instructables Pinch Sticks Instruction Manual
- June 3, 2024
- instructables
Table of Contents
Instructables Pinch Sticks
- Are you square?
- Not you personally, is your project square?
- Is the corner 90°?
How important is this? That’s questionable but different projects require
different levels of accuracy. So we use a square or similar for most checks.
But what if the item is bigger like a kitchen cupboard or a gate. 0.5mm out on
your 200mm square can equate to 10mm at the other end of the work piece.
This is where pinch sticks (pinch rods, squaring sticks, story stick) come
into play. This Instructable is about my alternative design on an age old
concept.
Supplies:
- Aluminium square tube (25mm, 20 internal)
- Aluminium rectangular tube (17.5 x 10)
- ACM (Aluminium Composite Material) – 3mm
- Acrylic (8mm)
Threaded wing-nut or a bolt or knob In theory you can make and use any kind of
materials for this – steel, brass, plastic, wood, but aluminium is light and
sti. I use what I have, in this case aluminum square tube from a skip, a
rectangular tube from a dismantled marquee, and acrylic and ACM (aluminum
composite material- thin aluminum sheet sandwiching plastic) from a skip. The
bolts were just from my workshop supplies.
Step 1: Why?
Pinch sticks have been around for hundreds of years in all countries in one form or another. The use of them started to decline when more modern hand tools and measurement systems came about, but at one time every decent tool box contained one or more. There are a variety of modern ones on the market – some quire expensive, but once you understand why you’re more likely to use them than not.
The basics are:
- 2 sticks – ô€€‚xed together in some form when required, but can be lengthened or shortened as required.
- To allow measurement between 2 internal surfaces
- To allow measurement between 2 opposite corners to compare.
If two opposite sides are the same length then the measurement between
diagonals will be the same. If the corner is from 90deg then the measurements
will change. I had an issue where the side lengths were accurately cut the
same, but I didn’t pick up on the fact that the wood was slightly bowed. I was
trying to use my square to set the pieces but couldn’t understand why my
diagonals were. By using a ratchet strap I was able to correct the ‘bulge’ and
continue. So potentially using a square and the pinch sticks will resolve most
issues.
Step 2: Design
The points I wished to cover:
- Use what materials I have
- Allow different length extensions
- Allow exchangeable ends
- Allow self support
So initially I needed pinch sticks to check the diagonals on the workbench I was building so I wanted them to reach around 1800mm. I also wanted to place them in situ and adjust without trying to hold them. Also due to an issue with bowed wood and straps across the work piece I could only sit the pinch sticks above, so the measuring points would need to extend below the sticks. Also using aluminium tubing would create a very light and long tool and with the other non ferrous materials being used, equalled no rust!
Step 3: Aluminium Tubing
The square tube was cut to 60mm handled smoothly. A hole was marked, and
drilled and a thread cut to accept a wing bolt. The rectangular tube – being
scrap, was just cleaned up and the plastic inserts were removed from one end.
I ended up with 3 pieces 850mm long.
Step 4: ‘Pinch’ Mechanism
The ACM -plastic sandwiched between aluminum – is light and strong, although
you could use an alternative. This acts as a washer between the knob and the
bars and tightening the knob applies pressure to stop the bars moving –
‘pinching’. This was cut easily with a hacksaw and nished. It was done so it
had projecting tabs to prevent it sliding out.
Step 5: Is It the End?
The 8mm acrylic was used for the end insert. This was already the correct
width and I wanted a deeper prole to extend past the tube to cater for above
surface measuring. This was cut and sanded into a ‘V’ (must be an angle less
than 45°). I cut some ACM into a boomerang shape to create my ‘self-support’
bracket. The design of this was so that the form allowed it to rest on the
project but didn’t obscure the insert point alignment. This was assembled
along with the acrylic insert and drilled and threaded to allow a 4mm brass
bolt. Its tight enough to allow the bracket to rotate when not in use. The
acrylic insert could be cut in different shapes to deal with different
scenarios. It could be a rectangular form with a nail inserted for instance to
allow measurements into tight corners. For now I have stuck with this form but
the design allows for other options.
Step 7: Additional Design Element
So the current alloy tube length means I can’t measure anything below apx.900mm. if I had more tube I’d cut shorter lengths to deal with this but I don’t and I’m not going to cut what I have. If I use the pinch brackets as they are I can create shorter wooden ‘sticks’, but I’ll design this specically for measurement transfer. Two strips of wood 9.5×19.5 were cut, apx 400mm long. One end was cut to allow the depth of the bracket on one piece. The other piece had an extension glued to one end. A 30° angled cut was done to each piece. The idea of this is to have an extendable tool with each end against the surface so when you transfer the measurement it’s more accurate. Very simple to make, uses the existing bracket and I can create a few different lengths. I now appreciate why a tool box would have once contained several length pinch sticks.
Step 8: Conclusion
The alloy tube works really well for long diagonals – it’s light and simple and the support ‘boomerangs’ work well with the extended end insert. The wooden stick version works well for measuring purposes as well. I need to look at ways of producing end inserts to be adaptive to both but for now it’s my design brief. Thanks for reading
References
- Yours for the making - Instructables
- HYPEphillips's Activity - Instructables
- Pinch Sticks : 8 Steps (with Pictures) - Instructables
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