Drilling Rubber

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richardbrennan

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I am having to renew the deck gland that takes the radar cable through the deck. Obviously I have to drill through the rubber seal in the gland, however the cable is about 1cm in diameter and I have not had much joy drilling through rubber on previous occasions. I wonder if anybody has any tips as to how this is best accomplished?
 
I'd use a laboratory cork borer.
Everyone has a set of cork borers don't they? ;)
 
Dip it in liquid nitrogen before drilling! Even putting it in a freezer for a while can help. Use a very sharp drill that will actually cut rather than tear the rubber.
 
Sandwich between 2 reasonably thick bits of ply.Put in vice and tighten well.If you have a clamp nip the bits of ply which are out the vice,this will stop the drill taking the tension off the ply thats out the vice.
 
When I wanted a cable gland, I bought one with a core hole the right diameter for the cable I was using. Are you sure you have to drill the one you have?

If so I'd go with the chemist's idea of using a cork-borer.
 
The Deck Gland is from Index Marine and the rubber is solid and about 12 mm thick, there were none in the chandlery that had pre-drilled holes. It looks like a cork borer is the best option but this is not the sort of thing I have lying about at home. I might try drilling first as "a sharp drill" is what is recommended on the pack.
 
Plug Cutters For Making Plugs To Hide Screw Heads In Wood Will Be Ideal

You can get plug cutters for removing plugs from wood to cover screw heads. Screwfix, BandQ etcetera all supply, usually in a set of 3 in a wallet. They have a circular chisel edge, not a saw profile and come in a variety of diameters. They are specified with internal ID but it would not take much to establish the OD of the cutter for your hole. The set I have are all about 10 mm OD anyway, with I think just a thicker wall for smaller plugs.

The chisel edge would slice through the rubber instead of tearing it apart. No risk of cold or hot burning of your finger tips!
 
I would imagine that your problem is holding the gland insert secure whilst drilling. It may be best to fit it into the fitting so as to grip it and then drill. I would prefer to sharpen the outer edge of a 10mm tube and use it as a drill bit, but I have easily drilled through a sorbo ball (from petstore) with a wood drill to thread on bungee as a drain stopper.

Rob.
 
I plan to screw the whole gland down on my workbench which should hopefully hold it during the drilling. I now just need to measure the diameter of the cable which I shall do when I am down on the boat tomorrow. I am hoping for sunshine!
 
I've had some success using twist drills for wood - you know the ones with a sharp tip.
Probably not as good as a cork borer, but the above are available on occasion from ALDI (sorry not much use to you currently).
Screwfix don't have any. Bother.
 
I fitted one of these deck glands a few years ago and didn't have any problem at all drilling through it as far as I recall using an ordinary cordless drill and a good bit. Never had a leak despite three cable running through the same gland (three separate holes of course). Just don't drill them too big!

John
 
Unless you have Vic's borers Nedmin's advice is spot on, a sharp ordinary twist drill or pellet hole counter boring bit, the flat bottomed twist drill for boring timber for pelleting, and clamping firmly between two bits of scrap ply or chipboard, drill though the lot and job done!
 
richardbrennan said:
I am having to renew the deck gland that takes the radar cable through the deck. Obviously I have to drill through the rubber seal in the gland, however the cable is about 1cm in diameter and I have not had much joy drilling through rubber on previous occasions. I wonder if anybody has any tips as to how this is best accomplished?
Click to expand...

Spray rubber with those freezer canisters they use for freezing water pipes then drill.
 
Ive just done this on a through deck fitting; use a normal drill the same size as the cable; apparently the hole the contracts a bit to get a proper grip. No probs at all doing it.
 
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