M8 tap, ER25 standard collet and steel

[Corn]

Dear All,

I was wondering will there be enough grip in standard ER25 collet to drive M8 tap to structural steel S355J2 / AISI A738? I don't have any square drive collets, so I'm asking dare I try..

Thank you in advance

 

[Clive603]

Good quality sharp spiral machine form tap with lubricant in the hole? Yep no problem.

Crappy old hand tap out of the drawer? Probably break it.

In between? It depends.

Structural steels can be very variable when it comes to this sort of thing. I've always found the key to be specialist paste type tapping lubricant wiped into the hole to ease the taps passage.

Clive

 

[trochoidalpath]

I have had good luck form tapping M8 in 4140PH. Structural steels can be a bit of an inconsistent mess but I think you’ll be okay. Make sure everything is clean, assembled properly, and torqued to spec.

 

[Scruffy887]

Dear All,

I was wondering will there be enough grip in standard ER25 collet to drive M8 tap to structural steel S355J2 / AISI A738? I don't have any square drive collets, so I'm asking dare I try..

Thank you in advance

RE Tap collets with internal sq drive are spendy but worth it. It only takes one broken tap down the hole to make the price look like a really good deal. I use them when I can't get a tap holder into use.
Once you watch a tap slide out of a regular collet its too late.

 

[doug925]

As stated above, yes it can be done, and done well. Most shops will have done it many times.
Also as stated above, it only takes 1 broken tap (due to spinning or pullout in the collet) and a 10hr part needs repair. Then square drive, tap collets become a need.

Doug

 

[Orange Vise]

It'll work fine in a pinch. I've never had a tap spin on me in properly torqued ER collet chuck. This includes taps up to 3/4-10.

That said, one of the biggest advantages of a tap collet is length control. It forces a minimum stickout and prevents an operator from choking up the tap too far and causing a Z crash in tight clearance situations, e.g. multiaxis.

 

[Scruffy887]

It'll work fine in a pinch. I've never had a tap spin on me in properly torqued ER collet chuck. This includes taps up to 3/4-10.

That said, one of the biggest advantages of a tap collet is length control. It forces a minimum stickout and prevents an operator from choking up the tap too far and causing a Z crash in tight clearance situations, e.g. multiaxis.

Exactly. When it times out I pull it and toss it. Put a new one in, reset timer, back to work.