No Luck Tapping

[12voltfun]

Well I have about no luck tapping aluminum plate! I rip the threads out of the top of the hole , and then its all down hill from there. Does any one have any advice?



BIGGER IS BETTER

[tom@vp]

Originally Posted by 12voltfun

Well I have about no luck tapping aluminum plate! I rip the threads out of the top of the hole , and then its all down hill from there. Does any one have any advice?



BIGGER IS BETTER

what size are you tapping, is it a roll tap or cut tap.

need correct drill size, start with one size smaller, then redrill with correct size drill, keep drill very straight or perpendicular to the work face.,

same with tapping, keep tap very straight, i dont what tools you have but if you can drill a hole in a block of wood or aluminum the size of the outter diameter of the tap do it, then use that for a tap guide.

[KBrog]

got oil?

[66bronco]

Make sure your tap is good and sharp, a dull tap just will not work.

[bob1961]

how thick alum plate 1/16" is tough but 1/8" should not be an issue......bob

....

[Seth]

X2, use cutting fluid!

[Dynamic Concepts]

Like others have stated, and a few other tips:

- Look up the proper tap drill size to use.
- Use a sharp tap that has a proper tapered lead-in, if it is a cut tap. A bottom tap does not have this feature, as it is used to tap to the bottom of a blind hole.
- With Aluminum, whenever possible, tap depth = 2 X bolt diameter.
- Use oil or cutting fluid.
- 6061-T6 Aluminum can be either cut or form tapped.
- Some Aluminum stock, such as Type 300 or ATP, should only be cut tapped.
- Make a tap guide, to ensure the tap stays square with the hole you are tapping.

[billybob_81067]

Use diesel fuel or kerosene as cutting fluid for aluminum. It will keep the aluminum from sticking to the tap.

[sumquak]

some taps are just junk. a mill guy told me once OSG brand taps are the best and i won't use anything else other than an occasional Balax brand. you can get them at machine shop tool supply stores like MSC, Western Tool, or maybe McMaster Carr. they are not cheap but i have tapped hundreds of holes with one tap many times. get a tap handle to turn it.

as far as cutting oil, WD-40 is the best cutting oil for aluminum, the only thing it's good for, imo. i have some O'Donnel o-lube laying around and found it works great also. a simple tapping block with a hole the size of the tap shank will help guide it straight into the hole and metric taps up to 3mm and SAE up to #6 all have the same shank so one hole does many different sizes. hope this helps

[scorpion ax-10]

viagra. heh just kidding, the previous posts covered it i just threw my 2 cents in there

[SMR 510RR]

Yea, lots of good stuff in here. Tap block is a must but make sure that your hole is straight first, cutting taps will cut at the angle you set them at regardless of where the hole is at, it will get harder and harder as you go down if the two dont match up. I would only recommend tapping a hole that is drilled on a drill press or mill unless you use some kind of drill bushing (Like the jeepin doug one for links) or unless you are tapping plastic.

For the average person hand tapping aluminum I would recommended a High Speed Steel tap, small carbide taps are just too brittle and will end up breaking if you put any side load on them, some of the super small ones will break just from the load of the tap handle if you arent careful.

The material "ripping" as it was described in the first post is a tell tale sign that your tap is dull. If one tooth is chipped it will screw the whole process up since on a taper tap each tooth cuts a little more than the last one. What ends up happening is that material is formed rather than cut and then you get a bulge out the top of the part because that material has to go somewhere.

I also like WD-40 for tapping aluminum, I prefer it from tapping oils because they tend to be a little too sticky and then your gullets get packed with chips and now you are dragging all the old chips through your nice tapped hole.

If you are tapping a blind hole I recommend a spiral gun tap, they pull the chips out of the hole like a drill so you wont have to stop all the time and blow the chips out.

And of course, get your taps from a machine tool supply place if you can. They are everywhere and you can usually just drop by and grab a tap and whatever else you need. Usually the people there are knowledgeable so if you have questions on what to use they will be able to help you choose the right tools.

One last thing, when tapping other materials you have to take the material into account. If you are tapping plastic use a ton of WD-40 to keep the temps down or your thread will be hairy and dull. If you are tapping a harder material like stainless steel you will need to over drill the hole.

My favorite tap drill chart:
http://www.physics.ncsu.edu/pearl/Tap_Drill_Chart.html

Notice it has two columns, one for 75% engagement and one for 50% engagement, it also lists the materials that fit within each category. It may not seem like much but lets say a 4-40 tap, 75% is .089 where 50% is .096...Trust me, it makes a huge difference.

Good luck and have fun tapping that hole

[TexasSP]

One little note I didn't see addressed. If you are tapping it with a drill instead of your hand don't. Always hand tap aluminum for smaller holes. It's always best when drilling the hole to be tapped to be on a flat level surface and secure the part to it. A drill press is your best bet but a hand drill works fine, just take your time and be patient.

when you tap, turn a little, then back off a little. Aluminum can gum up a tap fairly easily and needs to be cleaned out frequently when tapping. (some grades gum up worse than others). For cutting oil I use a product called Tap Magic which works very well.

[Crawling Calvin]

Tried chamfering the start of the hole slightly. I have found #1 it is SO much easier to tap and the threads come out cleaner. Even a small bevel is nice since it helps the tap line up better and makes using the hole easier with a screw by lining them up.

Cheap taps are hit and miss. I have had good results with Interstate taps from Enco but they are cheap and one I got was no good so I had to toss it out. But for $3 you can't grumble to much... right . Nothing beats my Greenfield gun-point TiN coated M4x.7 tap for CNC work, its amazing and makes awesome threads every time

[12voltfun]

Thanks everyone for your help. I have been using a drill press to drill with(3 and 4mm) and taping by hand with a crapy T handle. so i am on the look for some better stuff and to make a tap guide(great idea) .
I am tapping the 1/4" side of the alum. plate , 3mm mostly

thanks

[sim]

Since you have a drill press, see if this is possible. Is there a hole on the back of your hand tap? You could put a drill bit in there and hold that with the drill chuck. Makes a nice guide while you turn the tap.

[SMR 510RR]

Originally Posted by 12voltfun

Thanks everyone for your help. I have been using a drill press to drill with(3 and 4mm) and taping by hand with a crapy T handle. so i am on the look for some better stuff and to make a tap guide(great idea) .
I am tapping the 1/4" side of the alum. plate , 3mm mostly

thanks

Your using the correct drill right? Should be a 2.5mm or #39 drill.

[M1tch]

as you are using a drill press, either do as has been suggested and use a drill bit, or centre bit to hold the tap square, or if you dont have that, put the tap in the chuck and turn it by hand until the thread is in a few turns

i always use lube... would that be a good sig line

[Duuuuuuuude]

Originally Posted by TexasSP

If you are tapping it with a drill instead of your hand don't.

I tap everything with a cordless drill. Plastic, aluminum, steel, everything.

The key is lube, slow speed, using a drill with a brake when you let off the trigger, and keen senses.

Once you figure out the subtleties, you won't mess up threads or break taps. I haven't broken a tap in 3 years.

[TexasSP]

Originally Posted by Duuuuuuuude

I tap everything with a cordless drill. Plastic, aluminum, steel, everything.

The key is lube, slow speed, using a drill with a brake when you let off the trigger, and keen senses.

Once you figure out the subtleties, you won't mess up threads or break taps. I haven't broken a tap in 3 years.

Don't disagree, I was just directing it more to the inexperienced.

[vw_thing]

Originally Posted by TexasSP

Don't disagree, I was just directing it more to the inexperienced.

Yeah, tapping small holes (<6-32) with a hand-held drill or a press takes a huge amount of practice. I for one don't exactly have the required "surgeon's hands" while hefting a drill, no matter how light it is.

I'm definitely going to have to give some of y'alls ideas a try. I've played around enough to know what not to do, now it's time to learn what to do.

One other observation, which Dynamic Concepts mentioned, is that aluminum needs extra material to keep its strength, and cannot take a high torque load. Al bolts under 6-32 will snap heads, steel bolts will strip the Al threads. Consider switching to steel or maybe using threaded inserts if you need the extra thread holding capacity.