Tap

[carlboe]

Need to know what tap to use or thread mill the holes. The problem is I have been braking taps. I do not use hand taps I think I'm using machine taps. That is what I'm ordering. Oh that hole size is 10/32 blind hole .465 deep hole threading .400 deep. Can anyone suggest a tap. The tap brakes about every 8 to 10 holes.

Thanks
Carl Boe

[keebler303]

You are using a spiral flute tap?
You are using a good quality tapping fluid?
You aren't bottoming the tap in the hole?

It would help to know your tap drill size and of course what the material is.

Matt

[carlboe]

You are using a spiral flute tap?
You are using a good quality tapping fluid?
You aren't bottoming the tap in the hole?

It would help to know your tap drill size and of course what the material is.

Matt

The material is 6061 Alum.
Spiral Flute Tap
Morse,Osc, Taps
Drill size 22 even tried a 21
Flood coolant
T/C tapping head

I should be about .065 from the bottom. I'm using a bottoming tap. The threads don't go the the bottom

[zephyr9900]

Bottoming taps are chamfered 1.5-2 threads. .400 threads of 32 pitch in a .465 deep hole is 2 threads difference. If you are trying to cut full threads .400 deep, you are likely running the tap into the bottom of the tap hole. If you are just putting the end of the tap .400 deep, then your full threads will only be .34 deep or so.

Torque on a bottoming tap is also larger than on a plug tap (3-5 threads chamfer) because you are cutting the threads more suddenly instead of "shaving" them like a plug tap does.

Randy

[Bob La Londe]

The material is 6061 Alum.
Spiral Flute Tap
Morse,Osc, Taps
Drill size 22 even tried a 21
Flood coolant
T/C tapping head

I should be about .065 from the bottom. I'm using a bottoming tap. The threads don't go the the bottom

I tap 10/32 in 6061 all the time with a cheap tapping head in my drill press. I get about 30-50 holes with just a squirt of light mineral oil on each hole. I am doing it manually though, and I have the belts set at the slowest speed for the drill press. 750 RPM I think.

I am not bottoming though. I am tapping through. Usually 1/2" plate/bar, but sometimes 3/4".

I set my clutch per the instructions, and when it slips even once I throw the tap away and put in a new one. (Tighten clutch until it just barely does not slip, on tapping the hole with a new tap, then tighten about 1/16th turn further.) If I try to tap after the clutch slips once I usually break a tap within 1-3 holes. I am using uncoated HSS no-name off ebay sprial flute taps. I may try some coated taps in the future. I have two left so its about time to order some more.

I hope my experience helped.

Have you considered tapping with a tapered spiral tap, and then just finishing with the bottoming tap?

Are you sure you are not bottoming out (TAPPING DEEPER THAN YOU THINK) when your tapping head extends itself out?

... and remember. A broken tap costs a lot more than a new tap.

[keebler303]

Make sure you aren't bottoming out the tap.
Use tapping oil, not coolant.
If you can drill deeper and use a taper tap it will be easier as stated above.

Matt

[Don Clement]

I've had excellent results tapping 10-32 using Balax forming taps on 6061-T6 aluminum both with my Procunier tap head on both manual mill and Tormach or tapping manually using a Fisher micro-tap guide. The Balax works well with blind holes partially because there are no chips produced. Also I use Relton A9 tapping fluid.

Don

[carlboe]

I've had excellent results tapping 10-32 using Balax forming tapson 6061-T6 aluminum both with my Procunier tap head on both manual mill and Tormach or tapping manually using a Fisher micro-tap guide. The Balax works well with blind holes partially because there are no chips produced. Also I use Relton A9 tapping fluid.

Don

Thanks Guys

Deeper holes tapered tap threading oil and a forming tap. All makes for a good run of a 70 holes and NO PROBLEM.


Carl Boe

[Bob La Londe]

Thanks Guys

Deeper holes tapered tap threading oil and a forming tap. All makes for a good run of a 70 holes and NO PROBLEM.


Carl Boe

Dang-It! Now I'm jealous. I'm going to have to get me some of them good taps.

[Don Clement]

I regularly tap thousands of 4-40 blind holes 0.25" deep in 6061-T6 using my Procunier tap head on the Tormach with a Balax forming tap at 2400 RPM @30IPM downfeed, no dwell, and 60 IPM retract without breaking a tap.

Don

[beanbag]

The right tap for this kind of blind hole is a fast spiral tap. It causes the chips to pull out of the hole instead of packing at the bottom.

[shred]

The right tap for this kind of blind hole is a fast spiral tap. It causes the chips to pull out of the hole instead of packing at the bottom.

Plus some of the eBay sellers like to misidentify 'spiral point' taps as 'spiral flute', which do the opposite-- shove the chips in front of the tap, causing much woe if driven too far into a blind hole.