The original toy

Homemade version

How it works

The claw mechanism works by way of a small float within the bell that raises as the water enters thereby pulling the claws open. Water exits, claw closes.

Considerations in construction:

1. Everything should be a little loose and the float should not be tight within the housing. Too tight and the water entering the diving bell will stick the float to the sides.
2. The pivot points on the claw arms should be as close together as possible so that the connections to to the float can also be as close to center as possible. Too wide and the float slips off the claw. For that reason, the pivot axle for the claws is mounted on the outside of the bend rather than the inside. This matters a lot so make sure to pay attention to this point.
3. The float should be as low as possible within the diving bell.
4. The diving bell requires a balance between the bouyancy and weight. You can either use brass screws with washers or a copper ring. Getting the weight right with the copper ring can be tedious while the screw and washer setup allows for easy adjustment of the weight.

Materials

1. Length of 3/4" clear acrylic tubing.
2. Length of 1/2" clear acrylic tubing.
3. 1/16" sheet styrene.
4. Thinnest sheet styrene from Plastruct. Not sure what the thickness is but you can probably get away with using the 1/16" and just file it down or maybe leave it at 1/16". This is for the float and the goal is to keep it as low as possible.
5. Liquid glue for styrene. The kind that you brush on.
6. Length of 20 guage copper wire.
7. Solder.
8. Weight. Either two 6-32 x 3/16" brass screws and #6 brass washers or a piece of 3/4" copper pipe.

Tools

1. Wide flat file. Wide enough to file ends of 3/4" tubing.
2. Small file set. I used the flat, square and round files.
3. Soldering iron.
4. Hobby knife.
5. Drill.
6. Drill bits.
7. Hack saw. This is to cut the tubing.
8. Wire cutters.
9. Needle nose pliers.
10. Straight edge.
11. Square.
12. Circle template.
13. Pencil.
14. 6-32 tap if using screws for weights or tubing cutter if using copper pipe. If you don't have a set, you may be able to just screw into the plastic directly. The styrene is fairly soft.

1. Vice.
2. Helping hands to hold wires while soldering.
3. Dremel with cutting wheel and sanding wheel to cut screws and flash on plastic caps.
4. Small digital scale for getting weight just right (mostly if using the ring weight).

Steps

1. Layout the base of the diving bell. First cut a small piece of the 1/16" styrene that's about 2" sqaure. Make sure there is at least one corner with a true right angle. Use your square to draw a crosshairs. Center two circles over the crosshairs. These should be the inner and outer sizes of the 3/4" tubing. Mark ends of what will be a centered 3/8" slot for the claws. If you are using the screws for weights, draw another couple 3/8" centered marks on the other line for the screw holes.
2. Drill the holes in the base. To make the slot for the claws, use the point of your small rat tail file to make a series of set points between the two end points of the slot. Make sure that these are not too close together since the drill will wander. Drill the holes with a 1/16" drill bit. Use the hobby knife to remove some of the material between the holes then use the small flat file to finish the slot. If you are using the screws as weights, set the points and drill with a #31 bit then use your 6-32 tap if you have one. If not, try the screws without the tap. Maybe drill a slightly bigger hole if needed.
3. Cut the tubing. Cut a 1" length of the 3/4" tubing and file the ends as flat as possible with the large file. Cut a 3/8" length of the 1/2" tubing and file as flat as possible.
4. Make the claws. Strip some of the 20 guage copper wire and make 2 1" lengths and 2 1 1/2" lengths. Using your best method - I used the helping hands - align one long and one short piece into a cross shape leaving about 1/2" at the top of the 1 1/2" piece. Every end will later be trimmed so the exact placement isn't critical - just try to make it as square as possible. Now, solder at the joint then file the excess solder from the shorter pieces as this will be the pivot point. Use the edge of the needle nose pliers to bend a right angle on the long end for the claw and on the other end for the lever.

   IMPORTANT: Make sure that the pivot point is on the inside edge of the bend.

   If you use the exact length of the pliers, for the claw end, you will have the same length when you do the other arm. Using two pieces of 1/16" styrene glued together, make a small thickness jig to cut the pivot points of the claw arms and the claw hooks to approximately 1/8". Trim the lever end of the claw to roughly 1/4". This will be trimmed later once installed. Repeat this entire process for the other claw arm.

5. Make the bushing for the claw arms. For these two pieces, you want to create two parts with holes at the edge just large enough to hold the claw arms but allow them to pivot freely. The holes should be 1/8" apart. First choose a piece of 1/16" sheet styrene and file the edge of the sheet to be nice and square. This edge will be glued to the base. For now, keep this piece fairly large and don't bother trimming it just yet as it's easier to handle the larger piece. Mark off two sets of 1/8" wide marks and either drill each hole or slot with a file. I don't have the exact size drill bit so I drilled with a smaller bit then filed to size. Check the holes by butting the piece up against a flat piece with the claw pivot in the hole. Once it can spin freely in each hole, that hole is big enough. Once all holes are the right size, trim the pieces closely on all sides.
6. Install the claw arms. Place the claw arms in the slot then position one of the bushing over them, center and glue. As quickly as possible, insert the other once and adjust so that the claws open relatively evenly. Keep pressure on the pieces while drying and move the claws while drying in case the glue has melted the plastic at the pivot points. Using the inner circle as a guide, trim the lever side of the claw arms. Test by positioning the 3/4" tube over the base. The claws should open and close freely. If not, trim as necessary.
7. Create the float. Cut 2 1/2" square pieces of the thinnest material you have and glue them to either side of the 1/2" piece of tube cut in the above step. Once dry, trim the two pieces close to the edges of the tube with either an Exacto knife, wire cutters or my favorite, the cutoff wheel on the Dremel. Then file the flat pieces flush to the tube with the large flat file. Next, cut 4 1/8" x 3/8" strips and glue them upright on the rouded sides of the float you just made. Once dry, round them off with a file enough so the float fits inside the 3/4" tube. The fit should be pretty loose to avoid binding once water enters the tube.
8. Mount the float. The float mounts loosely to the claw arms with two small pieces of plastic with a notch to allow the claw arm to slide through. Make these pieces much like you made the bushings for the claw arms just with one hole each. Space them just wide enough to fix around the pivot arm bushings. Not too tight so that they bind up but not too loose so that they allow the claw arms to slip out. Glue the first one to the float then carefully position the float onto the claw arms and the other piece. Adjust the float and the other piece then glue the piece in place. Double-check the positioning as it dries and adjust as needed.
9. Close up the diving bell. Cut a 7/8" square piece of the 1/16" styrene and glue it to one side of the 3/4" tube. Trim with a knife, wire cutters, Dremel, etc. then file flush with the large flat file. Place the tube over the float and claw assembly and position it on center. Holding the top of the housing tight to the float and claw assembly and turn it upside down back and forth to make sure the claws and float easily open and close. Re-position if the edges of the claw arms are hitting the sides of the tube. Once satisfied with the positioning, glue the housing to the float and claw assembly. Once dry, trim and file the base of the float assembly.
10. Weight the diving bell. The weight needs to be just right. Too little weight and you can't squeeze hard enough to get the bell to lower. Too much weight and it won't be able to pick anything up. You can either use two brass screws and some washers or a ring of copper pipe. The easiest way to get the weight right is to use the screws and weight because you can just add and remove the washers. The copper ring looks a little better though. The brass screws will probably need to be cut unless you can get some really short ones. Do this with a vice and a hacksaw or the Dremel and cutoff wheel. What I like to do is thread the screw onto a nut and hold the nut with the vice for cutting. The copper ring is made out of 3/4" copper pipe used for house plumbing. First cut a ring about 1/4" with a tubing cutter. Then you will need to cut about 1/8" out of the ring so that you can make the diameter a little smaller so that it eventually clips to the diving bell. Attach the weight and test the bell. Adjust the weight as needed by either changing the number of washers or filing down the copper ring.
11. Finishing touches. One thing you may also want to do is fashion a small loop at the top of the bell like the original has. Occasionally the bell gets water-logged and stuck on the bottom. It's much eaiser to get out if there is a loop at the top to hook on to with a bent piece of wire like the original Parker Brothers toy came with. Of course you can also dress the bell up with some other plastic detail and paint it as well.
12. Selecting a bottle. You can use large (2 liter) or small plastic bottles and most have the same sized cap. The small ones are easier for kid sized hands. One thing I learned though is that some bottles are not shaped correctly. I thought I'd found the perfect bottle with a simple design but it turned out that since the bottom of the bottle turned up and into the bottle, it plumped back out as you squeezed the bottle which didn't allow the pressure to be transfered to the bell.
13. Dress up the aquarium. Use some fish tank gravel or sand to dress up the kit and add some items to pickup with the bell. I used some Lego pieces from my kid's vast collection. You can buy Lego pieces bit by bit with their Pick-a-Brick if you want.