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Old Oct 06, 2012, 10:01 AM
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There's also onlinemetals.com, they seem to have a pretty good selection...
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Old Oct 09, 2012, 05:34 PM
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Hansen or Rusty, any more testing/updates on this gimbal idea?
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Old Oct 09, 2012, 06:24 PM
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Hansen or Rusty, any more testing/updates on this gimbal idea?
Yes, Rusty is busy making one out of 10mm square aluminum tube. I am waiting for some parts to show up to finish up the 1/2" square aluminum tube version. Hopefully later today I will have some more pictures.

Rusty is keeping his build a secret for now but it is looking really good.

Since Rusty is making a 10mm version I ordered some 10mm carbon pultrude square tubes and 5/16" square basswoods. My plan is to cut the carbon tubes and CA glue the basswood inside. Then I will build a 10mm square tube version with the carbon/basswood to see how light I can make it.

Right now the 1/2" square tube version may very well be under 500 grams without the camera.
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Old Oct 09, 2012, 11:15 PM
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500 grams would be really good. If i recall, the CS is about 700 grams, which is pretty light for the size.

How are you liking your servos for the carbon tube version you made?
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Old Oct 09, 2012, 11:55 PM
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500 grams would be really good. If i recall, the CS is about 700 grams, which is pretty light for the size.

How are you liking your servos for the carbon tube version you made?
I am just about finished with the 1/2" alum gimbal. It is at 577 grams. So not quite below 500 grams. I hope the 10mm version will be lighter.

I also got some 10mm alum tubes from Rusty and I weighed them against the carbon tubes. On a 12" piece the difference is only 5 grams so I am not going to bother with the carbon tubes for now. Unfortunately the 10mm tubes are hard to find in the States.

I liked the servos I used on the CF gimbal. I only had one flight and the gimbal went to Matt for testing. I hope he will let us know how it is working for him.

On my one flight the roll was just fine and the tilt was over compensating.

I got most of the parts and pretty much finished the 1/2" alum gimbal. I just have to wait for the roll servo to show up from Servo City. I just realized all my servos need external pot and I am not ready to use one on the roll axis.
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Old Oct 10, 2012, 01:08 AM
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I think pictures make the thread less boring.
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Old Oct 10, 2012, 01:46 AM
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Old Oct 10, 2012, 07:41 AM
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Greetings,

I'm not sure I'd call the build "secret", but I know that things will change several times along the way, so I usually try to avoid posting pics until I'm close to the final design. The biggest thing I need right now is time.

500 grams will be tough, and maybe impossible without using directly bolted tubes. What you see in the crappy photos is 465 grams (yes my scale can read grams <g>) with the second servo and pulley included. The additional material will certainly push that over 500, but I haven't substituted the aluminum hardware yet, so that will help. Unfortunately, those servos are about 150 grams of the total.

Cheers,
Rusty
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Old Oct 10, 2012, 08:03 AM
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Hi guys,

I just got Hansens round tube gimbal last night, so far I've only had a chance to open the box and give it a quick once over. It does feel a bit heavy (about 730g including mounting hardware) but is really well built and quite clever in it's design. I'm not too worried about the weight since I'm planning on flying this on a Y6 which currently flies my gimbal / GH1 at half throttle, so should have enough power (I don't remember what my current gimbal weighs, will check later).

More thoughts and comments as I get it setup and use it.
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Old Oct 10, 2012, 01:29 PM
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Greetings,

I'm not sure I'd call the build "secret", but I know that things will change several times along the way, so I usually try to avoid posting pics until I'm close to the final design. The biggest thing I need right now is time.

500 grams will be tough, and maybe impossible without using directly bolted tubes. What you see in the crappy photos is 465 grams (yes my scale can read grams <g>) with the second servo and pulley included. The additional material will certainly push that over 500, but I haven't substituted the aluminum hardware yet, so that will help. Unfortunately, those servos are about 150 grams of the total.

Cheers,
Rusty
Looks great, Rusty! I like how adjustable and scaleable it's going to be and the simplicity. A few questions to satiate my curiosity:

1) What's your kit going to include? Plates, hardware (including bearing/bushings), pulleys.. ?
2) Can we expect that it will integrate nicely with your current isolation setup?
3) Where are you getting your alum tubes from?
4) What is that tilt pot you are using?
5) What ratio are you trying out in those pictures?

Also, HK has some CF tube that may work http://www.hobbyking.com/hobbyking/s...50x10_5mm.html. I would add dowels to help with torsional stresses
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Old Oct 10, 2012, 01:41 PM
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>>1) What's your kit going to include? Plates, hardware (including bearing/bushings), pulleys.. ? <<

Rusty can best answer that. I would imagine providing pulleys, belts, bearings and pot will be more convenient for the end user.

>>2) Can we expect that it will integrate nicely with your current isolation setup?<<

I have been thinking about that for a couple of nights now. I would like to see the isolator attachment points to spread out farther apart for less movement.

>>3) Where are you getting your alum tubes from?<<

Rusty will know. I don't.

>>4) What is that tilt pot you are using?<<

Rusty found them.

>>5) What ratio are you trying out in those pictures?<<

32 tooth servo side and 90 tooth gimbal side. So that's 2.8 to 1.

>>Also, HK has some CF tube that may work http://www.hobbyking.com/hobbyking/s...50x10_5mm.html. I would add dowels to help with torsional stresses<<

So does Radical RC and a couple of other vendors in the States. If 10mm square aluminum tubes are hard to come by in the US the square carbon pultrude will be an alternative. It will be slightly lighter but not by much. I weighed them.

You do have to sleeve the carbon tubes with either square basswood or round dowels for the ones with round holes in the middle.

Let me see if I can find some 5/16 balsa. I may try sleeving the tubes with balsa.
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Old Oct 10, 2012, 07:00 PM
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Originally Posted by jcmonty View Post
1) What's your kit going to include? Plates, hardware (including bearing/bushings), pulleys.. ?
Good question, and I wish I had a good answer

Seriously, the most basic kit would have everything but the servos, pulleys, and tubing. One or two ratios of pulleys would certainly be available as an option. Since the 10mm is so hard to get in the US, I'll almost certainly have to stock it as an option in fairly short lengths. I don't have any plans to stock, or modify servos at this time.


Quote:
Originally Posted by jcmonty View Post
2) Can we expect that it will integrate nicely with your current isolation setup?
Yes, there will certainly be a way to mount it to the current UAP1 damper plates. That's how I'll test it, though I probably don't have a worthy camera.

Quote:
Originally Posted by jcmonty View Post
3) Where are you getting your alum tubes from?

I've ordered from Parker Steel, though it's not cheap. They certainly are fast and efficient though. Of course only in America can you order metric tubing by the foot

Quote:
Originally Posted by jcmonty View Post
4) What is that tilt pot you are using?
What you see in the picture is this pot:
http://www.digikey.com/product-detai...502C-ND/222782

It was chosen because it has a nice long shaft that happens to be the right size for bearings. It's 5k ohms because "someone" said that was what his pots were. I notice now that the external pot Servo City left on my modified servo is 1500 ohms, but I'm not sure if the value matters much. I've never looked at the circuit, but I'm betting it's just a voltage divider, and it won't matter what the value is.


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Originally Posted by jcmonty View Post
5) What ratio are you trying out in those pictures?
As Hansen mentioned, 32 and 90.


Cheers,
Rusty
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Old Oct 10, 2012, 08:34 PM
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This is pretty exciting. I had 10mm square clamps already and have some 10mm alu tubing on the way but think I will wait until Rusty finishes his up. He always thinks it out and does a nice job Seismic nice job on your original too. I was ready to turn some parts on the lathe and do some milling after reading your first post. I have always been curious about backlash in a gimbal setup so figured it was time to build one and see what it was all about.

edit to ask: What torque range do the servos need to have? I have some low end small digitals that track great and maybe one of their bigger brothers might work for this.
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Old Oct 10, 2012, 11:43 PM
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>> Seismic nice job on your original too.<<

Thank you.

>>I have always been curious about backlash in a gimbal setup so figured it was time to build one and see what it was all about.<<

If you use a high ratio belt drive backlash is really not much of an issue. The main issue if flexing of the gimbal if it is not rigid enough. Mostly on the tilt axis. Then the other is the backlash of the servo if you don't use a good quality one.

>>edit to ask: What torque range do the servos need to have? I have some low end small digitals that track great and maybe one of their bigger brothers might work for this.<<

I found that the stronger the better without sacrificing speed. You don't need those .06 second transit time like the ones for the tail rotor of a singe rotor helicopter. However some where in the low teens will be nice. As far as torque I like those 300 to 400 ounce inch monster. That's just over kill. Generally 200 ounce inch will be just fine.
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Old Oct 11, 2012, 10:17 AM
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Thanks for the info. Sounds like the 48 oz digitals that I have are a little small but the larger model will do 300+ oz. Looks like +/- 45 degrees of travel so that should be plenty for me. Know absolutely squat about the AP part so this should be very interesting.
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