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-   -   Climb Stopping Mechanism (http://www.chiefdelphi.com/forums/showthread.php?t=154311)

Hitchhiker 42 03-02-2017 17:38

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by AdamHeard (Post 1640021)
You won't be able to release weight tension as you're literally clamping the field. Can't go the other way because of the ratchet as well.

You could have it so the ratchet is easy to take off. Then you could unwind the rope.

orangeandblack5 03-02-2017 18:21

Re: Climb Stopping Mechanism
 
Wait... if you're using a ratchet wrench, could you not just reverse the direction the wrench is ratcheting?

antman 03-02-2017 18:23

Re: Climb Stopping Mechanism
 
If you use a ratchet wrench you could clamp the non-ratchet end with a bicycle quick-release lever that can slide in a slot to drop below the wrench when the lever is opened.

AdamHeard 03-02-2017 18:26

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by orangeandblack5 (Post 1640078)
Wait... if you're using a ratchet wrench, could you not just reverse the direction the wrench is ratcheting?

Please, go try this with 150 in-lb (or more) on the ratchet.

Cory 03-02-2017 18:27

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by orangeandblack5 (Post 1640078)
Wait... if you're using a ratchet wrench, could you not just reverse the direction the wrench is ratcheting?

No...that's the entire point of the discussion above. If you have a ratcheting wrench, attempt to tighten an already tight bolt. While applying a tightening force, try to flip the ratchet switch. It won't work. The pawl is under tension as well and you can't overcome it without significant force...far more than your fingers could apply.

orangeandblack5 03-02-2017 18:39

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by Cory (Post 1640082)
No...that's the entire point of the discussion above. If you have a ratcheting wrench, attempt to tighten an already tight bolt. While applying a tightening force, try to flip the ratchet switch. It won't work. The pawl is under tension as well and you can't overcome it without significant force...far more than your fingers could apply.

Ah, thank you for explaining.

Nuttyman54 03-02-2017 20:34

Re: Climb Stopping Mechanism
 
I've been mulling over whether or not it's legal cut the rope to release the robot. It's legal for your robot to damage team provided ropes (G15) as long as it doesn't leave debris on the field, and once the rope has been removed from the Davit it's no longer considered part of the field (R08 blue box).

As far as I can determine, it would not be legal because up to the point where the rope is cut and the robot is released, it's technically a person damaging part of the field (even though that part of the field is legally allowed to be damaged by a robot. Just not anything else). But it was an interesting read through the rules.

*Apex Robotics is not planning to release our robot in this fashion. But it did make me curious if it's a quick fix for teams who haven't planned around this*

Oblarg 03-02-2017 21:30

Re: Climb Stopping Mechanism
 
We're using a flex-head ratcheting wrench, i.e. just an ordinary ratcheting wrench except there's a pivot between the head and the handle. In order to lower the robot, we simply undo the velcro strap holding the wrench handle in a constrained position (i.e. between two bolts) and pivot it out of the way. The wrench rotates with the winch as it unspools.

GeeTwo 03-02-2017 21:44

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by Oblarg (Post 1640147)
We're using a flex-head ratcheting wrench, i.e. just an ordinary ratcheting wrench except there's a pivot between the head and the handle. In order to lower the robot, we simply undo the velcro strap holding the wrench handle in a constrained position (i.e. between two bolts) and pivot it out of the way. The wrench rotates with the winch as it unspools.

Wow. I was at Lowe's shopping for ratchet wrenches this evening, and thought of essentially the same thing when I looked at the flex-head wrenges. I was thinking of using a non-flex head, non-reversible wrench, wedging it in a piece of aluminum channel (similar to your two bolts), and lifting it out parallel to the shaft. If you do this, be sure to mark the ratchet wrench as to WHICH SIDE FACES OUT, or you'll have a useless climber for a match or three.

Quote:

Originally Posted by Nuttyman54 (Post 1640127)
I've been mulling over whether or not it's legal cut the rope to release the robot. ...

I concur that with the rules as currently written, it would not be legal (Drive team damage vs robot damage). However, given the preamble to the answer to Q299, I suspect that a question on this topic would get a finding of legal even if it meant a rule change.

Oblarg 03-02-2017 21:50

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by GeeTwo (Post 1640153)
Wow. I was at Lowe's shopping for ratchet wrenches this evening, and thought of essentially the same thing when I looked at the flex-head wrenges. I was thinking of using a non-flex head, non-reversible wrench, wedging it in a piece of aluminum channel (similar to your two bolts), and lifting it out parallel to the shaft. If you do this, be sure to mark the ratchet wrench as to WHICH SIDE FACES OUT, or you'll have a useless climber for a match or three.

The nice thing about the flex-head wrench is that we can constrain the head in-place to avoid that exact problem (though we probably ought to mark it anyway).

For those who are interested, this is the wrench in question:

https://www.amazon.com/TEKTON-WRN570...words=WRN57010

Karibou 03-02-2017 22:02

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by GeeTwo (Post 1640153)
Wow. I was at Lowe's shopping for ratchet wrenches this evening, and thought of essentially the same thing when I looked at the flex-head wrenges. I was thinking of using a non-flex head, non-reversible wrench, wedging it in a piece of aluminum channel (similar to your two bolts), and lifting it out parallel to the shaft. If you do this, be sure to mark the ratchet wrench as to WHICH SIDE FACES OUT, or you'll have a useless climber for a match or three.

From my experience, that is much easier said than done (with the non-flexible non-reversing). The wrench always wedged itself pretty tightly against the stop and we still needed to lift or rotate the robot slightly to get it out. There needs to be pretty much no load on the wrench to be able to slide it along the shaft to get it off (or far enough along the shaft to not be impeded). Granted, I've always done it using two bolts/screws as the stop, never channel.

I'll second the comment about marking which side of the wrench needs to be facing out, or which way the switch needs to be flipped if you're using a reversible wrench. Drill it into your pit crew's and drive team's heads. You can never double-check too many times.

AdamHeard 03-02-2017 22:02

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by Oblarg (Post 1640147)
We're using a flex-head ratcheting wrench, i.e. just an ordinary ratcheting wrench except there's a pivot between the head and the handle. In order to lower the robot, we simply undo the velcro strap holding the wrench handle in a constrained position (i.e. between two bolts) and pivot it out of the way. The wrench rotates with the winch as it unspools.

Have you tried this after crashing into the top and holding full stall?


Depending on where it is in the gear reduction and the spool diameter it'll either be completely locked and tough to remove or trivial to remove by hand.

Oblarg 03-02-2017 22:07

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by AdamHeard (Post 1640168)
Have you tried this after crashing into the top and holding full stall?


Depending on where it is in the gear reduction and the spool diameter it'll either be completely locked and tough to remove or trivial to remove by hand.

The wrench is right on the spool shaft, and the spool diameter is 1.25''. It's got a nice long handle, and I seriously doubt it will be a problem though we have not tried "wedging" the robot like that yet (we will be current-limiting the climbing motor to prevent that, at any rate).

CalTran 03-02-2017 22:48

Re: Climb Stopping Mechanism
 
Quote:

Originally Posted by Oblarg (Post 1640170)
The wrench is right on the spool shaft, and the spool diameter is 1.25''. It's got a nice long handle, and I seriously doubt it will be a problem though we have not tried "wedging" the robot like that yet (we will be current-limiting the climbing motor to prevent that, at any rate).

Might as well test "catastrophic failure mode" while you get a chance to do so in a more friendly environment.

Chris is me 03-02-2017 23:31

Re: Climb Stopping Mechanism
 
After reading all this, maybe it would just be better to climb early and let the robot backdrive as time expires... This seems tricky otherwise.


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