[dalianharley]

hi,

is there such a thing? tap for self tapping screws. the part i posted earlier will fit with a plastic piece that we source elsewhere. it came with 3 self tapping screws. if we can tap the alum part with self tap threads then we don't need to source regular m3 screws.

thanks

Daz

[SCzEngrgGroup]

Self-tapping screws don't require tapped holes. That's the whole point....

Regards,
Ray L.

[dalianharley]

That's what I tried. I drilled 2.8mm holes for the little screw, but the screw snapped after 2 threads.
oh well guess we do need to source those tiny bitty screws...

thanks

Self-tapping screws don't require tapped holes. That's the whole point....

Regards,
Ray L.

[SCzEngrgGroup]

Is 2.8mm the hole size specified for that screw? Self-tapping screws do not require the same size hole as a tap. You need to consult the screw manufacturer, or experiment on your own to find the correct hole size. Obviously, if the screw snapped, the hole was too small.

Regards,
Ray L.

[johnedward]

self tapping screws are commonly meant for sheet metal or soft material like wood or plastic, use a machine screw for a thick metal part.

[SCzEngrgGroup]

self tapping screws are meant for sheet metal or soft material like wood or plastic, use a machine screw for a thick metal part.

Not true. There are many different kinds of self-tapping screws, many of which are explicitly designed to be used in thick materials, including metals. They will cut or form threads as they are driven in.

Just one of countless examples: http://www.itpbolt.com/products/scre...te-thdroll.pdf

Regards,
Ray L.

[johnedward]

i'd hazard a guess that the screws the op has are not the specialized ones you searched for and are the typical ones that i mentioned which are most commonly meant for sheet metal so my advice stands, use a machine screw.

[SCzEngrgGroup]

i'd hazard a guess that the screws the op has are not the specialized ones you searched for and are the typical ones that i mentioned which are most commonly meant for sheet metal so my advice stands, use a machine screw.

I realize you will always pi$$ on ANY post I make, but please try, for once, to actually READ my post before pi$$ing on it. As I clearly said, there are MANY different styles of self-tapping screws, suitable for virtually ANY material, and virtually any application. They are categorically NOT just for sheet metal - that is, in fact, what SHEET METAL SCREWS are for! I clearly indicated what I linked to was but "one of countless examples". There are many different styles that CUT threads and many others that FORM threads, and many, if not most, are designed for use in other than sheet metal. Do a little Googling, and you will see I am correct. Unless you are psychic, you have no clue what type of screws he has on-hand.

Regards,
Ray L.

[johnedward]

fyi i was giving advice to the op since it's HIS thread, far as i know you aren't the only one allowed to do that. search for self tapping screws and you will find many common uses are for sheetmetal just like i said. if the screws he's using snapped after just a couple turns again i hazard a guess ( doesn't mean i'm psychic) they aren't meant for thick metal.

[SCzEngrgGroup]

fyi i was giving advice to the op since it's HIS thread, far as i know you aren't the only one allowed to do that. search for self tapping screws and you will find many common uses are for sheetmetal just like i said. if the screws he's using snapped after just a couple turns again i hazard a guess ( doesn't mean i'm psychic) they aren't meant for thick metal.

So this:

"...self tapping screws are commonly meant for sheet metal or soft material like wood or plastic..."

becomes this:

"...search for self tapping screws and you will find many common uses are for sheetmetal..."

Surely even you don't believe those two statements are equivalent?

"...if the screws he's using snapped after just a couple turns again i hazard a guess ( doesn't mean i'm psychic) they aren't meant for thick metal...."

Hmmm.... I once broke a 3/8" bolt going into a metal part. I guess 3/8" bolts also aren't made for thick metal. Or, perhaps (and, I think MUCH more likely in this case...) perhaps the screw was just fine, and the hole was just drilled too frickin' small....

Regards,
Ray L.

[johnedward]

dalian, if you get past the ranting above here's another thought, do the parts you are attaching need to be removable? if not you could rivet them on easy as pie.

[Don Clement]

I realize you will always pi$$ on ANY post I make

Ray L.

" I'll need some information first.
Just the basic facts."

Perhaps on the Novocaine list list responses to your posts are more subdued.


Roger Waters + David Gilmour: Comfortably Numb, Live, O2 Arena 2011 - YouTube

[dalianharley]

John,

it'd be permanent. it works like a buckle clipon. i'm attaching the cnc part to a plastic clipon buckle with 3 screws - or rivets. the plastic already has 3 existing holes as we sourced them. it was meant to be attached to another plastic part with 3 self tapping screws and now we're replacing the top end w/ the machined alum part.
it'd be some very pecial rivets though, the existing holes are 3mm and the other part will have blind holes.

dalian, if you get past the ranting above here's another thought, do the parts you are attaching need to be removable? if not you could rivet them on easy as pie.

[johnedward]

i was thinking 3mm pop rivets in a length you need, for example...20Pcs Dome Head Sealed Type 3mm Diameter Blind Rivet - Collated Screws - Amazon.com these are way longer than you need i bet but you can find them shorter and much cheaper in bulk.

[Al_The_Man]

Unless already mentioned, there are self tapping self drilling, with a drill tip end to the screw.
Usually need a pilot, but it ensure the right size hole.
Al.

[NetblindPaul]

I've never used a pilot with those sort of screws and use them a LOT, but, never in CNC machines, always in hand held drill/drivers.

[Hirudin]

Why do you want to use self tapping screws in the first place? I ask because sourcing M3 screws is an easy proposition. They're less than 15¢ each.

[johnedward]

Why do you want to use self tapping screws in the first place? I ask because sourcing M3 screws is an easy proposition. They're less than 15¢ each.

from what i've read the self tapping screws come with the plastic part he is attaching to his machined part but the screws were meant for attaching to another plastic part i hazard.