Forum Discussion

jerryspoolman's avatar
jerryspoolman
Explorer
Jul 15, 2018

Stainless Steel Screw Standards

I purchased a large quantity of #8 stainless steel screws from BOLT DEPOT, to replace screws in my 14 year old
5th wheel. Most of the original screws had severe rust problems. Even screws that were covered with plastic trim, the heads were
OK, but the tips had rusted down past the threads.
When I tried to use the screws, I had terrible results with the heads stripping out and 1 just snapped. I had only used 5 screws, then
I realized that it would be foolish to replace approximately 300 screws with junk.

The new stainless steel screws could be picked up with a magnet.

Having had good luck with Graingers on other products; I decided I would check their web site. The following is a sample of 2 screws they offer:

Stainless Steel Tapping Sheet Metal Screw
with Pan Head Type and Plain Finish
$23.55 pkg of 50


Stainless Steel Tapping Sheet Metal Screw
with Pan Head Type and Plain Finish
$14.05 pkg of 100

The first screw is priced at $.47 per screw, while the second screw is priced at $.14 per screw.. The Descriptions are identical and there are others
priced between those two. How can I determine which screw is the proper value?

Any advise would be helpful
  • RJsfishin's avatar
    RJsfishin
    Explorer
    Jul 15, 2018
    All I know is that the seemingly good quality ss screws I've used from the local HDW stores, do not stick to a magnet.

    Having said that, they also are not as strong as a regular steel
    screw of the same size.
  • ktmrfs's avatar
    ktmrfs
    Explorer II
    Jul 15, 2018
    1) there are a large number of types of stainless steel
    2) not all stainless steel types are non magnetic. If it is not magnetic it is stainless, brass, aluminum etc. If it is magnetic it can either be stainless or "regular" steel.
    3) the degree of rust resistance depends on the type. It is "stain less" not "stain free" many exhaust systems are stainless but will develop surface rust. just won't rust through in a lifetime.
    4) the grades of stainless that are most rust resistance often are not as strong as regular steel hardware. In fact some are pretty brittle.

    to determine how stain free it is and how strong you need to know the grade of stainless and then look up that grade to see what it's properties are.
  • gbopp's avatar
    gbopp
    Explorer
    Jul 15, 2018
    My advice would be to check a sheet metal forum online or, contact a sheet metal shop.
    They could probably advise you where to buy good screws.
    I agree, it would be foolish to replace the factory screws with junk.
  • 2_many_2's avatar
    2_many_2
    Explorer III
    Jul 15, 2018
    Stainless screws are pretty soft, rated somewhat like a Grade 2 in hardness.

    You are most likely getting 18-8 stainless that is "rust resistant" and if they are made in China they are even more prone to rust. 316 stainless is more resistant, you might try that type, that is all I will buy if available.

    I buy all my fasteners from McMaster-Carr The choices are endless and the quality is the best I have found.

    Another thing that is nice at McMaster is you will probably get the choice of a Robertson Square drive that is less prone to stripping.

    Good luck
  • time2roll's avatar
    time2roll
    Nomad
    Jul 15, 2018
    Stripped head? Phillips or Robertson drive? I would take the square drive any day.

    And set the torque limit a bit lower on the drill to keep the heads on.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jul 15, 2018
    There are many grades of Stainless.
    Some are ferromagnetic (Picked up by a magnet) others not.
  • mike-s's avatar
    mike-s
    Explorer
    Jul 15, 2018
    Don't expect stainless sheet metal screws to thread their way through steel of any thickness. They're simply not as strong as steel screws. Make sure you get the right size (are you perhaps replacing #6 with #8?), and when installing them, use a hand screwdriver and go CCW until you feel the "click" where the screw drops into thread, and only then go forward so you're following the existing threads and not trying to create new ones.
  • Almot's avatar
    Almot
    Explorer III
    Jul 15, 2018
    McMaster Carr can be more expensive than Granger, but they have any possible fasteners, plenty of detailed info on SS grades and quality is usually good.

    Most commonly used are two SS grades: 18-8 and 316, both are mildly magnetic. There is also 410.

    In the end, I found a local fasteners store with prices half of McMaster and acceptable quality. Now I do my research at Mcmaster first, find out what exists out there, and then go to my local store, prepared.

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