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pic: 2980 practice bot Climber
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Re: pic: 2980 practice bot Climber
I think you can be almost completely certain that those gearboxes will not last you the entire season. I'm sorry to be the one to tell you this, but they are just not that strong and are not robust enough for this application.
I would recommend replacing them with a pair of Vex VersaPlanetaries, and using the JVN Mechanical Design Calculator to figure out a ratio that will allow your robot to climb well. I bet you can climb nearly 4 times as fast as this setup is geared for without much of a problem depending on the diameter of your winch and weight of your robot. |
Re: pic: 2980 practice bot Climber
Unless I am missing something in the picture, It looks like you are putting some significant side load on those gearboxes. You most likely will want to support your shaft with something other than the output shaft of the planetary gearboxes, such as a plate with a bearing in it that the shaft runs through.
From Andymark's Website: "Mounting a large load to the end of an unsupported shaft may damage the gearmotor. The shafts on these motors are supported by two ball bearings making them fairly rugged; however, we do not recommend them to be used with large overhung loads. We recommend using a design that supports the end of the shaft. If it is not possible to support the end of the shaft, we recommend mounting the load as close to the face of the gearmotor as possible and cutting the shaft to length." I speak from experience when I say: Nothing breaks planetary gearboxes faster than side load! ::ouch:: |
Re: pic: 2980 practice bot Climber
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Re: pic: 2980 practice bot Climber
The torque output at the motor shaft is divided by the radius of the drum to get force. Bigger drum, less force.
You'd be better, as mentioned above, using a lower gear reduction on a more powerful motor. We've tested 48:1 reduction on a CIM and a MiniCIM just driving a shaft, and they pull 120lb fast enough. |
Re: pic: 2980 practice bot Climber
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Re: pic: 2980 practice bot Climber
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Looks like this same label as here: http://www.andymark.com/Motor-p/am-2161.htm Also the motor has no cooling vents near commutator/brush assembly. The 775-18 has really big ones. |
Re: pic: 2980 practice bot Climber
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We thought we had done the math on these motors and gearboxes, but have yet to test them. Thank you all for the input. I'll have the team do some research and once we decide on something we'll post an update. Edoga |
Re: pic: 2980 practice bot Climber
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Re: pic: 2980 practice bot Climber
I like the way your drum (at least it looks like) rotates so that you get a couple of wraps before there's load on it. But I gotta ask, what kind of bolts are you using. Because it looks to me like to get that rotation on your drum your entire climber is held onto your frame with two bolts.
This means to me that the failure point of your climber is those two bolts, if those bolts aren't strong enough they will shear and it will be a really bad time. 150lbs of robot on two bolts seems like a likely failure scenario to me. You should be able to buy bolts with that shear strength, so it should be a (relatively) simple fix. |
Re: pic: 2980 practice bot Climber
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eedoga, go with the Versaplanetaries. Banebots gearboxes in high torque applications are just asking for heartbreak. And VPs are MUCH easier to tweak into different motor or gearing configurations. |
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The VersaPlanetary is stronger than both the P60 and the P80 series of gearboxes. |
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