Sheet Metal Screws 3

[BoltNutWasher]

Hello,

Does any one have the following to share.

1. Hole sizes for different sheet metal screw sizes
2. Till what material thickness can we consider fastening with a sheet metal screw.

Any good reference material or a website is appreciated.

NBW

 

[jte]

http://www.lmgtfy.com/?q=sheet+metal+screw+pilot+hole+

http://www.lmgtfy.com/?q=minimum+sheet+metal+thickness+tapping

 

[tr1ntx]

Check out McMaster's website. They have a lot of little info bits like that. You often have to go all the way through the selection process down to length, but then the product info will contain stuff like that. I know it will give you hole size. On some items, there is a product selection guide page that would tell you info like what size screw for given material thicknesses.

 

[tr1ntx]

mcmaster page 3010, there's a chart which shows hole size for various tapping screws, the sheet metal screw row is down toward the bottom

The max material thickness suitable for sheet metal screws depends on the load the screw will see, among other things. Just geometry-wise, the combined layer thickness needs to be ~65% max of screw pitch. So for a 12 pitch screw:

0.0833 in. X 0.65 = ~0.054 in. max thickness, combined, for however many layers you're joining

So you see, you're question is very application-specific.

 

[BoltNutWasher]

tr1ntx,

That's very informative information. Thanks for sharing it here.

May be I did not search hard enough, But I could not find the Pitch information for a Sheet metal screw. It may depended on Type again; But I could not find it.

Thanks
BNW

 

[tr1ntx]

BoltNutWasher,

That chart on page 3010 on the McMaster site shows available pitches for each diameter.

 

[StrykerTECH]

If you are going to use a sheet-metal screw for fastening sheet metal together, I would highly recommend using a "tinnerman" as oppose to a plain pilot hole. This helps prevent gauling and cuts down stripping greatly.
This is especially valid in thin sheets.

StrykerTECH Engineering Staff

http://www.stryker-tech.com/

 

[BoltNutWasher]

tr1ntx,
You are right. It was sharing 2 rows & I was confused.
Thanks

 

[BoltNutWasher]

StrykerTECH,

Thats interesting. From what I could understand; this is clip-on part generally used closed to the edge of sheet metal. You are right, it sure would resist stripping.

I think they wouldn't require any pre-preparation on the sheet metal prior to install. It might require a large clearance hole.

What are your comments.

 

[MikeHalloran]

There is no such thing as "_a_" Tinnerman.

Tinnerman makes a bewildering array of clip-on fasteners that accept sheet metal screws, and another bewildering array of similar clip-ons that accept machine screws, and another bewildering array of fasteners that clip sheets to sheets with no male fastener at all.

The most common ones for sheet metal require a punched round hole and a nearby edge or rectangular hole for application of the "clip nut" itself.

See bewildering arrays starting here:

http://www.araymondtinnerman.com/en/products/families

Many of Tinnerman's products are specific to the auto industry, and may be available only by the ton.

For parts available in smaller quantities, start here:

http://www.mcmaster.com/#clip-on-nuts/=afmevl

Mike Halloran
Pembroke Pines, FL, USA

 

[StrykerTECH]

No such thing as a tinnerman? We use them all the time. It isn't a clip on. It is punched into the sheet steel, we have used them up to 16ga. first you pre-punch a pilot, then you punch a "tinnerman" <-- that is what we call them, as well as our tool vendor. It is essentially a punched in helical half sphere. Then we use #10 or #12 screws to assemble. We use phillips hex head screws sheet metal screws type A, 18-8 stainless. In my opinion, It is the best way to put an 18-8 stainless fastener in stainless steel. But we also use them for cold rolled as well.
so tinnerman <--- no, helical punch similar to a tinnerman product, but a whole lot cheaper and easier to work with. YES.
Sorry my jargon got the best of me.

StrykerTECH Engineering Staff

http://www.stryker-tech.com/

 

[StrykerTECH]

Oh it also cuts down on the number of varieties of fasteners you need to stock. We only have 3 main categories. From 20ga to 12 ga.

#10 Sheet metal screw Tri-lobe
#12 Sheet metal screw Tri-lobe
#10 Tap tite screw. (great for thicker sheet steel.)

We are in the midwest, sheet metal is what we do up here.


StrykerTECH Engineering Staff

http://www.stryker-tech.com/

 

[BoltNutWasher]

Hey guys thanks for discussing your thoughts.
So it appears that using a special punch to produce that shape might be better than simply using a simple hole.
StrykerTECH you mentioned using this even on a 12 GA sheet. That's very thick and can you please share the specs of the one such feature and the specs of the screw that goes on it.

 

[ajack1]

Another option is the “Dayton process” this is commonly used in white goods like microwaves, fridges etc.

 

[StrykerTECH]

We only use the punched in piece up to 16ga. I was commenting that we only have three main categories of fastners up to 12ga.
For 12ga we mainly use taptite tri-lobular sheet metal screws. Those things are rock solid, can't strip them and our self-threading.
When we really need holding power WITH removability we go with extrusions in the metal and tap-tite screws for lighter guages.

StrykerTECH Engineering Staff
Milwaukee, WI

http://www.stryker-tech.com/

 

[StrykerTECH]

ajack1 ! ! ! !

nice job,
That is the process we used. We have just been calling in tinnermans, since it resembles the end result.

"Dayton process"

Star for you.

StrykerTECH Engineering Staff
Milwaukee, WI

http://www.stryker-tech.com/