Metric Hole Saws

Workarounds for when you need a round hole to accomodate a metric-sized insert. September 5, 2006

I am trying to find a metric hole saw for drilling for halogen lighting which is 55mm, and the nearest size I can find is 2 1/8", which is 54mm. We have quite a few holes to drill and would like to find an exact size if possible. Does anyone know of a source for this size hole saw?

Forum Responses
(Cabinet and Millwork Installation Forum)
From contributor L:
If you can't find one, you could always use the 2 1/8", then go in with a 60 grit drill-mounted drum sander. 0.5 mm shouldn't take that long to sand off with a 60 grit drum.

Another thought… If you bent 4 of the teeth (separated by 90º) on the saw out by .5 mm, you could make your own 55mm hole saw. You could probably do it by using a small pair of vice grips, or a punch and a hammer. It should be kind of tough to do because the teeth are hardened.

From contributor J:
What about the ole adjustable hole cutters? Cutting blade slides on a bar with the arbor for the chuck in the center on the bar?

From the original questioner:
Part of the problem with adjustable hole saws and others, for that matter, is that they don't stay sharp long in composite woods, like plywood or MDF core. Other than that, I will probably use a 2 1/8" hole saw and sand out the difference.

From contributor F:
If this is a one time need, I would use a fly cutter on the drill press. If you have anyone in the shop who can grind and hone, they are easy to sharpen. If you must go metric, try to Google a European tool source.

From contributor P:
Have you tried Sandvik? They make hole saws and some of the ones I use (in the UK) are marked only in metric.

From contributor C:
Why not use a 2 1/4 saw? Only 57 mm and the deco ring should be plenty to cover it.

From the original questioner:
Okay, here is the solution we found temporarily. We use a 2 1/8" hole saw, which is 54mm, and then use a small grinder in a drill chuck to open it up the extra millimeter. If you try to do it with a 2 1/4", it comes out too loose and will not friction fit in the way it was designed. Thanks for all the tips.

From contributor A:
We use a 54mm hole saw all the time for installing the 55mm lights from HERA. The hole comes out fine because there is at least 1mm of slop in the arbor of the drill + the saw diameter + the operator movement. We don't have to use any sandpaper or filing or whatever.

From contributor R: has metric hole saws.