How tomake threaded holes in metal?
RDL2004
Posts: 2,554
Hello,
I would like to be able to make threaded screw holes, mostly in aluminum, is this a difficult thing to do?
I have found that it takes a tool called a tap to make these threaded holes , but other information has been harder to find.
Most of my web searches have ended up with me learning more about using vertical mills than how to make screw holes.
What other equipment or tools are needed? The taps themselves do not seem too expensive.
I have a small drill press, a Proxxon TBM115, it's real small but can drill nice holes.
I would just like to be able to make holes with threads for the small screws like the 4-40 and 6-32 type.
Thanks for any info.
- Rick
I would like to be able to make threaded screw holes, mostly in aluminum, is this a difficult thing to do?
I have found that it takes a tool called a tap to make these threaded holes , but other information has been harder to find.
Most of my web searches have ended up with me learning more about using vertical mills than how to make screw holes.
What other equipment or tools are needed? The taps themselves do not seem too expensive.
I have a small drill press, a Proxxon TBM115, it's real small but can drill nice holes.
I would just like to be able to make holes with threads for the small screws like the 4-40 and 6-32 type.
Thanks for any info.
- Rick
Comments
You basicly drill the hole for the size you want in your case you use a .0888 drill then the 4-40 tap is used. You basiclly screw it in by hand there are handles for taps as well and they look like this http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXK377&P=M. After the hole is drilled use the tap which will cut the treads into the hole. YOu want to screw it in a couple of revolutions then you back it out. Doing this will get rid of the shavings that are created. If you attempt to go all the way with backing you could break the tap. This all deepens on how thick your piece is as well. Using some lubricant helps alot.
Paul
There are a couple ways for you to do this.
First is the drill and tap method, which is what you've started to find information on. The ohter way would be to use self tapping screws.
Starting with the drill and tap, you would first drill a tap hole. For 4-40 you would use a #43 drill (0.0890 Dia). For 6-32, a #36 drill (0.1065 Dia) is the nominal size (from my charts). Once you have the tap, they may have these (or slightly different) sizes on them as a suggestion.
Depending on how think the aluminum is, or how deep the threads are in a block of material, and for that matter what material, you may want to use slightly larger (by a "number size or two) drill. The deeper the threads, the harder it can be to do the tapping. When using the tap, you first trill the "tap drill" hole. If you're drilling into a block with a "blind hole" (not going all the way through), you need to drill about two diameters deeper than the depth of the the threads you are making. Next, put a little chamfer on the hole. If you don't have a chamfer or counter sink tool, you could also use a larger drill size. All you want to do is put an angle on the edge of the hole. Then you start threading the tap into the hole. When tapping by hand, you normally make about a half turn, then back the tap out about 3/4 turn. Then go back in and take about another half turn worth of cutting, and back out 3/4 turn (or more). Keep doing this until you cut the threads as deep as you need (or all the way through). Occasionally, you may want to back the tap all the way out, and clean out any chips from the hole and tap. If you find it too hard to turn the tap, you may want to try a slightly bigger tap drill. The above tap drill sizes and instructions are for thread cutting taps (the standard kind). There are also thread forming taps (they don't cut the threads, they move the metal around). These are probably not for the beginner, and will require different (and more accurate) tap holes than thread cutting taps. I only mention this so you don't buy a thread forming tap by accident. Thread forming taps are normally used in high volume machining.
The ohter way is to use a self tapping screw. These are machine screws that have a "tap" (or other mechanism) to make the threads themselves. Because there are different ways to make the threads (cutting vs. forming, and different types of cutting), each brand and size of screw will call for its own specific size hole. These hole sizes may also vary with the depth of the hole or thickness of material. Some of these screws may even drill their own holes in sheet metal, but that would require a power driver. Even by hand, the self tapping (or thread forming) screws can work well, especially in sheet metal or soft metals (like Aluminum). You just drill the hole as specificed by the manufacturer, and then you thread the screw into the hole. The screw makes the threads. You need to be careful with these screws, they don't always have "standard" thread sizes. Generally, you can get them in standard size threads (e.g. #6-32), and if you do get a standard size, you can usually replace the screws with a standard screw once the holes are initially threaded. In some cases this won't work, as the thread form (or shape of the "teeth" of the screw) may not be standard.
If you need more information, let us know.
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John R.
8 + 8 = 10
If you are just doing sheet aluminum then I have always drilled the hole with a hand drill, removed the drill bit and inserted the tap into the drill and ran it down the hole. Make sure you stop the drill before the end of the tap threads or it will strip out.
Like the other post says, do not use a drill press. A hand drill will move around a little giving less chance of the tap breaking.
This works like a charm and I have done it for the past 6 years on panels with up to 100 or so holes and up to a 10-32 tap. Using a tap holder and doing it by hand would take a long time...
Heli-coils are basically thread inserts. You drill a hole and then you put these little coils in the hole....the size of the screw will push the coil into the surrounding metal and hold it in.
They're not the greatest thing...but for small things they're handy.
The other thing I mentioned is a pemnut...or press-nut.
Basically it looks like flattened nut with little ridges on the top. There's a small lip that protudes from this 'ridged' side.
You drill a hole in your sheet of metal and then put the pemnut on the hole (I say on, because the pemnuts' ridge is slightly larger than the drilled hole....)...then you take a press and apply pressure and get the ridge to mash in to the hole and hold.
You have to use a drill press to make your holes, cuz if your hole is slightly larger than what you intended, the pemnut won't bite!
Both are for small mounting items. Good for fix things down on to a plate....I wouldn't hang things this way...but have seen it done.
(sorry for not including links....on a different computer that's not google-friendly)....
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Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Normally, Heli-coils are used to either repair stripped threads, or in soft metals (like Aluminum) where a harder surface is needed for wear or strength.
The heli-coils also normally go into a drilled and tapped hole. When you get the heli-coil, you also need to get a special tap to thread the hole for the heli-coil. These taps are special sizes so that once the hele-coil is inserted, the inside threads of the heli-coil end up at the correct size.
This is likely a significant overkill for what you're doing.
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John R.
8 + 8 = 10
I only used them once and it was 5 or so years ago and couldn't quite remember how we used them!
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Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Also, every hole I've ever tapped was done with a drill press. However, don't go runnin to the drill press yet. When I tap a hole I will always drill the hole with the drill press as usual, then I turn off the drill press, insert the tap into the drill press, UNPLUG THE DRILL PRESS, and disconnect the rubber belt at the top of the drill press. Then using hand power, I twist the spinle connected to the chuck, and use that method to tap my holes. This allows precision alignment with the tapped hole, without breaking the tap, or buggering up your workpiece.
Knight.
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If all you are doing is holding a cover on, tapping 6-32 or even 10-24 holes in 16 Ga Alluminum will work fine.· On the other hand, if you're trying to hold a power transformer in place on the same alluminum, no dice.
As long as we're in the process of learing about tapped holes, here are a couple guidlines:
For a "full strength" threaded hole (one where the screw would break before the threads strip), you need 1-1/2 times the diameter of thread length in steel.· Make sure this is "engaged" threads, not including the chamfer on the end of the screw, or any chamfer/countersink on the threaded hole.· For soft materials like Alluminum and Brass, usually, the 1-1/2 times will do, but a factor of 2X is better.· Keep in mind that "full strength" is probably stronger than you think.· A 1/4-20 SHCS has a tensile strength of over 6,000 pounds.
For "non load" applications (like holding on a cover), you can have effective use of threads with as few as 1-1/2 threads.· You can sometimes get by with fewer, but you are taking chances, and will limit the number of times you can "re-assemble" the threads.· Softer materials should have more threads if possible.
There are "tons" of reference materials available on the net, including engineering info sites, as well as hardware manufacturer's and distributor's sites.
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John R.
8 + 8 = 10
I would do what I did, and practice on a scrap piece to get the "feel" of how this works.
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Mike
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I was mainly thinking of·maybe making a case·by bolting panels to·rectangular aluminum rods, also things like·attaching transistors and voltage regulators to heatsinks.
Here is·where I got the idea.
http://www.briangt.com/gallery/cdpro2
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Mike
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2-fluted taps work better in aluminum than 4 fluted, or 3 fluted.· And, lubrication is highly recommended.
Chris I.
If you've ever seen a computer case made out of aluminum, you'll notice there are steel inserts at every tapped hole. There's a reason for this. I wouldn't recommend tapping aluminum to hold anything heavy..... Front Panels, transistors, small heatsinks, no problem.... if it's not in a high vibration area...
However, it was originally hard to tell what the original poster had intended to use the tapped holes for! Granted, a little bit of information is present with the fact that the original poster wanted to use a #4-40/#6-32 size screw, but it still isn't enough to know exactly.
I wouldn't want someone to expect a very thin sheet of aluminum, tapped hole could hold up a large transformer, only to find the transformer to fall and short cirtcuit a 120/240 Volt mains current.
Knight.
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-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-
This message transmitted with 100% recycled electrons.
-=-=-=-=-=-
Gravity doesn't exist. The Earth sucks.
-=-=-=-=-=-
Make a man a fire, and he will be warm for the night.
Light the man on fire, and he will be warm for the rest of his life.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-