Carvers Screws
A Carvers Screw can be expensive. They are available on line, but the Pfeil version is £72, and the one from Stubai is £56. Veritas have one for about £15.50, but I think they are all expensive for what they are. I got mine via the internet from Dieter Schmid Fine Tools, in Berlin. https://www.fine-tools.com/spannsto.html. The smaller one was £8.50 and the larger one £10.50, plus about £4.00 for postage
A simple alternative is to use "Easy drive" machine thread to wood thread, dowel screws, M8 X 75mm long. These are available from Screwfix (at £4.60 for a box of 10) but similar items, known as "Furniture Fixing screws", or "Wood to Metal Dowels" are available on Amazon or E-bay. The larger sizes are referred to as “Hanger bolts”. The most useful sizes are M8 & M10, from 100mmm to 200mm long. I use the M8 x 140mm most frequently. A pack of 5 cost me £6.99 on E-bay.
Finding the large wing nuts is however a challenge, and so I have used either a 40mm x M8, “Through Hole Star Clamping Knob” or a "Star Grip knurled knob" M10 x 50mm dia.
For the very big one I just used a ring spanner.
Hopefully these pictures illustrate the options.
