Problem- Ridgid Tapping 1/4-20

[southernexplore]

Does anyone have trouble tapping 6061 Al. with 1/4-20? It seems like I break an awful lot of taps! These holes are from 1/2" deep to 1" deep and I cannot figure out why I have so many problems.
I am using emuge taps with coolant at about 2.5.

Can someone give me pointers to fix my problem.


Tommy

[Geof]

Coolant at 2.5%?

Go much higher, we use 10% for tapping 6061 in all sizes from 4-40 up to 1/2-13.

What drill size are you using, we use 13/64 which gives about 75% thread maybe a bit less.

Do you Repeat Rigid Tap?

Normally if the thread is deeper than 1-1/2 diameters I will Repeat Rigid Tap making the first entry just over one diameter and the the rest at about 0.75 diameter further for each one.

For through holes use spiral point taps.

For blind holes use sprial flute taps.

Run at 1000rpm or faster; this gives better chip flow.

You should be able to do thousands of holes per tap; although you should cut off at about 1000 and start using a new tap because they do dull and cut undersize.

[southernexplore]

I am using a 13/64 drill but I am only going 500 RPM with 2.5 on the coolant.
I will have to try what you recommend.

Thanks,
Tommy

[panaceabea]

I am tapping 1/4 x 20 holes 1" blind in 7075 , 35% coolant , .3 pecks no problems

[robrea]

Tommy,

You should confirm that your rigid tapping is 'on'. One TM1 had it on then after a lightning storm the parameter was turned off.
We had a devil of a time tapping and all the old programs didn't work anymore. We called haas and the parameter had mysteriously been turned off. They gave us the code to turn it back on and it taps great again.

Another thought is to switch to form taps. Much less chip binding problems but these taps require more horsepower and 'slippery' coolant.

Robert

[behindpropeller]

Originally Posted by robrea Tommy, You should confirm that your rigid tapping is 'on'. One TM1 had it on then after a lightning storm the parameter was turned off. We had a devil of a time tapping and all the old programs didn't work anymore. We called haas and the parameter had mysteriously been turned off. They gave us the code to turn it back on and it taps great again. Another thought is to switch to form taps. Much less chip binding problems but these taps require more horsepower and 'slippery' coolant. Robert

+1 We PAID for it on our machine. I tried tapping a bunch of holes....driving me nuts! Well here the service tech never turned it on when he installed the machine.

Tim

[DSL PWR]

I like to use form taps whenever possible. No chip problems

[southernexplore]

I have increased my refraction to 8 (ran out of mix) and things are looking better so far, but I still need to get it up to about 10 or 15.

Tommy

[jr2840]

Just saying you might want to check and see if your repeat tap is on too. It will break taps if it is not on, learned the hard way.

[southernexplore]

So far all is good. I have my coolant up to 10% now and I have not broke a tap yet.

Thanks for the help,
Tommy

[JDenyer232]

Originally Posted by southernexplore I have increased my refraction to 8 (ran out of mix) and things are looking better so far, but I still need to get it up to about 10 or 15. Tommy

When these guys are saying 10% or 30% they are talking total % concentration, not the refractometer reading. For my coolant a 5.6% brix refractometer reading equals a 20% coolant concentration. Your coolant manufacturer has refractometer charts that will do the conversion for you. As others have said, use a form tap, especially on blind holes. Leave about
.020" of clearance at the bottom of the holes, and don't forget to subtract the depth of the drill angle from the tap depth. For a 118 degree drill point multiply the drill diameter by .3. Here is an example, a print calls for a 1/4-20 tap hole .500" deep. Your drilling depth should be .203x.3=.0609+.500=.5609+.020=.5809" drill depth. This is assuming that you are using a form tap, for other types of taps that cut the thread you will need to add more clearance to prevent chip packing at the bottom of the hole, this is especially true for deep holes, as there are more chips pushed in front of the tap. Form taps make no chips, and spriral flute taps cause the chips the be ejected out of the top of the hole. Both form and spiral flute taps are good choices for blind hole tapping in aluminum, they are a must for deep hole tapping in aluminum. Hope this helps.

[ultrapeter]

before you tap holes put rocol on tap and in holes.will work a treat.