Replacing Countertop Stove

I do volunteer work for some of our local seniors and the project I've been asked to undertake this Friday is to install a new countertop stove (4 burner electric jobbie). The new one is a gift to the client from her husband to celebrate their 63rd(!) anniversary, so I'd kinda like to do it right.
What I know so far:
1. The new cooktop is "wider" than the old one, so the opening needs to be enlarged. 2. The countertop is "formica".
Questions:
What is the best way to cut out the existing opening without chipping the hardtop surface? I can rig up a straight edge (I think) to guide
1. a router with a downcut spiral bit or 2. a Fein multimaster with a fine saw blade or 3. a Bosch jig saw with its anti-splinter insert and a fine blade or ???
Is it best to score the surface line first (box cutter, glass cutter)? I'm an amateur wood dorker, not a cabinet maker. I know there are some experts out there, so any advice would be appreciated.
Regards.
Tom
email: replace *** with air
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On 9/7/2011 8:25 PM, Tom wrote:

A straightedge guide isn't necessary. Every cooktop and sink I've ever installed has a mounting flange at least a centimeter wide -- if your cut deviates from the ideal cut line by a sixteenth of an inch, no one but you will ever know it, as it will be hidden beneath the flange.

All of the above will work. If using a jig saw (aka saber saw), get a blade that cuts on the down-stroke (most cut on the up-stroke).
It also helps to apply masking tape to the formica, centered over the cut line: it's easier to see your cut line on masking tape than on dark-colored formica, and the tape helps reduce splintering. Years ago, before down-cut saber saw blades existed (or before I knew they existed, anyway), I managed a perfectly acceptable sink cutout with an up-cut blade and masking tape -- with masking tape and a down-cut blade the results are very, very smooth.

Unnecessary, and possibly harmful: it's *really* easy to slip with a box cutter, and make a score mark where you don't want one.
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I just did one of those a couple months ago when the new stove was an inch wider than their old one. I used a circular saw (with a nice teflon-coated Freud blade) and guide, then the HF multifunction tool with a plunge blade in it to finish up what the circ saw couldn't get to. I was amazed that it had zero chipping. I usually use a circ saw on a new, upside-down, uninstalled formica countertop, and it works fantastically.
-- That's the thing about needs. Sometimes, when you get them met, you don't need them anymore. -- Michael Patrick King
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Jigsaw with a down-cut blade, made just for the job you're doing. Don't worry about the cut being too straight, modern drop-in cooktops have a wide flange.
CAUTION: Those down-cut jigsaw blades will try to push your saw upwards, make sure you anticipate that by adding more than usual pressure. If you let it go upwards, it WILL pogo-stick across the countertop and do a LOT of damage quickly. Not a blade for the faint of heart.
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In article

And make sure you buy several blades, that stuff blunts blades *very* quickly
--
Stuart Winsor




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responding to http://www.homeownershub.com/woodworking/Replacing-Countertop-Stove-523396-.htm Jasprt2 wrote: The router is prob your best method of ensuring a clean cut the formica. If you must use some type of a saw be sure to score the formica to prevent and chipping beyond the cut path.
Tom wrote:

-------------------------------------
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On 9/7/2011 10:25 PM, Jasprt2 wrote:

Nonsense.
A saber saw with a down-cut blade produces very little chipping; even an up-cut blade won't chip it enough to show outside the mounting flange, and the simple expedient of putting masking tape over the cut line eliminates most of that anyway. There is absolutely no need to score the formica first; in fact, trying to may do more harm than good -- it's easy to slip, and score something you didn't mean to score.
The cut is not going to be visible. It doesn't matter if it's not perfect.
Of the three options suggested by the OP, a router would be my *last* choice because of the ocean of fine dust it will create.
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On Thu, 08 Sep 2011 08:33:51 -0400, Doug Miller

Unless of course, he has a good friend with a Festool 2200 router and dust collector. Then he's golden. :)
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Tom wrote the following:

The accepted method for decades has been masking tape, a drill, and saber saw. Lay out the cutting dimensions on the masking tape, Drill holes at the cutout dimension corners to accept the saw blade and to eliminate making 90 turns with the saw, then saw cut from corner to corner. The minor chipping that may occur will be hidden by the range top.
--

Bill
In Hamptonburgh, NY
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First off - Good for you!
What is the counter made of?
Does it have an integral (post-formed or similar) back-splash that you cannot remove?
The accuracy of the cut-out is not a concern as the replacement unit will cover most minor "short-comings" with the "lip" provided. A new unit SHOULD come with a template, pattern or measurement for the required opening size (which will be smaller in both dimensions than the outside measurements of the unit itself.
Since you are enlarging an existing opening, you MAY be able to simply remove X-inches from each of the four sides of the existing opening. But CHECK FIRST to see how the new unit would lay in such an opening. It is possible that the front to back measurements of the two units are different as regards the offset from the front edge or back splash - crucial you know this before cutting.
Masking tape along the cut line has been suggested in cutting Formica counters.
The router will work for much of the cut - but the router (or jig saw, etc.) base plate size will likely prevent you from cutting close to the back splash - especially with the counter in place. One of those Trimmer Routers might do that part of the job for you. And, a router will surely make a clean cut.
Look, also, for obstructions below the cut line. Especially if the old unit fit above a cabinet sized to the old unit.
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Good questions and suggestions. I'll have to look when I get there tomorrow. Asking such questions of a couple of 80 year olds over the phone is often not very fruitful.
I suspect the the Multimaster will come in use if the back-splash gets in the way (and I'm sure it will - first corallary to Murphy's Law "Nothing is as simple as it seems").
Thanks and best regards.
Tom
On Thu, 8 Sep 2011 07:28:56 -0700 (PDT), Hoosierpopi

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Thanks to all who responded.
Concensus seems to be the jig saw. I have some Bosch 101A0 blades (20 TPI) that appear to have a zero rake and I just bought a pack of 101BR (10 TPI) that have a downcut rake. Between the 2 I'll figure out what seems to work best, with the masking tape as suggested. I'll set the jig saw to the "no orbit" position (it's a Bosch) to reduce the chance of chipout and go for it.
Regards.
Tom

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