Hole new problem

[Hippohay]

It's a long, and tragic, story, but we managed to lose the cowling of our outboard last year. Yamaha wanted some ridiculous amount for a new one so I've bought one from a breaker. Only problem is that I need to cut a circular hole (about 3in) in the top for the internal tank filler.
Any ideas of best way to go about the cutting? An electric drill with one of those large circular hole-cutters or by hand with a thin blade?
Any ideas appreciated!

 

[damo]

If you have never done it before your easiest option may be to take along to a local engineer or garage and get them to do it - it may be cheaper anyway if you haven't already got the tools.

Thin material is difficult to cut neatly unless it is held firmly. A hole cutter works best in a pillar drill, but your cowling may be too wide to fit underneath one. Working slowly by hand with a junior hacksaw blade is an option of course.

 

[awol]

Mark the outline - drill a series of holes with whatever size of drill you have around the outline, as close together as you can - break out the bit in the middle, may need a mini hacksaw blade or just sideways pressure on the drill - file the rough edge. (Or borrow a 3" cutter and use a backing piece)

 

[Clyde_Wanderer]

Right I had to do this last year as I fitted an internal tank to a 5hp mariner which came from a 4hp yam, Identical in nearly all aspects. the thing is I have a 4hp lid with an original hole which I could swap for yours without the hole, or to enable you to get the hole in the exact place I could take some measurements and pm you with them.
I used a hole saw in a slow rinning drill, much neater.
I have an external tank valve which fits where the fuel tap would be on an internal model, and if you were interested in converting it to remote tank, then you wouldent have to cut the lid at all.
Let me know if I can help.

C_W

 

[Hippohay]

Thanks for the offer, but I've already borrowed a friend's cowling to get the dimensions right. I'm kinda looking forward to having a go at the cutting - worst comes to the worst, I'll be back at the breakers!

 

[davidpbo]

If you are drilling into thin metal or plastic and want to do it neatly and accurately, clamp the cowling firmly and put an oversized wooden block under the area to be drilled to drill into. If it fits well and is firm it should limit any distortion of the material. Use sharp bits/cutters. If you took it to a metal fabricator they may have the correct size punch to punch it out which would be neatest.


If you are using a hole saw with centre drill bit drill a pilot hole first