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Old 27 May 2004, 03:46   #21
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If we were mates you could borrow mine. seriously I have loads of excelent kwality wood working tools and we are only opposite you in Drivers.
So give me a call if you need something
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Old 27 May 2004, 06:52   #22
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Quote:
Originally Posted by Rogue Wave
...using a high reving edge cuttin rotatin tool can go very badly wrong if you don't use these tools regularly..
Well, the following comments are made recognising that all tools are potentially dangerous. However, judging by this thread and its predecessor, a good number of folk on here are not entirely comfortable or confident with tools.

General (very important) rule. To be in proper control of a tool you must not be forcing it.

Examples; use a big hammer softly rather than a small one forcibly, use a long spanner smoothly rather that a short one with all your strength, and, topically, use an angle grinder gently rather than pushing a god awful jigsaw to make it move forward!

I agree with Matt about circular hole cutters. These are cutting the whole way around their circumference and that is a bigger cut than any other tool I can think of.

Jig saws are awful things. By definition they are designed to cut curves, therefore cutting dead straight is difficult. The surface always needs protection because the foot invariably bruises it. It cuts by vertical movement which tears and chips in action. It is often used from the top side of a surface which means the damage it inflicts matters. They rarely cut freely so force it necessary.

On the other hand, an angle grinder wants to cut. It can be applied very gently allowing full control. It is also possible to rest one's hands on the workpiece to steady it. It runs straight once into the cut. The down side; you need dust, eye, ear and hand protection.

A router is a very dangerous tool. They are becoming common but they need great care. For one thing they're a gyroscope and they can fight you. And they can win.

General note about boat materials. Fibreglass responds to abrasion. Sanding, grinding, filing, rasping all work well. Tools with cutting teeth generally don't.

Rubbers, surprisingly, respond to abrasion also. Sanding and grinding work well. It can be sliced with a very sharp blade, eg. a Stanley Knife but it hates toothed cutting tools and drilling.

Back to the thread. When making holes in fibreglass, don't underestimate chain drilling. It's much quicker than might be imagined and complex shapes can be generated.
The tedium of drilling a series of holes seems daunting but it really isn't too bad. Buy the time you make your way to the shop for this special thingy, you can have the hole drilled and finished!

Finish the shape with a file. Buy half round files, they are much more use than a flat file. Better still, buy a selection.

The big plus, no special tools are necessary. It's dead cheap and it'll improve your hand skills. So you'll be able to cut up that non-sliced bread a lot straighter.
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Old 27 May 2004, 07:38   #23
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Jig saws are awful things. By definition they are designed to cut curves, therefore c

JW
From my recent experience using a jigsaw with a fibreglass blade I was amazed just how well it cut, very straight, very smooth and no chipping.

I was apprehensive at first, but the whole job only took a 60 seconds or so to cut out a hole 180x100mm, having pre drilled the four corners.

The blade is very similar to the edge of a grinding disk. It has no teeth, just an abrasive surface that must "grind" rather than cut.

The package it came in describes it as carbide coated, for cutting ceramics and fibreglass.

The advantage as I see it, with a blade like this (in a jigsaw) over a grinder is the ability to control the cutting/grinding speed using the variable speed trigger on the jigsaw.

John
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Old 27 May 2004, 07:50   #24
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Yep, I know the type. If it works for you, good.
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Old 27 May 2004, 08:52   #25
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well, thank you everybody.

From what I thought was a rather dull question, a great deal of info has been forthcoming for which I am grateful.

I have a good idea of what to do now.
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Old 27 May 2004, 10:22   #26
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No one seems to have mentioned these:
- wrapping the jigsaw foot with masking tape
- using a fine toothed PLUNGE cut blade as opposed to pull cut. This will cause less gel coat damage. YES, they do exist, I used to sell them!
- overboring through the gel coat layer when drilling for screws - minmises crack propagation through the gelcoat.
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Old 27 May 2004, 10:42   #27
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wrapping the jigsaw foot with masking tape
It curls up, better to stick it to the surface to be cut, then you can mark out on it.

- using a fine toothed PLUNGE cut blade as opposed to pull cut. This will cause less gel coat damage. YES, they do exist, I used to sell them!
Not met them, got to be good idea.

- overboring through the gel coat layer when drilling for screws - minmises crack propagation through the gelcoat.
Or use screws (machine) and nuts and washers.
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Old 27 May 2004, 17:15   #28
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Here ya go. Straight, quick, no scratching, clean edge, very gentle but a bit dusty.
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Old 27 May 2004, 17:36   #29
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Aww come oh WJ you are a fine craftsman with bundles of experience so yes you could use and get a good result with an Angle grinder. I have a bit of experience of handling tools and I am pretty sure that I could use an angle grinder to do this job well. Also neither of us would need to ask how to cut an ole.

When I said that it could all go terribly wrong i was referring to the angle grinder sliiping out of the intended excavation site and making a new one accross the gelcoat. I didn't even think of the safety aspect as that is second nature, however the point you have raised are good ......d'ya think som guidance on safety an the use of tools would serve well in the reference section ?
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Old 27 May 2004, 18:18   #30
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Yes I suppose it might. We'd better ask folk whether they want it rather than being presumptuous.

Consider yourself asked.

Don't under estimate folk. I have 13 year olds using angle grinders without problem but they have difficulty with jig saws and coping saws. Even the seniors are not allowed to use a router. Not my rule but the authority's. They are one of the tools in a classification of dangerous along with circular saws and the like.
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