The Ultimate Helping Hands

I do a lot of soldering work, and after using a basic helping hands for many years, I grew frustrated with its deficiencies (see image). The two basic problems with these products are: first, the alligator clips often misalign when they grasp an object, such as a wire, making them useless for holding thin objects. Second, the metal ball joints, as they interface with the metal grip plates, are not very accurate and smooth, and often you have to loosen their wing nuts to get them into the desired position. And then there are those wing nuts, which are ergonomically terrible and hard to access given the current orientation.

All this led me to search out a better helping hand, or as Amazon calls it, a "Third Hand" type of tool. There are many much better solutions to this for holding PCBs, and they are expensive ($60+). They work well for soldering boards, but then they are not versatile for holding non-PCB objects.

I concluded that there is nothing that meets my requirements, so, being a product designer, start to contemplate designing and building my own. The following is my solution. It is not an inexpensive solution, but in my BOM, I've tried to source the minimum quantity of hardware choices.

If you have a 3D printer, a little ingenuity, and are as frustrated as I am with my current helping hands, then this is the project for you.

1. 2mm Hex Head Driver
2. 2.5mm Hex Head Driver
3. 5/16 Open-End Wrench
4. 6-32 Tap
5. 7/64 (.1093) or no. 35 Drill
6. 1/2 Inch Ball Endmill Bit (optional)
7. Drill Press (optional)
8. 5 Minute Epoxy
9. Soldering Iron (for Heat-set Inserts)
10. Loctite Blue (optional)
11. 6 ea. 1/4" width wood stir sticks

ITEM NO. / File Name / DESCRIPTION / (QTY.) / VENDOR / MATL.

1. base hsg BASE HOUSING (1) 3D PRINT ASA
2. base BASE PLATE (1} 3D PRINT ASA
3. Joint A JOINT A (2) 3D PRINT ASA
4. Joint B-1 JOINT B (2) 3D PRINT ASA
5. Joint B-2 JOINT B (2 3D PRINT ASA
6. Joint C-1 JOINT C (2) 3D PRINT ASA
7. Joint C-2 JOINT C (2) 3D PRINT ASA
8. Joint D JOINT D (2) 3D PRINT ASA
9. Finger Tab FINGER TAB (2) 3D PRINT ASA
10. B0FRSCXLWY 6-23x1” rod (2) AMAZON STEEL
11. B0FRSCXLWY 6-32x2” Rod (2) AMAZON STEEL
12. B0G4TY1B75 1/2x12” Tube (1) AMAZON STEEL
13. B0FJDKV9TM 5MM Styrene Tube (2) AMAZON STYRENE (optional)
14. B07TLJKY11 ½” Nylon Ball (4) AMAZON Nylon
15. B0FMRCMXPD 6-32 SS Nut (4) AMAZON STEEL
16. B0FJDKV9TM 5MM Styrene Tube (2) AMAZON STYRENE (optional)
17. B09TW598NJ ¾” BINDER CLIP (2) AMAZON STEEL
18. B0DFWVD621 1/4-20 INSERT (7) AMAZON Brass
19. B0D9DG4GN5 1/4-20 ThumbScrew (7) AMAZON ABS
20. B0F59KW6TQ 4-40X.5” Screw (8) AMAZON STEEL
21. B0DRFYD3JN 6-32 Insert (4) AMAZON Brass
22. B0DJ48GMY8 4-40 Insert 8 AMAZON Brass
23. B0DJ8T18BG M2.5 x Insert (2) AMAZON Brass
24. B0G2PZYFLY M3 Shoulder Screw (2) AMAZON STEEL
25. B0C33B5HSW 5MM Spring (2) AMAZON STEEL
26. B01LYKI8GC M2.5 Self-Tapping 3 AMAZON STEEL

I've tried to source everything off of Amazon. McMaster Carr is my usual Go-to site but wanted to make this as inexpensive as possible. Therefore, I've prefixed the parts with the AMAZON ASIN code.

Download the .STL files and Print on your 3D printer. Refer to the BOM document since there are multiple parts. I printed my parts in ASA 1.75mm with 100% infill, Shrink Factor on Filament = .95 on my Prusa Core One.

I've included both .STL to print from directly, but also .STEP files if you choose to make your own modifications.

This is an optional step, but if you want smooth action on Joint B, Joint C, then you can use a 1/2 inch ball end mill on your drill press to clean up the ball concaves. Slightly plunge the concave with the end mill until the layer lines disappear and you have a smooth concave face.

Using a soldering iron tip, you can carefully heat-set the various inserts. One thing I like to do is to use my Drill Press to hold my soldering iron for inserting. This ensures that I get relatively good perpendicularity when inserting. If you're doing it by hand, take care to make sure that when you heat-set them, you are inserting them perpendicular to the hole that they are going into.

1. Base Housing - 1/4-20 insert
2. 2ea. Joint A - 1/4-20 insert
3. 2ea. Joint B1 - 2ea. 4-40 insert and 1ea. 6-32 insert into end
4. 2ea. Joint C1 - 2ea. 4-40 insert
5. 2ea. Joint D - M2.5 insert

Make sure that when you heatset the insert, it ends up flush with its surrounding surface. Don't go too fast when melting it in.

Optionally, but highly recommended, is to weigh the base housing with some weight. I used approx. 2.5 lbs of lead shot (600 grams) (or sinkers - you can obtain shot and sinkers from your local sporting goods store). With the Base Housing inverted and held secure, load it with the weight of your choosing. Fill it so that it is just shy of the screw bosses. Once you've filled it, attach the Base and secure it with 3 M2.5 x 10mm screws using a medium Phillips screwdriver.

Install the 1/2" steel tube and secure it with a 1/4-20 Thumb Screw. Next, install the 2 Joint A parts at either end of the tube and secure them with the 1/4-20 Thumb Screws.

1/2 inch Nylon balls with a 6-32 hole pre-drilled are hard to come by, but if you can find them, more power to you. I ordered mine off of Amazon, and then tapped the 6-32 holes myself. First, drill a 7/64 hole 1/2 inch deep into the ball. If you have a drill press, first clamp a wood block right underneath the chuck of your drill and clamp it to your table, and lock your table. Now drill a 7/16 hole in the block so that the ball can rest in the hole just proud of it. While the block is clamped, now replace the 7/16 drill with the 7/64 drill bit and drill into the ball 1/2" deep. This technique ensures that you center your hole in the center of the ball. Do the remaining 3 balls using the preceding steps. You can then tap the holes by hand or with an electric drill set on low speed. Additionally, if you can obtain a 6-32 Bottoming Tap (finishing tap), that would help complete the threads at the bottom of the hole.

There are four total Ball joint assemblies: two of which use a 2-inch 6-32 threaded rod, and the other two use a 1-inch 6-32 threaded rod. Optionally (but highly recommended), apply Loctite Blue (medium strength) to the holes of the 4 balls. While gripping the ball with a soft vice grip or other appliance, insert the 2-inch and 1-inch threaded rods into their respective ball and tighten until they bottom out in the hole. Optionally install the different lengths of Styrene tube onto the open ends of the rods and set aside. Now thread a 6-32 nut onto the other end of the rods and tighten it against the styrene tubes using a 5/16 wrench. If not using the styrene tubes, thread nuts onto the threaded rod approximately 1/2 inch.

Take the 1-inch Ball Subassembly and assemble it into Joint B-1's end and tighten with a 5/16 wrench. Do this for both the left and right Joint B-1 and 1" Ball Assemblies.

Take Joint B-1 and Joint B-2 and assemble them together using 2 ea. 4-40 x 1/2" screws. Do not tighten but leave about 1/8" out of hole. Now insert the 2-inch Ball Joint assembly into the concave pocket between Joint B-1 and Joint B-2. Install 1/4-20 thumbscrew through B-2 into the insert of B-1 and tighten, clamping around the ball. Tighten two 4-40 screws.

Assemble the 5MM spring onto an M3 x 20mm Shoulder Screw. Attach the shoulder screw to the end of Joint B's M2.5 insert and tighten with a 2 mm hex wrench

Prepare a dab (about the size of a quarter) of 5 minute expoxy. Mix well with a wood stir stick. Lay Finger Tab Concave thumb detent down. Fill the C-shaped groove with epoxy. Lay Binder Clip's wire into groove. IMPORTANT - make sure the orientation of the Binder Clip is as shown. Once the Binder Clip is seated in the Finger Tab, apply more epoxy onto the Binder Clip wire so that epoxy completely covers it. Do this for both left and right Joint B and Binder Clips. Set aside and let it dry.

Prepare another batch of epoxy. Mix well with a stir stick. Fixture Joint D in a vice or by some other means so that it is stationary with the slot end facing up. Carefully apply some epoxy to the 1/16" slot at the barrel end of Joint B. Before the epoxy is set, insert the other wire form of the Binder Clip/ Finger Tab assembly into the slot as shown. IMPORTANT - make sure the orientation of the Binder Clip is as shown. Apply a bit more epoxy in between the two sides of the wire form so that some of the epoxy fully envelops both sides of the Binder Clip's wire form. Do this for both left and right Joint D parts. Let dry.

I have provided STEP files so that if the Binder Clip of Joint D does not suit your needs, you can alter its geometry with your CAD to adapt it to aligator clips or whatever type of end effector you desire. I chose Binder Clips because they work for almost anything and avoid the problem mentioned above about alligator clips.

Gather Joint C-1 and C-2. Insert Joint C-2 onto Shoulder Screw of Joint D. Compress 5mm spring with a sharp object so that it is compressed against the inside wall of Joint C-2. Assemble Joint C-1 onto Joint C-2 using 2ea. 4-40 x 1/2 Sockethead screws. Do not tighten, but leave approximately 1/8 inch of head above the hole. Do this for both left and right Joint sets.

Assemble Ball of Joint B into the concave pocket between Joint C-1 and Joint C-2. Once seated, assemble a 1/4-20 Thumbscrew into the hole at the top of Joint C-1 and tighten to insert in Joint C-2. Do this for both left and right Joint subassemblies. You should have something that looks like this.

Now take the subassembly arm (Joint B, Joint C, and Joint D) and insert the threaded rod of the Ball Joint sub-assembly into Joint A's 6-32 insert. Turn clockwise until the 6-32 nut is seated against Joint A. Tighten the 6-32 nut against Joint A to lock it. Do this for both left and right Joint subassemblies.

Your final assembly should look something like shown here. If the joints do not hold firm and start to rotate, check to make sure the 6-32 rods are tight against 1/2 balls nuts of Joints A, B, and C. Apply more Loctite at the 6-32 rod ends in Joints A and B if needed.