iso of these screws/ bolts

[McSalty]

Hi! These bolts come from the boarding/swimming ladder, (dont know the correct term in English) - they are strange.
The head is smaller than the nut (15mm versus 20mm)
The shaft is 30mm and its diameter is 8mm
The nuts have strange "grooves" for some "special tool" (?) to tighten them.
Unfortunately 8 are missing - so its either "replacing them all" or finding these thingies here. Any ideas where to look?

[Deadcat7382]

You might be better off replacing them all.

[GordMay]

Could they be a type of T-Nut?

➥ Stafast Fasteners - T-Nuts

➥ T - Nuts for Wood

[captain465]

Those are "security nuts"........obtainable from McMaster-Carr..the tool is also available there.

[Pau Hana Daz]

I'd check here: McMaster-Carr

[McSalty]

Originally Posted by DWJensen

I'd check here: McMaster-Carr

Thanks, did check, nothing remotely similar there, guess I will have to go with the advice to replace all of them.

[goboatingnow]

These are M8 Kinmar security bolts. popular in the UK. kinmar permanent security bolts and nuts

Dave

[David M]

The idea is they can only be tightened, unless you buy a special tool or cut or grind them off.

[delmarrey]

Get a closer picture and contact these guys. Spanner Nuts

or http://www.jwwinco.com/products/section11/din1804/

[McSalty]

Originally Posted by goboatingnow

These are M8 Kinmar security bolts. popular in the UK. kinmar permanent security bolts and nuts

Dave

Thanks Dave! Perfect! (almost) - them kinmar have 4 "grooves" and mine only 2 - but THAT I sure can live with.