2014:Collection Subteam

Todo

• 4-12-14:

Finished up second cradle motor mount assembly. Complete ready to go. Motor was bench tested OK and unit was trail fit on RB2. Complete unit with #25 chain is in a work tub on shelf SB4 in the shop closet. Just to summarize today's activity working with the drive team and Manuel. A new 4 mm key was fitted to the motor shaft and the 16T sprocket to maximize shaft engagement. This also required a new spacer (between the motor and 16T sprocket (0.220" long with a notch in it for the longer key). This second unit uses an Allen cap screw 1/2" dia x 3" long. The assy process is fit the bracket motor assy to the mounting post, slide it up as far as it will go, then assemble the chain over the sprocket, push down on the assembly to tighten the chain. The chain should be taunt but not overly tight. When you have the right tension, select an appropriate Allen wrench and slide it through the hole above the top of the motor mount bracket to hold the bracket down keeping the tension on the chain. Assemble one of the larger aluminum washers on to the 1/2" dia. bolt, then insert the bolt from the inside of the robot through the first motor mount bracket, then through the 1" x 2" rectangle post, then through the second motor mount bracket. Then assemble the second larger aluminum washer, then a larger steel washer, then the lock washer, and lastly the 1/2" -13 hex nut. Use a 3/4" wrench to securely tighten the 1/2" bolt assembly. You can push down slightly on the bracket to keep tension on the chain as you tighten the 1/2" bolt. Re-evaluate the size of the Allen wrench to see if a larger one will fit in the space? Once the Allen is thru the upper hole and preventing both sides of the bracket from moving up, you can put a 1" x 1" piece of duct tape on the "L" end of the wrench to prevent it from sliding out.

As reference this #2 motor mount assembly on Thursday 4-10-14 was discovered to have both the motor attaching screws very loose and one of the transmission screws partially stripped. The motor mounting screws were removed and cleaned, and Red loctite on both the screws. The transmission stripped bolt was cleaned up and Blue loctite was used on all four screws to secure.

Also one of the new 25:1 transmissions was assembled this afternoon. The pinion was pressed onto the motor shaft using the small arbor press and a precision "Vee" block to keep the motor square during the press. For this particular transmission the pinion stick-out (Top of pinion to transmission mounting flange)has to be less than .290" or the pinion will rub on the gear plate. The pinion press was set to .260". Red loctite used on the 2 motor screws and lock washers. Blue Loctite was used on the 4 transmission screws. The transmission was greased and the assembly was tested in both directions under power and it ran very well. The motor transmission assembly was placed in a work tub in the shop closet on shelf SB4. In the same tub as the 64:1 motor transmission assembly that was removed from RB2.

It was discussed with the drivers and Mark M. the pros and cons of the 25:1 transmission. Biggest con is the 25:1 will back-drive which could allow the ball to slip off the bumper if it is being held there.

Any questions see Tom Cavaliere.

Current Design

• Roller with 5 in green wheels
• Using Banebots 550 motor with 64:1 gearbox, bevel geared to roller shaft
• Motion is determined by linkage
• 1 Potentiometer to determine angle
• Surgical tubing to counteract gravity
• Lift linkage powered by am-0915

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