CHAIN TOOL ACTIVITY - FTC HARDWARE

CONTEXT & BACKGROUND

What is a chain tool?

Typically in drive train applications, teams will build a chain drive which often consists of sprockets to achieve motion. The size and function of the chain drive often varies depending on the size of the robot, the function it will be used for, and the number of materials available.

This is an image of what it generally looks like.

When designing our mechanism for a chain drive, we need to ensure that the length of our chain is appropriate for the distance between each sprocket. This is where the chain tool comes in - we can break our supply of chains into pieces that fit the desired length.

How does a chain tool work?

We can take a look at the anatomy of a very common chain tool that we use in FTC robotics - the Rev Chain Tool 25.

There are three main parts to a functioning chain tool -

1. The chain tool comes with a pin-screw, which is attached to the rear-end of the chain tool. This pin will be pushed into the chain at a certain length, functionally breaking the chain into a size that we want.
2. Near the front end, we have the cutpoint screw, which is the larger one in the image. This component is used to prevent the pinscrew from coming all the way out. We will remove this when cutting a chain.
3. Next to the pinscrew, we have the compression screw, which holds the chain in place so we don’t bend the pinscrew.

THE PROCEDURE

What materials will I need for this activity?

There are a few things that you will need -

1. The chain tool (preferrably a REV 25)
2. An allen key of the appropriate size
3. #25 Chain
4. Masterlink
5. Pliers

How do I proceed?

1. Ensure that the chain tool is ready to be used. You can do this by checking whether or not the pinscrew and compression screw are not interfering with the middle channel in the chaintool. (TIP: if the chain-tool looks exactly like the picture above, then you’re good!)

2. You need to determine how long your desired chain length is. There is some math that can be used depending on the sprockets and chain length to calculate this, but you can also just physically mark the desired cutoff as pictured in this video.

3. Set your chain in the midsection of the chain tool at the correct distance.

4. Take your allen key, insert it into the compression screw, and screw it down until it firmly holds the chain in place.

5. Once it is in place, use the allen key to drive the pinscrew down into the chain. Make sure your cutpoint screw has been removed from the tool. Continue to drive the pin down until it is no longer in the piece of chain.

6. Now that it is complete, remove the pinscrew from the chaintool and set the severed chain aside. Then use the allen key to unscrew the compression screw from the tool.

7. Take the chain that you just cut and put the two ends close to each other. Connect them using the masterlink and place the plate over it. The chain should be between the two components in the image below.

8. Now, you need to use your pliers to get the pin correctly holding everything together.

Once you have completed this step, you have successfuly linked together your chains using a chain-tool and masterlink. Good Job!

Questions?

Feel free to ask anyone in the makerspace. There are ways to do this process if you do not have a masterlink, and tons of guides online that will walk you through this. If you would like to see a demonstration of the steps listed in this guide, please refer to this video.