night on the imbalanced motor and checked on it this morning, it had hardened and it's in there to stay this time! (curing time was overnight if indoors in the heat) Then I spooled it up this morning and the vibration is history. The guy I spoke with said to put part of the compound on the vertical fin and part of it on the top of the housing (in the corner where the two meet), he said it would bond better that way and I immediately saw his point.

I'm glad you got everything all balanced now!! :)

For mine, in calm wind, it sit there in a very steady hover with no vibrations at all. We shot raw video from a tripod with a good DSLR at 60fps with a 24-70 Zeiss lens, then slowed it WAY down in the software to see if there were any vibes, it was all good!! I'm very pleased!! :)

All the best,

Joe
 
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#84
Looks very slick, Joe. A viable alternative indeed.
These adapters in combination with the Dubro Balance kit may work very well. Then again purchasing a couple sets of motor hubs along with EJ's balance Rod as mentioned would have probably worked as intended without removing and reassembling the hubs as suggested.
I should have thought of that before deciding to return it. Stupid is as stupid does. I never thought to check the availability of those hubs. : (
Generally some parts are not readily available, but I should have checked anyway. : ) Thanks for going forward on this, again very nice workup.
 
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#85
Looks very slick, Joe. A viable alternative indeed.
These adapters in combination with the Dubro Balance kit may work very well. Then again purchasing a couple sets of motor hubs along with EJ's balance Rod as mentioned would have probably worked as intended without removing and reassembling the hubs as suggested.
I should have thought of that before deciding to return it. Stupid is as stupid does. I never thought to check the availability of those hubs. : (
Generally some parts are not readily available, but I should have checked anyway. : ) Thanks for going forward on this, again very nice workup.

Hi Skynet1,

Don't feel bad, I do stuff like that all the time and later kick myself for not thinking of it myself (or if someone else points it out to me).
At my age, I'm almost old enough to call it a "Senior Moment" :rolleyes:

I done some research on the new 1345T prop hub conversion kits made for the Inspire 1 series and finally found the evidence I had been looking for.
Those conversion kits are for sure made specifically for the 3510 motors and NOT the 3510H motors because the balance of the two motors of ARE different.
They are telling me that the conversion kit is only compatible with the 3510 Inspire 1 models and NOT the Inspire 1 V2.0 or the Inspire Pro models. (I decided to call DJI support and that's exactly what they told me). It took me a while to get through to them but eventually I did get to talk to someone.
I also found a supplier that states that the conversion kits are only compatible with the Inspire 1. >>>>>>Check it out HERE<<<<<<<. Look at the tab where it reads Compatible With (2).

DJI Support says: "Don Not Use the Conversion Kit Hubs on the 3510H Motors" that come with the Pro or V2.0 models. They WILL be "Out of Balance"
So, the only choice for replacement hubs for the 3510H motors is to buy the hubs made for those motors (again, because of the balance). I suspected that DJI added the needed weight to the conversion kit model and they in fact did just that according to DJI Support (The DJI support guy transferred me to one of their tech guys over the phone)
The biggest problem at the moment is that the hubs for the 3510H motors are not so easy to get your hands on yet. So it's a good thing that you didn't buy the conversion kit (if that's what you were thinking of doing). I was hoping they would work too so I could buy one myself. I want a set to use with to use with EJ's adapter (which I still have). I guess I'll just wait until the 3510H hubs are more readily available. I actually like EJ's adapter.

gray52 has already added a disc to his design but there's no counterweight on the disc. I'm not sure if that's a problem until I try it. I'm going to order one to see how good it works.
He lives in the UK and there seems to be a slight communication gap there but he does have them in stock. Not too high priced either, they are $15 with the rod, plus $10 for shipping to the USA.
I'm not sure how well they fit but I'll find out as soon as I get one.

I'm attempting to try all of the available options that are already out there before I try to talk someone into making my design. As I understand it, gray52 isn't interested in making them.

Please keep in mind that I'm only trying to help people with balancing these props as easily and as accurately as they can.

I'm one of those guys that won't stop at good enough if there may be a better way. Also, I don't stop until I've exhausted all possibilities. If that approach doesn't work, I'll design something and try to talk somebody into making them for us.

Has anyone been able to check the difference in weight between the standard props and the full carbon fiber props yet? I may buy a set of them myself to see if the same method can be used for either one with good results.

I have to admit that I personally have a much simpler method of balancing these props with a laser but I can't advise people to do what I do. It's one of those "Don't try this at home" things.:D
It is safe if you really, really pay very close attention to what you're doing to keep from getting cut or at least nicked. I don't use a strap at all but I do use a dense but spongy foam rubber pad under one leg. It only takes me about 20 minutes or so to balance eight props. I have to advise people to do it the safest way possible. I don't want anyone getting hurt as a result of my advice.

Off topic here but I done some filming of a power plant today, I was also filming the coal piles and the coal trains today with the winds at only 6 mph with overcast skies. I was filming something that needed to have overcast skies.
I was monitoring my handheld STS7600VOR Aviation Transceiver but I didn't hear any radio traffic even on the unicom frequency (I was scanning too). Suddenly, I heard a full scale helicopter nearby. I asked my VO to find out where that bird was coming from and which way it was headed and do it fast as I began to bring my Inspire down to land since I didn't know where the helicopter was at! The helicopter popped out from behind some trees and it turned out to be a Bell Ranger and was about 400 ft away from my Inspire. I was only flying at 200 ft. altitude but I was afraid mostly that his downwash would knock my Inspire around too much (possibly to the point where I may loose control). I had quickly tilted my Inspire to about 45 degrees and came down fast but it still caused my Inspire to begin wobbling around violently (even at around 500 ft away by that time). The inspire held without rolling over and the only problem with the video was the occasional view on of the arms and props in the top of the video. The video was still very steady even in those conditions.
BTW, I was 15 miles out in the country and 20 miles away from the nearest airport or heliport. Turns out that the Ranger was landing at the power plant and was on an unpublished or private frequency (that's my guess anyway). I had talk with the GSO Tower and asked them to advise of any traffic in the area but I never heard anything from them. I contacted them afterwards and they said that they couldn't see it on their radar. I guess they were flying the treeline around the lake at the time and it didn't show up on the radar. I have a good relationship with GSO. I've been flying a Cessna 172 out of GSO since 1987 so we know each other pretty well.

I bought a plaque to hang on my wall years ago that reads: "Flying is hours and hours of boredom, punctuated only by moments of stark raving terror" I bought that plaque right after having to land in a 40 knot crosswind (about a 45 degree angle crosswind). :( Talk about a serious crab angle!! whew!! After landing on the upwind side of the runway, they wind literally pushed me to the other side of the runway and into the grass facing into the wind. I had to fly the 172 while on the ground till they came out to tow me back to the hanger. It was a good landing though! I was able to walk away from it! :)

Oops, this has almost turned into a book :D

All the best,

Joe
 
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#87
Anyone got any links to UK suppliers. Just got my first batch of pros for the new I1p and need to balance them. Any other suggestions appreciated
I've been searching for a UK supplier but without success, sadly.

I keep dipping in to Google now and again in the hope of coming across a UK supplier or even a USA supplier that will ship to the UK
 
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#89
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#94
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#95
Hi Skynet1,

Don't feel bad, I do stuff like that all the time and later kick myself for not thinking of it myself (or if someone else points it out to me).
At my age, I'm almost old enough to call it a "Senior Moment" :rolleyes:

I done some research on the new 1345T prop hub conversion kits made for the Inspire 1 series and finally found the evidence I had been looking for.
Those conversion kits are for sure made specifically for the 3510 motors and NOT the 3510H motors because the balance of the two motors of ARE different.
They are telling me that the conversion kit is only compatible with the 3510 Inspire 1 models and NOT the Inspire 1 V2.0 or the Inspire Pro models. (I decided to call DJI support and that's exactly what they told me). It took me a while to get through to them but eventually I did get to talk to someone.
I also found a supplier that states that the conversion kits are only compatible with the Inspire 1. >>>>>>Check it out HERE<<<<<<<. Look at the tab where it reads Compatible With (2).

DJI Support says: "Don Not Use the Conversion Kit Hubs on the 3510H Motors" that come with the Pro or V2.0 models. They WILL be "Out of Balance"
So, the only choice for replacement hubs for the 3510H motors is to buy the hubs made for those motors (again, because of the balance). I suspected that DJI added the needed weight to the conversion kit model and they in fact did just that according to DJI Support (The DJI support guy transferred me to one of their tech guys over the phone)
The biggest problem at the moment is that the hubs for the 3510H motors are not so easy to get your hands on yet. So it's a good thing that you didn't buy the conversion kit (if that's what you were thinking of doing). I was hoping they would work too so I could buy one myself. I want a set to use with to use with EJ's adapter (which I still have). I guess I'll just wait until the 3510H hubs are more readily available. I actually like EJ's adapter.

gray52 has already added a disc to his design but there's no counterweight on the disc. I'm not sure if that's a problem until I try it. I'm going to order one to see how good it works.
He lives in the UK and there seems to be a slight communication gap there but he does have them in stock. Not too high priced either, they are $15 with the rod, plus $10 for shipping to the USA.
I'm not sure how well they fit but I'll find out as soon as I get one.

I'm attempting to try all of the available options that are already out there before I try to talk someone into making my design. As I understand it, gray52 isn't interested in making them.

Please keep in mind that I'm only trying to help people with balancing these props as easily and as accurately as they can.

I'm one of those guys that won't stop at good enough if there may be a better way. Also, I don't stop until I've exhausted all possibilities. If that approach doesn't work, I'll design something and try to talk somebody into making them for us.

Has anyone been able to check the difference in weight between the standard props and the full carbon fiber props yet? I may buy a set of them myself to see if the same method can be used for either one with good results.

I have to admit that I personally have a much simpler method of balancing these props with a laser but I can't advise people to do what I do. It's one of those "Don't try this at home" things.:D
It is safe if you really, really pay very close attention to what you're doing to keep from getting cut or at least nicked. I don't use a strap at all but I do use a dense but spongy foam rubber pad under one leg. It only takes me about 20 minutes or so to balance eight props. I have to advise people to do it the safest way possible. I don't want anyone getting hurt as a result of my advice.

Off topic here but I done some filming of a power plant today, I was also filming the coal piles and the coal trains today with the winds at only 6 mph with overcast skies. I was filming something that needed to have overcast skies.
I was monitoring my handheld STS7600VOR Aviation Transceiver but I didn't hear any radio traffic even on the unicom frequency (I was scanning too). Suddenly, I heard a full scale helicopter nearby. I asked my VO to find out where that bird was coming from and which way it was headed and do it fast as I began to bring my Inspire down to land since I didn't know where the helicopter was at! The helicopter popped out from behind some trees and it turned out to be a Bell Ranger and was about 400 ft away from my Inspire. I was only flying at 200 ft. altitude but I was afraid mostly that his downwash would knock my Inspire around too much (possibly to the point where I may loose control). I had quickly tilted my Inspire to about 45 degrees and came down fast but it still caused my Inspire to begin wobbling around violently (even at around 500 ft away by that time). The inspire held without rolling over and the only problem with the video was the occasional view on of the arms and props in the top of the video. The video was still very steady even in those conditions.
BTW, I was 15 miles out in the country and 20 miles away from the nearest airport or heliport. Turns out that the Ranger was landing at the power plant and was on an unpublished or private frequency (that's my guess anyway). I had talk with the GSO Tower and asked them to advise of any traffic in the area but I never heard anything from them. I contacted them afterwards and they said that they couldn't see it on their radar. I guess they were flying the treeline around the lake at the time and it didn't show up on the radar. I have a good relationship with GSO. I've been flying a Cessna 172 out of GSO since 1987 so we know each other pretty well.

I bought a plaque to hang on my wall years ago that reads: "Flying is hours and hours of boredom, punctuated only by moments of stark raving terror" I bought that plaque right after having to land in a 40 knot crosswind (about a 45 degree angle crosswind). :( Talk about a serious crab angle!! whew!! After landing on the upwind side of the runway, they wind literally pushed me to the other side of the runway and into the grass facing into the wind. I had to fly the 172 while on the ground till they came out to tow me back to the hanger. It was a good landing though! I was able to walk away from it! :)

Oops, this has almost turned into a book :D

All the best,

Joe
Hi Joe,

firstly, thank you for all of the time and effort you've put in to coming up with a solution for balancing the 1345T props. I've been trying to balance mine for quite a while now and am still no closer to a solution i'm confident has actually balanced them correctly. The reason I really want to get them spot on is so I can use the Olympus 45mm for video as well as stills. With video and this lens i'm getting slight jittering which makes it unusable for professional use. I realise that DJI say this lens is only for stills with the inspire but i'm sure that if the aircraft is perfectly in tune with itself then it could be used for video also.

I do have an adapter which I bought from eBay but have the feeling i'm putting them further out of balance than they were when just left as supplied. The adapter is quite crudely 3D printed and the tolerances just didn't look right. (I don't want to name the company by the way because some people may have had success with them).

Having only just come across this thread this morning, and reading about your endeavours with great interest i'm wondering if a workable solution for static balancing was found or if anyone printed your CAD model and have they been real life tested etc?

Thanks again for all your work and if only you lived in the UK i'd love to pop over for a cup of tea and a chin wag!

Jon
 
Joined
Apr 20, 2014
Messages
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#96
Hi Joe,

firstly, thank you for all of the time and effort you've put in to coming up with a solution for balancing the 1345T props. I've been trying to balance mine for quite a while now and am still no closer to a solution i'm confident has actually balanced them correctly. The reason I really want to get them spot on is so I can use the Olympus 45mm for video as well as stills. With video and this lens i'm getting slight jittering which makes it unusable for professional use. I realise that DJI say this lens is only for stills with the inspire but i'm sure that if the aircraft is perfectly in tune with itself then it could be used for video also.

I do have an adapter which I bought from eBay but have the feeling i'm putting them further out of balance than they were when just left as supplied. The adapter is quite crudely 3D printed and the tolerances just didn't look right. (I don't want to name the company by the way because some people may have had success with them).

Having only just come across this thread this morning, and reading about your endeavours with great interest i'm wondering if a workable solution for static balancing was found or if anyone printed your CAD model and have they been real life tested etc?

Thanks again for all your work and if only you lived in the UK i'd love to pop over for a cup of tea and a chin wag!

Jon
Jon,

As a POI, the last I spoke with Joe he was in the process of acquiring someone to CAD his work into a viable balancing head to use in static balancing the DJI 1345T props, however there had appeared to be a bump in the road obtaining an interested party to accomplish the task.
Many don't feel comfortable taking on the project is my understanding for fear DJI may simply decide to once again change up its propeller design for some reason, if I understood his explanation correctly.
I'm sure Joe will either confirm or deny this explanation at some point once he has had an opportunity to read this post.

While many have found the stock propeller tolerances close enough for normal use, those who are looking for a more precise method of balancing have found the laser method described previously in the post a good alternative.

Best of luck on your efforts.
 
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#97

The Editor

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#98
Guys, a word of warning if you are going the route of using 'the laser method' to balance your props.
Whilst it is an ingenious and relatively accurate way of achieving the task users should be aware of the potential dangers involved in doing this.
Obviously your props need to be attached when attempting this and some throttle input is required to accelerate the motors.
The danger comes from a phenomenon called integral wind up.
This occurs when the flight controller is attempting to correct for attitude errors but no feedback of the sensors is received (because the craft isn't flying and therefore changing pitch/roll attitude). The FC then considers there is more extraneous force acting on the aircraft and so speeds up the motor(s) to try harder to correct the (uncorrectable) attitude.
This CAN actually cause the Inspire to lift off or even flip over on a table top etc with no stick input from the user.
It is NOT a fault or bug in firmware but simply a characteristic of a closed loop feedback system.
As was shown on the demo, you should have someone (strong) holding down the Inspire on the table when you do this.
Just please be mindful of this effect which can (but not always) happen.
 
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#99
About to order a trio of tools here; The du-bro 499 prop balancer, EJH prop balancer, and DJI 1345 hubs (would rather not remove mine from the AC.

I have an Inspire 1 V2, stock with the QR upgraded motors. Can anyone confirm that these are the hubs I need to purchase for this balancing effort? I want to make sure I'm not buying an adapter kit for V1 to V2.

TIA

Amazon.com: DJI Inspire Part 70 - 1345T Quick Release Propeller Installation Kit - USA Dealer: Toys & Games
Jon,

As a POI, the last I spoke with Joe he was in the process of acquiring someone to CAD his work into a viable balancing head to use in static balancing the DJI 1345T props, however there had appeared to be a bump in the road obtaining an interested party to accomplish the task.
Many don't feel comfortable taking on the project is my understanding for fear DJI may simply decide to once again change up its propeller design for some reason, if I understood his explanation correctly.
I'm sure Joe will either confirm or deny this explanation at some point once he has had an opportunity to read this post.

While many have found the stock propeller tolerances close enough for normal use, those who are looking for a more precise method of balancing have found the laser method described previously in the post a good alternative.

Best of luck on your efforts.
Thanks for your reply skynet,

Still no word from Joe. I'm really not confident about using the laser method so would like to stick with the static approach if possible. I'll try and buy a couple of spare motor hubs I think for now and get the EJH rod to go with them. Would you happen to know the part number of the I1P hubs? I don't want to mistakenly get the I1 conversion kit hubs and end up chasing my tail!

Many thanks

Jon
 
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Sorry for the late response, guys! :-(


It's been pretty hectic to say the least and I simply missed all of this activity.
My computer decided to upgrade itself to windows 10 from 8.1 so I've had some issues with getting some of my software to work properly with the new windows upgrade. All in all, it's pretty good so there's no regrets or complaints except for the fact that I didn't choose to upgrade it.

The editor is very much correct when he mentions the need for the I1 to be held to the table so it won't move in any axis. The prefered method is to use straps to hold it down, and work on the prop farthest away from your body (not the one next to you) and only balance one at a time while making sure to fully stop the motors before reaching toward the prop! It does need to be on a soft foam pad to prevent table resonance from entering the equation as well. Don't wear any loose clothing and be mindful of the spinning motors that don't have props on them!
Again, "Be Careful" if you choose use the dynamic method! I did go pretty far with stressing safety in using this method.
Again, one of the issues is that the motors themselves aren't perfectly balanced, they do balance them at the factory within a very close tolerance though. Normally it's considered "Close enough" if you're using fairly wide angle lenses.
Having the props balanced with the motors and marked so they go back on the same motor and in the same orientation is important if you're after a perfect balance.
Keep in mind that self resonant frequencies are a factor as well. Every rotating part will vibrate at certain speeds no matter what you do. The best you can do is tune it to the point where it vibrates the least amount over a range of speeds.

I bought one of the 3D printed static balancers and yep, they were very crudely made. I doubt that it's even properly centered on the rod so I tossed mine in the trash as it would vibrate even without a prop when rotated at a high speed (I'm just guessing it's around 6500 rpms which is probably the average speed the I1 motors turn unless you're traveling at full speed).

The EJH static balancing rods are pretty good as long as you use the correct hub. The conversion hubs are made different and won't work properly. So, there's one of two choices here, 1) you can remove two of the hubs from the I1 you already have (one CW and one CCW) to use with EJH's balancing rod or, 2) buy a CW and a CCW direct replacement for the pro model (or the Inspire 1 V2.0 model, they are the same and use the exact same motors and hubs). I think this company can order the original replacements for ya DJI Phantom 4, Phantom 3, Matrice 100, Thermal Drones, S1000 and many more drones available. Crashed your drone? We are the largest authorized DJI repair center in the US.
I think they can get most anything you want except for electronic parts.

I couldn't find anyone willing to take on printing my design. Skynet1 understood my explanation correctly and If I had a 3D printer, I'd be happy to print them myself but it's a pretty big expense and I have a lot going on right now. If things slow down some, I'll buy a 3D printer and give it a go.

Jon,
I'd say that since you're using the Olympus 45mm lens, you will need to perform a dynamic balance to get it spot on but if you're not comfortable doing it that way, don't try it!!
Would you happen to have a friend in the hobby or drone business that "is" comfortable using the dynamic method? Maybe someone who does repairs at a local hobby shop? Just an idea.
A fella by the name of Mike at one of our local hobby shops is very familiar with dynamic balancing. He has asked how I balanced mine so I explained it to him, then he tried it and now offers to balance props for his customers using the dynamic method. He offers that service now since there are so many pilots that aren't comfortable doing it themselves.

If you'd like, I can make an instructional video of the dynamic balancing process by the end of the week.

I suppose I should just plan on doing a video with my I1 V2. That way it'll be there for those who feel comfortable with it. If you choose to use the dynamic method, don't' allow yourself to be distracted by anything else! It does require your full, undivided attention! If you're careful and have your mind only on what you're doing, it's as safe as when you takeoff, fly or land your I1.
When you takeoff, fly and land your I1, you have all four props spinning in midair fairly close to you rather just one spinning while strapped down. In a way, it's safer than flying one. On the other hand, if you're not paying close attention and taking your time, it's not safe! That's the next thing, you can't be in a hurry!! You really need to count on taking the time required, it's not a quick process unless you've done quite a few and even then, you can't allow yourself to become complacent.

I still prefer to use the dynamic method so the prop is matched with the motor and to keep the electronics from receiving unnecessary vibrations. The gimbal absorbs a lot but there's no dampers for the onboard electronics. That's the main reason I want mine to be so well balanced. Vibrations on the electronics can cause some undesirable events over the long run.

For example:
I have a Raptor E720 3D single rotor helicopter I use for fun (use to compete F3C with it but I kinda got tired of that a couple of years ago).
I use BeastX MicroBeast Gyros on all of my sport helicopters, the E720 had a vibration that I couldn't find. I wound up removing the foam from under the gyro because it was drifting to the left pretty hard on it's own. I installed a 3M gray double sided adhesive that's made for attaching car trim and is about 1.8" thick. Whala, it flew great!! :) ................................for about 40 flights..............:-(.................then the gyro completely failed and the E720 went completely crazy, eventually it took a hard dive inverted and destroyed itself when it hit the ground. The gyro was being overworked for too long and simply failed due to stress. Mine wasn't the only one (far from it) so it was collectively determined that it was caused by vibrations on the gyro.
Yep, I built another one but I made sure it didn't have any undue vibrations and now have nearly 300 flights on it with no issues. It's a 12S Lipo setup and I usually get about 100 flights on a set of 6S 5000 mAh Lipos, I've replaced them twice and it's due for another set now.
That Microbeast is one of the most reliable gyros I've ever used or seen. None of my other sport helicopters ever had an issue with the Microbeast (no abnormal vibrations either, they all vibrate a little even at their best).
The same thing will happen to the I1s at some point if there are undue vibrations.

I'd like to point out that the I1s go through a lot more gyro and accelerometer excitations than any 3D helicopter because it's constantly trying to hold GPS position and/or a fly in a perfectly straight line for waypoints, self leveling, etc, etc.
3D sport helicopter gyros are only holding the helicopter in whatever orientation it's put in by the transmitter. it's not fighting to stay in one place or fighting to fly in perfect straight line, It tends to go with the flow so to speak. It will drift with the wind without fighting it and it's usually never noticed because of how fast it's being flown.
In comparison, it's very important to have the I1 as vibration free as humanly possible if you want to fly it for very long.
The batteries for the I1 seem to last about 100 flights or less as well. I had to replace mine recently, I bought two batteries and just replaced them. The Pro model has right at 190 flights on it. My V.20 only has about 20 flights on it.
My sport helicopters only fly about 6 minutes per flight but they draw a lot more current than the I1.

I've concluded that I don't know how to write a short response. Pretty obvious, eh? :)
Sorry about that!!
 

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