Sunday, May 13, 2012

35mm hinge boring jig . . . without a drill press

The easiest way to bore holes for 35mm hinges (a/k/a cup hinges, concealed hinges, or Euro hinges) is with a drill press, and one of my other posts shows a great drill press jig for making sure all your hinges are in consistent locations. A drill press is great to have, and I think it's one of the first machines you should get, BUT it might not be something you buy with the first $1,000 you spend on woodworking equipment. Most of us will want a tablesaw or bandsaw, a router, and perhaps a planer first. 

The 35mm hinge is the standard for kitchen cabinets because it's affordable, it's durable (if you buy a good brand), and most of all, it's adjustable, so that when you put the door in place and it's not quite parallel with its opening, or a bit higher than it's supposed to be, you can adjust it with the turn of a couple of screws, while the door remains in place.

The hinge fits into a hole of 35mm (1-3/8") diameter about 12mm (1/2") deep, bored in the stile of the door. The hole is best bored with a "forstner" bit, or other bit that leaves a flat-bottomed hole, since you don't want the pilot of a spade bit or auger bit to poke through the face side of the door. And forstner bits are notoriously tricky to use with a handheld drill, especially in larger diameters, because of their extremely short pilots - - the very feature that makes them good for this job. So what to do, short of going out and buying a drill press?

Give this jig, or one like it, a try. It's simply a good, thick slab of flat material with a 35mm hole bored in it.* Actually, the hole in this one is 1-3/8", but that's close enough for Euro hinges, just a hair loose but it works fine.

If you're going to use it with a handheld drill, the jig needs to be at least as thick as the body of your forstner bit, plus the pilot, so probably around 3/4" thick. If you're going to use it with your router and a pattern cutting bit, the thickness needs to be enough to let the bit spin freely while the bearing is low enough to follow the edge of the hole. So if the cutting length of the bit you're using is 1", you should use a jig around 1-1/4" thick. The one in the photos is 1-1/2" thick, which is a bit too thick for the bit I used, as you'll see.

Position the hole so that it's around an inch in from the long edge of the jig. That will leave room for a fence, which will determine the distance between the edge of your door stile and the hinge hole. This distance is critical for determining how much your door overlays its opening. In the next photo you can see the fence, which is made of nice straight wood that's thinner than any door I'll ever bore with this jig:

The fence is positioned to put the edge of the hinge hole about 3mm in from the edge of the door stile. This distance works great for the hinge I use most often, Blum's Clip-Top 120.

Using the jig is simple: clamp it down where you want your hole, carefully put the drill bit into the hole, spin it up to full speed before it hits wood, and drill until you're deep enough. The sides of the hole in the jig keep the bit square enough to the stile for your purposes.

(Safety notes: you see those safety glasses on the bench? Those are extras. I was wearing mine but you can't see them in the picture. For real! Safety glasses aren't optional when you're drilling a big hole. Also, you nitpickers have already noticed I need to replace the power cord on this drill. This is a 5-minute job and will be the subject of a subsequent post, because most power tools need a new cord every few years.)

Here's the resulting hole:

You can also use this jig with a plunge router and a pattern following (bearing above cutter) bit:

Notice that the jig is thick enough for the bit to spin freely (not cutting wood) while the bearing is low enough to be guided by the jig. This is important. On the other hand, with this bit I think a thickness of 1-1/4" instead of 1-1/2" would work better.

And here you see why: notice how the columns are bottomed out? I could barely plunge a hole deep enough for the hinge without starting to rub the bottom of the collet on the jig.

Using this jig with the plunge router is easy. Clamp jig to workpiece at a comfortable height, plunge bit to within 1/8" of workpiece surface, turn on motor, and rout around and around the hole while gradually plunging to the full depth of your hole. Most pattern bits aren't designed to plunge straight down to full depth, so you have to keep moving the router and let the side of the bit do the cutting instead of the end.

Routed hole on the left, drilled hole on the right. The routed one is slightly cleaner and doesn't have the dimple in the middle from the drill pilot - - but all this is covered up once the hinge is installed. The router takes about the same amount of time as the drill, but throws the dust around more violently (and grinds it finer). 

*I hear the objection: how can I make this jig if I don't have a drill press? I have several suggestions.
1) make friends with someone who has a drill press, and show up at their house with your prepared jig stock, the 35mm bit you'll use to bore your doors, and an appropriate gift.
2) buy this jig from me. Oops, sorry, my son asked if he could have it. I'm not sure why. 
3) pay me to make a new jig. Oh, did I just say that? I guess I could. I'm kind of busy, though.
4) make your jig out of mdf, like I did. It cuts like cheese. Try your hand at using the forstner bit freehand. Your first try won't go well. Your second try might go better. Once you finally get a sort of clean hole (typically, they have messy beginnings and neat endings, the opposite of love affairs), use your best hole as a jig for making a better hole. Use that hole as the jig for making this jig.
5) buy a 1-3/8" spade bit, a good one with spurs on the edges, and use that to make the jig.
6) buy a 1-3/8" hole saw, and use that to make the jig. (Note: I don't know if this will work. Just an idea. The resulting hole might be way too big!)