Security screws

[Dellquay13]

Does anyone know the name for these anti tamper screws please?
I need to open my very elderly autohelm ah800 analogue, to see why it has started stuttering instead of running smoothly.
TIA
Chris

 

[Poignard]

I wondered if it might be Torx but it's difficult to see.

Looks like somebody has had a good tamper with it already!

 

[wallacebob]

My AH800 has 8 simple Phillips screws, it may be a bodge? Doesn’t look like any security bit I have, but maybe a very butchered Torx Pin. Good luck………

 

[Dellquay13]

I wondered if it might be Torx but it's difficult to see.

Looks like somebody has had a good tamper with it already!

Thanks, but it's not torx, it is round and castle-ated but not sure how it is spelled, castellated? Crenellated? Raised rounded bits like the top of a castle, a bit like a nut on a trailer wheel bearing. Not a good picture because it is tiny

 

[Dellquay13]

6 raised and slightly rounded pizza slices...

 

[Poignard]

Thanks, but it's not torx, it is round and castle-ated but not sure how it is spelled, castellated? Crenellated? Raised rounded bits like the top of a castle, a bit like a nut on a trailer wheel bearing. Not a good picture because it is tiny

This help?

 

[Dellquay13]

 

[dankilb]

‘Bristol’ looks closest to me…

 

[Dellquay13]

This help?
View attachment 126459

it's looking a bit Bristol fashion, but a little bit wrong on the relative dimensions of pizza slices to centre pin...

 

[dankilb]

Will a small pair of needle nose pliers not grab them? Guess depends a) how many? And b) how tight?

 

[dankilb]

Or a dab of thickened epoxy under a small hex machine screw/bolt?

 

[DanTribe]

This help?
View attachment 126459

This help?
View attachment 126459

That's a handy chart, I shall pinch that, thanks.
A Bristol pattern looks the closest. I can now legitimately say "get yer Bristols out"

 

[Dellquay13]

Will a small pair of needle nose pliers not grab them? Guess depends a) how many? And b) how tight?

i don't think so, some are deep set in recesses, a couple quite corroded, years of butchering screws with the wrong tool have made me look for the right tool this time

 

[Dellquay13]

https://upgradedhome.com/wp-content/uploads/2021/05/bristol.jpg

This picture of a bristol screw has the flukes inset instead of raised

 

[Wing Mark]

A left handed drill bit is good for most of these things.

 

[Poignard]

Cut a slot, use a screwdriver?

 

[Blueboatman]

Cut a slot, use a screwdriver?

My thoughts too
A Dremel and a fair bit of patience , then replace with something a bit more friendly ..

 

[snowbird30ds]

I've filed a slot in the tip of a flat screwdriver to undo similar in the past as long as they're not too tight.
Looks like some sort of torqueseal to pick out first.

 

[Dellquay13]

My thoughts too
A Dremel and a fair bit of patience , then replace with something a bit more friendly ..

Some are recessed about 18mm down narrow access tubes, i did think about drilling them on a pillar drill then using stud extractors, but its tiny work, i don't have the above tools, and my past experience is a litany of disasters, compared to hopefully just identifying and buying a £7 bit from an online supplier

 

[captainboo]

Looks a bit like this but don't know about sizing:-

Cemobile Gamebit Screwdriver 4.5mm 3.8mm, Double-End Bit Security Gamebit Screwdriver Kit for Opening NES, SNES, N64, Gameboy, Gamecube, Virtual Boy, Sega, Nintendo Consoles, Game Cartridges : Amazon.co.uk: DIY & Tools