The Handsome & Co Educational Taster: Pinch Rods
First term of 2017 and the Handsome and Co educational taster was for the students to make a pair of pinch sticks.
What are pinch sticks? Well, pinch sticks, also know as pinch rods are a very simple woodworking tool that allows for very accurate measurements of the squareness of cabinets as well as for checking other woodworking dimensions such as whether the distance between two legs of a table are the same at the bottom and at the top.
By sliding the two sticks apart, each pointed end is placed across diagonal corners of a cabinet and compared to the opposite corner. If they match you have a square carcass, if they don’t some correction of joinery or with clamps when gluing up is required.
One final benefit of the pinch sticks is that when a cabinet is clamped, often the sides can be distorted by the pressure of the clamps. Testing the internal walls or external sides with an ordinary set square or engineers square will give a false reading, as once the clamps are removed the sides will return to normal.
Like some of the previous educational tasters, this one was a mix of both metalworking, woodworking and a little spray finishing thrown in for good measure.
The taster also introduced many students to using a false bed on the thicknesser. Typically this is a piece of 18mm MDF which is used on the bed of the thicknesser to machine pieces that would be too thin to do normally. The students learnt how to adjust their measurements to take into consideration the thickness of their material as well as the thickness of the false bed.
While some students machined their wood for the project, others got stuck into cutting the steel tube which would be used to house the pinch sticks. Even though the steel tube had only 2mm walls, many students soon realised how much easier wood is to cut by hand compared to steel. We discussed the similarities between holding and using a hacksaw to accurately cut steel and using a tenon saw to accurately cut wood.
Once each student had cut two pieces of tube, we marked the centres and drilled a couple of holes. Students learnt that its much easier to start with smaller hole and progressively drill it out bigger than just drilling the final dimension. Two of the holes needed tapping for an M6 bolt. Some of the students had some experience with tapping wood from an earlier educational taster and were familiar with the process, although now on a smaller scale.
With all the holes drilled, tapped, de-burred and edges smoothed off it was time to spray them. Students learnt two simple lessons when it comes to spray finishing; maintaining a consistent, fixed distance from the piece being painted as well as a ‘less is more’ motto. It’s easier to build up thin coats to achieve a good result than try and do it all in one go.
Finally, it was time to chisel out the clamp pads. I think this was the most challenging aspect of the taster and forced many students to really focus on their work and, importantly, sharpen their chisels.
All up most students finished the sticks and now have a useful tool for future use as well as understanding a little more about how to correctly check for square.
Written by Liam Thomas – Tutor.
Website: We Eat The Sun