How do you make the hole larger

[Shadow Catcher]

I was winterizing the trailer a week or so ago and went to turn on the main 12V switch and nothing. I managed to jumper power to the pump so I could turn it on and run antifreeze into the system.
I never liked the switch


So I decided to replace it with a Blue Sea which can be surface mounted or mounted in an up to 3/4" thick panel.



The current hole is about 1 1/2 inch through 3/4" particle board and the hole for the Blue Sea needs to be 2 5/8" http://assets.bluesea.com/files/resourc ... series.jpg
From experience trying to use a hole saw on an existing hole will not work (Painfully Ugly Hole you have to disguise),

Any one with a nifty idea on how to enlarge the hole ?

[michaelrsydney]

If you have access to the rear of the panel screw a piece of scrap plywood to the rear face to cover the hole, then place the pilot drill of your hole saw in the centre of that.
Looks like you could even drill the four mounting screw holes for the new switch first and use those to locate the ply.

[eamarquardt]

If you have access to the rear of the panel screw a piece of scrap plywood to the rear face to cover the hole, then place the pilot drill of your hole saw in the centre of that.
Looks like you could even drill the four mounting screw holes for the new switch first and use those to locate the ply.

Using plywood on the backside would be your first choice but you could also screw some ply to the front surface and accomplish the same thing. Place the screws in the border that will be cut out so that you don't have any holes to patch.

"Piece of cake if you're smooth" (a Navy/Marine expression regarding carrier landings).

Cheers,

Gus

[GuitarPhotog]

You can also use the cover as a stand-off and use machine screws to mount it over your existing hole.

<Chas>

[halfdome, Danny]

I don't know how much access you have so...
If it were me I'd use that 1 1/2" hole saw and make another plug for my jig.
If you have a slightly bigger hole saw that would produce a 1 1/2" plug, that would work too.
If not, glue 4 wood shims equally spaced, to fill the gap, so the new plug fits into the old hole.
Now you have a pilot hole to drill the new hole.
Danny

[Shadow Catcher]

I knew I could count on you, This comes under the heading of I did not think of it that way. I made a cover plate out of brass to cover up screw holes and an additional OK what the heck did they use that hole for hole. It now has a 2 5/8 hole, cut it out with the 2 1/2" and then used a high speed air tool with a carbide tip to get the additional 1/8" and I can use it as a guide.
Tom

[jgrote]

All of the above are great ideas. However, I have done one more that is a little more adventurous. First mount your 2 3/4" holesaw onto your mandrel, then screw your 1 1/2" saw on, with a couple of washers (if possible) in between the two to give you a bit more depth difference between them. The smaller one will be deeper and thus help keep you centered while starting the larger hole. I've only done this in cases where I could not do any of the other ways first.

[Vedette]

All of the above are great ideas. However, I have done one more that is a little more adventurous. First mount your 2 3/4" holesaw onto your mandrel, then screw your 1 1/2" saw on, with a couple of washers (if possible) in between the two to give you a bit more depth difference between them. The smaller one will be deeper and thus help keep you centered while starting the larger hole. I've only done this in cases where I could not do any of the other ways first.

I have never heard of this method.....but it sounds like it would work if there was no other choice.
I have always used the - new piece of wood on the back if you have access.
But with as much difference in the hole size as we are talking here.....I would use a hole saw larger than the small hole but smaller than the large hole required, and cut out a round plate from steal or aluminum. Then drill a couple small holes in it to screw it over the existing hole (centered of coarse). Then using the center pilot hole I would hole saw out the larger hole. I always keep all of my cut out metal holes, so I can usually just pick out the one I need to make this work.
Good Roads
Brian

[Corwin C]

Another trick that I've used is to use the hole saw on a piece of scrap, clamp the scrap to the location that you want your final hole and then cut the final hole. The scrap piece will help you see where the final hole is going to be and hold the hole saw while you start the cut. This also works when the final hole needs to be off center of the original one. Make sure that the scrap is clamped securely.

[pmowers]

All of the above are great ideas. However, I have done one more that is a little more adventurous. First mount your 2 3/4" holesaw onto your mandrel, then screw your 1 1/2" saw on, with a couple of washers (if possible) in between the two to give you a bit more depth difference between them. The smaller one will be deeper and thus help keep you centered while starting the larger hole. I've only done this in cases where I could not do any of the other ways first.

I was thinking along similar lines, using one of those cheap 7 blade hole saws and having both the 1 1/2 and 2 3/4 blades in the arbor at the same time.

Pat

[Bogo]

My usual method, if I have time, is to glue a plug of wood in the old hole, then drill out after the glue hardens. I've also used the two hole saw method.

[jgrote]

I only use the two hole saw method when the other options won't work, or I don't have the tools/material to finish the job on hand. A scrap of wood, either clamped or screwed into place, is the most sure fire way to get a good outcome. Now we WANT PICS of your newly enlarged hole.

[CarlLaFong]

You need this. Less than 10 bucks
http://www.youtube.com/watch?v=iwvnsIYIOiw

[Larry C]

You need this. Less than 10 bucks
http://www.youtube.com/watch?v=iwvnsIYIOiw

That's a great idea using 2 hole saws Thanks for sharing

[Tinbasher]

simple. just use dynamite! slow

Or check for gas leaks with a lighter?