Motor Mount Reinforcement Braces

[924]

The beauty of this situation for DJI, I think, is that prevailing in a lawsuit against a company in China would be a monumental task. The USA would certainly get no cooperation from the Chinese government and how would you collect? I suspect (and I can't say that I KNOW) that the protection enjoyed by them due to the boundary of the Atlantic Ocean and governmental hostilities makes it pretty easy to ignore the complaints of customers who are upset about the props and other perceived problems. Maybe DJI isn't ignoring complaints at all, and are feverishly working on certain issues, but it certainly isn't made apparent by responses like "there isn't a problem."

Attorneys definitely go after the deep pockets but in the meanwhile my aircraft have registration numbers on them that are attributed to me, so the perceived problems that I have the power to address are going to have my attention.

I sure as heck don't want to ground MY aircraft and I need to know that I'm doing what I can - and Fickert appears to know what he's doing.

I still like my DJI aircraft, by the way.

 

[pepeticos]

I do not have enough hardware for another set at the moment so this would be for just the plastic components. I can go and buy some if you are willing to wait. I can do the plastic pieces themselves for $65 shipped and $85 shipped with hardware. These will be a high end commercial ABS. I can also use a higher end plastic which would be a mixture of Nylon and Carbon Fiber. I only have enough of this though to print 2 or 3 sets at the most. I would sell that for $105 (the filament is $65 for 500g, so it doesn't go very far when you include failed prints and support structures, each set of braces including raft and support structures are roughly 125-130 grams)

I do want to say for the pricing, this is reflective of 200-250 hrs of design and printing I have done to get where the design is so far. Already killed a spool of ABS in the process (about $45 for 1kg for this high end ABS). If prices seem unreasonable please say so but they are based on what I feel has been involved and materials / machine time that has been used.

Lastly,

I also came across another design I had that I am going to look into again when I get home. The current design does not allow clearance in the GP or Drone hanger cases without modification. This other design could remedy that, and so far looks like it will be more sturdy in all. So if you are not in a rush I recommend holding off for me with an update, otherwise I have good confidence the current design I have posted here is very nice as well.

Let me know your thoughts.

If you make a good and light brace i think betweeen 60 and 100 us dollars is an ok price for the 4 of them of course. Please let me know as soon as you have the final version of it. [email protected] i live in Argentina but could posible receive it on Miami.

 

[Fickert]

If you make a good and light brace i think betweeen 60 and 100 us dollars is an ok price. Please let me know as soon as you have the final version of it. [email protected] i live in Argentina bus could posible receive it on Miami.

Thank you for the feedback. Let me finish up this revised design. See how it turns out

 

[mmarian]

It is always good to have a choice and different products at different price range addressing the same (alleged) issue.
I would like to share my experience with the DroneDepot braces which I received yesterday. I was genuinly impressed when I inspected them up close. They are very well made from high quality aluminum with lovely black anodized finish, they have the look and feel of a premium product. They are very lightweight too, only 68g for all four including all screws. The fit is perfect too. For me personally they are worth the price.
For the suspicious minds, I have no association with the company whatsoever, never bought anything from them until now.

 

[DaBone]

Here is a clamp, if you have a 3D-printer..

Inspire 2 motor mount to boom clamp by DavidCanfield

 

[RobH2]

I'm wondering if just putting a small M2 bolt in each side of the overlap, being careful not to impact any wires, would be a sufficient solution? I would just provide a mechanical lock instead of just adhesion.

 

[mmarian]

I'm wondering if just putting a small M2 bolt in each side of the overlap, being careful not to impact any wires, would be a sufficient solution? I would just provide a mechanical lock instead of just adhesion.

That was my first idea, jesus bolt with locknut. But I was advised against it, as you would need to drill a hole through the CF halftube inside of the mount which would impact on integrity of the CF material and once you do that all bets are off. The Dronedepots beackets are expensive but well made and will do the job just fine. There might be alternative and perhaps more economical brackets on the market in the near future..

 

[RobH2]

I don't know much about carbon fiber but that makes sense if puncturing it does weaken its integrity.

I just did a bit of reading and it's not that drilling it ruins it, it's that it's tricky to drill well. If not backed up, it will splinter, and it's going to be difficult to back it up in that tube that's already full of wires. Another issue is that you need a square end bit and not a v-shaped standard bit. Of course, you can just buy one but most of us have v-shaped bits only on our workbenches. The bit's have to be very sharp and unless you use a drill press, you can get wandering and get a poor hole that is weak. Finally, the dust is bad. You need to wear a mask and eye protection and if you get the dust on your skin you'll have an itch worse than fiberglass. So it sounds like a tedious and questionable endeavor to drill it.

So yea, I think I'll design a clamp like the several mentioned here and print it on my 3d printer. Afterall, I think the issue occurs in a small percentage. But, we never know when we become that small percentage, until the "incident," do we? I have had over 300 flights and my frame seems as sound as it was brand new. But, a little inexpensive mechanical insurance can go a long way, especially as my Care Refresh has expired. I flew yesterday, and having read the threads now about motor mount separation, it was the first time since my early learning days that I flew with dread that something awful could happen, nothing did thankfully.

 

[David G]

Are you selling these ?

 

[Fickert]

Quick update for everyone, the mounts finally got a test print, I had an unexpected trip to Detroit this weekend.

Below are some of the new mount design. Still more to come though as it needed slight modifications and I would like to get fasteners into the underside through the clamps as shown.

I am at work now but can toss them on the scale when I get home.

 

[Fickert]

Are you selling these ?

I plan to here once I have this new design worked out

 

[David G]

I plan to here once I have this new design worked out

Awesome!!!!

 

[RobH2]

In another thread, I proposed the use of a set screw by drilling a hole and inserting a screw or bolt. Some subsequent posts suggested that drilling the carbon fiber would weaken it.

I then did some reading that indicated that it can be drilled but you have to do so carefully and you are likely to get a wicked case of the itches if you don't protect skin and airways.

Tonight I found this.

The voice over is not in English but you can see this guy put a rivet in. I think it's a pretty clean solution. It's difficult to imagine my I2 with 4 honking clamps on it.

Maybe some carbon fiber gurus will weigh in. If carbon fiber is as so much stronger than steel, I don't see why, if drilled carefully and cleanly, that a rivet or bolt won't solve the issue. All we need is a mechanical lock instead of an adhesive one.

 

[Dobmatt]

It's not that simple like many of us think. To understand design challenge in this case, one must know specific physical and mechanical properties of carbon fiber tubes. Carbon tubes are providing amazing strength to weight ratio lengthwise, yet they're very brittle and prone to collapse under excessive clamping stress. Special tooling and technique is necessary to perform cutting, drilling or notching. Any not-reinforced opening in the wall will create stress concentration around, challenging the worthiness of such joinery:

https://www.google.ca/search?q=stre...=chrome..69i57j69i60&sourceid=chrome&ie=UTF-8

Epoxy adherence proved to be one of the best ways of carbon fiber structures assembly. With proper kind of hardware and adhesive my structures were failing anywhere but on joints, when tested for destruction. Rare Inspire 2 motor housing disengagement is caused by incidental manufacturing fault, not design flaw. IMHO, naturally.

 

[Fickert]

In another thread, I proposed the use of a set screw by drilling a hole and inserting a screw or bolt. Some subsequent posts suggested that drilling the carbon fiber would weaken it.

I then did some reading that indicated that it can be drilled but you have to do so carefully and you are likely to get a wicked case of the itches if you don't protect skin and airways.

Tonight I found this.

The voice over is not in English but you can see this guy put a rivet in. I think it's a pretty clean solution. It's difficult to imagine my I2 with 4 honking clamps on it.

Maybe some carbon fiber gurus will weigh in. If carbon fiber is as so much stronger than steel, I don't see why, if drilled carefully and cleanly, that a rivet or bolt won't solve the issue. All we need is a mechanical lock instead of an adhesive one.

As much I like this solution it is still weary to me to be honest. Its clean and simple which is why I like it, but having such a high concentrated stress on a sectioned cut carbon fiber tube puts a bad taste in my mouth...

I am going to try to do some simulation tests and calculations to see if this is reasonable (the rivet)

The whole intention of my clamps are to remove the stress and vibes beating not only on the epoxy but also the section cut portion of the carbon fiber tube. It a serious stress riser with that sharp corner.

 

[Fickert]

Hopefully this can also become of use to some of us. In summary there are a few things to take away from the article about fasteners and composites (Carbon Fiber)

Summary of Article:

• Fasteners are used with composites, but with limitations.
• As mentioned, delamination while drilling and fastening is likely to occur which can create a continuing delamination during operation.
• Trying to mate a contouring (round) surface with a flat washer and flat rivet creates high stress concentrations where the washer meets the carbon tube, likely resulting in more delaminations. This is hard to simulate though, most results with carbon fiber have to be bench tested.
• Lastly not a major concern but a lot of rivets are steel and aluminum. Galvanic corrosion is likely to occur with aluminum and carbon fiber composite materials; In short, corrosion will occur on both there carbon and aluminum, but the more corrosion prone aluminum will degrade first. Not a huge concern really, but something to consider if you fly in warm, salt water areas. I actually am certified in corrosion analysis and its very neat stuff, this all happens due to electric current running through both materials (very very small amounts but is enough for electrodes to travel to the aluminum and away from the carbon fiber, causing corrosion)

I get Machine Design Articles once a week in my email I recommend anyone sign up as it always has quick and useful information.

Joining Composites

I also ran some quick simulations to show the stress concentrations on the carbon fiber tube with the section cut area. I lowered the safety factor to 1 for these illustrations.

This shows just 15 pounds applied to the ends where the carbon tube is cut. Notice the red and yellow areas at the sharp cut corners. If there is a minor delamination from manufacturing then this is a huge issue. Additionally if you drilled a hole it is likely that delamination would occur there as well, potentially causing a surface crack (like a crack in a windshield) and continue to spread and flex until failure. Most damage will probably come from landing, and travelling. If we remove the failing epoxy, (with a rivet) this is where the next failure will occur.

My whole approach to a solution was to override this area in the carbon fiber tube all together. No chance of delamination, and use proven methods of clamping the carbon tube, not fastening to it.

My two cents.

 

[DamesNY]

Hopefully this can also become of use to some of us. In summary there are a few things to take away from the article about fasteners and composites (Carbon Fiber)

Summary of Article:

• Fasteners are used with composites, but with limitations.
• As mentioned, delamination while drilling and fastening is likely to occur which can create a continuing delamination during operation.
• Trying to mate a contouring (round) surface with a flat washer and flat rivet creates high stress concentrations where the washer meets the carbon tube, likely resulting in more delaminations. This is hard to simulate though, most results with carbon fiber have to be bench tested.
• Lastly not a major concern but a lot of rivets are steel and aluminum. Galvanic corrosion is likely to occur with aluminum and carbon fiber composite materials; In short, corrosion will occur on both there carbon and aluminum, but the more corrosion prone aluminum will degrade first. Not a huge concern really, but something to consider if you fly in warm, salt water areas. I actually am certified in corrosion analysis and its very neat stuff, this all happens due to electric current running through both materials (very very small amounts but is enough for electrodes to travel to the aluminum and away from the carbon fiber, causing corrosion)

I get Machine Design Articles once a week in my email I recommend anyone sign up as it always has quick and useful information.

Joining Composites

I also ran some quick simulations to show the stress concentrations on the carbon fiber tube with the section cut area. I lowered the safety factor to 1 for these illustrations.

This shows just 15 pounds applied to the ends where the carbon tube is cut. Notice the red and yellow areas at the sharp cut corners. If there is a minor delamination from manufacturing then this is a huge issue. Additionally if you drilled a hole it is likely that delamination would occur there as well, potentially causing a surface crack (like a crack in a windshield) and continue to spread and flex until failure. Most damage will probably come from landing, and travelling. If we remove the failing epoxy, (with a rivet) this is where the next failure will occur.

My whole approach to a solution was to override this area in the carbon fiber tube all together. No chance of delamination, and use proven methods of clamping the carbon tube, not fastening to it.

My two cents.

Dude I’m sold a thousand times over.
Can I just buy them please?

 

[Fickert]

Dude I’m sold a thousand times over.
Can I just buy them please?

Hi,

Sorry not quite yet XD. My current design was okay but I am still working on a revised design. A few more tweaks and I will be willing to sell them. The material is PETG not ABS as I am saving that for the final design, although I am greatly considering Carbon Fiber PETG. Wil try the carbon fiber nylon I have on hand first.

I am not sure if I have updated the thread with my latest test prints.

Regards,
DustinView attachment 18119View attachment 18120View attachment 18121View attachment 18122

 

[DamesNY]

Hi,

Sorry not quite yet XD. My current design was okay but I am still working on a revised design. A few more tweaks and I will be willing to sell them. The material is PETG not ABS as I am saving that for the final design, although I am greatly considering Carbon Fiber PETG. Wil try the carbon fiber nylon I have on hand first.

I am not sure if I have updated the thread with my latest test prints.

Regards,
DustinView attachment 18119View attachment 18120View attachment 18121View attachment 18122View attachment 18123

Word is Nov inspire 3 will be announced! Better hurry.

 

[Fickert]

Word is Nov inspire 3 will be announced! Better hurry.

I am not going to be upgrading to it, actually I will not be buying a new DJI Product ever. Their position on using geofencing unlock procedures will make me build my own bird when the time comes. I refuse to give this company any more money when they kill jobs for operators almost every day due to their faulty unlocking system. I have firmware that was released back in April I think that was pre-geofencing, never locking out my inspire.

But for other users, the parts should be good to go, and by the end of the week I will be able to start taking orders.