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I need to cut two 1-2mm slots into the edging of some c channel

What is the most effective way to make these cuts?

Using a 1mm drill bit and making holes side by side does work but it's slow and doesn't provide a consistent slot.

Another option could be to use a chisel and hammer very hard in one-attempt, but it may need too much force to penetrate.

The pictures below denote the grooves by the red lines and the picture circled red shows the notch that fits into the grooves.

inner c channel

outer c channel

c channel notch

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  • 1
    Those wouldn't be grooves they'd be slots.
    – Huesmann
    Commented Aug 24, 2023 at 13:52
  • 1
    Grinding them out probably the easiest. That small might go with a rotary tool instead of an angle grinder. Do you want a groove or a slot in the metal?
    – crip659
    Commented Aug 24, 2023 at 13:52
  • Good point let me update wording Commented Aug 24, 2023 at 13:52
  • 1
    This feels a bit like an XY Problem to me. What is it that you're really trying to accomplish? It might be that a grove/slot may not be the thing you're after.
    – FreeMan
    Commented Aug 24, 2023 at 13:54
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    @FreeMan I think the OP is trying to develop a "tab A into slot B" situation.
    – Huesmann
    Commented Aug 24, 2023 at 13:55

2 Answers 2

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Normally, one makes grooves with a router and an appropriate bit (though that's generally in wood - you'd need a specific bit designed for cutting metal), or with a circular saw blade.

A table saw would be an ideal method for making a long groove like this, but good luck finding a blade with a 1mm kerf.

The existing grooves (it appears that there are some already) were, most likely, either cast/extruded into the parts at the factory, or were routed out in a CNC router after the parts were formed

It appears to me, though, that you really don't need a long groove, but a slot so that tab in the 3rd picture can fit through it. If that's the case, then a small cutoff disk in a Dremel™-type hand-held rotary tool would probably be your best bet.

The cutoff disks are very slender so you might actually have to make a couple of passes to make the slot wide enough to get that tab into it. However, with the metal clamped down, you should have plenty of control with a small rotary tool to be able to make a reasonably accurate slot.


If you really need to make the groove all the way along the channel, then the rotary tool would probably still be the way to go. You'd want to make a jig to hold the tool and a table/fence to support the metal as you run it across the spinning blade. This would, in effect, be very similar to a table saw or router table. The table/fence would support & control the metal, while the clamped rotary tool would spin the cutting disk as you run it across the metal.

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  • Or, could a oscillating multi tool also work? The left right cutting motion could provide a more repeatable slot Commented Aug 24, 2023 at 13:55
  • @Davidjones depends how short you need each slot to be. An oscillating tool has a certain length across which the blade...oscillates. So even if your blade was zero mm wide, it'd create a slot maybe 5 mm wide. So if the smallest metal-cutting blade width you can get is 10 mm, you get a 5 mm slot. (IDK what the smallest blade is, just using a number.)
    – Huesmann
    Commented Aug 24, 2023 at 13:58
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    That might do the trick, however, as @Huesmann noted, you'll need to know the sweep of the cutter. The nice thing is that cheap oscillating tool blades are, well, cheap, so if you can't find one narrow enough, you can make one narrower by cutting/filing/grinding it to the desired width.
    – FreeMan
    Commented Aug 24, 2023 at 14:09
  • Additionally, @Davidjones, if you'll take the tour, you'll learn the proper way to say "thanks" around here.
    – FreeMan
    Commented Aug 24, 2023 at 14:09
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Your best bet for making these slots would probably be a Dremel (or similar) with a cutoff wheel.

Another option would be to simply punch the slots with a sheet metal punch. Not sure exactly what tool would be best.

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  • A sheet metal punch would be good but I think the pressure required would be hard to get from a hammer... maybe a vice could apply it Commented Aug 24, 2023 at 16:39
  • Depends how thick the metal is.
    – Huesmann
    Commented Aug 25, 2023 at 14:56

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