Make larger hole in work surface.

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Old 01-14-10, 10:07 AM
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Make larger hole in work surface.

I need to increase the size of 2 existing holes in a work surface from 1.25 to 1.5 inches. I don't see how a typical hole saw can do this. Any ideas?

Work surface is usual particle board with laminate surface.
 
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Old 01-14-10, 10:18 AM
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if the do not have to be concentric with the current placement, one can often use the properly sized hole saw and hold it at an angle near one edge of the hole in place already and, with some strong effort, hold the saw against the inner edge of the hole and work it so as to re-cut the hole the proper size. You would start at an angle and start the cut. Then slowly tip the drill to a vertical positition while keeping pressure against the inner side of the hole.

if it is need to place the large hole concentric to the existing hole, use the smaller hole saw to cut several plugs of some material. Make enough so as to be able to stack them inside of the larger hole saw so they protrude from the larger hole saw. Then simply place the protruding plug into the old hole and use them as a guide for the larger hole saw.

If you need to be more accurate or that does not provide a clean enough hole (as there will be the thickness of the actual hole saw left as a gap between the plug and the hole), if the arbor for the hole saws is long enough, you could attach the smaller hole saw and the larger hole saw on the same arbor but by putting a spacer between the two, you would cause the smaller hole saw to protrude enough to be used as a guide for the larger hole saw.


In either of the last two methods, once you get the larger hole saw to have a decent cut into the counter, you can remove the smaller guide so you do not have the problem of material jamming into the small gap between the plug and the larger hole saw. The saw really does not need the guidance anymore if you drill carefully.
 
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Old 01-14-10, 10:27 AM
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Another method I've used, if I understand what you're trying to do, it to place a sacrificial piece of wood over the current hole and drill through it into the surface you're trying to drill through. This, of course, depends on whether you have the space to do it. Depending on the situation, I've clamped the piece onto the surface and sometimes used double-backed tape.
 
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Old 01-14-10, 10:35 AM
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Depending on on what tools you have, and how thick the wood is, you could use a cordless laminate trimmer as well. By being careful you could get pretty close to being concentric but I like the previous idea as well.

If you need it to be in the same exact spot, you could even put the sacrificial piece of wood on the underside if it is accessible. This way you can see your original hole and be more precise. Just measure out dead center first and pilot a hole so that the arbor bit has a place to start without skipping or sliding off center before it bites. Just make sure you have a long enough arbor bit.
 
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Old 01-14-10, 10:50 AM
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Originally Posted by riggstad View Post

If you need it to be in the same exact spot, you could even put the sacrificial piece of wood on the underside if it is accessible. t.
very good method as well especially if it is close to an edge where you could easily clamp it. You could also screw it to the underside but use caution and not too long of a screw.
 
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Old 01-14-10, 11:03 AM
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My method is a combination of all of the above. I fasten or clamp a board to the back side of the hole.

With a hole saw the size of the existing hole I start the pilot bit. That way I'm perfectly centered.

I replace the pilot bit of the hole saw with one that will extend beyond the hole saw at least the thickness of the wood plus 1/2'.

Now i just line the hole saw up with the already centered hole in the back piece and drill.

There is also a rig used by locksmiths to enlarge holes that just clamps on. You might be able to rent one. Or you could just use a drill press if you have one. I have in the in the past use a cheap drill guide with a base clamped to the work piece to do this. IIRC the drill guide was less then $20 way back when. It consisted of a base with two guide rods and a drill chuck that slid up and down the guide rods. Drill chuck on the guide had a short shaft that you inserted into the chuck of your drill.
 
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Old 01-14-10, 11:11 AM
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Thanks everyone for some great ideas. I am working in a confined space and so will need to remove the surface mounted sinks, but I think that will be the cleanest way to get access to the hole.

I did think about working from below in the cupboard but I don't think I can get a clean hole then.

The bigger hole is to accommodate larger connection pipes that came with new faucets. I looked at trying to modify those but it was too complicated.
 
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Old 01-17-10, 09:50 PM
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If able to, use your 1.5" hole saw and make a hole in a 3/4 board or ply then using that board, line up the hole to the new location over the 1.25 " hole, set the hole saw into the hole as a guide in the 3/4 board and make your new hole. The 3/4 board can be clamped, screwed, or taped to hold it in place. I have made jigs like this in order to enlarge the bore in some old doors for a new lockset.
 
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Old 01-18-10, 09:28 AM
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My final solution was to screw a piece of plywood under the hole. I then replaced the standard auger with one of my longer drills that could reach the plywood below the hole. I could then get my center on the plywood.

This worked great.
 
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Old 01-25-10, 02:23 PM
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Using a 1.25" hole saw, cut a piece of wood 1.25" in diameter and epoxy it in the existing hole. When the epoxy cures, use a 1.5" hole saw and cut the new hole. The pilot hole in the plug should perfectly center the new cut.
Ken
 
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