i've never tried spiral fluted ones before. Ive had to tap 1.25" BSP in a steam loco boiler once, you shoulda seen the size of the tap wrench!! was a pain trying to keep it straight to, as it had to be done freehand and was less than an inch deep. That was still straight fluted, but the big boss man there was a bit of an old fuddy duddy and completely unnaccepting of new fangled things such as that.
Shall we give some details of tapping techniques as this is supposed to be educational, ill get my tuppence in first
drill the tapping size hole according to datasheets, or a little smaller than the core diameter of the thread (can be roughly measured by measuring the inside diameter of a corresponding nut, or again consulting thread data tables)
remove all swarf from the hole, and do not deburr the edge of the drilled hole, as this makes it a little easier to get the tap to make that initial 'bite', and start drawing itself in, though this only really counts for larger sizes of tap (1/2" and above from my experience, also doesn't help that we had to use prewar taps half the time)
start with a taper tap, in a tap wrench, and line up carefully with the hole, and begin screwing it in
it will be quite easy at first, as the tapered section of the tap wont be removing much material, however, as you get deeper the swarf will begin to glog the flutes, so work the tap back and forth to loosen this up. Parafin also helps the cutting a bit. On deeper holes it may be necessary to remove the tap completely and clean all the swarf (swarf is the lil shavings of metal produced by cutting) away, or it will damage the thread being created, as mentioned by magura earlier (is your name related to magura hydraulic brakes).
Continue this until the bottom of the hole is reached, then remove the tap. if its an open hole, then just wind the tap right down the bottom to finish the thread. If however its a blind hole, finish it off with a second and then a plug tap. Experience will tell you when you can get away without using a second. Then just clean up and duburr the entry to the hole. (deburring is when you remove the sharp edges (burrs) created by cutting. generally removed with a file)
There we go, thats how I do it, assuming it's freehand and theres no access to a milling machine or something to keep the tap on-axis
Steve
Shall we give some details of tapping techniques as this is supposed to be educational, ill get my tuppence in first
drill the tapping size hole according to datasheets, or a little smaller than the core diameter of the thread (can be roughly measured by measuring the inside diameter of a corresponding nut, or again consulting thread data tables)
remove all swarf from the hole, and do not deburr the edge of the drilled hole, as this makes it a little easier to get the tap to make that initial 'bite', and start drawing itself in, though this only really counts for larger sizes of tap (1/2" and above from my experience, also doesn't help that we had to use prewar taps half the time)
start with a taper tap, in a tap wrench, and line up carefully with the hole, and begin screwing it in
it will be quite easy at first, as the tapered section of the tap wont be removing much material, however, as you get deeper the swarf will begin to glog the flutes, so work the tap back and forth to loosen this up. Parafin also helps the cutting a bit. On deeper holes it may be necessary to remove the tap completely and clean all the swarf (swarf is the lil shavings of metal produced by cutting) away, or it will damage the thread being created, as mentioned by magura earlier (is your name related to magura hydraulic brakes).
Continue this until the bottom of the hole is reached, then remove the tap. if its an open hole, then just wind the tap right down the bottom to finish the thread. If however its a blind hole, finish it off with a second and then a plug tap. Experience will tell you when you can get away without using a second. Then just clean up and duburr the entry to the hole. (deburring is when you remove the sharp edges (burrs) created by cutting. generally removed with a file)
There we go, thats how I do it, assuming it's freehand and theres no access to a milling machine or something to keep the tap on-axis
Steve
My ID is a ripoff of the brake people.
A few comments :
You should allways deburr the hole prior to tapping, when done after you destroy the thread. With quality taps that have been used for one metal only(you should keep your taps out of reach of ferrous metals at least, if you want to caut aluminium with them), its no problem to start the thread. When cutting >M5 I use spiral flute taps as they do blind holes as well as avoid the problem with chips getting stuck.
As for the diameter of the respective drill. For metric 60 degree thread its quite simple. The nominal diameter of the thread minus the pitch = drill diameter.
M3 - 0.5mm pitch
M4 - 0.7mm
M5 - 0.8mm
M6 - 1.0mm
M8 - 1.25mm
M10 - 1.5mm
M12 - 1.25mm
Make sure you lubricate plenty.
For the respective materials:
Aluminium - alcohol
Copper and brass- vegetabilic oil
Steel and stainless steel - Rocol
MAgura
A few comments :
You should allways deburr the hole prior to tapping, when done after you destroy the thread. With quality taps that have been used for one metal only(you should keep your taps out of reach of ferrous metals at least, if you want to caut aluminium with them), its no problem to start the thread. When cutting >M5 I use spiral flute taps as they do blind holes as well as avoid the problem with chips getting stuck.
As for the diameter of the respective drill. For metric 60 degree thread its quite simple. The nominal diameter of the thread minus the pitch = drill diameter.
M3 - 0.5mm pitch
M4 - 0.7mm
M5 - 0.8mm
M6 - 1.0mm
M8 - 1.25mm
M10 - 1.5mm
M12 - 1.25mm
Make sure you lubricate plenty.
For the respective materials:
Aluminium - alcohol
Copper and brass- vegetabilic oil
Steel and stainless steel - Rocol
MAgura
Here's how I do tapping: http://www.diyaudio.com/forums/showthread.php?s=&postid=69414&highlight=#post69414
Hi peter,
Must have taken a while to file the top off the tap!!
Personally i never like powered tapping unless its very accurately located and controlled (cnc machining center), or of large size and up in a lathe on a very low speed.
I suspect you can get a better finish by hand too, as your hand is more sensitive than a drill clutch as to sensing when swarf is starting to clog and becoming a problem.
Im sure this method is perfectly good only working on a 1/4" deep thru hole though
For the purposes of small sizes like the M3 you give as an example, you can get little ratcheted tap wrenches that I find slightly easier to keep small taps on axis freehand, than traditional tap wrenches.
Steve
Must have taken a while to file the top off the tap!!
Personally i never like powered tapping unless its very accurately located and controlled (cnc machining center), or of large size and up in a lathe on a very low speed.
I suspect you can get a better finish by hand too, as your hand is more sensitive than a drill clutch as to sensing when swarf is starting to clog and becoming a problem.
Im sure this method is perfectly good only working on a 1/4" deep thru hole though
For the purposes of small sizes like the M3 you give as an example, you can get little ratcheted tap wrenches that I find slightly easier to keep small taps on axis freehand, than traditional tap wrenches.
Steve
I will not agree with you on that. Doing it with cordless drill is much more accurate (better alignment and it's almost impossible to break the thread). I tapped 3/4" deep, blind holes in copper, this way, and it was no problem.
I shaved the tap on a bench grinder, took me 2 sec.
PS: Some people make seem tapping like a big affair, but it is not. I will never do it by hand.
I shaved the tap on a bench grinder, took me 2 sec.
PS: Some people make seem tapping like a big affair, but it is not. I will never do it by hand.
Ahhhh yes a bench grinder would do it! so long as you don't lose the temper in the steel.
In copper? Really? Pure copper? Ive always found that stuff sticky as hell to tap, or drill for that matter, and wouldnt trust myself with anything other than hand tapping for that. Maybe im just clumsy or using too many crappy taps. If it was some copper alloy, like halfway to brass or something it may be different though.
In copper? Really? Pure copper? Ive always found that stuff sticky as hell to tap, or drill for that matter, and wouldnt trust myself with anything other than hand tapping for that. Maybe im just clumsy or using too many crappy taps. If it was some copper alloy, like halfway to brass or something it may be different though.
Most of the taps that I have sold to the people here on the board were M2.5 M3 or M4.
Dont try to tap with any of those sizes using a powerdrill. They will not like the weight of the drill and will most likely break.
M5 and up I agree with Peter on that a powerdrill could be used, but only as long as you dont need to make deep thread or need the thread to accept long bolts, since you have no chance to measure the angle youre holding the powerdrill. For a thread in a 5mm sheet, the angle can be several degrees off, and it will all be just fine anyway.
As for tapping copper with el cheapo taps, If you measure the strength of the thread, its most likely down to 2/3rd's of what can be achieved with the right lubricant and a high quality tap. Its naturally a matter of what quality youd like/-need. Personally i like to make thread the best way possible, cause you know as a fact that the thread is a weak link, and if you aim for the best....its less problematic if your result isnt quite as good as you expected, it will most likely be as strong as what youd achieve with a perfect thread made with lower quality equipment.
Magura
Magura
Dont try to tap with any of those sizes using a powerdrill. They will not like the weight of the drill and will most likely break.
M5 and up I agree with Peter on that a powerdrill could be used, but only as long as you dont need to make deep thread or need the thread to accept long bolts, since you have no chance to measure the angle youre holding the powerdrill. For a thread in a 5mm sheet, the angle can be several degrees off, and it will all be just fine anyway.
As for tapping copper with el cheapo taps, If you measure the strength of the thread, its most likely down to 2/3rd's of what can be achieved with the right lubricant and a high quality tap. Its naturally a matter of what quality youd like/-need. Personally i like to make thread the best way possible, cause you know as a fact that the thread is a weak link, and if you aim for the best....its less problematic if your result isnt quite as good as you expected, it will most likely be as strong as what youd achieve with a perfect thread made with lower quality equipment.
Magura
Magura
id imagine this to be particularly true with copper though, as blunt/poor geometry tooling does tend to rip copper rather than cut it
can you get specialist taps for different materials with different flute geometry suited to cutting that material. we never bothered using anything other than standard taps at the train place, but im sure in a more production oriented environment where every second counts there must be more specialist taps.
Steve
Ive been searching for speciality drills for copper for a while for mass production, speciality countersinkers for copper as well. The end of that was that I have bought regular tools and have had them ground to specs. and plated for the purpose. Id expect the same to be true for taps.
You can get tools specific for brass and stainless steel, even aluminium, but copper seems to be such a small branch of cutting tools that nobody cares. I process roughly 100 tons of copper annually, and thats big in pretty much anyones book. Compared to tonnes of machined steel, its almost nothing.
The only solution is to have a set of taps for each metal, that makes generally better thread and extends the lifespan of a tap dramatically.
Magura
You can get tools specific for brass and stainless steel, even aluminium, but copper seems to be such a small branch of cutting tools that nobody cares. I process roughly 100 tons of copper annually, and thats big in pretty much anyones book. Compared to tonnes of machined steel, its almost nothing.
The only solution is to have a set of taps for each metal, that makes generally better thread and extends the lifespan of a tap dramatically.
Magura
I wish it was that simple...its definitely not.
Its also greatly influenced by the twist of the helix, and the helix, the clearance and the land angle have to cooperate to get the chips to break into short pieces and to get out of the whole as well without getting bent over the edge of the hole so they make deep scratches in the surface and destroy the edge of the hole. On top of that you have to take power consumption into account and lifespan as well....trust me, i spent more than a year developing the tools we use now.
Magura
Its also greatly influenced by the twist of the helix, and the helix, the clearance and the land angle have to cooperate to get the chips to break into short pieces and to get out of the whole as well without getting bent over the edge of the hole so they make deep scratches in the surface and destroy the edge of the hole. On top of that you have to take power consumption into account and lifespan as well....trust me, i spent more than a year developing the tools we use now.
Magura
take care all
Magura said:Most of the taps that I have sold to the people here on the board were M2.5 M3 or M4.
Dont try to tap with any of those sizes using a powerdrill. They will not like the weight of the drill and will most likely break.
M5 and up I agree with Peter on that a powerdrill could be used, but only as long as you dont need to make deep thread or need the thread to accept long bolts, since you have no chance to measure the angle youre holding the powerdrill. For a thread in a 5mm sheet, the angle can be several degrees off, and it will all be just fine anyway.
As for tapping copper with el cheapo taps, If you measure the strength of the thread, its most likely down to 2/3rd's of what can be achieved with the right lubricant and a high quality tap. Its naturally a matter of what quality youd like/-need. Personally i like to make thread the best way possible, cause you know as a fact that the thread is a weak link, and if you aim for the best....its less problematic if your result isnt quite as good as you expected, it will most likely be as strong as what youd achieve with a perfect thread made with lower quality equipment.
Magura
Magura
You won't break the tap when you adjust your cluch properly (I assume you know I'm using cordless drill with a clutch).
I was tapping effectively 4-40 sizes (which is rough equivalent of M3), 0.3" deep in copper and I wouldn't hesitate to use that method with M1
You are actually much off with the correct angle, when you do it by hand, as when using the drill you see much better if you are straight or not.I'm not measuring the strength of the thread, as it's completely irrelevant to me. As long as the screw holds, it's good enough.
Personally I don't care if the tread is perfect or not (but usually it is). This are not rockets, but home entertainment equipment, only.
The reason for the tap to break is if you move the drill accidentally, then its sure gonna snap. You obviously have very fine skills with a cordless powerdrill, but the average diy'er would brake a M3 tap if done like that, heck most people can hardly do it without the 1 kilogram powerdrill hanging at the end without braking the taps frequently.
Peter, i cant email you, please email me.
Magura
Peter, i cant email you, please email me.
Magura
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