Rahz
Well-Known Member
Thought the topic might merit it's own thread. @Positivity might have some things to ad.
I started out lubricating with propylene glycol (e-cig juice). Better than nothing. I've tried WD-40 which is claimed to be great for aluminum. Works okay. The best household product is probably cooking oil. If you want to get serious with it buy some thread cutting oil at the hardware store. It's called thread cutting oil for a reason.
Since we're working with aluminum we don't need the absolute hardest tap material. High speed steel is perfect for aluminum and more durable than the high carbon versions.
The cutting edge is just the tapered part of the tip. The rest of the spiral is just a guide to keep things straight. This is worth considering when choosing a tap since it comes in 3 versions, tapered, plug and bottoming. The tapered tap offers the largest cutting edge while the bottoming tap has a much smaller cutting surface. A bottoming tap is useful when working in shallow material when the hole doesn't go all the way through. It allows you to get threads all the way to the bottom of the pilot hole. The plug is in-between. Unless there are special needs always choose the tapered version since it's larger cutting edge will keep it in shape longer, as well as make it easier to start the tap straight.
With the right tap and oil it's possible to go straight through a proper size pilot hole without ever backing out. I was down to about 15 seconds per hole with 20 turns each, eventually broke the bit. I was getting sloppy and putting uneven pressure on the handle. You can do everything right and still break a bit by putting sideways pressure on it.
I have some interest in using a drill. I suspect in a professional capacity tapping is done with specialized milling machines or drills that have coordination between the spin speed and plate/shaft movement. A drill press is unsuitable for this purpose. An electric hand drill can get the job done but it's difficult to keep the drill at a low enough speed to count the revolutions. If you're tapping straight through and don't need to count then this is a great option. I want to try a pneumatic drill since it's much easier to keep at low speed and count the revolutions, but it may be that the sudden force would be bad for the bit... and if the trigger is accidentally squeezed too hard the bit's probably a goner.
I started out lubricating with propylene glycol (e-cig juice). Better than nothing. I've tried WD-40 which is claimed to be great for aluminum. Works okay. The best household product is probably cooking oil. If you want to get serious with it buy some thread cutting oil at the hardware store. It's called thread cutting oil for a reason.
Since we're working with aluminum we don't need the absolute hardest tap material. High speed steel is perfect for aluminum and more durable than the high carbon versions.
The cutting edge is just the tapered part of the tip. The rest of the spiral is just a guide to keep things straight. This is worth considering when choosing a tap since it comes in 3 versions, tapered, plug and bottoming. The tapered tap offers the largest cutting edge while the bottoming tap has a much smaller cutting surface. A bottoming tap is useful when working in shallow material when the hole doesn't go all the way through. It allows you to get threads all the way to the bottom of the pilot hole. The plug is in-between. Unless there are special needs always choose the tapered version since it's larger cutting edge will keep it in shape longer, as well as make it easier to start the tap straight.
With the right tap and oil it's possible to go straight through a proper size pilot hole without ever backing out. I was down to about 15 seconds per hole with 20 turns each, eventually broke the bit. I was getting sloppy and putting uneven pressure on the handle. You can do everything right and still break a bit by putting sideways pressure on it.
I have some interest in using a drill. I suspect in a professional capacity tapping is done with specialized milling machines or drills that have coordination between the spin speed and plate/shaft movement. A drill press is unsuitable for this purpose. An electric hand drill can get the job done but it's difficult to keep the drill at a low enough speed to count the revolutions. If you're tapping straight through and don't need to count then this is a great option. I want to try a pneumatic drill since it's much easier to keep at low speed and count the revolutions, but it may be that the sudden force would be bad for the bit... and if the trigger is accidentally squeezed too hard the bit's probably a goner.
