Catflap in steel door

[Chris Styles]

Okay, so I just drilled the hole at each corner of the square I need to cut out of my door to fit a capflap, only to find that the dman thing is made of steel... To be more precise, the outter skins of the door (inside and outside) are made from I'd say 1.5mm thich steel, with a filling of rigid (expanded?) foad in between.

I've bent a couple of hacksaw blades trying to cut out the square (using the hacksaw blade on it;s own like a regular woodworking saw) and I am now fairly sure that's not a go-er.

Will a jigsaw with the right blades (TC?) be upto the job, or will I need something more fancy. The missus is going to realise any moment now that we have 4 12mm holes in out back door, and no chance that the catflap is going to be fitted today ;-)

Cheers

Chris

[.]

yes. failing that use a gas axe.

[Ian Stirling]

A standard HSS blade will work just fine. Alternatives are to chain drill ~100 holes, seperated by 2-3mm, and snip with wiresnips.

[Matt]

If it's the type that use magnetic collars on the cats I reckon you ought to read the instructions carefully.

To keep the whole thing rigid while cutting out I'd drill through a couple of inches inside of your cutline and fasten the skins together with a few small bolts. Cutting with a padsaw using a wide (1/2" high) non-flexible hacksaw blade wouldn't take too long, you could bodge up a padsaw like handle with a wrapping of newspaper and gaffer tape. A metal cutting jigsaw blade would fly through in a few minutes (no need for TC)

[Rob Morley]

I'd use an angle grinder with a metal cutting wheel for the skin, then the hacksaw blade for the foam. You really need to reinforce the sides of the hole once it's cut - pop rivets and steel are probably best for that (assuming that the foam will stop you from welding).

[dennis]

That sounds like a good way to do some serious hand damage when the blade snaps. A flexible blade wont snap so is much safer.

[Chris Styles]

Yeah, the instructions make it quite clear about the magnets collars... but they are godawful things. The magnet is about 25mm long and about 12mm diameter... a big chunky for a petite cat...

Also had a bad experience with one of those a few years ago. Out cat came in late one night, and went and sat on top of the still warm 19" CRT monitor (which 8 years ago was an expensive piece of kit), with a really quite strong manget around his collar. Despite repeeated degaussing, the picture was never the same again :-(

[Dave Fawthrop]

|Okay, so I just drilled the hole at each corner of the square I need to cut |out of my door to fit a capflap, only to find that the dman thing is made of |steel... To be more precise, the outter skins of the door (inside and |outside) are made from I'd say 1.5mm thich steel, with a filling of rigid |(expanded?) foad in between. | |I've bent a couple of hacksaw blades trying to cut out the square (using the |hacksaw blade on it;s own like a regular woodworking saw) and I am now |fairly sure that's not a go-er. | |Will a jigsaw with the right blades (TC?) be upto the job, or will I need |something more fancy. The missus is going to realise any moment now that we |have 4 12mm holes in out back door, and no chance that the catflap is going |to be fitted today ;-)

A small Angle Grinder, wielded with care would do it.

[owdman]

I did one through the wall instead not to spoil the door. Hire a 6 inch core drill , would make a hole big enough for most cats or you could hack a square hole perhaps? Then build up the catflap part on the inside or outside.

cheers

Jacob

[Andrew Gabriel]

Jigsaw will work fine, with regular metal cutting blades. The blade will get hot enough to melt/burn the foam, and this might gunge up the blade, so I suggest you buy more than one.

Also, protect the door surface from the base of the jigsaw which will mark it if they are in direct contact, and you'll probably need some ear defenders.

[Rob Morley]

That often seems to be a better solution, but people tend to shy away from it.

[Chris Styles]

It is an option, and it did get approval from the missus. Sadly, there is no convenient place to put it through the wall. Besides, I figure it'd be easier to repair/replace the door than to repair/replace the wall!

Cheers Chris

[Colin Stamp]

As others have said, an HSS jigsaw blade will do it fine, but make absolutely sure it's either long enough to go right through the door even at the innermost end of it's travel, or short enough to never get to the opposite skin. Otherwise you could end-up knocking a huge inverse dent into the opposite side of the door.

If it was me, I'd reach for the angle-grinder.

Cheers,

Colin.

[Chris Bacon]

Yes a jigsaw will do the job - you may be better off with a short blade so that you can cut out the inside and outside sections separately. What is TC? I haven't seen tungsten carbide jigsaw blades (except tile cuting type). HSS is fine - use slow speed, low pendulum, keep firm control so as not to let the thing jump, fine pitched teeth. Don't go at it fast or the blade will get hot. A drop of oil smeared on the surface may or may not be worthwhile.

[Peter Parry]

I've done a couple in steel doors and a standard metal cutting blade in a jigsaw works fine. It's only fairly thin mild steel in the doors.

[Rob Morley]

Depends on the wall. If it's brick outside just carefully remove the bricks and save them, then repair is a matter of mixing some mortar and sticking them back in. Inside, patching a small area of plaster is easy, invisible repairs to wallpaper less so. In those sort of cases repair cost and effort is fairly minimal. But without a suitable location that's moot anyway.

[Matt]

Flexible blades are useless for cutting when not under tension. Rigid blades are really the only way to cut safely using a blade that is unsupported or restrained only over part of its length.

50 layers of newspaper triple wrapped and covering the end of the blade followed by half a dozen layers of gaffa tape is not going anywhere. I'd use either a proper padsaw or a jigsaw but building up a handle for a one off job out of available household materials can give just as safe a solution. It's just two 1.5mm skins of steel FFS!

Oh and despite the hype flexible blades can snap too.

[Rob Morley]

So cut on the pull and tension is applied.

I find a bit of rag tightly wrapped works fine for occasional use, but I only use that sort of arrangement for cutting small components where access is a problem.