How to make an existing hole bigger??

Richard10002

Richard10002

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I've managed to thread my new toilet discharge hose but, as it is super duper Vetus, it's very stiff, and thicker than the normal stuff..... so I cant get it through the hole just behind the toilet:

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Super Duper Vetus hose - internal 38mm, external 50mm

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Existing hole 50mm, with not much room behind for pipe to bend.

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Hole cutters available:

The red one is a really tough 83mm cutter
The others are a bit flimsy, with a max of 63mm

I'm tempted to cut a big hole with the tough red cutter, but am concerned about slipping about when getting started, as there is nothing for the centre drill bit to grip and keep me on centre.

Any tips, and any reasons why I shouldnt cut such a big hole.

The only downside I can think of with a bigger hole, (other than cosmetic), is that the shower is over the loo, and water may get behind the fittings, (I think it then drains to the bilges, so not a mega problem).

Many Thanks

Richard
 
If you can get behind drop a piece of plywood down and use a couple of self-tappers to hold it over the hole - sort of a square with the circle hole in the middle sort of thing.
Then use the plywood to give you a solid centre on the hole to use for the pilot of the hole cutter.
Without something to hold the pilot of the hole cutter you will have great fun getting a decent hole cut.
Other option could be to use one of those rotary rasp type cutters you can get, sort of a hedgehog on a stick type thing, or the ones like a drill bit with cuts in the shaft?
 
Dependng on the access I would suggest clamping a piece of wood behind and across the hole to locate the pilot bit into to keep the hole cutter concentric.
 
Not a difficult job at all but you won't be able to use either of the two cutters that you have in the photographs as they can only be used to cut a virgin hole. The small centre drill requires material into which it can cut and hold steady.

May I suggest an ordinary power drill, possibly with a flexible drive and some form of flat bottomed mill, something like a router bit (Trend Routers).

Not much panelling to remove, you could do it with a round or half round file but it would be tedious as you don't have much depth behind.

Don't forget, you must mark out very accurately and then recheck the markings BEFORE you start cutting.
 
Some people should read the thread a bit, not mentioning any names! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
 
You will need to support the hole cutter and pilot drill as already pointed out. You can glue a piece of plywood on the surface with Sikaflex or something like Evostick
 
G'day Richard,

You don't want a nice round hole, you need an oval, this will improve the angle on entry and reduce the bend needed in the small space.

A simple Dremell tool or drill with a 40 grit flap sanding wheel will do the job in a few minutes.

Keep the hole a small as small as possible and run some sealant around it when finished. The last thing you want in your bilge is fresh water, the only thing worse than fresh water is soapy fresh water.

Hope this helps.

Avagoodweekend......
 
Get a large half-round file- then you can make the hole oval, to allow for the lack of bend in the pipe. It only takes ten minutes to bodge it, but you'l be cursing your impatience for years to come- every time you use the heads!
 
[ QUOTE ]
Other option could be to use one of those rotary rasp type cutters you can get, sort of a hedgehog on a stick type thing, or the ones like a drill bit with cuts in the shaft?

[/ QUOTE ]

Just happened to have one.... and it's done the trick!!!

Not the tidiest job, but not many people are going to see it /forums/images/graemlins/smile.gif

Could probably have got some ply behind, but it would have been a hell of a job.

Thanks to all for the help... yet again.... and so quick!!!

Richard
 
Yes you CAN use either of the cutters you have to recut the hole. The proviso is that you dont mind having the new hole with a slightly shifted centre. The technique I used was to get the hole cutter to bite by running it slightly off plumb so that the outer radius of the cutter runs up against the existing hole radius. I used a battery, variable speed drill until the hole cutter ran true then switched to an industral scale 220v drill, shifted to plump to the material and ran through. The original centring bit was not even installed for this exercise. My operation was to go from a little raymarine depth sounder to the massive bronze fitting for a forward looking sonar and went through 25mm of solid laminate in the bottom of the Benny.


The bulkhead you are working through looks thin, you ay be able to run through with a rechargeable drill. I dont forsee much trouble or any reason why you can't go for the big cutter. You will have 'daylight' round the pipe that may look a little unsightly. Get a sheet of polyethlelyne material. cut a 50mm hole in in the middle, cut a 100mm circle around it feed the pipe through it and use it to cover the hole once the pipe is in place.
 
Rather late to help now but for what it's worth here's my idea.

Cut a short length of the old hose(I assume it is a close fit in the original hole) and slip it into said hole fit over this a hole saw of the required new size and thus using the old hose as an alignment tool carefully approach the surface to be cut by applying pressure on hole saw which will push old hose through hole as new cut is made
 
Since we're all going for Suggestions After The Fact......

Cut a hole in a piece of board using the required hole saw. Place it concentrically over the existing hole. Use two sided tape or mirror pads. Possibly wedge with battens from adjacent bulkhead. Cut using the wood as a guide for the hole saw. Remove guide and scrape off tape.

Could work for someone else even though the original job has been done now.
 
Here's the finished job at the loo end:

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Tidying it up with an external circle will have to go on the to do list, (which runs to several pages /forums/images/graemlins/smile.gif

Thanks again for all the help.

Richard
 
[ QUOTE ]
Astonish cleaner will help clean up the hose. /forums/images/graemlins/laugh.gif

[/ QUOTE ]

Very Funny /forums/images/graemlins/smile.gif

Added to the list!!!
 
[ QUOTE ]
What a crappy hole!!!!!

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You should use your hole cutters to make a nice teak ring which you can cut in half and re-glue to trim your "crap hole".

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I know it's a crap hole!!!

but which bit of:

"Tidying it up with an external circle will have to go on the to do list, (which runs to several pages) "

did you miss? /forums/images/graemlins/confused.gif
 
If you have a tapered bung which will fit the hole you can cut it logn enough to go into the hole but have say 5mm sticking out which you can then drill into with the pilot drill of your hole cutter.
 
[ QUOTE ]
If you have a tapered bung which will fit the hole you can cut it logn enough to go into the hole but have say 5mm sticking out which you can then drill into with the pilot drill of your hole cutter.

[/ QUOTE ]

That's probably the best way of achieving the goal with a neat hole but, with respect, there is no way that pipe is coming out of that hole for another 14 years if I have anything to do with it!! /forums/images/graemlins/smile.gif

It'll certainly be at/near the top of the list if I have to make any more holes bigger.

Thank You

Richard
 
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