Question about counter-sinking fasteners into sheet steel

[Howard]

Let's say I have a sheet of 16 gauge steel, and I want to put countersunk machine screws through it (Philips head or whatever). Because it's so thin, I'm thinking you can't countersink like you do with wood.

Is this feasible?

Drill hole through steel for fastener
Drill same size hole through pine or other soft wood
Fit fastener through steel and wood
Apply LOTS of torque to the head and nut

Will the steel deform satisfactorily (to fit the contour of the head), the fastener system fail, or neither?

 

[Howard]

How about 18 gauge?

If a "normal" screw was used with the same shape head... the torque capacity should be higher, because the force is distributed over all the thread area, not just one section.

 

[Colt45]

how big are the machine screws

 

[Howard]

The shank should be just under 1/4". Not sure about the head...

 

[Ornery]

How flush do you want it to end up? With precise countersink depth, it can be done, but there won't be much meat to hold anything. Key is the precise depth.

You certainly can deform the sheet to make it flush, but that risks distorting a larger area of the panel. It would require a better die than wood.

 

[Howard]

Well, the forces the fasteners will have to endure will be VERY low - less than 5 lbs in any direction, I'd say. I'd use some sort of epoxy for steel, but the joint can't be permanent.

Plus, there'll be 4 machine screws.

With precise countersink depth, it can be done

I'm not sure I understand?

 

[Howard]

Maybe I could take a big nail and pound it on the holes a few times...

 

[Ornery]

Precise means, if you countersink it to a diameter of .477", it will sit flush, but if you go to .512", it will pull through. You got a nice drill press?

Here's the dimensions...

 

[Howard]

That's the problem, I'm not sure how to countersink it.

 

[TitanDiddly]

Use undercut flat head screws- 70% of the head depth of normal flatheads.
McMaster.com page 2876

 

[Howard]

Thanks for the info.

 

[TechnoKid]

they have finishing washers you could use for your purpose, instead of having to countersink the thin metal sheet, unless you want the screw head flat/level with the surface.


edit: illustration on this page

 

[QuitBanningMe]

You use a dimpling tool or countersink. You find them (and fasteners) at aviation tool suppliers.

Edit: or other sheet metal industry suppliers.

 

[Howard]

Originally posted by: TechnoKid
they have finishing washers you could use for your purpose, instead of having to countersink the thin metal sheet, unless you want the screw head flat/level with the surface.


edit: illustration on this page

Yeah, I'm putting some artwork on top of the sheet so the surface has to be completely flat - rather, there can't be any protrusions.

Originally posted by: QuitBanningMe
You use a dimpling tool or countersink. You find them (and fasteners) at aviation tool suppliers.

Edit: or other sheet metal industry suppliers.

Thanks! I think this is what I'm looking for.

EDIT: They're not as cheap as I thought.

 

[TitanDiddly]

Originally posted by: Howard

Originally posted by: TechnoKid
they have finishing washers you could use for your purpose, instead of having to countersink the thin metal sheet, unless you want the screw head flat/level with the surface.


edit: illustration on this page

Yeah, I'm putting some artwork on top of the sheet so the surface has to be completely flat - rather, there can't be any protrusions.

Originally posted by: QuitBanningMe
You use a dimpling tool or countersink. You find them (and fasteners) at aviation tool suppliers.

Edit: or other sheet metal industry suppliers.

Thanks! I think this is what I'm looking for.

EDIT: They're not as cheap as I thought.

How about $9 for 3?

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=45620

Use coolant(WD-40, or actual cutting fluid) when using them with steel and harder materials.

 

[Ornery]

I think he's referring to the dimpling tool. Only $10.00 for that MS-DT1.

 

[Howard]

Originally posted by: Ornery
I think he's referring to the dimpling tool. Only $10.00 for that MS-DT1.

I was looking at that list and my eyes somehow saw $20.