Barge-Mounted Clamshell Crane

[Jared]

If my math is correct, the servos are theoretically capable of lifting 23 lbs. The drums are about 3/4" in diameter and the servos are supposed to be good for 139 oz-in. I divided 139 by the radius of the drums, .375" which comes out to 370 oz, which is 23.1 lbs. Did I do that right?

[lorenzo]

Many thx for the pix. Your tagline arangement is very interesting. Did you calculate the force that the spring should have or just did you do it by trial and error.

[Jared]

Originally Posted by lorenzo

Did you calculate the force that the spring should have or just did you do it by trial and error.

Trial and error. You can see all the holes I drilled in the lever.

Thanks, td9clyde.

Originally Posted by 9W Monighan

Very nice and simple. I like the tag line set up. On some of the early 1900's machines I've been around: I saw a weight that runs up and down a track on the boom this was on a Erie steam crane. My buddy has a Insley half swing machine he's starting restoration on and it has a pipe with a pully on top where a weight just slides up and down inside the pipe,but that was probably for the trip rope when it has a shovel front mounted.

Thanks. I toyed with both ways a little bit but I couldn't figure out how to make it slide smoothly without pulling too hard and without being too bulky. At this scale friction plays a bigger part than it does on bigger stuff.

Originally Posted by tc1cat

NICE!!! Now you just need to scale it up to 1/16th so you can play with all of the semis We need something like this for bigger scale trucks to use instead of just the elevators and payloaders. 30" in 1/48th is about 90" in 1/16th So about a 8' boom would be fun to watch

Thanks. I've been kicking around a 1/16 scale Bucyrus Erie 22B, but that won't happen for some time yet due to a shortage in the employment department.

Originally Posted by sparkycuda

did you weight the lower pulley crossbar or was it heavy enough by itself?

Thanks, Ken. I had to weight the crossbar a little bit.

Originally Posted by kerst

the clamshell bucket is beautiful. I once built one for my Manitowoc. I really enjoyed that project.
how did you convert the servo motors to run the winches?

kerst

Thanks, kerst. It was kind of a trip when I got it put together and not only did it look like a real clam, it acted like a real clam. On the servos, there are two ways. I couldn't find the page I used, but this is basically the way I did it, though these aren't the best instructions: http://www.instructables.com/id/How-...or-Continuous/

Or you can do it like this: http://www.seattlerobotics.org/encod...0for%20PWM.htm
I'm not really an electronics guy and I didn't feel comfortable poking around the electronic guts. But this is probably the better way to do it because you don't have to worry about the pot changing position.

[W900snowman]

Very impressive I love the video and thanks for posting the pictures. Everyone around here sets the bar pretty high.