Thread Forming

[Big B Sprint88]

I have a particular progect that i need to have 0-80 threads .125 deep and the max depth of the tap drill hole is .145. I have never tried threadfrorming and was wondering if anyone has any experiance with this. I am leaning to this opperation because thredforming leaves no chips to fill the bottom of my tap hole?? Any ideas??

[Rekd™]

I use form threads exclusively, (Unless the customer specifies NOT to. *cough, Remec, cough*)

 

Aside from no chips, (which you can get with high spiral taps that pull the chips OUT of the hole,) form taps, a.k.a. roll taps, are stronger and give a better, stronger thread in most materials.

 

I've had great luck with them, (luck? err, um... superior skill and cunning, yeah. That's it).

 

'Rekd

[specv]

We use form taps all the time, on stainless and aluminum, what material are you working on? and what info would you like?

[chris m]

We roll threads all day, every day, in a variety of materials and sizes. The smallest we've done that I know of is #2-56. The depth to dia ratio of your hole seems OK so I don't think you'd have a problem as long as your material isn't a real bear.

 

If you are doing aluminum or something you'd probably be OK with a YMW, Greenfield, or some other 'generic' tap. If you are doing stainless or a tougher steel I strongly recommend OSG Exotap NRT taps; we tap 100s of holes in heat-treated stainless unattended using only coolant with these taps (its the 'NRT' part you need to remember, these are different taps than the regular 'ExoTIN' taps you usually see).

 

C

[KCollins]

I've had no experience with these...How are the speed rates? Can you form a tapped hole quicker than cut it with a standard tap? Are there any issues with wall thickness around the tapped hole, such as a alum casting, and possibly deforming, or cracking the casting?

[Big B Sprint88]

I am only working with 6061 alum. so the material issue should not be a problem. I will give it a try and let everyone know what happened in a day or so. thanks

[MetalMarvels]

Thread forming is my choice for 6061 aluminum and 360 brass. I have done several thousands of 0-80 blind holes with a VegaRoll tap made by VegaTaps (making a couple of miniature antenna models for a customer). I did find out that cast aluminum plate (tooling plate) will grab the roll tap and break it - had to go to a spiral flute cut tap in aluminum tooling plate. The other thing I found with the small taps is to start the thread above the material about 0.100 - almost no breakage when I did that.

 

[Harryman]

Tap drill diameter becomes a huge deal when forming very small holes; hole too big, no threads, hole too small, broken tap.

 

My notes show #54 drill for 0-80 form tap. Material 304 stainless. Use same for 6061.

 

Form tapping is the way to go on this project!

[MACHINEMASTERG]

like they say in the shop hear rockem sockem and rollem

[specv]

quote:

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like they say in the shop hear rockem sockem and rollem

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I dont think they are talking about taps...lol

[MACHINEMASTERG]

and hear i thought that funny smell was the tapping fluid misting up the shop?????/

[Surface]

quote:

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Tap drill diameter becomes a huge deal when forming very small holes; hole too big, no threads, hole too small, broken tap.

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I've used plenty of roll-taps, but have noticed that after roll-tapping a hole drilled to the correct tap-drill size, often the hole will not close to the "conventional" tap-drill size.

This doesn't seem to matter wether the hole is 0-80 or 1/2-13.

It's not that the customer needs more or less thread, just that they have over-zealous inspectors.

[chris m]

Most wall charts for tap drills (for roll taps) are for 65% thread which will often not get your minor diameter down far enough to be in spec. I always use the tap manf recommended smallest tap drill if I'm concerned about minor diameters; most of the time it works out.

 

Nobody ever pins tapped holes to check minor diameter anyway...

 

I hope

 

 

C

 

[ 07-22-2003, 12:50 PM: Message edited by: chris m ]

[bhyde]

Nobody pins minor diameter holes????? Wow! I have not had to for quite some time, but at the previous job, couldnt get away with a tapped hole out of "spec". This inspector acted like some of these parts wouldnt survive if the minor was out by .002. (this would also be the inspector that would make you ruin a purty, fresh aluminum machine job with SCOTCH BRITE taken to the WHOLE part!!!!

 

BAHHHHHH!...Machine finish beats scotch brite anyday!

[A-ron1286490684]

As it was explained to me rolled or formed threads are stronger regardless of the larger minor diameter simply because the act of forming is akin to forging: aligning material at the molecular level. Another beauty of the threadfloers is that the geometry at the bottom lends itself to getting REAL close to the actual predrill cone tip. We would use the threadfloers with the vent groove up the side for deep hole applications when slamming right up to the predrill depth was required. Since the hole is almost airtight as the tap goes in the vent groove lets coolant/tap fluid and air escape before breaking a tap. I’ve even muffed on the depth and had the tap “dimple” the bottom of my holes and still go all day. They are awsome.

 

EDIT:After re-reading this thread I have to agree with Gary W. I've seen the thread ID's on cast material come out looking pretty nasty when roll tapped. I would also reccomend cutting taps for cast material.

 

[ 07-22-2003, 03:48 PM: Message edited by: A-ron ]

[Guest CNC Apps Guy 1]

quote:

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...the inspector that would make you ruin a purty, fresh aluminum machine job with SCOTCH BRITE taken to the WHOLE part!!!!

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This guy should be taken out back, Center Drilled, Drilled, Bored, Reamed, and Shot! I soooooo dig freshly machined aluminum.

[Chris Rizzo]

quote:

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EDIT:After re-reading this thread I have to agree with Gary W. I've seen the thread ID's on cast material come out looking pretty nasty when roll tapped. I would also reccomend cutting taps for cast material.

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Ah ha! So I'm not crazy!! (Well, at least as far as this is concerned.) I've only done a bit of thread forming, some of which was in cast tooling plate. Needless to say I was un-impressed, and went back to traditional spiral-flute cutting taps. I'm glad to hear that it was the material causing my problems, and not necessarily the process.

[Big B Sprint88]

Thanks for all your help. I ren the parts last night and it worked great. Only ran the tap at 800 rpm because it seemed if I ran faster thatn that the spindle spent more time slowing down and reversing than it did taping the whopping .125 depth.