Solution found

[Limey Linda]

The semi-removable section of my deck is secured with 40+ #10 stainless
self tapping c'sk screws. The holes have minor hairline cracks around them and look really bad. Went searching for some finish washers in SS to cover up the cracks etc. and spread the load on the fiberglass.
Found this page:
http://www.aircraftspruce.com/menus/ha/washers.html

Scrol down. I chose the flat ones. Price is Ok and service is excellent. 50 washers for $7.40 inc. shipping. They have lot's of other good stuff.

[codprawn]

Excellent - very useful for my next project!!!

[martini]

I like the CSK finishing washers, I've only been able to find them in brass until now!

[ian parkes]

Seller: boltmeup (9031)
Shop: stainlessbolts

Try here on ebay , they seem to have the lot .

i think nylon washers under stainless washers would be the way to go

[Limey Linda]

Originally Posted by martini

I like the CSK finishing washers, I've only been able to find them in brass until now!

I was thinking of you when I posted as you have the same problem as me but much bigger. I have never seen them before, but they are much lower profile than the beveled ones.

[ian parkes]

Not trying to tell you how because i haven't seen the problem ,
but surely anything countersunk will make the cracks worse as it pulls into the hole

[Limey Linda]

Originally Posted by ian parkes

Not trying to tell you how because i haven't seen the problem ,
but surely anything countersunk will make the cracks worse as it pulls into the hole

Yes, exactly. The cracks are caused by the radial stress caused when the screw is tightened. The plan is to open out the C'sink slightly, add blob of silicone, and washer, so all the stress is axial.

[ian parkes]

proper job

[pathalla]

Originally Posted by Limey Linda

Yes, exactly. The cracks are caused by the radial stress caused when the screw is tightened. The plan is to open out the C'sink slightly, add blob of silicone, and washer, so all the stress is axial.

Hey Limey, when you set the screws use 3 M 5200. It's gooey and messy to work with but that stuff will grip and hold the screws in MUCH better than conventional silicone. What's more you'll still be able to take them out with a screw gun or screwdriver, that stuff (5200) makes em a hell of a lot more vibration proof. Believe it.
Great Info for all the ribbers on Aircraft Spruce, I used to buy aircraft fittings for fuel and oil lines from them back in the day when I was restoring Nortons and Triumphs and had forgotten completely about them, thanks for that update, I'll be using them for a few things I have planned.

Just so all you ribbers know, not many two wheeled vehicles are prettier than a nice Bonneville or Commando, just my opinion, I have owned a few...

[Limey Linda]

Originally Posted by pathalla

Hey Limey, when you set the screws use 3 M 5200. It's gooey and messy to work with but that stuff will grip and hold the screws in MUCH better than conventional silicone. What's more you'll still be able to take them out with a screw gun or screwdriver, that stuff (5200) makes em a hell of a lot more vibration proof. Believe it.
Great Info for all the ribbers on Aircraft Spruce, I used to buy aircraft fittings for fuel and oil lines from them back in the day when I was restoring Nortons and Triumphs and had forgotten completely about them, thanks for that update, I'll be using them for a few things I have planned.

Hi Pat,
Will do on the 5200, thanks for the tip. It seems we have too much in common: that may be worrying! My last Triumph restoration was a 1961 TR6.
Sold it 10+ years ago and wish I had not.
BTW, I have only been to Cleveland once to attend a seminar at Lincoln. I used to work for David Lincoln.