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I want to mount a Qi phone charger flush into my desk. So I need to put a circular hole into the desk that's about four inches across and a quarter-inch deep. What is the appropriate tool for this job?

  • Does it matter if the hole has a deeper hole, just at the center (like this)? – wallyk Sep 17 '14 at 21:35
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    Whatever you do, I strongly suggest you practice it on scrap lumber before attempting it on the actual desktop. Whenever possible, make your mistakes on something cheap! – keshlam Sep 18 '14 at 5:23
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    A router and a template. A forstner will make a mess of it. – Hot Licks Sep 18 '14 at 16:42
  • What type of wood is your desk? – treeNinja Sep 19 '14 at 14:39
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Use a router with a pattern bit or a pattern collar and a end-cutting (plunge) bit.

Create a circular template route out the interior. You can adjust the depth very accurately and bottom of the depression should be pretty smooth.

  • I haven't used a router before. Is there a good introduction to routers (fixed base? plunge?) that would point me in the right direction for this? – Ben Dilts Sep 17 '14 at 22:53
  • Hm. I think I'd suggest a pattern collar on the router baseplate and an end-cutting (plunge) bit, rather than a pattern bit. Pattern bits are great things when you can run their bearing on the pattern, but if you're going to take successively deeper cuts (which is definitely the safest way to do this) a pattern bit won't handle that. Collar does mean having to size the pattern to allow for the difference between bit radius and collar radius, but would allow coming down to the full depth in stages. (Yes, this cut has to start as a plunge; a plunge base makes that safer and more controlled.) – keshlam Sep 18 '14 at 5:21
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    ... but the more I think about it, the more I like this approach. I'd re-emphasize my point above about "learn to use the tool on scrap, THEN do it for real", and routers require more respect and careful handling than a hand-drill does... but it's a tool worth being familiar with if you plan to do any significant amount of woodworking. One caveat: Routers themselves aren't unreasonably priced, but there are so many things they can do and each of those either requires or benefits from buying yet another bit... (smile) – keshlam Sep 18 '14 at 5:37
  • Looking at the answers, I feel this is the best approach for the cleanest depression in the wood. – diceless Sep 18 '14 at 15:35
  • Additionally, if you want a nice 'finish' to the hole, and it's appropriate for your use, you can use a "tray" routing bit. It will leave rounded corners at the bottom of the hole instead of 90 degree corners. Having rounded corners will make it easier cleaning out the hole and just looks nicer I think. – Arluin Sep 18 '14 at 21:05
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A 4" forstner bit would require a drill press, so you would need to put the desktop on a drill press table to drill out the hole. Depending on where the hole is located (distance from edge of desktop), this could be very difficult with most drill presses (a radial drill press would be great for this, I love mine). If you try to use a 4" forstner bit in a hand held drill, you are likely to break your wrist - that is a LOT of torque (I did try this once with a smaller 1 1/4" forstner bit - it was a bad idea)

Moving on - you can use a 4" hole saw if you are ok with having a hole left in the center of your 1/4" deep depression. To make sure you don't drill too deep, place a piece of painters tape around the hole saw, 1/4" above the top of the teeth. Stop the cut when the bottom of the tape meets the top of the desktop.

You can use a router, but you will need to follow a template. Don't try to freehand "color inside the lines" with a router, you will probably ruin your desktop - definitely use a template. With regard to the type of router, I have a few routers - a Tritan plunge router, a cheap Ryobi 2hp plunge router and a Dewalt trim router. I dig the Dewalt for small jobs like yours. You are only going 1/4" deep, so buying a plunge router seems excessive, and the less expensive ones are really more of a pain to use, they plunge poorly. Get a good quality trim router like the Dewalt. You will need to do your first cut at 1/8" and your second cut can remove the rest. With regard to bits, get a good straight plunge bit with a top bearing (to follow the template).

Good luck!!

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    I don't see why a hand held drill would be an issue. I use mine all the time with a 3 inch forstner. Once does have to mind the angle and the pressure to prevent kickback or jams, but this is easily learned by trial and error, maybe even on a final piece. – wallyk Sep 18 '14 at 5:20
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    It isn't the safest method in the world, and it can lead to an injury. Of course, people are free to do as they please. I just didn't want to make that recommendation without clearly stating that this is dangerous. I used a 1 1/4" bit in a piece of sugar maple once and sprained my wrist. Jammed in the maple and the drill kept spinning. Given he is asking this question, I didn't think trial and error was something he wanted to engage in. A $35 bit, a drill that can handle it, and a lot of trial and error, OR use a hole saw and fill the center hole left behind. That seems safer to me. – Jenine Sep 18 '14 at 13:56
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Hole saw, drill part way down (just to depth or just past, not all the way down). Then with a chisel, remove the wood inside the circle.

  • ... which is essentially what a Forstner bit is; it just has the chisels built into it. – keshlam Sep 17 '14 at 21:35
  • at 4 inch's that is going to be a pretty expensive bit if it could be found. Plus, the torque required would put this in a bench press only usage. I'm offing a cheap option that can be had with off the shelf tools from a big box hardware store. – diceless Sep 17 '14 at 21:58
  • Agreed. I'm not criticising, just pointing out that your answer and Tester101's are agreeing about the general approach. – keshlam Sep 17 '14 at 22:02
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    And hole saw, because it isn't trying to chisel as it drills, needs a lot less torque. A band of tape around it in the right place could serve as an indicator that the needed depth had been reached. Remember that if drilling down you may have to pause repeatedly to extract sawdust; might be worth considering turning the desk on its side or back so more sawdust gets thrown aside on its own. – keshlam Sep 18 '14 at 5:30
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    I think this is the best answer -- I'd be willing to bet that if OP is going to buy tools for this job, he'll get a lot more future use out of a 4" hole saw and a chisel than out of a 4" Forstner bit. – Mike Powell Sep 18 '14 at 13:04
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The router is the best power tool for this, but making an appropriate template will be a challenge. Finding a base for the router that has a pivot point so that you can make a circle is a better way (easier) to go. However...

I'm not surprised that no one has suggested a bit and brace. This is "old" technology, but in this case I think it's the best solution. It won't require a drill press, a template or even an extension cord! It's cheaper than buying a new router and bits and such, and it will do the job.

OK, it's not a lot cheaper. In fact, it may be more expensive. But it will do the job. Just google "bit and brace adjustable" because you'll need to buy an adjustable bit to make a hole the size that you want.

  • You'd have to use a fly cutter, and the bottom of the hole would be nowhere near smooth. – Hot Licks Sep 18 '14 at 16:45
  • What is a "adjustable bit"? I know exactly what a bit and brace is, but I've never heard of a a adjustable bit – Lyndon White Sep 18 '14 at 17:40
  • @Oxinabox, Adjustable bit is similar to a paddle bit but the paddle is adjustable. You have to google it to get an idea. – diceless Sep 19 '14 at 5:14
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You could use a Forstner bit, if you can find one large enough. I've heard rumor of 4 inch bits, but wasn't able to find one online.

2

You are really asking two questions here:

  • how do I make a large circular cut that needs to look good
  • how do I hollow out a large area to a pre-set depth

Forstner bits try to do both at once, but it has been well-discussed that a 4 inch model requires a lot more force than your wrist can provide. They're not cheap ($400 !!) and you will likely never use it again.

A 4-inch hole saw comes in cheap-and-nasty or really expensive, and need a 1/2 inch drill. Depth control is difficult. But a fly cutter will do exactly what you want: engrave a slot in the desktop X mm from the center.

Once you have the outer slot cut you carve out the center with a router and a square bit, any convenient size. Set your depth (1/4 inch can be done in one pass, run it a tiny bit deeper to allow for glue) and just work from one side to the other.

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While the router and template solution is a good one (particularly if you need to make a bunch of these holes) it does have the small complication of requiring you to first make a template.

For a single hole, a simpler solution would be to route out progressively larger holes using a combination of a rabetting and pattern bits.

The process starts with a more reasonably sized forstner bit (one that you can handle freehand and that may actually be useful in the future). This hole is then enlarged using a rabetting router bit, running the bearing around the existing hole. Next the pattern bit is used, with its bearing running along the larger hole made by the rabetting bit. This can be repeated as many times as necessary.

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As the brief article linked above mentions, you have to calculate out the the final size using the bearing offsets and the starting hole diameter. They also mention building up a surface for shallow non-through holes of the type you describe, although I would suggest it a better idea to use this technique on some 3/4 MDF to perfect a 4" hole, and then use that as the template for routing the actual desk. The template can be attached to the desk using double stick carpet tape.

Finally, if this is a desk you intend to keep longer than the charger, it would be convenient to make up some filler blanks to pop into the hole before you loose track of the template.

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