Metric tapping screw

[Maerin]

I'm planning to R&R my stainless rub rail to re-bed it and correct any loose fasteners. I've discovered that the tapping screws attaching the rail are metric. Best I can determine they are 5.5M x 65. If I convert them to a #12 screw that is the closest match, the head will stand proud of the rail enough to grab any surface I rub against (rarely occurs ) and perhaps could even pull a screw sideways or otherwise create damage. There are 46 screws per side, so modifying the countersink isn't practical, not under consideration. If that's not enough, I believe I really should use 316 SS with the constant exposure to seawater. I'm striking out on locating metric tapping screws in 316.

Any suggestions WRT sourcing the hardware? Dimensions on the attached.

 

[Cigatoo]

Did you try Aquidneck Fasteners?

Home - AQUIDNECK FASTENERS, INC.

 

[AusCan]

They could be a metric metric screw.

By the looks of your drawing, they appear to be a 82 degree countersunk head which is commonly found on metric screws.

The most common imperial countersunk screws have a 90 degree head but small head screws can be 60 degrees. Keep this in mind when shopping around.

Do you have a very small protractor to measure the screws?

 

[Maerin]

They could be a metric metric screw.

By the looks of your drawing, they appear to be a 82 degree countersunk head which is commonly found on metric screws.

The most common imperial countersunk screws have a 90 degree head but small head screws can be 60 degrees. Keep this in mind when shopping around.

Do you have a very small protractor to measure the screws?

Thanks! I'm not sure about the angle, the drawing isn't an exact representation of the actual screw, it's just a key for the dimensions. The head does appear to be 90 deg, the countersink hole does seem to neatly fit the square corner of a scale.



I did a test fit of a #10 screw, it finishes just shy of flush, probably not a bad thing for the rub rail, and with all the screws the same, would not be an aesthetic problem. I plan to fill holes with thickened epoxy, might as well do them all, then the #10 screws will fit fine. I'd likely be the only person who would notice...