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Old Oct 14, 2012, 12:34 AM
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Originally Posted by SeismicCWave View Post
The whole idea behind this build is to make a super rigid gimbal. My first attempt with the carbon tubes was 730 grams. The second one with 1/2" square aluminum tubes was 577 grams. Now Rusty using 10mm square tubes actually managed to bring it down to sub-500 grams and still retaining the rigidity.

The only flex will come from the vibration isolation.

The video quality will reflect more on the gimbal controller than the gimbal.
Yeah my 12mm carbon fiber tube (~500g) version felt really stiff as well. Unfortunately the down tube was able to twist and this caused major issues. I went to 12mm aluminum tube and that eliminated (greatly reduced) the twisting flex I had on the main downtube. I haven't worked with the square 10mm tube before so I don't know how it would compare. It's definitely tweaked my interest though. I'll be following closely and if you guys get good results I may design a 3d printable parts version using square tube. My current version is probably 650 grams now with the changes I've made. I'd love to make a 500gram version. I am hoping this one flight test well. Fingers crossed here.

As for vibration isolation I am doing this now and it is working very well.

http://www.rcgroups.com/forums/showp...3&postcount=54
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Old Oct 14, 2012, 12:41 AM
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Originally Posted by 13brv3 View Post
Before Christmas should be a safe bet, particularly since you didn't mention what year

Seriously, this takes way longer than most people realize. It's easy if you just want to put one together to use, but if you're trying to make the best choices for the most situations, there are a LOT more options to consider. What I never want to do is start to sell something, then have to change it 5 times in the first month, because then I can't necessarily know what anyone got with their particular kit.

All that being said, I have the first prototype assembled, though I've taken it apart and changed things about 5 times in the last couple days. Before I can even flight test it, I need to stop making major changes. I'm hoping to get this one in the air tomorrow, but no guarantees. I've already got a list of things to order to try for the second prototype, so I wouldn't expect to see a kit for a couple weeks.

Rusty
Well seeing this year marks the end of the world as we know it.. I hope it's this Christmas

Agreed, though. Get the product perfect before rushing it to over-eager people like myself. What i see looks really good.

Are you planning on going with the G10 plate for the camera mount portion or the alum tube? I liked the idea for the alum tube since it would be more adjustable and scalable plus a bit more rigid I would think
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Old Oct 14, 2012, 12:44 AM
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Originally Posted by 13brv3 View Post
It's pretty darn stiff, so I can't imagine any problems with flex. I left it larger than it needed to be just to give it more of a chance to flex.

The biggest challenge will be remembering how to fly it

Rusty (too busy making stuff to fly)

I was wondering why you left it larger. I think that was a good idea. Make sure you guys test it with a heavy camera and lens

It sure looks good and I like the adjustability of the design. The best part about it is the low weight. If the videos look good I think I'll give a square tube one a shot for my next version. I'd like to have something to compare against my first version. Anyhow keep up the great work!

Brendin
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Old Oct 14, 2012, 01:12 AM
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>> I'll be following closely and if you guys get good results I may design a 3d printable parts version using square tube. My current version is probably 650 grams now with the changes I've made. I'd love to make a 500gram version. I am hoping this one flight test well. Fingers crossed here.<<

Yeah the idea is to generate interest and inspiration. The more people that experiment the better ideas we all can share.

>>As for vibration isolation I am doing this now and it is working very well.

http://www.rcgroups.com/forums/showp...3&postcount=54<<

I saw that on your thread. Excellent idea! We are all continually doing experiment which is really exciting.
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Old Oct 14, 2012, 03:26 AM
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I'm not interested in buying the kit from Rusty I guess...I'm interested in sourcing parts myself & for that some sort of plan would be handy to have...But never-mind I'll just design my own gimbal when ever I'll need it.
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Old Oct 14, 2012, 03:49 AM
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No free lunch...
Buy a set and you have the physical dimensions for all you like..
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Old Oct 14, 2012, 05:00 AM
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Well than change the thread name since it implies open-sourceness of the design.
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Old Oct 14, 2012, 04:03 PM
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Well than change the thread name since it implies open-sourceness of the design.
Neither the thread title or anything posted here implies or suggests the gimbal being open source. The design is extremely simple using many items found locally to most people and it would be rather trivial to build one based solely on the posts and images found here. If you want exact dimensions buy a kit and take your measurements to build another for your own use.
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Old Oct 14, 2012, 08:52 PM
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Originally Posted by msev View Post
I'm not interested in buying the kit from Rusty I guess...I'm interested in sourcing parts myself & for that some sort of plan would be handy to have...But never-mind I'll just design my own gimbal when ever I'll need it.
I started this thread not because Rusty is going to offer some kit. I started this thread because I figured I can collect/source some parts and just put together a gimbal. I put together the carbon tube gimbal with zero plans and no drawings. None is needed. I just cut some plates, drilled some holes and voila. Bolt it together and it works.

Then Rusty has the idea of using aluminum square tubes. I just so happened to have a bunch of them that is not being used. So again I just started cutting, drilling and bolting. No plan or drawings what so ever.

That's the idea. It is a simple design that does not require plans. You just find the parts and put them together.
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Old Oct 14, 2012, 09:00 PM
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Well than change the thread name since it implies open-sourceness of the design.
Yes it is open source because there is no source. I can't send you any drawings even if I want because I don't use any. For example on the first carbon tube gimbal (please go back and look at the pictures if you don't believe me) I cut a piece of carbon 1" X 1.5". I scribe a line down the middle and put a boom block on the plate. I mark the position for the holes and drill. No plan needed. I then mark the other sets of holes and drilled. Then I cut 8 more pieces of carbon. Sanded them a bit to almost even size. I put the first one on top. I clamped all nine plates together. I drilled one hole. Then I put a bolt through the hole so all the other holes will be the same. Then I drilled the rest. Now I have nine plates. I just bolt the boom blocks together and look for tubes. I didn't even measure the length of the tubes. I find some left overs laying around. I found two about the same length and put them side by side and yes they are the same length so I use that.

Nowadays we get too much into the planning and not enough into the "doing" part of things. Just look at all those threads about "how I have designed a multi rotor frame" or "how I design, this or that". Many of them don't even make it into anything real. Any geek with a computer and a CAD program can start drawing. Drawing is no good unless you can translate that into something tangible and useable.

So humble yourself and don't get all self righteous and make it sound like I owe you a drawing. Ask questions and I will be more than happy to show you where I get all the parts. If you have such an entitlement feeling and not play nice you can't expect others to be nice to you.

Another idea that came out from this design (if you can call it a design since it is nothing earth shaking. Just a bunch of tubes held together) is the flexibility and scalability. You can follow the concept (that's better than calling it a design) and make one any size you want. You can make it small to hold a GoPro. I have made the first one large enough to hold a Canon T2i body. It was only because I have the body sitting on the bench.
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Old Oct 14, 2012, 10:07 PM
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I finally had the chance today to install and fly my Y6 with Seismic's CF tube gimbal and have some thoughts for anyone thinking of making their own.

- Installation onto my UAP was fairly easy (probably the easiest I've had with any gimbal so far) but it still took some extra parts that may or may not be included (Rusty, here's a hint...include them!) and also took drilling holes into those parts to actually make it all work. Seismic included two long narrow pieces of CF that had clamp blocks on them which I mounted to Rusty's round floating damper plates. I used three nylon standoffs on each of the gimbal mounts, and had to drill those three holes. Like I said, not really a big deal, definitely easier than most other gimbals I've bought and had to try to figure out how to mount. But you still need to have those parts to make it work and also a drill and breathing mask. You could also probably mount clamp blocks directly to the bottom of the UAP and attach the gimbal to that but you will be giving up vibration dampening.

- The gimbal is low profile which after having had a couple of fairly tall gimbals is nice, but since I'm flying a Y6 this means I don't have much upward pitch available before my props will be in view. Not too big of a deal, a slightly longer vertical post so it hangs down lower will solve the problem. But again it's something to keep in mind when you are making your own or buying a kit, if you are flying a quad or hexa it won't be an issue but if you fly a Y6 or X8 then it might be.

- Speaking of copter options, another issue that could come into play with a Y6 and maybe X8 if you are using tube legs is with the roll axis. The servo side of the gimbal hits one of my landing gear legs before it reaches maximum deflection (EDIT: it hits just as it reaches maximum deflection, so in my software I reduced the servo range by just a notch and it doesn't hit anymore). The options are to try to slide my legs forward a little bit more (not much space due to the lower props) or to get a longer vertical post so it hangs down a little lower, or narrow the width of the camera tray (I'm using a GH1 currently which takes up most of the tray). Again this probably won't be an issue with a quad or hexa where you can move the legs out further.

- The roll axis section is pretty clever in how it works (at least I think so!) but it is also a little difficult to get to if any part of it needs adjustment / replacement. From the pictures it looks like the roll axis area on the square gimbal is a bit more simplified and easier to get to.

- The gimbal and camera tray are nice and rigid, I doubt there will be any issues with flexing or holding a decent amount of weight. The one concern is with the vertical post slipping, Seismic recommended once I have it at the height I want to put a pin through it so that the post can't come out.

I shot some video during my test flight but it's not very impressive, my copter is not flying well at the moment (I could see it bouncing all over) so it's not a fair evaluation of the gimbal. I'm also still having major issues with my pitch axis not working well, which is my controllers fault (eventually I'm going to install a dedicated gimbal controller but I'm not ready for that yet). I'm going to rebuild as a hexa since I've had the most stable flights in that configuration, do some more tuning, and will try again the next chance I get.

One thing I can say is I definitely noticed the weight difference in flight. I still had plenty of power and was able to hover at just over half throttle (previously it was just under half throttle), but the copter flew much more sluggish and acted / felt a lot heavier. With my last gimbal it was a little sluggish but still fairly nimble. For comparison my previous gimbal weighed in right at 500g vs 730g for the tube gimbal, so anyone worried about weight or performance should definitely go with the square tube gimbal over the round tube version (at least until we figure out how to reduce it's weight a bit ).
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Old Oct 14, 2012, 11:23 PM
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>>- Speaking of copter options, another issue that could come into play with a Y6 and maybe X8 if you are using tube legs is with the roll axis.<<

I am wondering if you can off set the roll axis a little bit to one side for the servo to clear. You can slide the boom block by what ever amount within the tube.

>>One thing I can say is I definitely noticed the weight difference in flight.<<

Yeah my first test was with a quad. I did feel the weight.

>>but the copter flew much more sluggish and acted / felt a lot heavier.<<

I wonder if that will help in the wind.

>>so anyone worried about weight or performance should definitely go with the square tube gimbal over the round tube version (at least until we figure out how to reduce it's weight a bit <<

You can get rid of the boom blocks (those are the heaviest parts in the gimbal) and use square tubes. Hmmmm.....those plates will work with the towel bar from Home Depot.
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Old Oct 15, 2012, 01:08 PM
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Yes, I am still using a Lontair MIBL servo on one of Andrey's gimbal.
How are the MIBL servos? I was thinking of trying them on a direct-drive gimbal. Possibly using antagonistic pair on the tilt axis to eliminate geartrain slop if needed. We're talking about the $80 HK servos right? I think the company is actually Iltair?

This thread is really interesting. I have been working on my own gimbal design using the same approach. Only thing is I have been planning on welding square aluminum tube for the ultimate in light-weight and stiffness.

I think you guys have uncovered some of the problems with the other gimbal designs out there, even the expensive ones. Too large, and flimsy construction using flat plate, round tube, and a million connector pieces. They end up being to flexible and create their own Jello problems.

I am amazed at how jello free my video is hard mounting a Contour HD directly to the frame on my 600 helicopter. No damping at all. This tells me that the gimbals must be creating a lot of the vibration problem.
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Old Oct 15, 2012, 01:27 PM
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>>How are the MIBL servos?<<

Hard to tell. It works but no substantial difference. The main difference I found is that the servo is very hard to turn by hand with no power. Which probably meant it has a high gear ratio.

>> I was thinking of trying them on a direct-drive gimbal.<<

I don't remember the specs on the servo. It is pretty powerful though.

>> We're talking about the $80 HK servos right? I think the company is actually Iltair?<<

I think that's the one.

>>This thread is really interesting. I have been working on my own gimbal design using the same approach. Only thing is I have been planning on welding square aluminum tube for the ultimate in light-weight and stiffness.<<

I am also very interested in getting the aluminum tubes welded together for ultimate in light weight and stiffness. I don't have the equipment to do it anymore so I have to find a machine shop in town to do it. If you can do it I would love to hear of your outcome.

>>I think you guys have uncovered some of the problems with the other gimbal designs out there, even the expensive ones. Too large, and flimsy construction using flat plate, round tube, and a million connector pieces. They end up being to flexible and create their own Jello problems.<<

Yes, that was a very pleasant surprise. I didn't realize how rigid that gimbal can get with just the metal tubes until I built a couple. Then the lightness surprised me even more.

>>This tells me that the gimbals must be creating a lot of the vibration problem.<<

I am a believer in that. Probably a lot of resonance from the vibration. So the gimbal is probably making the matter worse.
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Old Oct 15, 2012, 01:43 PM
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Hmmm... I was hoping the MIBL's would have less geartrain backlash, and less deadband. Can you comment on that?

Otherwise, I'd just get the cheaper MI's. I already have a number of high speed high voltage MI's on a helicopter and like them. They are nice for the price.

Quote:
Yes, that was a very pleasant surprise. I didn't realize how rigid that gimbal can get with just the metal tubes until I built a couple. Then the lightness surprised me even more.
It's the same thing with multirotor frames. $1500 for 400g of lightweight ultra-strong Carbon Fiber, and then 600g of steel screws and flimsy plastic connectors to fasten it all together.

I'd love to do a welded monocoque aluminum frame sometime. If I can get past the fear of crashing ( = total write-off) then I might do it sometime.

I was shopping for gimbals, ready to drop a chunk of change on one. Then I saw this great thread on multirotor forums where they're diagnosing a problem on an AV200 and they reveal what junk it is. Bunch of cut CF plate with flange bearings simply pressed in, not retained in any way.... The bottom camera mounting plate that has slots milled out of it is like a spring-board... Guys bolting blocks of 1/8" FR4 on top of the plate to stiffen it. Felt washers sandwiched in the joints to hold the bearings in place and dampen the free play, which then creates sticktion. What a nightmare.

A big part of the problem is everybody insisting on flying with a 2kg camera, and then wanting to save weight on the gimbal. I think the gimbal should weigh at least as much as the camera. How could it not?!
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