# Hand Sharpening A Spiral Flute Tap



## Nick Hulme (Jul 8, 2016)

I needed to tap a hole 1/8" BSP this afternoon and found I'd forgotten to buy a replacement for my 1/8" BSP spiral flute tap when I blunted it, I do have a tap set but I really wanted to do it in one operation. 
Looking at the form of the blunted tap I realised that the right size ball could run against the cutting edge of one flute, giving the correct undercut, whilst being guided by the trailing edge of the flute in front. 
A quick delve through my Dremel drawer found a set of spherical tipped diamond burrs with one that looked good for the job. 
I don't know how many times you'd get away with this rough'n'ready fix but it works well enough the first time to get you out of a hole! 

 - Nick


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## gus (Jul 8, 2016)

Nick Hulme said:


> I needed to tap a hole 1/8" BSP this afternoon and found I'd forgotten to buy a replacement for my 1/8" BSP spiral flute tap when I blunted it, I do have a tap set but I really wanted to do it in one operation.
> Looking at the form of the blunted tap I realised that the right size ball could run against the cutting edge of one flute, giving the correct undercut, whilst being guided by the trailing edge of the flute in front.
> A quick delve through my Dremel drawer found a set of spherical tipped diamond burrs with one that looked good for the job.
> I don't know how many times you'd get away with this rough'n'ready fix but it works well enough the first time to get you out of a hole!
> ...




Thanks for sharing. Most my taps are Japanese Made. But I do have some Chinese Made and tapping bad thread and sharpening required.

Going back to 1961,we broke some worned BSP Taps and were remanded by the instructors for being careless. And true enough while in the process teaching us the correct tapping technique,he broke one too. His senior dropped by and advised that most of the taps were  WW-ll army surplus and worned out and hence prone to breakage. Ha Ha. In those days tap sharpening skills were none-existing yet.


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## Nick Hulme (Jul 8, 2016)

Gus, 
The tap was a good English made item blunted when I drilled an "on size" hole in stainless, I forgot to refer to the chart giving over-sizes recommended for difficult materials.


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## goldstar31 (Jul 9, 2016)

An interesting thread( pun intended) and suggestion. However there is a difference between 'worn' and 'broken' One usually follows the other.

The last post( pun not intended) was years ago when an old WW2 submariner used a slip stone to re-furbish the lands( correct name- sorry)

Since then, my main stock of taps also have been 'underwater' and considerably rusted. Winter storms and the roof came off the workshop. No time for a rescue .

So ignoring the interesting quick fix, what suggestions emerge for a more practical approach?

Hint, replacing my vast collection of taps- ( and dies, too) would break the bank.

Apologies for stealing the thread but other people have worn taps etc 

Regards

Norman


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## Nick Hulme (Jul 9, 2016)

goldstar31 said:


> the lands( correct name- sorry)



If he was working the heel, flute and the thread too (correct names- sorry), yes, but the trailing edge is the heel and the leading edge is the flute, I was describing what I did in a way most likely to be understood by all but I sharpened only the flutes using the heel of the adjacent land as a guide, 
Regards, 
Nick


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## Blogwitch (Jul 9, 2016)

Blunt taps can be a PITA as they can very easily get stuck or even break. For smaller sizes, as soon as they give any sign of a squeak, they are rejected and a new one used, but on larger taps, they are just too expensive to do that.

For spiral or straight taps, I find that a set of diamond riffler files or mainly for straight, diamond stones work wonders just by rubbing them along the front cutting faces. You can only do it a few times, but it can get around a problem when the shops are closed.

http://www.arceurotrade.co.uk/Catal...nd-Needle-Files/10pc-Diamond-Riffler-File-Set

http://www.arceurotrade.co.uk/Catalogue/Diamond-Tools/Diamond-Stones

John


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## goldstar31 (Jul 9, 2016)

Nick Hulme said:


> If he was working the heel, flute and the thread too (correct names- sorry), yes, but the trailing edge is the heel and the leading edge is the flute, I was describing what I did in a way most likely to be understood by all but I sharpened only the flutes using the heel of the adjacent land as a guide,
> Regards,
> Nick


 
Actually, he did sort the matter out- fully. From the Quorn drawings, he fabricated a rather more versatile and slightly larger one. Again, he changed the working speeds.  He couldn't afford all this - going to the shops for this and that. 

I presume that there is a place for such people. :hDe:


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