3d Printed TwistLock Clamp

This TwistLock clamp is a new pursuit to make a strong and fully 3d printable clamp.

improving the hand screw clamp

When I released the hand screw clamp didn’t expect it to gain so much interest among the Thingiverse community. Something I thought was a niche tool for specific needs actually had a broad appeal to people as a gadget to demonstrate the power of a 3d print. This motivated me to use what I learned from the last clamp design to make something even stronger.

The twistlock clamp uses many similar techniques to the hand screw clamp: print orientation of the jaws and threads and rib reinforcement give it additional strength. However, there are some key differences aimed at simplifying and strengthening the design even more.

When the clamp applies force, there will always be some component resisting that force. With the hand screw clamp, it was a small pin running through the adjustment knob. This weak link was always the part to break and could not get larger, because the knobs and threads would also have to grow. In the TwistLock clamp, the main thread column, which is much more robust, counteracts the clamping force.

Many destructive tests were needed to improve the geometry around the thread column for stronger clamping. The images below show the design progression from left to right.

When the threads were strenghtened, adjacent parts such as the wingnut and retaining pins began to fail and also needed to be reinforced. For the threads, ribs needed to be added running lengthwise, and ultimately the upgraded threads needed to be prevented solid to keep teeth from breaking.

The outer wall of the knob needed to be thickened so it didn’t crack under pressure. With an improved thread pattern, reinforcement ribs needed to be added to prevent the threads from collapsing under pressure (right two knobs).

The retainer pins take a lot of compression force and a washer was added to help the knob turn more smoothly.

free vs upgrade

As I went through the refinement process, I decided to make a simpler free clamp, and a stronger clamp that used additional parts and more specialized print requirements.

The biggest advantage for the upgraded clamp is the use of an alternate thread form called buttress threads. These have more of a saw-tooth pattern and the contact surfaces are perpendicular to the force. This means that tightening the clamp will not be as difficult and squeaky when it is applying a lot of force.

I have even made some alternate pads for these clamps in different shapes and sizes. There is even an adaptable pad and interchangeable attachments such as a camera mount.

I would say that these clamps are a great improvement over the hand screw clamp and their strength has exceeded my expectations. They can lock down heavy wood boards, bend thick metal caps, and even lift my chair off of the ground!

see it in action