If you want to splice ropes then a common tool is the “Selma” fid. Essentially, it is a metal tube with a blunt point at one end. There are other styles but this is the most common.

Rope is loaded into the rear of a fid and the pointed tip is used to work into and through rope. In this way it can be used to splice rope much like a needle is used to stitch fabric.

You’ll see that a lot of rope-work tutorials use fids and, crucially, fid lengths to describe the various techniques. For limited hobbyist use fids are expensive to purchase and I wanted to avoid the expenditure whilst teaching myself rope splicing.

A common work around is to buy metal knitting needles, cut them down to size and shape the rear to hold rope. The trouble is finding the correct length can be difficult so I’ve written this quick article to refer back to later.

You can find the appropriate fid length by taking the rope diameter and multiplying it by twenty-one (21). The fid diameter is three-quarters (3/4) of the rope’s diameter. Finally, the short fid mark is made at three-quarters (3/4) of the fid’s overall length from the pointed tip.

   fid length
|--------------|   = 21 x rope diameter
           |---|   = 1/4 of fid length
           `-> short fid mark

So, if we’re working with 10mm diameter rope (most rock climbing rope is some where between 10mm and 13mm):

  21 x 10    = 210

  3/4 of 10, which is the same as
  0.75 x 10  = 7.5

Short fid mark:
  3/4 of 210, which is the same as
  0.75 x 210 = 157.5

The following measurements are all given in millimetres.

Rope diameterFid lengthFid diameterShort fid mark

That should be all the information you need to start making fids of your own. You’ll probably also need a pusher to force the fid through the rope. This is a handle with a sturdy length of metal wire protruding from it. When a fid gets stuck; the pusher can be used to exert force on the rear of the fid.

Where even this struggles you can use a loop of wire to pull the rope through with pliers instead of pushing it. There are commercially available options here called needles and the D-Splicer.