Hi,
Does anyone know where I can source the secret masonic screwdriver head that fits the ST60 instrument rear covers? Its not flat head or philips or any derivative I recognise. Not allen key either. Scoured the internet to no avail.
Many thanks,
Craig
If I recall correctly, they are Pozidriv.
Nick Caballero
Retired C36/375IA Mk II Technical Editor
If you can post a photo I'm sure we can help.
Steve
'96 36 mkII #1569 Waltzing Matilda Channel Islands, CA
Looks like good old fashioned philllips#1 to me. ST60 Tridata.
Hummina
1987 Catalina 36 MKI
#741
Bayfield, WI. Usually.
It is hard to tell by the photo but I believe Nick is correct it is a Pozidriv.
The Pozidriv (sometimes spelled incorrectly as "Pozidrive") is an improved version of the Phillips screw drive. Pozidriv was jointly patented by the Phillips Screw Company and American Screw Company. The name is thought[by whom?] to be a portmanteau of the words "positive" and "drive." Its advantage over Phillips drives is its decreased likelihood to cam out, which allows greater torque to be applied.[5][18][19][20] In ANSI standards, it is referred to as "Type IA."[21] It is very similar to, and essentially compatible with, the Supadriv screw drive.[22]
Pozidriv drive bits are often designated by the letters "PZ" plus a size code of 0, 1, 2, 3, 4 or 5 (by order of increasing size);[5] the numerical bit size codes do not necessarily correspond to nominal screw size numbers.
Attempting to use a Phillips screwdriver bit is likely to cause damage because the design difference between them is fairly significant even though at first glance they appear to be very similar.[5] A Phillips driver has an angle on the flanks, a pointed tip and rounded corners. The Pozidriv screwdrivers have straight sided flanks, a blunt tip and additional smaller ribs at 45° to the main slots.[5] The Pozidriv was designed specifically to allow much greater torque to be applied because of its more positive engagement.[5]
The Pozidriv screws are visually distinguishable from Phillips by a set of radial indentations (or "tick marks") set at 45° from the main cross recess on the head of the screw.[5] The manufacturing process for Pozidriv screwdriver bits is slightly more complex. The Phillips driver has four simple slots cut into it, whereas in the Pozidriv each slot is the result of two machining processes at right angles. The result of this is that the arms of the cross are parallel-sided with the Pozidriv, and tapered with the Phillips.[18]
The chief disadvantage of Pozidriv screws is that they are visually quite similar to Phillips; thus many people are unaware of the difference or do not own the correct drivers for them, and often use an incorrect screwdriver. This results in difficulty with removing the screw and damage to the recess or driver, often rendering any subsequent use of a correct screwdriver unsatisfactory. Phillips screwdrivers will loosely fit in and turn Pozidriv screws, but will cam out if enough torque is applied, potentially damaging the screw head or driver. Because the drive wings on a Pozidriv screwdriver are square edged, their fit in a Phillips screw head is even worse, so they are more likely to slip or tear out the screw head.[5]
'96 36 mkII #1569 Waltzing Matilda Channel Islands, CA
Pozidriv screws are usually identified by having four tick marks or indentations around the cross. If you see those tick marks, then you have a Pozidriv screw. Pozidriv is an improvement over Phillips. A Phillips screw driver will often work just fine as long as the screw is not too tight, which is what Pozidriv allows for - tighter screws.
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Another option is Bondhus tamper resistant wrenches. I forget if the fastener is a star shaped indent (Bondhus "Torx" style) or 6 flat side indents (Bondhus "Hex End" style).
Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B
The Bondhus wrenches will work with the Navpod enclosure. Didn't realize you were working on the actual Raymarine instrument. Sorry for the confusion
Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B
Thanks All,
I went sailing yesterday and realised that what I need is a wrench to access the back of the Navpod that happens to hold the ST60 instruments. A quick search founds some sources. Sorry for wasting your time.
Paul, you're exactly right - the pod has star shaped outers with an inner pin. Never encountered them before but then I'm getting used to that feeling!
Thanks all for your replies.
Regards from Dubai.
Craig