Tapping with keyless chuck on lathe

Occasionally the keyless chuck (Albrecht)loosens up when reversing. All I do is put a little tightening torque on it by hand while reversing and it holds fine. I'd never give up the keyless just for this reason.

I regularly power tap up to 3/8-16 in the mill with a 1/2" Albrecht chuck--it works just fine. (Before installing a VFD I plug reversed with a static converter for many years when power tapping, which is also contrary to RCM dogma.)

A keyless chuck that's worn and/or been greased in the wrong places may cause problems. The chuck will feel springy when being tightened and release too easily when reversed.

Ned Simmons

Depending on the size of taps you are using, keyless can be a good or not so good choice. Every time the grip is loosened by the action of the tool, whether from reversal or slipping in forward, the chuck jaws get some amount of damage. An Albrecht is an expensive tap holder. I'm not saying I don't use my Albrechts to tap, just use discretion.

Some time ago, when using a 3/4" keyed chuck to hold 7/8 and 23 mm taps in the tailstock to tap chromo, I would get slippage. On investigation, I learned that Morse taper tap drivers have been available since before I was born. Look ma, no more slippage.

michael

Ive pretty much stopped using keyless chucks on my mills when tapping as it seems they nearly always slip for me. So Ive reglegated them to the drill press or drilling only..which can be a problem as Ive a lot of screw machine drill bits (left handed)

Gunner

"A vote for Kerry is a de facto vote for bin Laden." Strider

You can often improve a keyless chuck that releases too easily. Disassemble and degrease the parts. Check for burnishing on the conical surface inside the hood where the jaws ride. Scuff up that surface with crocus if you can see shiny tracks from the jaws. Relube the parts before reassembling, but do not get any grease on the inside of the hood or the mating surface of the jaws.

Ned Simmons

There are special Albrecht chucks with diamond grit in the jaw faces, designed to grip hardened shanks like mill shanks or taps.

There are also Albrecht chucks with a locking ring to prevent unintended loosening.

However, swapping in a Jacobs geared chuck is cheaper. :-)

And I would use a TapMatic tapping head on the mill, just as I do on the drill press -- unless I had a CNC which could measure the angular rotation of the spindle, and feed proportionally, and do the same in reverse for rigid tapping.

Enjoy, DoN.

Ned, Translation for us Brits please. What is crocus?

John

Presumably crocus powder or jewellers rouge - a very fine abrasive consisting of ferric oxide

Andrew Mawson Bromley, Kent, UK

Crocus (cloth) is a (US?) generic term often used interchangeably with emery paper or cloth. In my neck of the woods, it means the fine version of the long thin rolls of abrasive.

Gunner

"A vote for Kerry is a de facto vote for bin Laden." Strider

Crocus cloth is actually thin cloth charged with a layer of fine iron oxide rouge.

Emery is a specific mineral that used to be used for abrasive paper, but I think it is almost never used any more. There is an old emery mine near here that was being used as a quarry to supply crushed rock, the owners were under pressure to abandon it because it is in a residential area.

They claimed they were still mining emery, as this would have been an original use and would be permitted under zoning. But the vast quantity of rock being removed told otherwise.

Jim

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Exactly. Probably not strictly correct, but fine abrasive cloth is the common usage around here as well.

Ned Simmons