Cutting Holes in 5mm fabric reinforced Neoprene

Ian_Edwards

Ian_Edwards

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Hi, and seasonal greetings

I'm back in boat maintenance mode, after spending the later part of 2018 travelling.

I needs some advice on how to cut 8mm diameter holes in 5mm fabric reinforced Neoprene.

The application is fitting new centre board rubbers to my Southerly 46, think centre board rubbers on a sailing dingy, only much bigger, the slot is over 3m long, and the centre board weighs 2.5 tons. The Neoprene is held in place by 2 SS strips, with SS inserts fitted into the cast steel grounding plate. I need to be able to cut or drill the holes fairly accurately to get the SS strips to line up with the holes in the neoprene and the inserts in the cast steel grounding plate.

I've got about 30 holes to cut, at around 8mm diameter.

I've tried drilling with a brand new drill, and punching holes with a hole punch, part of a set I bought at Bunnings in Australia, but the hole punch just bent when I hit it with a rubber mallet, it was a cheapo set, so I wasn't surprised. And I don't seem to be able to get a drill bit to cut, it just produces a very ragged hole.

What's the best way to cut holes in Neoprene?

With 30 odd holes to cut and the prospect of having to do this every few years, I don't mind spending bit of cash to get good tools to do the job.
 
A punch would be my first thought.
The one you tried was obviously not intended for heavy use.
 
Ian_Edwards said:
Hi, and seasonal greetings

I'm back in boat maintenance mode, after spending the later part of 2018 travelling.

I needs some advice on how to cut 8mm diameter holes in 5mm fabric reinforced Neoprene.

The application is fitting new centre board rubbers to my Southerly 46, think centre board rubbers on a sailing dingy, only much bigger, the slot is over 3m long, and the centre board weighs 2.5 tons. The Neoprene is held in place by 2 SS strips, with SS inserts fitted into the cast steel grounding plate. I need to be able to cut or drill the holes fairly accurately to get the SS strips to line up with the holes in the neoprene and the inserts in the cast steel grounding plate.

I've got about 30 holes to cut, at around 8mm diameter.

I've tried drilling with a brand new drill, and punching holes with a hole punch, part of a set I bought at Bunnings in Australia, but the hole punch just bent when I hit it with a rubber mallet, it was a cheapo set, so I wasn't surprised. And I don't seem to be able to get a drill bit to cut, it just produces a very ragged hole.

What's the best way to cut holes in Neoprene?

With 30 odd holes to cut and the prospect of having to do this every few years, I don't mind spending bit of cash to get good tools to do the job.
Click to expand...

Wad punch !

PRI94013.JPG
https://www.ffx.co.uk/tools/product/Priory-Pri94008-5054605392232-Wad-Punch-5-16In-8Mm
 
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The two tools I can think of are either a leather punch or a cork borer. Both are sharp(ish) hollow cutters that will be available in that sort of size.
 
Ian_Edwards said:
What's the best way to cut holes in Neoprene?

With 30 odd holes to cut and the prospect of having to do this every few years, I don't mind spending bit of cash to get good tools to do the job.
Click to expand...

As others have said, a hollow hole punch (8mm bore steel tube with a bevel on the outside) but with a big block of dense wood underneath on a hard floor and hit the punch with a hammer not a mallet.

Www.solocoastalsailing.co.uk
 
vyv_cox said:
That's what I would use. Your link shows an up-market one, my complete set cost little more than that at a steam fair but the difference is obvious. Still not a lot for a quality tool.
Click to expand...

People dont seem to have the tools these days...... Wad punches are just one of those things in an old OXO tin on a shelf in the garage

r2rozo.jpg
 
The right tools have been mentioned above, but I have used red-hot nail to put holes in brittle plastics with some success. Good luck with neoprene.
 
The trick, with fabric, is to put your wad punch into a drill press and use it as a regular drill bit. This cuts a very quick, clean hole.
You could just as well use a pistol drill but do try it first, with a bit of scrap, to see if it grabs on the rubber, I think you will be ok.

I have also seen wad punches called Saddler's Punches
 
Thanks for all the input, WAD punches ordered.
I'll be interesting to see how well they work, I'll try spinning them in a handheld drill, 5mm of reinforced Neoprene is quite a lot of a ask a punch to drive through.
Would a little soapy water help to stop the punch gripping the Neoprene?
 
Ian_Edwards said:
Thanks for all the input, WAD punches ordered.
I'll be interesting to see how well they work, I'll try spinning them in a handheld drill, 5mm of reinforced Neoprene is quite a lot of a ask a punch to drive through.
Would a little soapy water help to stop the punch gripping the Neoprene?
Click to expand...

I think wad punches will be too chunky ( thick walled ) to use in that way

Laboratory cork boring machine might do the trick.

Soapy water will be a suitable lubricant. Maybe a water based "personal lubricant" will be better. ( Every workshop should have a tub of anal lube handy ;) )
 
Ian_Edwards said:
Would a little soapy water help to stop the punch gripping the Neoprene?
Click to expand...


Can't hurt, you will not want to overheat the punch but I think you will be ok. Let us know how it goes.

PS

It's true, thick walled punches could bind. I have a set that came from Aldi and the walls are thinner with a longer taper.
In the past I have also used steel tube sharpened with a file whilst spun up in a chuck.
 
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VicS said:
I think wad punches will be too chunky ( thick walled ) to use in that way

Laboratory cork boring machine might do the trick.

Soapy water will be a suitable lubricant. Maybe a water based "personal lubricant" will be better. ( Every workshop should have a tub of anal lube handy ;) )
Click to expand...

Brings back memories. I remember the sets we had for quick one-off jobs and often wish I'd kept a complete set of those for odd boat jobs over the years. They were very soft but came with a sharpening tool. I do have a couple of old wad punches but never seem to have exactly the right size. I think VicS is correct about these thick walled punches binding if rotated in a drill.

I must admit that neoprene sounds a bit soft for that duty unless they aren't what I'm thinking of on my old Southerly. My S95 didn't have anything to stop the keel bracket hitting the grounding plate and it used to make a nice clunk on the way down. I was always careful to lower it slowly fort the last few inches.

I seem to remember fitting bump stops over the retaining pin which straddled the gap in the rear of the slot in the plate. It was a large diameter pin and the only thing stopping the keel dropping through the slot to dangle underneath. I think these bump stops were made from the stout rubber rings you find on fishing nets and they lasted forever.
 
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Mistroma said:
Brings back memories. I remember the sets we had for quick one-off jobs and often wish I'd kept a complete set of those for odd boat jobs over the years. They were very soft but came with a sharpening tool.
Click to expand...

Surely everyone has a set of cork borers , don't they?

2ik4ms2.jpg
 
DownWest said:
Used to sell a lot of cork (bowles and tiles) but never seen those tools. Look very useful..
Click to expand...

Old chemists will recognise them immediately. They also used to value old silver coins and most had a prized shilling or even half crown. VicS will know what I'm talking about and probably even know the relevant years (most others won't have a clue :D).
 
VicS said:
People dont seem to have the tools these days...... Wad punches are just one of those things in an old OXO tin on a shelf in the garage

r2rozo.jpg
Click to expand...

I still have a few OXO tins along with various biscuit tins. Then came good quality plastic containers, 2 lb salt bottles and tough ice cream containers. Now they split the first time I put anything heavy in them and they are 'designer' shaped so they won't stack.
 
Use a club hammer with the wad punch & use something like an (MDPE?) chopping board underneath to punch into so you do not damage the edge ,but essential that all is supported on something with mass not a flimsy bench.
Jim
 
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