Self tapping screws,
Printed From: Unofficial Allis
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Forum Name: Shops, Barns, Varmints, and Trucks
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=182201
Printed Date: 16 Jun 2025 at 7:27am
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Topic: Self tapping screws,
Posted By: DougG
Subject: Self tapping screws,
Date Posted: 01 Aug 2021 at 1:38pm
| This is a peeve of mine - how many do you have to try to get one to take hold ? Ive done all kinds , stainless , just reguluar supposed to be the latest and greatest- and will not even go thru 29 gauge metal- call the supplier, yeah keep track on all you cant use --- grrrrr aggrivating |
Replies:
Posted By: DMiller
Date Posted: 01 Aug 2021 at 2:03pm
| Hole has to be shank of screw diameter, cannot be too small or too large otherwise burns off screw threads or strips hole. |
Posted By: DougG
Date Posted: 01 Aug 2021 at 4:01pm
| But they are supposed to be self tapping! No pilot hole needed, says the paperwork in the box! |
Posted By: DMiller
Date Posted: 01 Aug 2021 at 4:20pm
| Self drilling heads? |
Posted By: Trawler II
Date Posted: 01 Aug 2021 at 4:20pm
| You must mean self drilling, as the name suggests they drill their own pilot hole. There are different grades of self drillers depending on gauge or thickness of metal. The difference is significant. TEK screws of one grade will drill and fasten light gauge sheet metal no problem. Try using the same grade on 1/8” -1/4” steel and they will snap. You may need to upgrade the screws you are trying to use, maybe check with Fastenal or another supplier. |
Posted By: jaybmiller
Date Posted: 01 Aug 2021 at 5:37pm
|
the biggest issue I have is seeing guys NOT letting up on the drill speed ,once the hole is made , and then spin 10,000 rpm, and destroy the metal. Usually see this when HVAC ducts are being 'secured'. Also ZERO need to use an impact to drive them. ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: DougG
Date Posted: 01 Aug 2021 at 6:02pm
| Yes self drilling is what I meant - they have the drill bit sides on the screw- the ones in this kit are just aggrivating! |
Posted By: FREEDGUY
Date Posted: 01 Aug 2021 at 7:26pm
Where did the term "self tapping" come from ? Even I've been corrected about them being "self drilling   after I called them "tappers" .
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Posted By: Ray54
Date Posted: 01 Aug 2021 at 8:35pm
From screws that make real threads in sheet metal. Use a search engine and look at what they show you can see the different type screws. The self drilling have flutes like a drill bit, the self tapping are pointed with thread starting in the point.  Some real information on the net if you look for it.Now my question for the world of auto building. There are pointed cap screws used in auto body panels. Generally the panel has square much like nut welded to the panel. Do those bolts cut the threads as they are screwed in or are there threads in the nut looking things. The point is a real help in putting things back when you don't have guys to hold panel in place as put screws in. As my mini search did not find any of those hex headed screws under self tapping.
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FREEDGUY wrote:Posted By: Jim.ME
Date Posted: 01 Aug 2021 at 8:52pm
| There are self tapping screws. 5/16-18 with T40 countersunk heads are commonly used to secure wood decks on trailers. Tips are tapered about like a tap and the first few tapered threads are the tap. Lay the deck board, drill through the deck board and cross member with a tap drill, then drive the screw. |
Posted By: Dusty MI
Date Posted: 02 Aug 2021 at 10:32am
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I've done furnace install work, have a sheet metal shop, make my own duct. I have/use self pursing screws, and self drilling screws for heaver sheet metal. Yes need to turn screw slow to keep from striping.
Piercing. ------------- 917 H, '48 G, '65 D-10 series III "Allis Express" |
Posted By: FREEDGUY
Date Posted: 02 Aug 2021 at 5:58pm
It's also been "my" experience that using a 1/4" impact driver is NOT the tool of choice for these types of fasteners
!! |
Posted By: WF owner
Date Posted: 03 Aug 2021 at 6:52am
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I find that, like almost everything, self tapping (or drilling or piercing) screws come in a variety of quality. I bought a variety pack from Harbor Freight, that I carry in our RV. It gives me a selection, but they aren't very good quality. The ones I used to get from Fastenal or Grainger for my work crew, were much better quality (drilled better, stripped less and broke off less). I (and my crew) used 1/4" impact drivers to install self drilling screws for years. I believe, as with any metal drill, that drilling them at a slower speed works much better. If you don't have a variable speed impact driver, you may not have that option, but, personally, I wouldn't buy an impact driver that isn't variable speed.
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Posted By: DiyDave
Date Posted: 03 Aug 2021 at 6:42pm
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Something in this thread reminded me of this old Buffett song: https://youtu.be/LL9O0B0gzZE" rel="nofollow - https://youtu.be/LL9O0B0gzZE
------------- Source: Babylon Bee. Sponsored by BRAWNDO, its got what you need! |
Posted By: HD6GTOM
Date Posted: 03 Aug 2021 at 9:51pm
| I bought some at H.F. years ago. Any more I get them from our local hardware store. They arn't that much more expensive but sure are better quality |