Clamshell Bucket Build

[Rvjimd]

Quick video pictures and test video of my second attempt at a clamshell bucket.

I need to decide if I'm building a scratch crane or how to use the new bucket. The plan is to use it to unload sand hopper barges that are loaded with the dragline.

http://youtu.be/yeKCyHXmbCY

Jim

[doodlebug]

Look's like yer having fun! I like it.
Cheer's, Neil.

[FlyingBeagle]

Cant wait to see videos of it bringing up wet sand and rocks from the bottom of the pond. It looks great. Are you going to build a new crane for the clamshell or use it on the existing crane you have? A new barge mounted crane with its own tug would be awesome.

[Rvjimd]

FB,

all great ideas! For now I'm going to rig it on the Menck crane. My primary mission for the clam is to unload sand from the barges, but i also wanted to have a dedicated dredge operation.

I may need to build another clam, buy and convert another crane, and I am still pondering the idea of some type of custom unloading crane for the unloading area. I'm thinking some form of a trolley style crane that would be cantilever out over the water/barge and trolley back over the stock pile.

Jim

[sparkycuda]

Nice job with the clam bucket! Being made of brass, I wondered if it would have enough weight to bite-in adequately, but looks like it's not a problem at all.

Ken

[Rvjimd]

First let me say, clamshell ops is WAY more prone to trouble than dragline.

Here are two pics with the top bracket on and rigged on the Menck. I loaded it for a crane capacity/balance test, I did NOT scoop that much sand with the crane.





I'm gona have to re rig and skip one pulley, cause my scale and length of closing rope exceeds the available hoist distance and the shackle hit the boom tip before I get the bucket raised to a reasonable height.

Also, need to make a mid boom pulley for the calming line and counterweight.

Jim

[modelman]

Jim- that is an interesting set-up with the counterweight. What is the purpose of the counterweight? If you are using a 2-part line that cuts your speed of movement in half but doubles your torque. Looks good. Keep at it.

[Rvjimd]

MM,

with two ropes running thru the boom tip and down to the bucket, the bucket spins around fouling the ropes, unless you have a calming line running back up to the boom down low. The calming line needs to stay taught but go in and out as needed when the bucket is hoisted or lowered.

I'm my testing phase I have run the calming line over the outer pulley, normally used for the drag rope. I attached a few weights to it for now.

We will see how it works out. Small scale may get the better of this experiment...

Jim

[Seilbagger]

Hello Jim,

here the construction of the calming rope, but to build this in 1:50, i would become crazy

[Rvjimd]

Ya, I had seen that and you are right on the scale creating difficulty.

I think the way I have it running to the front drag rope pulley is going to work, until I try to dredge deep water, then I'll have to think of something else.

Jim

[Rvjimd]

Da, da da da..,

Here it is in action. We just so happen to get a barge load of sawdust in at the sea wall today to test out the new clamshell. Sand is okay, but if a small pebble gets caught in the jaws and holds it open a bit, the dry sand pours out around it. Hence the need for a screener.

Wet sand is okay too, but neither one fills the bucket. I think in such a small scale the clam is just not going to dig in very well.

I did try it in the canal, dredging sand off the bottom. I was able to get a good enough load that my counter weight on the crane was not enough to keep the crane in position. I think the bucket turned out a bit too large. Not sure if a bit more narrow might dig better?

I would like to try another one with teeth for wet sand and not so wide.

http://youtu.be/8ouiHyJ_mvg

Jim

[Lil Giants]

Add more weight to your center pin so the jaws open much wider for a bigger bite, get a bigger load?

[modelman]

Jim-I agree the clam looks a bit large for the scale but whatever you can make work. The larger clam will be more efficient loading. Is that a 1/50 scale truck you are loading? I agree with Joe. It needs to open wider and adding weight should make it dig better. You may need to add counterweight to the dragline. Your getting there. Are you having fun!!!

[Rvjimd]

Ya, the truck is 1:50 but it seems that some of the less expensive
stuff in 1:50 is not always right on in scale. It is a quarry hauler
so it probably ought to look bigger compared to the bucket. Also the
barges seem pretty small compared to the bucket, but I knew they are a
fair bit smaller that 1:50. I think they would be like 4' long or
something like that if they were scale!

I can add some weight pretty easy. I also wonder if the angle of the
jaws when they come together should be a bit more steep to keep the
digging and downward pull at work more?

And, since I decided not to incorporate teeth, because I wanted to get
smooth on the barge bottom that must make an impact as well.

I guess I could try a nearly empty barge where the edge can get to
clean surface in spots?

And, might just be the small scale is never going to work great.

Im on the search for some coarse sand blast sand or something else that
might look like the coal you would see hauled in a barge. Hoping that
might be a good material for my machine.

Jim

[Rvjimd]

I took a close look at the clam on the bench. The closer line up to the shackle was a bit too short and was limiting the the amount of opening, so I fixed that. Then, I noticed a slight interference issue at the top hinge point of the A arms at the top pivot. The outside bars where colliding with the inner set like a scissors so I rounded them down and took care of that.

If I could figure out how to clutch the rope drums so I could drop the bucket, even a little, it would take care of it.

After the two fixes that I made I tried it again and got lucky on a hump of sand. The bucket set down in the sand with the center pivot resting in the sand. It closed up nice and was to heavy to lift!

The next two scoops caught a rock in the side, holding it open so much that the sand just poured out as I hoisted.

I'm gona work with it a bit more and see how it goes.

Thanks for the tips.

Jim