PinChomp Locking Pin Back Removal Tool

Overview

I came across a request from someone asking for an tool to help with opening locking pins back, as their physical issues made that difficult. After getting ahold of some of the type of locking backs I saw that their removal was problematic. I also like these locking backs for their functionality better than the ones I've had that have a hex screw in their sides. So I ended up creating this tool to make their use simple and painless.

Printing

Print all the models provided, including the arm piece twice.

Settings

• 0.28mm layer height

• 3+ walls

• enable supports

• default infill (the walls will provide most of the needed strength)

STEP vs STL

I've included .step files because they give smoother results with smaller files as long as your slicer (such as Orca Slicer) supports them. The .stl versions are included for those who need them for their workflows, but are normally of a poorer quality due to tessellation being baked in.

Do not be fooled by the Printable's 3d preview. They recently added support for .step files (nice!), but run their preview conversion at a much lower quality than Orca slicer and its ilk use when opening .step files. So it is still better to use the .step versions if your slicer supports it.

Needed

• 1x JawA

• 1x JawB

• 2x Arm

Additional Parts

• 5x M3x12 cap head screws

• 5x M3 nuts

Assembly

Print all the needed pieces and have the screws and bolts ready. Also have the locking backs and an enamel pin to test on

First push a cap head screw through one of the holes on an arm, with the end coming out through the hex shaped hole on the outside. Screw one of the M3 nuts on to it.

Then being sure to line up the nut with the edges of the hole, turn the screw to get the nut to seat fully.

Repeat for the other two holes in that arm.

Repeat the process with the other arm, but skip the center hole and only seat nuts into the two outer holes.

Place the two arms together with their center round parts matching, then insert one of the M3x12 cap head screws in the open side, going all the way throw, and screw it into the nut on the other side until it is about flush.

Line up the JawA piece so that it sits on top of the lower arm and secure it into place with one of the M3x12 cap head screws.

Turn the whole assembly over to reveal the other side, and line up the slot in the bottom of the JawA piece with the hole in the arm that is now on the lower side.

Secure with one of the M3x12 cap head screws, being sure it properly catches the nut and is mostly tight (a little looseness will be needed for things to slide, but only a little).

Slide the JawB piece into place and secure with a M3x12 cap head screw in the hole at the front.

Turn the whole assembly over again and secure with the final M3x12 cap head screw going into the remaining slot.

The tool should now move with firm pressure, but not too hard. If it slides too easily, tighten the screws. If it doesn't move, loosen them slightly until it barely moves open and closed. Work it a few times to get the motion more easily functional.

Usage

With the jaws open wide slide the JawA end between the upper and lower rims of the locking pin back. It may or may not stay by itself, but the only important thing is to get the jaw started between the two rims.

Gently start to close the jaws and you should see the locking pin back start to be pushed onto the ramp on the JawB part. It should take almost no force. If you feel strong resistance check to see that everything is lined up properly.

Once the jaws are fully closed the pin back should be in the open position and should lift right up with no force at all

The pin back will be lifted up, held in the jaws of the tool

Open the jaws and use your fingers to remove the locking back. If it is not easy to remove, there is a hole on the top to use as an eject mechanism. Simple push down into the hole with a paper clip or piece of filament and the locking back should pop right out.