I’m looking at using AL5D in an all-day demo situation, so durability is key. For that reason I was thinking of changing some of the servos, and I wanted to get the opinion of some current users to see if that makes sense.
For the three standard size servos (base, wrist, gripper) I was going to use the HS-645MG. The goal here is 1) use metal gears for all three, ideally somewhat increasing durability, and make all 3 interchangeable so I can have a spare. The only drawback I can see is that the gripper becomes a touch heavier, correspondingly decreasing lifting capability.
Unfortunately the shoulder and elbow servos are not identical, so I can’t follow my sparing philosophy. Or could I come up with some sort of modification that allows me to use the same servo? I would also consider upgrading these two metal gears, again for durability.
It all comes down to heat generated - if the servos are under load for a long time, they will generate heat. Hitec produces some very reliable servos, and we have had very few fail in-house. This having been said, should you want to push their limits, your approach is sound. Aside from using as many similar servos as possible, you can upgrade the elbow servo to the 755MG (as opposed to 755BB). There is also an MG option for the 805: robotshop.com/en/hitec-hs755mg-servo.html robotshop.com/en/hs-805mg-gi … motor.html
Touch the servos every so oftento get a sense of the heat they are generating and let them cool off as much as possible.
If I wanted to have the same shoulder and elbow servo (say the larger 805) can I simply replace the ASB-203 C bracket with a ASB-205, or do I need to replace additional parts? I’m not familiar with all the parts, and it is hard to be certain looking at the parts breakdown and assembly instructions
The C bracket and multipurpose bracket for the 805 servo are different than for the 755 (we only sell them separately in pairs). lynxmotion.com/c-116-large-h … ckets.aspx
Note that the 805 brackets will need the Mechanical Dampener.
Comenan,
Thank you, I see what you mean, I would have to purchase the C bracket and multi purpose bracket to make the 805 into an elbow. Since each is sold in pairs, I would end up with two extras. By the time I add the price of those two, I may as well just buy a second spare servo.
I will show my ignorance, as I’m just starting to work on robotic arms… If I did proceed down this route, I would obviously be adding some weight to the arm due to the heavier elbow servo and larger mounting hardware. This would **decrease **the shoulder’s lifting capability. On the other hand, the elbow would be a more powerful servo, which would **increase **its capability. Under “normal” motion, is this likely to result in a net benefit or detriment to the overall performance of the arm?
The servo under the most torque / load / stress is the one in the shoulder, and by adding a heavier servo at the elbow, the shoulder servo is under increased load. The only situation where upgrading the elbow is advantageous is when yhe shoulder -> elbow is relatively straight up, which means very little torque is imposed on the shoulder servo.
