Hi /diy/
I have to put a couple of M5 threaded holes into a ~1 cm thick aluminium block by hand. Should I cut the thread or should I go with roll form tapping?
Is roll form tapping doable by hand at all?
I have a press drill to stabilize the tap but I will apply the torque by hand.
The highest priority is to avoid breaking the tap, the strength of the thread is secondary.
Thanks!
>>1006195
Given that you don't care about thread strength and it's not a very deep hole, there's no reason to really prefer either in your case. You should be able to form tap with a thread that small in a material as soft as aluminum.
You'd REALLY have to be trying (or be using a really shitty tool) to break a tap in aluminum. Assuming you're using tapping fluid, anyway.
>>1006198
Thanks, I'm planning to use WD-40.
>>1006195
rolled threads are mechanically stronger, but the taps would require more torque for forming the threads. I wouldn't recommend applying torque by hand in this instant. Try placing the tap in a mill, drill press chuck, or tapping jig/station and use a wrench/key/lever to rotate the tap thus preventing you from bending the tap sideways.
t. machinist.
>>1006195
Rolled threads are very nice but ultimately a luxury for most things. Particularly in aluminium where the fastener is typically harder than the ali - therefore I wouldn't bother.
I only spec formed threads on steel studs and and so on that are going to be used frequently and are safety-critical.
A thread thread!
>>1006195
Depending on how many you need to make, there are "one shot" drill/taps..
Rolled thread in an application not needing it is a bit of a wasted effort.
>>1006207
While better than nothing, definitely not what you want. WD-40 doesn't do well in extreme pressure environments.
Just use a standard tap and some motor/machine oil. Nothing in this operation needs overthinking.
>>1006195
First off--"roll forming" is not a description for taps, at all. Roll forming is a tool that does what a die does--it puts threads on the *outside* of a piece of metal stock by pinching it in-between three grooved metal rollers.
Pic related: the Hozan bicycle spoke threading tool is an example of a roll forming tool... Bicycle and motorcycle spoke threads are usually roll-formed. If you look closely at a bicycle spoke you can see that the threads stick out farther than the round sides of the spoke. The groove of the thread is pushed inward for half the thread depth, and the displaced metal stretches outward for the other half of the thread depth. If you cut them with a die, they won't expand to the proper height and will not be nearly as strong.
I don't own any forming taps for two reasons:
1--the correct hole size is far more critical to get good results, and-
2--the two places I usually buy taps, forming taps cost roughly 3 - 5X what spiral-point taps the same size cost.
Where I shop--forming taps also aren't available in as wide of size ranges and thread fits as spiral-point taps are.
>>1006261
>"one shot" drill/taps..
which are not very good
forming taps like said, require accurate tap drill sizes, and good torque to form
considering your priorities
>to avoid breakage
your material
>aluminium
thickness
probably 9.5mm
tools
>drill press
and the fact that you dont need to use a form tap, and the fact that you are asking us if you should
all tell me that you should just cut the threads
and you will not even benefit from the main reason to form tap, which is
>no chips
dont bother making things more complicated
if you cant hold a tight spec on the hole, dont bother
>>1006198
>You'd REALLY have to be trying (or be using a really shitty tool) to break a tap in aluminum. Assuming you're using tapping fluid, anyway.
Tapping aluminum with a brand new tap and a lot of patience can still turn into a disaster. The logic that aluminum is soft therefore easy to tap is the opposite. Aluminum tends to be prone to galling which can lead to a gummed up tap which can break or rip all your threads out. And good luck getting a broken tap out of aluminum. Using a spiral flute tap can reduce the chance of chips getting gummed up but I have found they tend to like to break. Just go slow, making sure to blow out chips.
Also pic related. Warning: Once you use this stuff you will never want to use anything else.
>>1006255
Hehehehehe
>>1006195
Get a good cutting fluid bro. I cut a lot of black pipe for natural gas lines in homes. Cutting fluid is important bro.
Throw on a few drops of 3-in-1 before you spray with WD-40 for some real over-kill lubrication. You'll be fine.
By the way, if your tool breaks, you need a better tool. If you're careful, properly lubricate, and have a good tap and die set, you'll be just fine.
>>1006195
Just cut the thread with your tap. 1/4 turn in, back the chips out. Rinse, Lather, Repeat. An M5 tap probably has a 1.25 mm thread pitch, so you're looking at maybe 32 repetitions per hole, which still isn't bad. Once you've got the tap started and running true, you'd be hard-pressed to screw it up by hand.
Like the others said, just make sure you use cutting fluid. WD-40 can work, but it's not like Tap Magic is expensive.
I have broken 1 tap 1 time, and that was a 3/8"-16 that I was using on a CT rotor. And it broke because I tried to do too much too quickly. It's hard to break a tap if you're patient.
>>1006360
Back when I was slaved to my dad in his garage, cutting oil I'd often use was gear/diff oil- lot of viscosity, very good under higher pressures too, so its a good substitute as well.
You might try ATF fluid as well but its got some slightly different properties.
aluminium has its own specific cutting fluid that prevents guming up of the tool, its the green shit A9
>>1006367
>An M5 tap probably has
0.8 thread pitch
also only poor people need to chip break
me n ma blueband machine gun taps blastin ass through alu all day
I'm also going to be doing some tapping in the near future. I've never tapped my own threads before. I need to tap some M5 threads into a piece of sheet steel, with some type of added support material on the back side(either strips of aluminum, or ABS plastic). It shouldn't be more than 1/8in thick either way, and I plan to hand torque the tap.
I'm curious how important tapping fluid is, and what sort of general purpose lube you guys might suggest for the job. I don't plan to buy something JUST to use for tapping,
>>1006442
Any cutting oil is better than no cutting oil. I'd use 3 in 1 oil before I used nothing. Do you change your own motor oil? You could use that. Hell, I'd try olive oil before I used nothing. Why the backer though, anon?
I have used wax (boelube which is probably cost prohibitive) on aluminium with great success. Best tap fluid is moly-dee hands fucking down, but also very expensive. Douglas.
>>1006456
>Do you change your own motor oil? You could use that.
Right now thyis second, I have 10W-40, and maybe one or two other motor oils in my garage. I also have WD40, white lithium grease, and graphite powder. I have plenty of options for lube, but I just don't know what type would work best.
>Why the backer though, anon?
My plan is to build a custom PC case from scratch. I really don't trust the sheet metal alone to support the full weight of all the hardware without adding some stress to the cards. I figure the backing strips would cost me 15 bucks at the most, so the added support is worth it.
>>1006482
I worked with a fellow machinist that swore by using lard to tap aluminum with. It was as cheap and relatively available being that I live in Alabama. It also had the added benefit of making the shop smell like bacon if the part needed any welding afterwards.
>>1006524
ANY kind of clean lubricating or motor oil is better than nothing. You want to avoid any evaporating stuff, but anything else is good.
I have some Castrol moly-dee "real" tapping fluid but don't use it unless I'm working with a harder steel. The damn bottle nozzle drips all over and runs down the side of the bottle.
I usually use way oil, because that's the nearest oilcan around.
Also stop buying hand taps, they are an unnecessary bother to use.
Get spiral-point taps instead, from a machinist supply place.
They eject the chips forward so you don't need to back up at all to clear chips (assuming the hole goes all the way through). For this reason they have smaller flute cuts in them, and they are much stronger than hand taps.
If it is a blind hole, you just turn the tap in until you hear the chips crunching a bit, then back it out, pick out those chips, and run it in again.
Spiral-point taps are usually plug taper, so they're still pretty easy to start by hand as long as you make the correct-size starting hole.
Plus (at enco) the spiral-point taps are usually cheaper than the hand taps.
And how about tapping a really soft metal like copper? I read people used form taps there.
