I’m having a heckuva time connecting galvanized steel round ductwork. I have 1/2” self-tapping sheet metal screws. They don’t go in too easy but after they penetrate the outer duct, the screw just pushes in the inner duct. I have done a few DIY ductwork jobs over the years and never ran into this. Maybe I am just getting old or maybe these Hilllman screws from Lowe’s ****. Any tips? Thanks a lot.
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Ductwork Fasteners
- Thread starter artbuc
- Start date
yes, the screws need a real sharp point. not general purpose screws
matt_i
Well-known member
I just drilled a pilot, forgot the size but envision the minor diameter of the screw. But it was no problem to zip them in with a nutdriver after that.
Leaflessshadetree
Well-known member
You could try self drilling screws.
You could try self drilling screws.
Is there a difference between self tapping and self drilling?
Sounds like the screws are the issue. I like the Malco screws that Home Depot sells, they seem to have a sharper point and are the same brand sold by the local HVAC supply house.
I’ll get them, thx.
I just drilled a pilot, forgot the size but envision the minor diameter of the screw. But it was no problem to zip them in with a nutdriver after that.
Pilot is ok for one or two, but not practical for a larger job.
It tends to be a problem when drilling through one piece of metal into another. You could try drill point screws (instead of Zip-in pointy styles) but if you still have problems, time to punch holes through the outer metal and let the threads gripping the inner metal pull the connection tight.
Zip-in style: https://www.malcoproducts.com/product/zip-in-self-piercing-sheet-metal-screw/
Drill point or Bit-tip style: https://www.malcoproducts.com/category/sheet-metal-screws/bit-tip-drill-and-tap-screws/
Zip-in style: https://www.malcoproducts.com/product/zip-in-self-piercing-sheet-metal-screw/
Drill point or Bit-tip style: https://www.malcoproducts.com/category/sheet-metal-screws/bit-tip-drill-and-tap-screws/
metaldad
Well-known member
mr. bonneyman is correct
Angry welder
Well-known member
I did duct work for years and know all about the problem your having. One, if your placing the screws to close to the edge it wont matter what screws you use they will probably never catch. Second, the faster you can spin the screws the better off you are. Also, for any round pipe duct work use (these screws are also used for attaching hanger strap to anything wood and for screwing hanger strap together around something like bar joist or around the duct pipe)
https://www.malcoproducts.com/product/zip-in-self-piercing-sheet-metal-screw/
If your are using square duct - S and Drive duct, TDX, TDC or anything else then use screws like.
https://www.malcoproducts.com/category/sheet-metal-screws/bit-tip-drill-and-tap-screws/
https://www.malcoproducts.com/product/zip-in-self-piercing-sheet-metal-screw/
If your are using square duct - S and Drive duct, TDX, TDC or anything else then use screws like.
https://www.malcoproducts.com/category/sheet-metal-screws/bit-tip-drill-and-tap-screws/
I did duct work for years and know all about the problem your having. One, if your placing the screws to close to the edge it wont matter what screws you use they will probably never catch. Second, the faster you can spin the screws the better off you are. Also, for any round pipe duct work use (these screws are also used for attaching hanger strap to anything wood and for screwing hanger strap together around something like bar joist or around the duct pipe)
https://www.malcoproducts.com/product/zip-in-self-piercing-sheet-metal-screw/
If your are using square duct - S and Drive duct, TDX, TDC or anything else then use screws like.
https://www.malcoproducts.com/category/sheet-metal-screws/bit-tip-drill-and-tap-screws/
Thx...getting the Malco zips today. I was slowing my drill to allow the screw to tap the inner duct. Guess I was just making it worse. I remember on my last project the screws zipped in pretty easy. Almost for sure I have crapper screws. Or, as suggested, maybe these Hillman self tappers are not designed for galvanized steel.
For thin metal you want a self piercing screw not a self tapping screw.
Local yard carries a brand called Zip Screws come in 100 packs in small boxes like panel nails. Point so sharp they will cut you if you dont pay attention. Work great
Local yard carries a brand called Zip Screws come in 100 packs in small boxes like panel nails. Point so sharp they will cut you if you dont pay attention. Work great