can I use a circular saw to cut a channel

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Gary111

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Hi, I need to cut a 10mm wide channel in a few fire doors to fit smoke and heat seals.

Ive been struggling to find a router under £50, which is a bit much, Ive got an old circular saw, I was wondering if I can get a good result by running it up and down a few times.

I guess the channel has to be quite flat as the seals are self adhesive.

Failing that is there a way of using a drill with a router bit ?

Alternatively I can get seals that dont need routing, cost around £39, Im a bit skeptical tyat they will stay on though.

thanks
 
Door seals need a slot of the proper width and depth, otherwise they won't seal anything.

An 'old circular saw' will rip a shredded untidy mess into the side of the door. You will then need to buy a new door.
A drill is far too slow for any router bit and doesn't have any way to guide it in any dimension. It would be exceptionally dangerous to even attempt it.

There are two choices - get the proper tools or pay someone who has the proper tools.
 
Gary111 said:
Ive got an old circular saw, I was wondering if I can get a good result by running it up and down a few times.
Click to expand...

I’ve used a good, new circular saw to make slots. It might work, if you’re lucky and careful. Find something to practice on first.
 
I'm with flameport - DON'T attempt this job with a circular saw unless you have a decent saw and are very proficient in its' use, and even then I doubt that the end result would be good enough. Any pro will tell you that a router with an intumescent groove cutter is the fastest, most accurate, easiest, safest and least stressful way to do the job. Running a circular saw down the edge of a door to space two exactly 4mm deep grooves exactly 15mm apart isn't something I'd not want to do, at least not willingly. Google "Wealden tool" and look for their intumescent cutters ( e.g T5841) then beg, borrow or even hire a router for the day....

Bear in mind that for an intumescent seal to stay put the groove needs to be a snug fit with a regular, flat bottom (without which the self adhesive tape on the strip won't adhere very long). Additionally the groove is supposed to prevent fire (and is often a statutory requirement) and that in order to do that properly it needs to be installed in the correct width and correct depth groove. Note that 10mm seals are only supposed to be used on older doors, or as part of a dual door/dual strip install (e.g on an electrical riser door) - the current norm is for a 15mm wide intumescent strip

The plant on seals i've seen (mostly Intergraf) are really designed for use in retrofitting doors in places like listed buildings (where the doors cannot be replaced) and are generally installed in conjunction with the door being refinished in an intumescent lacquer or paint. My experience is that they aren"t too long lived on doors subject to high traffic
 
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You didn't mention how to set out for that though
 
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