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View Full Version : [Question(s)] RX-24F, Pro & Cons?have you use it?



wiweet
10-20-2012, 07:43 PM
As an upgrade to my AX-12A humanoid, I want to move to RX-24F. I Know that RX-28 and MX-28 are the most popular dynamixel right now, as DARwin-OP use them, but honestly RX/MX-28 price is beyond my budget.

So I choose RX-24F for my upgrade. What I want to ask here is about the RX-24F Pro & cons, because I had read in another at this forum (http://forums.trossenrobotics.com/showthread.php?5723-RX-24F-useful-for-quadropods)that said RX-24F is not a best upgrade from AX-12, mainly due to its tendency to overheat quickly. is it right? as a side note my humanoid would have around 2 or 2.2 Kg of weight(including 6 RX-24F that I will used as upgrade).

Anybody have ever got a hand or use RX-24F, please share your experience/opinion please?

regards,

wiweet

darkback2
10-27-2012, 02:46 PM
I know the price is moderately exciting...an RX servo with pretty decent torque ratings for $125 or so...especially given the MX or RX 28 is over $200, and a huge complaint of mine has been that robotis doesn't really have a middle weight servo between the ax-12/18 and the RX - 28...but honestly the RX-24 is not it. I currently use them in Hikari's shoulders. The servos go into thermal shutdown if they are under any kind of load at all in a matter of seconds. I got my 24s used and got a pretty good deal on them all things considered, but in reality they are just placeholders until I can save up to get RX-28s. If I had it to do all over again I would have skipped them all together and just waited until I had the money to do things right.

I'm really sorry, and if you have your heart set on the RX-24s then just keep it light...think along the lines of Tybes RX-24f kungfu humanoid. http://www.youtube.com/watch?v=WOIRp25odm4

Hope this helps.

DB

jwatte
10-27-2012, 04:58 PM
The Herculex 0201 seems like it is in the same ballpark as the RX-24, both in performance and cost.
The US distributor ("road narrows") is currently out of stock, so I can't get one to try it out... Btw: they've done a terrible job of showing up on Google when you search for them.
Will Trossen get these, too?

wiweet
10-28-2012, 09:20 AM
.... I currently use them in Hikari's shoulders. The servos go into thermal shutdown if they are under any kind of load at all in a matter of seconds....

I'm really sorry, and if you have your heart set on the RX-24s then just keep it light...think along the lines of Tybes RX-24f kungfu humanoid. http://www.youtube.com/watch?v=WOIRp25odm4

Hope this helps.

DB

can you tell me how much load you have on them(Hikari's shoulder)?
could you give me some approximate weight here, regarding "then just keep it light"?
Just for my curiousity, what is the total weight of your Hikari?

Thanks a lot Dark Back.

darkback2
10-28-2012, 12:39 PM
can you tell me how much load you have on them(Hikari's shoulder)?
could you give me some approximate weight here, regarding "then just keep it light"?
Just for my curiousity, what is the total weight of your Hikari?


Hikari is a big heavy girl. I stopped paying attention to that when she breached 10 pounds. I just say 5kg and call it good.

The arms weight .5 kg each total and are usually bent tucked up against the body or at 90 degrees which puts the farthest part of the load about 15 cm away from the shoulder. The issue is when she is on her back most of the load is on the shoulder rotation servo which goes into thermal shutdown...I would say in 30 seconds...might be a tidge longer.

The crazy part is that the shoulders used to be AX-18fs...didn't have this problem at all. I switched up because the RX-24s were just sitting there doing nothing after I took them out of the hips where they were totally useless.

By keep it light I'm suggesting that the only weight on your bot be servos, a controller, the most minimalist aluminum or plastic brackets and a mill spec battery. don't think you are going to build this up into a mech or pc based bot...24s and 28s are completely different animals.

Hope this helps,

DB

wiweet
10-28-2012, 01:00 PM
Thanks DB, your experiences with the RX-24F really worth to be noted.
From the RX-24F specs point of view, maybe its "current hungry" characteristic that made it overheat quickly ( Stall Torque : 2.65N.m (at 12V, 2.4A) ) compared to RX-28 (Stall Torque : 3.77N.m (at 18.5V, 1.9A)) and the MX-28 (Stall Torque : 2.45N.m (at 12V, 1.5A) ).

regards,

wiweet

jwatte
10-28-2012, 01:44 PM
I still wonder if the heat can be managed somehow. Add cooling flanges? Add water cooling hoses? Double heat sinks? :-)