I am wondering if I can use the lynx system to build a larger replica of the Lynx 6 control arm? Is it possible for example to build one with larger motors connected to the same record control box that the kit comes with? If I buy large stepper motors what modifications would I need to make if any?
FYI, when I say large I mean like I want to build one 5 feet high
Any help would be great!!
The parts included in the Lynx arm kits are designed for that particular size of arm. If you want to make a larger arm then you would have to custom cut your own parts. You can use a ruler to measure all the dimensions and then make like a 5x scaled version. If you create a 3D CAD model in like SW or other programs you can get companies to cut the parts out for you.
Contact brokenlaser if your interested. He said he can cut stuff for people.
Check out his topic: lynxmotion.net/viewtopic.php?t=1312
One thing you should note: By enlarging the arm, you will be putting more stress on some components. I suggest you reinforce parts of the arm to add strength to it. Solid Works has a cool stress simulator I think. Chunga used it before I think. Ask him 
Cheers and good luck with the gigantic arm!
-robodude666
Well thats great, so that means that I can use the software designed for the small robot arm with a larger version then? Any specifics on the motors themselves that I need to know about?
If you are talking about using the RIOS or SSC software, then yes. You will need to make sure you get the geometry of the arm correct though or else the arm won’t function correctly. I think in majority of SSC-32 arm files jim included a geometry definitions section where you can change the size of the arm.
By motor, do you mean servos? Or DC motors? Using a DC motor would be um, awk in my opinion. You would need to create lots of custom brackets. I think using megaservos would be a little bit easier.
While model of the lynx6 arm do you have? I believe there were a few versions of each arm.
P.S. I am not sure of your technical level so I will assume you know what the hell I am talking about. If your lost about some parts, feel free to ask.
I’m actually going to buy the Lynx 6, basically I would like to create a motion control rig for a movie camera and I think this might work for me. So then I should use Stepper motors you think?
Stepper motors are frequently quite loud and suffer mechanical resonance problems at low pulse rates unless microstepping drivers are used. DC servomotors are not as efficient perhaps but are generally less noisy and require simpler electronics to apply. Each has their place in control system design and each has a set of costs and benefits. Rarely do you start a successful design by picking the control system before defining the limits of the system to be controlled. You started the thread talking about a 5-foot high version of the lynx 6 arm. You really should do some mechanical study of the weight and torque requirements for such a project and then pick your drive systems. If you start by picking the motors then you run the risk of designing a system that can’t pick itself up much less move a payload from point A to point B with little to no shake, vibration, or stuttering along the way and can be heard whining away in the background of whatever you are filming.
Well my original premise was based on the arm, with minimal change I could integrate a camera system into it, but I wasn’t sure if upgrading the motors was even possible, my ultimate goal is to create a frame accurate recordable motion playback system with he arm. Fairly optimistic to be sure, but I’m willing to try, as for noise, it make no difference, the arm will be used in special effect shots to which the noise will be canceled out anyway in post production.
My biggest concerns are, what type of motors are compatible with the recording system, anything with a basic (+,-) lead or?
are you talking about a video camera like a mini-DV, or a (digital) camera where you are taking single frames and advancing its position?
how much does the camera weigh?
what kind of motion rates would you expect to need to cover with the camera, meaning for example the maximum number of inches per second you might need to move the camera from point A to point B?
There are small digital cameras people put in r/c airplanes in the 4-5oz range. A mini-DV camera though is probably more like 2-3lbs. when you know the weight then you can put that weight at a distance from an axis and compute torque, like oz-in or ft-lbs. that help will determine the strength of the motors you need.
For example, the lynx 6 arm page lynxmotion.com/Category.aspx?CategoryID=25 says the lift weight with a fully extended arm is 3oz. at the base it uses two HS-475 servos in parallel to supply enough torque. each servo is rated about 76 oz-in. so you can guess-ti-mate the torque required to support the arm, elbow, wrist, and gripper is (76 x 2) / 14.5" extended length = 10.5 oz - the 3 oz payload = about 7.50z. So say you wanted an 8oz payload, 8 + 7.5 = 15.5oz, multiply by the 14.5" and divide by 2 = a minimum 112 oz-in torque rating for those servos to support the additional payload. An HS-654MG would seem to meet that requirement, the HS-5645MG even more so plus it will hold its position better due to being a digital servo.
You need to do similar kinds of calculations to increase the strength of the elbow, wrist, and grippers. You also need to consider that if the new elbow, wrist, or gripper servos weigh more than the old ones it adds to the requirements of each servo as you move up the arm and back factor that into the earlier requirements.
Another thing you need to consider is if the materials the arm is made out of are strong enough to support the additional strain of higher torques and loads. You could put each unassembled piece on a photo copier and take a 1:1 picture so if you found out later you could break them you can then use the 1:1 picture to have a new part fabricated from something stronger… and then you will have to consider any weight added by the new part and see if your servos can still take the load.
for accuracy, it seems like there have been a few discussions about servo accuracy and precision in the past and for whatever reason I seem to have come away with the notion the digital servos are good to a few tenths of a degree. If you are always moving the same load in the same arc you might get better results just because you eliminate gear backlash.
So this is all based off the assumption of increasing the load range of a lynx 6 arm. The intent is to give you an idea of the kind of thought processes you need to consider if you go about scaling the arm up. At some point you will exceed the capabilities of either r/c servos or your wallet and need to look into designing a different drive system and whether it makes sense to go to a micro stepping drive on a stepper motor or a bigger dc servo drive and a fractional hp gearhead motor.
on top of all of this you’ll need to conquer the software bit. I don’t own it personally but I get the impression the RIOS thing will be helpful in at least getting your feet wet with a promise of some success. only you will be able to decide if it will let you do everything you need or if it’s time to start writing your own code.
Hobby servos.
Standard motors will not work…
Hobby servos contain within them a small motor, a gearbox (for more torque), an H-Bridge (speed and direction driver for the motor), and a circuit/microcontroller for positional control.
Long story short, servos hold the position that you tell them to.
Motors do not.
