Tapping oversize

[Metric]

I have trouble to get 2-56 3B STI tap to get to size.(nogo is going) I tried form tap also cutting tap.

Min. tap drill size too.Please give me any idea (any kind of tap or speed and feed)

The material is aluminum 2404. :(

Thanks a lots.

[Goldorak]

does the tap is made for 3b tol

 

generally taps are made for 2b thread

 

thread mill can be a solution too, i am cutting thread as small as 0-80 with great success

[Metric]

Hello Martin,

Thanks for replied.Could you show me how to check which tap for 2B or 3B? When you thread mill which brand of cutter?The 2-56 only .0938 minor dia the thread mill tool should be .0625 dia then?And how fast you go for this small cutter?

 

Best regards.

[Goldorak]

generally the class is indicate on the tap

 

for thread mill brand, we use vardex and iscar

 

rpm at maximum and .0001 to .0002 ipr .001 to .003 step over , i still prefer tapping for such a small tap, but our parts need a .0625 deep 0-80unc blind hole, so it's impossible for a tap to get the dept needed

[Metric]

Thanks a lots

[machinedudester]

Make sure that your drill size is correct, it is different depending on the class and whether it is form or cut tap. It should be 5/64" drill for a form tap or .078"-.080" ,and a #51 drill for a cut tap or .067"-.069".

[Ralph@Faustson]

Class of tap should be H1 for a 3b Thread

[Guest]

OK, have you pinned the hole after drilling to make sure it is the correct size?

 

Have you checked the tap for runout? what's the tap being held in? Have you tried a different tool holder?

 

Is this a blind hole? Is the Tap bottoming out? Rigid or spring load holder?

 

Is the coolant crap? That grade Aluminum is gummy as heck and will tear, especially with bad coolant?

Can you try some Aluma-tap instead?

 

Are the tap and gauge the correct grades?

[McLaren]

I have trouble to get 2-56 3B STI tap to get to size.(nogo is going)

 

Perhaps because you are using a tap for helicoils?

[Philcott]

OK, have you pinned the hole after drilling to make sure it is the correct size?

 

Have you checked the tap for runout? what's the tap being held in? Have you tried a different tool holder?

 

Is this a blind hole? Is the Tap bottoming out? Rigid or spring load holder?

 

Is the coolant crap? That grade Aluminum is gummy as heck and will tear, especially with bad coolant?

Can you try some Aluma-tap instead?

 

Are the tap and gauge the correct grades?

 

 

Pinky's tap trouble shooting guide. All good suggestions John.

[MotorCityMinion]

"Perhaps because you are using a tap for helicoils?"  Good  catch McLaren.  The no go would almost drop in the hole.

[Metric]

Thanks all Bro's.

Yes it is STI tap for helicoil.We have tap gauge for helicoil.

I use spring load holder.The hole is through.For 2-56 STI tap the tap drill

is .100" for rolling tap for the cutting tap is .0938" I thing the tap i have is not for

class 3b it is BH2 My boss will get the BH1 class Tomorrow.

Thanks for all replied.

[McLaren]

If your hole is the right size before you tap it I'd try tapping it by hand. That'll tell you if the tap is no good.

[G10X0Y0Z0]

Thanks all Bro's.

Yes it is STI tap for helicoil.We have tap gauge for helicoil.

I use spring load holder.The hole is through.For 2-56 STI tap the tap drill

is .100" for rolling tap for the cutting tap is .0938" I thing the tap i have is not for

class 3b it is BH2 My boss will get the BH1 class Tomorrow.

Thanks for all replied.

 

the tap drill for a 2-56 STI form tap is .1015. we run that all day long with no problems. make sure the thread gauge is for the correct class thread you are trying to produce. for a thread that small the difference in tolerance dimension is very minimal. my 2 cents

[Colin Gilchrist]

You said spring loaded holder. Is it possible that you are getting syncing errors with your

Spindle and your Z axis? Too much tension on the holder when retracting?

 

I think hand tapping is an excellent idea. That will tell you if it is the tool or if it is the machine instantly.

 

You can never go wrong with treadmilling. Thread mills allow you to use cutter comp, so you can just dial in the hole size.