What do you do if your gripper can't grasp your objects? Here are ten types of object that may require custom fingertips.

You've done your homework to find the perfect gripper. You've researched the market, read up on all the pros and cons, and finally bought a gripper that seems to suit your needs.

But then… disaster! The gripper simply doesn't grasp objects as well as you'd hoped it would.

Perhaps your objects are too flexible and the gripper can't get a good hold on them. Or perhaps they're an awkward shape, or fragile and easily damaged. 

Should you give up and forget about robots completely?!

Not so fast. There's a solution: custom fingertips. Many of the experts in our community make custom fingertips to overcome the challenges presented by their applications.

Sometimes custom fingertips are the best solution!

Why would you want custom fingertips?

You have two options if your gripper doesn't grasp your objects properly:

1. Get another gripper—This is expensive, time-consuming, and not even guaranteed to work, since the new gripper could have the same problems as the old one.
2. Make custom fingertips—This is cheap, quick, and highly flexible, since you can design new fingertips that work exactly the way you want them to.

Members of the DoF community use custom fingertips all the time. Application Engineer Grady Turner from Cross Robotics says he prints 2-3 custom fingertip designs every week to test applications for customers. This allows the company to adapt robots to suit specific applications.

Custom fingertips aren't always necessary. There are many advantages to using an adaptive gripper without customization. For example, these grippers can grasp a wide range of objects without needing to have their fingertips changed. 

However, when your application has special requirements, custom fingertips are often the way to go.

10 objects that might need custom fingertips

How do you tell if an object requires custom fingertips? The easiest way to know for sure is to test it out! Try using the gripper as it is first. If you run into problems, a new set of fingertips could get you out of trouble.

Here are the ten most common objects that regularly require customization:

1. Cylindrical objects

Ideally, the gripper should be able to grasp an object with more than two points of contact. This isn't possible with flat fingertips and a cylindrical object. You can either use the gripper's encompassing grip mode to solve this problem, or add a V-shaped fingertip for an extra two points of contact.

2. Large objects

Some objects are too big for most grippers. We created an extra wide gripper to overcome this problem. However, you might not need a new gripper altogether, since custom fingertips can extend the gap between the fingers beyond the specified stroke of the gripper.

3. Small objects

If you've ever tried to pick up a ball bearing, sewing needle, or grain of rice yourself, you'll know that small objects are hard to grasp. Even with a precision gripper like our Hand-E, you might need custom fingertips to get a good hold on small objects.

4. Thin objects

Few objects are thinner than a playing card. As part of the Olympus Games back in 2016, Tyler Berryman and the rest of the Robotiq team created a robot Blackjack dealer in 48 hours. They used custom 3D printed fingertips to pick up and deal the playing cards.

5. Fragile objects

If your gripper has a good force resolution, it should be able to hold an object without squeezing it too much. However, using a low gripping force can introduce other problems, such as the risk of dropping the fragile object. For example, the aforementioned Blackjack robot also had to offer a shot of liquor to the winner of each game, which meant holding a small glass securely yet gently.

6. Flexible objects

Bendy, squishy, and otherwise flexible objects aren't easy to pick up with a robot. Custom fingertips are often a good solution.

Sebastien Blanchette from Revtech Systems was looking for a way to pick up magazines and flexible books with a gripper. He asked on DoF and fellow community members helped him work out a solution using wide custom fingertips.

7. Objects with strict force/torque needs

If you need to control the force or torque applied by your robot, a sensor is usually a good option. However, sometimes a custom fingertip can improve your control or even negate the need to add an extra sensor.

DoF member Vijay Chhapparghare from Ford Motor Company was looking for a way to screw in bolts with zero torque. Our integration coach David Gariepy suggested custom fingertips that would allow the gripper to twist without applying torque.

Grady Turner also told us that he's used fingertips with custom ridges to get a better grip on bottle caps and apply more torque. 

8. Low-friction objects

Objects with sheer, shiny surfaces can be tricky for gripping. You need a lot of force to ensure the robot doesn't drop the object, but you also don't want to damage it.

We supply silicon fingertips for increasing friction between the gripper and the object. Alternatively, some members of the DoF community have found their own ways to increase fingertip friction!

9. Hollow objects

Tubes and hollow objects can be picked up with a normal encompassing grip. However, another gripping strategy – and one which people sometimes forget about – is the internal grip.

This is when you pick up the object with the outside edge of the gripper fingers instead of the inside surface. For some hollow objects, you might have to add custom coverings to the outside edge (e.g. to increase the friction).

10. Objects with a combination of the above

Sometimes you're faced with an object that combines many of these problematic properties. Just imagine a small, flexible, hollow cylinder made of thin, low-friction, fragile material. When you've got so many restrictions, custom fingertips are often the best way to ensure your gripper maintains a reliable hold on the object.

Need some help? Benefit from the wisdom of the most knowledgeable robotics experts we know by sharing your application with the DoF community.