tap help

LEDBE
aljsk8

aljsk8

Enlightened
Joined
Sep 7, 2006
Messages
435
Location
Wigan, UK
simple question for you guys

i want to tap threads into holes for holding led stars down ive chosen
M3x0.5 machine screws

from what ive read i need to drill 2.5mm holes which i have done
now i need to order the tap

i see that there are 1st 2nd and 3rd taps do i need all of these or just one?

thanks

Alex
 
1st 2nd and 3rd taps do i need all of these or just one?
Click to expand...

You just need one, but there are at least six choices :D

The three taps you refer to are called taper, plug & bottoming:

TAPER TAPS * have 8 to 10 threads chamfered for easy starting and are used for tough threading jobs.

PLUG TAPS * used for ordinary threading and have a 3 to 5-thread chamfer, or relief, at the point.

BOTTOMING TAPS * with their short chamfer (1 to 1-1/2 threads),are used where the thread must go to the bottom of the hole.


There are three other types of taps that often work better than the three listed above.


For through holes, a spiral point tap pushes the chips out of the hole ahead of the tap. They make through hole tapping fast & easy.


For blind holes, a spiral flute tap pushes the chips up (backwards) so the bottom of the blind hole stays clean. They are awesome for blind hole tapping.


Thread forming taps don't cut metal at all, but displace metal to form threads. They can be used in both through holes & blind holes.








 
As I see the OP is in the UK your terminology is a bit off Precisionworks. Over here the term plug and bottoming are interchangable, we refer to taper, second and usually plug. Also with some manufacturers the taper and second do not necessarily cut to full depth of thread though this is becoming increasingly rare. If it's through hole the answer is you'll probably get away with a taper but look for something of quality like a Dormer or Presto.
 
ok that info helps a lot

ive been looking at very low cost ones is it that they wont last long or that they will actually produce a poor finish

i want good threads but i will probably only use this tool for 8 holes and then never again

as usual trying to complete project on a tight budget
 
precisionworks said:
Here's a thread former that should work well, and is located on the right side of the pond :D

http://cgi.ebay.co.uk/Fluteless-Tap...in_3?hash=item2c4fcbabcd&_trksid=p3286.c0.m14

It looks like it's made by Dormer in Sweden.
Click to expand...

The price though for a few holes:eek:. You could buy a full 3 tap HSS set for less than that, probably 2. One good set of taps at that size would last the average CPFer many years, you just have to remember where you put them. I know I have some somewhere. If I don't find them then they'll last a lifetime:thinking:.
 
Low cost taps USUALLY work OK, but they dull quickly or break. You should be able to get 8 holes out of cheap taps. Look for the CPF threads on tapping. There is a nice techique where you dril the hole and then (without moving anything) use the drill press to keep the tap lined up with the hole. That minimizes the chances of breaking.


Daniel
 
that would be great if i had a drill press

cordless drill and hand tools here!

will it make a difference that im tapping into copper?

thanks for all the advice guys
 
Copper is one of the worst metals for machining due to it's high ductility. You'll get the best results using carbon steel taps as they are generally sharper than HSS and cut better in copper, cheaper too. Don't forget that you don't wind a tap straight through, go 3/4 turn, then back off the tap to break the chip then repeat. Use some lubricant too, if the tap starts to squeak back it out fully, it's telling you it's binding and going to break.
 
Last edited:
Copper, like some types of aluminum, is gummy. A forming tap, like the Dormer referenced above, would be my first choice.

best results using carbon steel taps as they are generally sharper than HSS
Click to expand...
Carbon taps are sharp, but HSS taps are much tougher & break less easily. A 3mm tap is delicate, no matter what you use. The forming tap, because it has no flutes, is the toughest. HSS is next, carbon steel is last. The only "benefit" of carbon steel is that they are dirt cheap.

cordless drill and hand tools here!
Click to expand...
Even though you have only a few holes to tap, each one has to be a perfect 90 degrees to the surface. Use a small square to guide the drill & to start the tap. If the tap is started the slightest bit tilted, it will bind & may break.
 
cheers guys im going to go for hss - the former would be nice but i dont have that kind of money for something ill probably never use again - ive spent all the money on the leds!

ill try to put into practice the things you have mensioned

not sure how to use a square to line it all up - do you mean have the thin part of the square pointing vertically then line the drill up with it by eye? and the same with the tap

i might see if i can find someone with a drill press. if someone could tell me the tapping procedure with a drill press or link me to some instructions that would be great
 
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Get a block that is about 2/3's of the length of the tap tall and find someone with a drill press to drill your holes to be tapped and to also drill a hole in the block that is a slip fit for the tap and use the block as a guide to keep the tap straight.

I'll try to post a pic to help to explain what i am talking about.


Jason
 
precisionworks said:
Copper, like some types of aluminum, is gummy. A forming tap, like the Dormer referenced above, would be my first choice.

Carbon taps are sharp, but HSS taps are much tougher & break less easily. A 3mm tap is delicate, no matter what you use. The forming tap, because it has no flutes, is the toughest. HSS is next, carbon steel is last. The only "benefit" of carbon steel is that they are dirt cheap.

Even though you have only a few holes to tap, each one has to be a perfect 90 degrees to the surface. Use a small square to guide the drill & to start the tap. If the tap is started the slightest bit tilted, it will bind & may break.
Click to expand...

A forming tap is of little benefit in this situation, it's hardly a high torque load so a cut thread is more than adequate. There also isn't the raised rim which would undesirable here.

HSS may well be tougher but it's also not as sharp and more likely to bind and break unless you have a 'feel' for tapping.

I think also it's a good time to point out that a lubricant is necessary, every metal has a suitable lubricant but for such a small hole a bit of 3 in 1 or engine oil will work.
 
I have even heard milk can be used for tapping in copper.
Click to expand...
+1

The nice thing about milk or cream is that the small, single serve dispensers are free whey you buy a cup of coffee :D

Plain lubricating oils do not make good tapping fluid.
Click to expand...
Engine oils work by keeping metallic parts separated by a microscopic layer of lubricant. In tapping, there is no metallic separation but rather extremely high pressure as the tap shears (cuts) metal ... or displaces the material with a forming tap. There's a can of Tap Magic at both drill presses, the mill and the lathe - which is why the gallon can is the best value if you do much drilling or tapping.
 
ok ive got one of you saying HSS and one saying carbon steel

im going to buy on monday which one should i get??

that block is a great idea ill probably have to make something from wood

ok im my shed i have

lithium grease - the orange stuff for cars
lithium grease - the white stuff for bearings
silicone spray
wd40
oil for garden tools
ptfe chain lube

in the kitchen i have

milk
butter
cream

in the bathroom i have

baby oil :thumbsup:

so which should i use??
 
I'd go with a quality HSS tap - the price diference is small - If it's a through hole, ise what is called a "sprial point" (aka a 'GUN') tap - they do not break as easily as a 4 flute 'hand tap'

Of your choices of lube, I'd use the cream!!

That said - pick up a can of tapmagic etc - I'd normally say "grab some dark sulpher cutting oil" but they tend to REALLY discolor copper/copper alloys

BTW - cutting/tapping - for Aluminum, if you can get ORIGINAL Tapmagic for Aluminum or Original Formula Alumi-tap - grab it. The first is no longer made as far as I know, the second is, but can't be shipped to say, California - both are Chlorinated Hydrocarbons (aka Ozone layer depleaters), but boy do they WORK
 
aljsk8 said:
cheers guys im going to go for hss - the former would be nice but i dont have that kind of money for something ill probably never use again - ive spent all the money on the leds!
Click to expand...
The former is what you want. You may spend more money and time if you go the other route and end up breaking the bit off in the work. Then you will have to start over with a new piece of metal. Ask me how I know. The former is sooo much easier. The results are much better too as the threads are tighter.
 
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