Saturday, 7 October 2017

Landing net rubbers

Most landing nets, especially the cheaper ones, are supplied with an O-ring at the bottom of the thread that is used to attach it to the handle. When I bought a set of three nets recently, one of the O-rings was missing. Rather than go back to the supplier, I thought this would be the ideal opportunity to try out something I have been thinking about for some time.

A neater solution than the usual O-ring
The usual O-ring that is supplied with most landing nets is inclined to twist out of shape and become malformed if the handle is overtightened to the net-head. This can mean the joint will have a tendency to loosen, especially if a big fish is in residence. What is really needed is a washer that can be tightened onto but will also have a bit of 'give' in it so the joint will undo without the use of tools.
It occurred to me that a tap washer would be the perfect substitute. A rummage around in my plumbing gear uncovered a box of mixed tap washers. Just to confuse the issue here, tap washers were originally sized according to the size of the threaded connection into the bottom of the tap, this means the stated size of the washer does not match up with its actual physical size.

I knew these would come in handy one day...

I selected a washer that actually measures 5/8 inch (aproximatly16mm) diameter. The washer I picked has a rubber core and a bonded mesh on each side making the mating surface particularly resistant to scuffing as it is tightened onto. The only problem with a tap washer is the hole in the centre is too small to wind it onto the thread of the net head. My first thought was to pop into the workshop and bore the hole out to a more suitable size. A simple job with a cordless drill and twist bit - wrong!

Larger than life O-ring and washers. The one of the far right has been bored out
The first problem is that it is impossible to hold by hand. Okay, that is easily cured by boring a hole is a scrap of wood, holding that down over the rubber and passing the drill bit through the hole to make the hole in the washer bigger. All that did was to expand the hole in the washer to become a very tight interference fit on the drill bit. The washer had merely expanded under the pressure of the drill. All I want to do is make the hole in the washer bigger. It would be so much easier to just punch it out to the correct size, well it would be if I had a punch!

The washer is prevented from expanding by fitting it in a blind hole of appropriate size
Nothing for it I am now going to have to make a jig, just to bore a hole in a tap washer. What I need to do is to stop the washer expanding as the revolving drill bit is applied to the hole. The jig is easily made by boring a shallow, 16mm diameter blind hole in a piece of MDF. A second piece of MDF has a hole bored through. This hole needs to be the same size as the drill bit to be used. Because the hole in the washer will close up a little after the re-sized hole is bored in it, I have found that a 9mm diameter bit seems to be just about right.

These parts need to be held together while boring out the washer
To use the jig, place the washer in the blind hole, centre the hole in the second piece of MDF over the washer to trap it. With the drill on its fastest speed setting, lightly bore out the hole in the washer through the hole in the second piece of MDF.

Done and now it will fit on the thread - albeit a tight fit
It sounds far more complicated than it really is. The washer can now be fitted to the net head and when the net is tightened up to the handle will not scrunch the washer up and will be securely attached to the handle. This is a straightforward fix, and once you have made the jig, you can convert any number of tap washers to a fishing application.