Extra long F550 arms.

olof

Osprey
The cost of producing any part.

To make a prototype of an arm, would probably take 40 hrs, and the cost of materials would be a couple hundred. My shop rate is about $125/hr.

Set up to run a small beta testing batch, 25 units. 25hrs.

Put it all together and ship to to testers. Get feedback and redesign a few changes. $2-3K.

OK so now you have a product. How many do you have made or make yourself? You have probably just spent $5-8K at this point.

To market, I don't think you can sell just by writing about it on a few boards, you will have to advertise in magazines etc., and become a sponsor on a bunch of boards. Create and maintain a website and an ordering system, find distributers. This will run in $10K units (like many 10x10 or $100,000.00) at least unless you already have this set up.

OK so lets say all this is done for $60,000.00 now you have to pay for the first batch lets say 100,000 arms. Even at a cost of $12.00 each w/o packaging and shipping, that is 1.2 million. Smaller batches will cost a lot more. So you can see why this is not something you can just jump into.

I can beat Chinese manufactures for short run production but I can't beat them for mass production. Short run high quality parts that are relatively expensive and I know the market and I may only sell a hundred of I do well at. But I don't have the kind of budget needed for a large run of parts that may not sell and people want to pay $10.00 for, it just does not work economically.

This is my take on it anyway. The cost of production is only a very small part of the cost of a final product. Did I mention product liability insurance.
 

helloman1976

Ziptie Relocation Expert
The cost of producing any part.

To make a prototype of an arm, would probably take 40 hrs, and the cost of materials would be a couple hundred. My shop rate is about $125/hr.

Set up to run a small beta testing batch, 25 units. 25hrs.

Put it all together and ship to to testers. Get feedback and redesign a few changes. $2-3K.

OK so now you have a product. How many do you have made or make yourself? You have probably just spent $5-8K at this point.

To market, I don't think you can sell just by writing about it on a few boards, you will have to advertise in magazines etc., and become a sponsor on a bunch of boards. Create and maintain a website and an ordering system, find distributers. This will run in $10K units (like many 10x10 or $100,000.00) at least unless you already have this set up.

OK so lets say all this is done for $60,000.00 now you have to pay for the first batch lets say 100,000 arms. Even at a cost of $12.00 each w/o packaging and shipping, that is 1.2 million. Smaller batches will cost a lot more. So you can see why this is not something you can just jump into.

I can beat Chinese manufactures for short run production but I can't beat them for mass production. Short run high quality parts that are relatively expensive and I know the market and I may only sell a hundred of I do well at. But I don't have the kind of budget needed for a large run of parts that may not sell and people want to pay $10.00 for, it just does not work economically.

This is my take on it anyway. The cost of production is only a very small part of the cost of a final product. Did I mention product liability insurance.

It's amazing anything can be made and sold at that rate, if I hadn't have run several businesses myself I'd buy all that but I don't. You can buy a home CNC machine and make parts for yourself for less than that so that's just absurd. A home purpose CNC machine is around $3k to $10k depending and it'll make arms all day long. 1lb of aluminum in ingot form is about $8 and I can program anything on this planet and do CAD as well. There's just no way brother, maybe at your lawyer rate of $125 a hour sure but that would be all labor. I could cast parts out of aluminum with a smelter faster than you could get your designs out lol... come on man. I've been working on hot rods and cars all my life and there is just no way sorry, I could make arms out of billet titanium for that.
 

olof

Osprey
It's amazing anything can be made and sold at that rate, if I hadn't have run several businesses myself I'd buy all that but I don't. You can buy a home CNC machine and make parts for yourself for less than that so that's just absurd. A home purpose CNC machine is around $3k to $10k depending and it'll make arms all day long. 1lb of aluminum in ingot form is about $8 and I can program anything on this planet and do CAD as well. There's just no way brother, maybe at your lawyer rate of $125 a hour sure but that would be all labor. I could cast parts out of aluminum with a smelter faster than you could get your designs out lol... come on man. I've been working on hot rods and cars all my life and there is just no way sorry, I could make arms out of billet titanium for that.

Like I said earlier I can easily make parts for myself, but if you try to make a living at producing parts and selling them, that is another whole ballgame.

I don't know any machine shop with lower than $125.00 p/h most are a lot more especially for 4 and 5 axis machines. And the sad fact is about half of the CNC shops around here are gone. Trying to compete with cheap foreign production, but also from a lack of skilled labor. I don't know any machinists that are younger than 50, and most are older about to retire and can't find anyone to take over. It is sad.

The other part of production in quantity is assembly, stocking, marketing and sales, packing and shipping. Like I said the cost of production is only a small part of the cost.

I do run a successful small manufacturing shop and we also sub out quite a bit of stuff. And I do beat Chinese prices on some items, but only short run products.
 

It's amazing anything can be made and sold at that rate, if I hadn't have run several businesses myself I'd buy all that but I don't. You can buy a home CNC machine and make parts for yourself for less than that so that's just absurd. A home purpose CNC machine is around $3k to $10k depending and it'll make arms all day long. 1lb of aluminum in ingot form is about $8 and I can program anything on this planet and do CAD as well.

With that said... why don't you start making these aluminum arms?
 


hoggdoc

New-Bee
Like I said earlier I can easily make parts for myself, but if you try to make a living at producing parts and selling them, that is another whole ballgame.

I don't know any machine shop with lower than $125.00 p/h most are a lot more especially for 4 and 5 axis machines. And the sad fact is about half of the CNC shops around here are gone. Trying to compete with cheap foreign production, but also from a lack of skilled labor. I don't know any machinists that are younger than 50, and most are older about to retire and can't find anyone to take over. It is sad.

The other part of production in quantity is assembly, stocking, marketing and sales, packing and shipping. Like I said the cost of production is only a small part of the cost.

I do run a successful small manufacturing shop and we also sub out quite a bit of stuff. And I do beat Chinese prices on some items, but only short run products.

How about using a 3D scanner to duplicate the original. Once the scan is done the part could be modified by anyone with CAD knowledge. New 3D printers should be able to produce the end result.
 

hoggdoc

New-Bee
:shame:
I'm using them. They seem pretty solid with very little flex. I'm still on 4S with Avroto motors spinning 12inch APC props. This set up works great.

View attachment 12937

View attachment 12938

Wow just the image I was looking for. Since you actually have the arms is it possible to give all of us accurate measurements of the total length of the arms? Also wonder what the weight is, stock DJI F450/550 arms are 55g on my scale.

BTW if you don't have a arm not mounted, could you measure the diameter of the F550 boards with these longer arms attached. Again stock DJI mounted to F550 board measures 593.725mm tip to tip.

Does anyone know what material is used in the longer arms?

Thanks :nevreness:
 

hoggdoc

New-Bee
Considering I go through a few arms every couple of months at $4.50 + $2.00 shipping and that an aluminum arm would not break I'd pay a premium for a premium part. Check this out, there are carbon fiber propellers that people pay $20 each for so don't be shocked if they fly off the shelf. Also consider that you can make them longer, which people ALSO want and is NOT AVAILABLE right now without some garbage CNC plate extension. How about 650mm arm replacements so we can spin 12" or 14" props or whatever? There are many things you can do here, get creative and you can charge a premium. I'd probably pay $25 an arm to be realistic and $30 and arm for the extended version. Again, cast them if it's cheaper...make them out of tin...I don't care as long as they are hard, stable and won't break.

Or even better, how about a carbon fiber tube conversion kit for the View attachment 13024 550 where you only make the CNC aluminum piece that goes between the 2 DJI F550 plates where you can put the carbon fiber rod of your choice in there. Just my thoughts...

And they can't be that expensive or other companies would not be making them and selling them already... Here's the QAV500 aluminum arm replacements and they are $22 each so it can be done cheap.

http://www.getfpv.com/qav500-replacement-aluminum-arm.html

With all this talk about "unbreakable" arms, that are longer, I think we are forgetting the affect this will have on the boards. The energy that is absorbed by the arms (breaking) will be transferred to the boards most likely damaging them. Not only the increased rigidity of the arms comes into play, but their additional length. I think its a fine line we must balance on in the design of these aircraft. Sometimes more is not better!
 

gtranquilla

RadioActive
This posting is an attempt to answer several recent questions.

Last night I measured the arms....... the 800mm will be the diameter of the assembled frame from between the center holes in the arm for each motor.
3D printing involves the use of relatively low quality plastic that is easier to work with. But these arms are made of polymide which has a much higher strength to weight ratio and well suited to high volume mass production to keep costs down.
RCT resolves the issue of structural weakness in the center boards by bolting in several nylon standoffs.....
One can skip the very costly 3D scanner and put together a 3D sketch to pass along to an CAD operator...... but it still requires a lot of time and money which only makes sense if you are serious about mass production.
 

gtranquilla

RadioActive
Aluminum Arms: Aluminum and it's alloys, in particular 6061-T6 aircraft grade alloy is likely the lightest available metal c/w adequate strength and therefore has been widely used for constructing aircraft since before WW2.
Remaining excessive weight issues are resolved by "brute force" using the typical very high energy density fossil fuels. Plywood fell out of favor in part due to degradation from fuel and oil leaks.

For electric powered aircraft especially multi-rotors, the fight is on to get the weight as low as possible without compromising structural strength. typically one minute of airtime is gained for each 100 grams of weight reduction.
Hence the ongoing effort to increase the energy density of the batteries. The laws of diminishing returns kicks in when too many batteries are needed to get your payload in the air and a high quality video camera such as the Red Epic still has a lot of weight.

G10 polyester based fiberglass composites are very heavy as are epoxy based fiberglass composites. As well polymide with it's high strength to weight ratio remains heavy.
The remaining materials most suitable for MR construction are:
fiberglass or carbon fiber reinforced plywood and carbon fiber plate and tubes.

But milling carbon fiber plate remains a major problem that a typical CNC machine is not able to handle well at all..... and there are serious health concerns with carbon fiber dust particles.


It's amazing anything can be made and sold at that rate, if I hadn't have run several businesses myself I'd buy all that but I don't. You can buy a home CNC machine and make parts for yourself for less than that so that's just absurd. A home purpose CNC machine is around $3k to $10k depending and it'll make arms all day long. 1lb of aluminum in ingot form is about $8 and I can program anything on this planet and do CAD as well. There's just no way brother, maybe at your lawyer rate of $125 a hour sure but that would be all labor. I could cast parts out of aluminum with a smelter faster than you could get your designs out lol... come on man. I've been working on hot rods and cars all my life and there is just no way sorry, I could make arms out of billet titanium for that.
 

helloman1976

Ziptie Relocation Expert
They have 800mm Hexacopters so it's just simply not an issue. The damage will be transferred sure, it'll probably rip the screws out of the top plate if it crashes that bad but I'm not building for crashing, I'm building for flying and I only RE-build when I crash. The arms are $6 each, the top plates are next to free as I have about a dozen of them laying right next to me. The QAV500 uses aluminum arms and others use carbon fiber and are sometimes 1200mm long so it's just not an issue honestly, not for me is what I'm saying. Carbon fiber is so strong it might as well be steal in paper form. :)
 

The upgrade was worth it... Arms are very strong.
 

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gtranquilla

RadioActive
Here is my RCT800 c/w clone S800 landing gear modified to fit the RCT800 arms (not an easy fix but worth it IMHO).
Design intent is to remain with 4S batteries and not carry cameras much heavier than the Hero GoPro3.... Might try to add retractable landing gear kit later.
View attachment 10861
 

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helloman1976

Ziptie Relocation Expert
Here is my RCT800 c/w clone S800 landing gear modified to fit the RCT800 arms (not an easy fix but worth it IMHO).
Design intent is to remain with 4S batteries and not carry cameras much heavier than the Hero GoPro3.... Might try to add retractable landing gear kit later.
View attachment 13860


Wow, looks really good. Your intentions are the same as mine, 4S all the way...nothing heavier than a GoPro. I'm about to go with a Y6 setup though, moving away from the H6 and back to the Y6. They're easy to transport and there's no issues with things being in the way of the camera. I don't use a gimble and I have no intention, right now anyway, of using one which saves me the extra weight. The next one I build won't even use the Go Pro camera case and will instead use the lens protector and a bare camera giving me more power with less weight.

How much do those arms flex? Have you flown a DJI anything with the plastic arms to compare to, if so how do they compare? I love the S800 but it's a huge ripoff for what you get or what you can build yourself so that's an interesting kit there + modifications.
 

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