A Thread On Tapping

[AquariusPanta]

Hello everyone and welcome to a new thread.

I created this thread in the hopes that others, without prior experience, will further their expertise in LED/COB crafting. Until recently, I was using zip-ties to hold down COBs but now, with a little data gathering, am incorporating screws into the equation. A big advancement in my setup to say the least.

Part of this thread is dedicated to @stardustsailor, while the rest goes out to the bunch of you out there. Without all of you, this wouldn't be as enjoyable. As for Sailor, he has continuously shared his designs, techniques, and passion for this art - something only a select few of us here on RIU can offer.

 

[AquariusPanta]

I'll share some photos of what I've recently been working on and offer some insight on my method.

I encourage any of you to post photos and the details of your procedures, as there surely cannot be just one right way.

 

[AquariusPanta]

I decided using 4-40 rather than M2.5-3.0 screws, as the tools for them were easily accessible and affordable.




I then practiced tapping by hand on a random square tube. I tried both the prescribed #43 and a 5/32 drill bit, the latter being slighlty thicker in diameter.

The former drill bit proved more desirable, as there was less wiggle room despite the rougher tapping process.



After deciding to spin with the #43, I went ahead and lined up my Vero 18 upon my Arctic Alpine 11 Plus and made marks for incision. Notice how I made use of the Kapton tape.



With just the marks and the COB off to the side, I finally drilled a hole to proper depth and cautiously tapped. When it came to the screw, I inserted it without the cob first then after with the COB.



I do recommend applying some form of lubricant where applicable.

 

[churchhaze]

Are you using a center punch? That will make it much easier to drill the holes in the right place.

As a quick dirty trick for that, I actually use a hammer and nail. I really do need to get a real center punch.

Also, what kind of lube are you using?

 

[churchhaze]

also, careful drilling with the vero in place. The aluminum strands tends to get stuck to the bit while drilling, and will draw scratchy circles on the heatsink if you're not careful (don't let them get long). You don't want those circles on the LES. No one likes scratched eggs!!

 

[Abiqua]

I hate to be a broken record, but I do not recommend that tap....at the very least people should try to use a bottoming tap, even if it is just a spiral point.....

these spiral tips aren't the greatest for blind holes and they push chips forward into your hole, which can cause binding and then breakage, something to keep in mind.

 

[captainmorgan]

I used a 5-40 tap with a #38 drill,I have a large fastener supply house near me with anything you can think of. With the Arctic 11 I drilled through the heatsink into the fins to avoid the blind hole. I used kerosene for drilling and tapping without a single problem so far.

This was for CXA3070's with Ideal holders.

 

[AquariusPanta]

@churchhaze

I edited one of the paragraphs above: I removed the COB from the HS during the drilling/tapping processes. Good point to make.

Also, I used this stuff that is similar to WD-40 for lube

@Abiqua


Haha yeah you've been warning us for sometime now about which taps which work best. However, I couldn't find the kind you were recommending so I went with what's above.

@captainmorgan

I use a hand drill - took aaround 15min to drill one hole and it was for a tiny screw. Going into the fin section sounds like a time consumer. Care to shed some insight on your approach?

 

[Abiqua]

@churchhaze

I edited one of the paragraphs above: I removed the COB from the HS during the drilling/tapping processes. Good point to make.

Also, I used this stuff that is similar to WD-40 for lube

@Abiqua


Haha yeah you've been warning us for sometime now about which taps which work best. However, I couldn't find the kind you were recommending so I went with what's above.

@captainmorgan

I use a hand drill - took aaround 15min to drill one hole and it was for a tiny screw. Going into the fin section sounds like a time consumer. Care to shed some insight on your approach?

These are the two types I recommend, @ballist used the roll taps, which I have looked and heard Balax was the most desirable

4/40 Roll Tap Ebay Search [aka roll form, thread form, roll tap]
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.X4/40 roll tap&_nkw=4/40 roll tap&_sacat=0

4/40 Spiral flute bottoming [Ebay Search]
http://www.ebay.com/sch/i.html?_odkw=4/40 roll tap&_from=R40&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.X4/40 spiral flute bottoming tap&_nkw=4/40 spiral flute bottoming tap&_sacat=0

 

[Abiqua]

 

[Abiqua]

 

[captainmorgan]

I had a few years experience in machine shops in my younger days and with tapping alignment is very important and that's why a drill press makes things much easier. I got one of these,they go on sale quite often.

http://www.harborfreight.com/8-in-bench-mount-drill-press-5-speed-60238.html

You also want to countersink or chamfer the hole before tapping. While tapping,especially with small taps after you have gone deep enough to be cutting full threads (taps are tapered at the end) you need to back the tap out slightly to break the material the tap is removing into smaller pieces rather than long ones (helps keep the tap from jambing or breaking),one full turn or so in then back to break the material and repeat. Blind holes with a bottom are more work and if they are shallow you may need to remove the tap and blow out the hole with air to remove the debris then tap deeper,they also have special taps for tapping the very bottom of the hole if needed. Different materials need different lube,kerosene for aluminum and a special wax for copper work best but you can use other things.

 

[Abiqua]

Some ways [tools] to make tapping easier:

[Thread]Tapping blocks .............not to be confused with flooring which also uses a "tapping block"

Drill guides

also referred to as drill guides:

Tap and Reamer combo for straight drilling:

Drill stands for tapping:

Hand tapper:

 

[Abiqua]

I had a few years experience in machine shops in my younger days and with tapping alignment is very important and that's why a drill press makes things much easier. I got one of these,they go on sale quite often.

http://www.harborfreight.com/8-in-bench-mount-drill-press-5-speed-60238.html

You also want to countersink or chamfer the hole before tapping. While tapping,especially with small taps after you have gone deep enough to be cutting full threads (taps are tapered at the end) you need to back the tap out slightly to break the material the tap is removing into smaller pieces rather than long ones (helps keep the tap from jambing or breaking),one full turn or so in then back to break the material and repeat. Blind holes with a bottom are more work and if they are shallow you may need to remove the tap and blow out the hole with air to remove the debris then tap deeper,they also have special taps for tapping the very bottom of the hole if needed. Different materials need different lube,kerosene for aluminum and a special wax for copper work best but you can use other things.

I would like to add that a ratio works well for cutting taps.....1 to 1.5 turns, then stopping and and reversing .5 to 1 full turn in reverse and blowing chips out.

Can't stress enough about removing chips from the hole! #1 cause of tap breakage, another reason that bottoming taps should be used and not just any "ole" like the spiral point's that are way too common....

Also these rules apply mainly only to Cutting taps...roll form's don't seem to be nearly as finicky [ they don't cut, so no chips, faster speeds, harder formed threads]

 

[captainmorgan]

Great work Abiqua,that about covers it.

 

[bicit]

P.S. Thread forming taps avoid the whole 'chipping' problem since they don't create any. They simplify and speed up the whole tapping process significantly. They cost a little more, and you need a bigger hole than traditional taps. However they're well worth it IMO, especially for the inexperienced. For working with aluminum I recommend using a bright finish, with no flutes. They can be had for $10-20 each on ebay or amazon and should last for thousands of holes assuming proper tapping procedures are followed.

 

[AquariusPanta]

A few helpful sites for anyone interested in tapping:

https://www.boltdepot.com/fastener-information/us-tap-drill-size.aspx

http://www.gearhob.com/eng/design/drill_eng.htm

http://www.custompartnet.com/tap-size-chart

 

[alesh]

Out of a few hundreds screws into aluminum I've done so far, I've never tapped a hole. I use 2.5mm drill bit and M3 screws. Not saying it's better or something, I'm just lazy and this works well enough.

 

[bondoman]

Out of a few hundreds screws into aluminum I've done so far, I've never tapped a hole. I use 2.5mm drill bit and M3 screws. Not saying it's better or something, I'm just lazy and this works well enough.

yeah I really don't think it's a huge issue for aluminum, being how soft it is. If the screw you're using is stronger than aluminum it will most likely dig into it.

 

[AquariusPanta]

Out of a few hundreds screws into aluminum I've done so far, I've never tapped a hole. I use 2.5mm drill bit and M3 screws. Not saying it's better or something, I'm just lazy and this works well enough.

Are the screws you've been using self-tapping, meaning the threads are angled and sharp?

I considered a similar approach but wanted to test out my mechanical abilities with the tap wrench. Drilling the hole takes a long time for me, while the tapping process is much quicker.

Looks like the Kapton tape will be getting benched for future COB mounting; the stuff I have is no good with EZ PicoMate cords.