Cat door sensor jammed by steel (metal) enforced wall

SandWiz

May 21, 2026
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Hope this is the right forum for this!

Hi.
I have installed an electronic cat flap in the wall so my cat is the only cat that can enter from the outside.
However, the wall has a 2-3 mm steel (or other metal) enforcement that prevents the chip reader to function when it is installed. The cat flap works fine when not installed - even just 5 cm from the wall. Does anyone have an idea how I can shield the reader or otherwise get the chip reader to function?

I have tried to insulate the reader by putting tin foil around the entrance area on the cat door.
Is this caused by magnetism?

Attached are 2 images of the installment.

Thanks in advance :)
 

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crutschow

May 7, 2021
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The metal wall apparently acts as a shield that prevents the ready from functioning.
Where is the metal in relation to the mounting hole?

One way around that might be to enlarge the hole by 5cm on each side with a wood frame to mount the cat flap.
Is that feasible?
 
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SandWiz

May 21, 2026
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The metal wall apparently acts as a shield that prevents the ready from functioning.
Where is the metal in relation the the mounting hole?

One way around that might be to enlarge the hole by 5cm on each side with a wood frame to mount the cat flap.
Is that feasible?
The metal is on the entire front of the wall, and looks the same and has same thickness as the inner wall shown on the first photo. (Under the tape and yellow highlight)

Yes apparently it shields… but I guess your solution would make it work! I would rather see if there is another way though ☺️
But thanks a lot for the idea 👍
 

crutschow

May 7, 2021
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Not really...there is only a few cm that the front covers up
So what about adding wood trim to replace the removed metal?

What is the purpose of the metal wall?
 
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SandWiz

May 21, 2026
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I guess it s protection. Probably an insurance issue.
But the whole idea was to try and find out if it could be done without replacing the plate. We just got it installed 😊
 

Martaine2005

May 12, 2015
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The electronics are in the front, not the tunnel section you put foil over.
Also, adding foil is doing the same thing as the metal section.
I wonder what type of cat flap it is?.
When installed into the door, does the flap stay unlocked or locked?.
I ask because some have a magnet in the cats collar while others have the magnet in the flap itself.
Or is it a definitely a chip in the collar and reader in the flap?.
I used to install quite a few for a pet shop back in the early 90s. The ones with a chip in had a set of four red dip switches that you could change to alter the distance and sensitivity. The switches were behind a small access panel on the front mounting plate.
If yours has these, it may well work.
 

Martaine2005

May 12, 2015
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RFID!. Interesting.
You said it works about 50mm (5cm) away from the door.
I would first try a plastic barrier.
A half inch (1/2”) plastic around the opening to form a barrier.
This obviously means opening the hole by a further 1/2”.
 

SandWiz

May 21, 2026
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Yes, metal can effect radio waves of RFID. It can disrupt and de-tune the radio signal. Plastic will form a barrier.
When you say plastic, how could I do that?? Here are some photos of the hole and cat door - you can clearly see the metal front in the wall ...hard to grasp that just 1 mm thickness can do that much of a trick!
 

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Martaine2005

May 12, 2015
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The second to last photo and the last photo show the overall aperture. 1/2” plastic strips inside the aperture forming a barrier.
This means opening the aperture/hole a further 1/2” all round.
 

SandWiz

May 21, 2026
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The second to last photo and the last photo show the overall aperture. 1/2” plastic strips inside the aperture forming a barrier.
This means opening the aperture/hole a further 1/2” all round.
Hi again Martaine. I must say I don't fully understand what you are telling me.
- What type of plastic strips are you suggesting? (normal strips?)
- and do you mean for me to put them around the entire inner side?

(and are you sure that will work)

I really appreciate you taking time to answer and help!! :-D

Thanks a lot -
Cheers, Morten
 

crutschow

May 7, 2021
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The plastic is just to provide more space between the sensor and the metal wall.
It does nothing by itself otherwise to block the effects of the metal.
 
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