[jpeach1]

In the middle of trialing a new post that includes tapping with a procurnier tapping head.
Have calibrated the spindle speed, calculated the feed in, x2 on the way out, the tapped hole turned out really nicely.

Problem: Post / path pilot turned the spindle off before the tap was completely reversed out of the hole.
Everything stopped, z movement continued + and pulled the works out of the spindle.

How do you make the spindle stay on longer on the way out (I suppose it the same thing for starting it earlier)..?
I'm going to play with the heights in Fusion 360, but if anyone knows the quick answer, I'd certainly appreciate it.

Jim

[SCzEngrgGroup]

All you should have to do is set the "Top Height" in Fusion high enough above the top of the hole that you can be certain the tap is fully backed out of the hole before reaching that height. Something like 1/2" above the top of the hole will usually be enough.

I will give you a warning about the Procunier tapping heads: Unlike most other tapping heads, the Procunier cannot tolerate ANY over-feed on the way down. This means you MUST KNOW your actual spindle RPM when tapping, or intentionally under-feed to ensure you NEVER exceed 100% feed. If you do over-feed, you WILL break the tap, if not the Procunier itself.

Regards,
Ray L.

[jpeach1]

All you should have to do is set the "Top Height" in Fusion high enough above the top of the hole that you can be certain the tap is fully backed out of the hole before reaching that height. Something like 1/2" above the top of the hole will usually be enough.

I will give you a warning about the Procunier tapping heads: Unlike most other tapping heads, the Procunier cannot tolerate ANY over-feed on the way down. This means you MUST KNOW your actual spindle RPM when tapping, or intentionally under-feed to ensure you NEVER exceed 100% feed. If you do over-feed, you WILL break the tap, if not the Procunier itself.

Regards,
Ray L.

Thanks Ray,

I calibrated the spindle using an old school Starrett machinist speed indicator and a stop watch. Had it within about 4 rpm best I could tell after multiple checks(calibrated @ 500 rpm, the speed I'm tapping 1" aluminum) . One off tapping went well. As soon as I went to multiple holes, on the second operation something undesirable happened. I'm guessing the feed / retract calibration was not close enough and the tap broke. Before much longer the procuriner collet nut was trying to bore a hole through my stock, I'm guessing the Z reference was interrupted because of the broken tap, I started crashing on the top of the part after the 2-3 tapped hole.

Is the < 5 rpm calibration is a difference maker?
Should I back off on the feed rate and 2X retract rate (inferring from your reply).

Appreciate your help,

Jim

[SCzEngrgGroup]

As I indicated, the Procunier has ZERO tolerance for over-feed. The collet can move up only until the clutch engages, and no further. Attempting to move further will PUSH the tap through the work, and can easily damage the Procunier. So, without a servo spindle that is 100% coordinated with the Z feed, I always program a 10% under-feed, just to be safe. This means the clutch may very briefly slip or disengage on the way down, but this is harmless, as long as you keep the Procunier properly lubricated. That is the (small) price you pay for the better-smooth engagement of the Procunier as compared to the lesser tapping heads with dog clutches that "bang" into engagement.

Regards,
Ray L.