Make an Ultimate Helping Hand Jig




About: I believe that the purpose of life is to learn how to do our best and not give in to the weaker way.

Here is a helping hand jig that is useful for soldering, gluing, painting and macro photography. It is highly configurable to hold various small objects in many positions.

While this version is 3d printed, it could also be made using traditional hand methods.


Step 1: How It Works

While this may not be the ultimate jig for everyone, I have found it very useful for soldering and gluing small projects. It can be adapted with different grippers for different kinds of projects.

I was experimenting with various ways of 3d printing self-assembling hinges for future use in robot arms and legs. Making some hinges that can lock in place seemed like a good way to test the strength of the structures.

The helping hand has six configurable, lock in place, arms with interchangeable grippers. While this version was 3d printed, a similar jig could be made using acrylic or other plastic sheet material. It could even be made out of thin plywood. Three layers could be laminated together to make the arms.

Step 1 pic shows it set up for soldering with flashlight and magnifier. Pic 2 shows it folded up.

Step 2: Tools and Materials

I used a Makerbot Replicator 2 to print the parts in PLA plastic. If you do not have access to a 3d printer you could make the jig by laminating hand cut sheet plastic or plywood.

100% silicone caulk and corn starch to make Oogoo. Details on making Oogoo can be found here:

sheet metal

24   4-40 x 1" round head screws and nuts
6     4-40 x 3/4" round head screws and nuts

2     1/2" diameter x 3/8" long neodymium magnets

Step 3: Making the Arms

This jig was designed in 123D Design beta. Step 3 pic shows a drawing of the arm. Pic 2 shows a closeup.

Each arm is printed as one self assembled piece (arm.stl). The conical pins hold the hinges together even without the screws.

All 3d printed pieces were printed using a Makerbot Replicator 2 with the following settings:
Standard resolution with a raft
10% infill
2 shells
.2mm layers-standard resolution

If a space of .01" or larger is left between movable parts, all kinds of movable mechanisms can be 3d printed including hinges, shafts, and bearings.

Print the Knobs
The knobs (knobs4-40.stl)are designed to fit a 4-40 size screw tightly. Do not over screw and strip the hole.

Step 4: Making the Interchangeable Grippers

The gripper halves are printed as one piece. A rubber band donut provides the gripping power.

Pic 2 shows the two halves of a gripper and the silicone donut.

Pic 3 shows how the silicone donut was cast using 3d printed form: donut.stl. Oogoo works well to cast the donut. A 3 silicone Caulk to 1 corn starch by volume produces a silicone that will set up in two or three hours. More details on using Oogoo to make rubber bands can be found here:

Most of the rubber donuts were made using Dragon Skin 20 silicone which pours real nicely and is available from

Step 5: Making the Magnetic Grippers

The magnetic grippers work by holding small components against the silicone pad on the base.

You can print out maggrip.stl and then glue in 1/2" diameter magnets. Or you can make your own magnetic grippers in a shape that suits your needs.

Step 6: Making the Base

The base can be printed using base.stl

The bottom of the base has been hollowed out to allow for a piece of sheet metal to be glued in with silicone caulk. The thicker the sheet metal, the better it will attract the magnetic grippers.

A 1/16" thick silicone pad can be cast using Oogoo and the mold: hexmold.stl. It can then be glued on to the base using silicone caulk. This provides a grippy surface so components can be easily held in place.

Step 7: Soldering

Step 7 pic shows how a surface mount LED can be held in place to solder by the weight of a sharp screw pivoting on an arm. Metal nuts can be put on the screw above the gripper to increase the pressure.

Pic 2 shows how the magnetic grippers can be used to hold wires and small components to solder them. The silicone pad on the base can handle the heat of the soldering without melting.

See also the step 1 pic for a full soldering setup.

Step 8: Painting and Photography

Pins or nails can be used to support objects in the arms while they are spray painted top and bottom. A plastic bag can cover the jig with just the pins sticking through.

Pic 2 -The jig can also be used to hold objects or a camera as an aid in macro-photography.

Step 9: Other Possibilities

The step9 pic shows a couple of experimental helping hand robots I designed that used friction ball joints to hold things in place. Magnets in the feet hold them upright. While they worked fairly well, they could not hold much weight without slipping. So I started to experiment with locking joints.

Pic 2 shows an experimental arm that uses a ball joint for the gripper. It was all printed as one piece. While it worked, it had problems. When the screw was tightened, it tended to permanently dent the ball. So a much larger joint would have to be used that squeezes uniformly around the plastic ball.

Pic 3 shows a puzzle box design with hidden conical hinges. The box is printed in one piece.

Pic 4 shows the printed box closed.

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13 Discussions


4 years ago on Introduction

Just an idea for a little improvement: wouldn't be the arm grip improve by using hexagonal bolts and nuts on the knobs? Obviously that would imply the knobs should have an hexagonal hole instead of a rounded one which might imply a slightly greater knob size, but I believe this would greatly improve the amount of force you can put on each joint and achieve great stiffness when required.

What do you think? May be it's a design you have already tried and found as failing...

1 reply

Reply 4 years ago on Introduction

Hexagonal head bolts would certainly work. I used the pan head screws because they are cheaper and I had some of them on hand.

It turns out that the pan heads provide plenty of force to lock the arms solidly in any position.


4 years ago on Introduction

When you say it is printed as one piece, are you saying you actually printed it already assembled? How does it work, you leave a tiny amount of support PLA which you break at first use?

3 replies

Reply 4 years ago on Introduction

The hinged arms are printed one at a time as one piece, flat without supports. The grippers and base are printed separately.


Reply 4 years ago on Introduction

And the parts are printed "glued" and then broken apart by hand?

So far the best quote I got from 3D print services is 72€... quite pricy :-(


Reply 4 years ago on Introduction

The hinged parts are printed with a gap that allows the hinges to move. Depending on the precision of the filament printer used, they may be slightly sticky, which a little force will overcome, resulting in a smooth rotating hinge.

Sadly, most print services are useless for anything but very small prints or very expensive prints.

If your want to pursue this method of fabrication, your best bet is to find a friend or a maker space with a filament printer.


4 years ago on Step 3

I have tried printing the arms in PLA in two orientations and they remain stuck together and break when I try to unstick them. I am printing at 0.2mm layer height and perimeter width of 0.4mm. You mention 0.2mm layer - do you know what extrusion width your slicer uses?

1 reply

Reply 4 years ago on Introduction

I am using Makerbot software which does not provide info like extrusion width.

Whenever I have trouble with printed hinges sticking, I enlarge the print by 1% or more until the gap between the moving parts is enough.

You may have to enlarge the base by the same amount.


5 years ago on Introduction

Great project! This is a really great design!


5 years ago

You should add this to thingiverse. I'm sure it'll be very popular!

The base at its widest points is 4.77" and it is .66" thick.

If you download the stl files, you can load them into a free program like Netfabb or Meshmixer and get the dimensions that way.