Although "helping hands" are very versatile, I find them a bit flimsy when the going gets tough in the soldering world. Thus I decided to build a circuit board holder to satisfy the following needs: Very sturdy, easy to mount and flip over circuit boards, be able to be clamped to the work bench so it can't move around, and be able to accommodate different board sizes.
Step 1: The Basic Principle
In the pictures above you can see the design I came up with.
The circuit board is held between two jaws with a slot in each one to engage the ends of the board.
The jaw on the right hand side can be adjusted to the board's size by sliding the wooden rod it sits on. The jaw on the left hand side can be loosened or tightened with the orange knob.
Both jaws can spin freely to allow the board to be turned over, but the "clutch" (a soft rubber washer) behind the jaw on the right hand side brakes movement depending on how much the knob on the left hand side is tightened.
To use the contraption, you first move the left hand jaw as far as it will go to the left using the adjusting knob. Then you slide the wooden rod on which the right hand jaw sits until the slots on the jaws engages the ends of the circuit board. The third photo shows close up how the end of the board fits into the slot of the right hand jaw.
Lastly you tighten the orange adjustment knob on the left to clamp the board firmly in place at the required angle. To turn the board over, you loosen the adjustment knob somewhat, turn the board over, and then tighten the knob again.
The circuit board holder is attached to the workbench with the inbuilt clamp on the bottom, with the orange knob facing towards you. That way you have easy access to both sides of the board. The circuit board holder can of course be built to accommodate any size of circuit board. I decided on a maximum of 12 cm between the jaws, as I only work with relatively small boards.
Step 2: Construction: Materials
I used a piece of 18 mm pine plywood for the base, and pieces of 20 mm pine shelving for the other wooden parts, and glued two pieces together to a thickness of 40 mm for making the mount for the adjustment rod. Bolts for the jaws are 6 mm, and the washers for making the jaws are 25 mm in diameter, except for the one for the adjusting screw for the adjustment rod, which is 12 mm. The second picture shows the measurements for the main parts.
Step 3: Construction: Adjustment Rod and Its Mounting
I used a piece of 24 mm thick broomstick I had lying around for the adjustment rod, because it made construction easy.
For the mounting I glued together two pieces of 20 mm pine, and cut it to its final size of 40 x 40 x 100 mm high. Then I used a 24 mm spade bit to drill a hole through the mounting for accommodating the adjustment rod.
A 2 mm wide slot sawn from the top of the mounting down through about three quarters of the body provides a simple clamp for the rod, which can be tightened with a bolt which fits through the two halves of the mounting.
I screwed the mounting to the base with two wood screws, not using glue to provide for possible future adjustments or alterations.
(Of course the right hand side jaw could also be fitted directly to a mount sliding on a rail to provide adjustment capability. This would eliminate the rod sticking out from the circuit board holder, and provide constant support underneath the jaw, also eliminating any sagging which is possible with my rod system. However it would be more difficult to build, and in practice the rod system turned out to be very sturdy, without any sagging.)
Step 4: Construction: Bracket/mounting on Left Hand Side
The thickness of your workbench top will determine the distance between the base of the holder and the adjustment screw to clamp the unit to the workbench with (first picture).
In my case the workbench top was 37 mm thick, so I provided a space of 42 mm.
The top part of the bracket houses the adjustment bolt for the left hand jaw. I first tried a single T-nut just pressed into the wood with it spikes holding it to accommodate the bolt, but it was much to flimsy.
I then decided to glue a T-nut from each side into the 8 mm hole for the bolt, after first flattening the spikes to make fitting easier (second picture). This proved to be an extremely secure fitting.
I used a two part epoxy glue, and kept a bolt threaded through both the T-nuts while the glue was setting to ensure alignment of the nuts and particularly the threads (last picture).
The bracket was screwed to the side of the base with two 45 mm wood screws, and glued to ensure rigidity. The centre of the adjustment bolt is 60 mm above the base, as is of course the centre of the adjustment rod on the right hand side.
Step 5: Construction: the Jaws
This is the most difficult part of building the circuit board holder, but still relatively easy.
The left hand jaw (first picture) consists of a 6 mm bolt, 50 mm long, with a 25 mm washer pressed up against the head with a locknut, but with the washer still able to spin freely.
An 8 mm thick wooden ring, 25 mm in diameter, with a slot sawn into its face is then glued to the front of the washer. The slot must not be so deep that the edge of the circuit board will foul the head of the bolt.
The right hand jaw (second picture) is identical, but instead of the lock nut, a soft rubber washer presses the metal washer up against the head of its bolt. The bolt is screwed into the wooden adjustment rod so that the washer can still move, but not spin freely. A similar wooden ring with a slot on its face is again glued to the washer, but this time should be thick enough so that the top of the bolt does not foul the edge of the circuit board held in the jaw when the rubber washer is compressed.
Using a bolt for the right hand side jaw is perhaps a bit of an overkill. A suitable, short wood screw will do just fine.
Step 6: Making the Wooden Rings for the Jaws
I first took a piece of 8 mm thick wood, and made a slot across its face with a band saw (first picture). Then I drilled a 12 mm hole through the centre of the slot (second picture). I then carefully positioned my hole saw over the hole, and cut out the ring. My aim was not perfect, but good enough (fourth picture). In the next picture the ring is ready to be glued to the washer, and on the second picture from the right it is positioned in its place on the washer.
Tip: It is not really necessary to buy a locknut for the left hand jaw's bolt. You can just damage the bolt's thread in the right place with a punch (last photo), and the nut should stay in its place once screwed over the damaged threads.
Step 7: Finished!
The circuit board holder is now ready for use (picture). Of course you can spruce it up with some paint to improve its appearance.