Just had a Kryo parting tool explode on me !!

[SteveFulgoni]

Two days ago, I had a very serious incident with a tool and I think it is worth mentioning on this forum.

I was using the Henry Taylor Kryo Thin Kerf Parting tool to part off a piece of walnut that I was preparing for a project.

The walnut piece was about 3†in diameter and was fairly green but not wet. While turning at a reasonable speed, the Kryo tool shattered in my hands, sending fragments of steel throughout my shop.

I have attached two photos of the tool, the walnut piece (after I finished parting off with another thin tool) and a small razor blade to show size reference.

As you can imagine, the accident happened in an instant, but what surprised me is that there was little or no kickback of the handle, the blade simply shattered and left me with the handle in my hand.

Fortunately, I was wearing a facemask and was not hurt by the flying pieces.

I have been turning for 15 years and have never had anything like this happen before. I feel that it is important to bring this up here because it might save an accidient in the future.

I am wondering if this has happened to anyone else? Did I get a defective tool, or is the Kryo process resulting in a tool that is too brittle for a thin parting tool?

Any thoughts?

Thanks

Steve

 

[Doug Stevens]

Steve,
Thanks very much for posting this. I will be checking my parting tool like this one for evidence of any defects. Hopefully your experience was an isolated incident. Glad you were not injured.

Back to work!
Doug

 

[Richard Chan]

WOW.... Thats got to scare the (insert) out of you.

Glad you didn't get hurt

Richard

 

[Dave Moore]

Spooky.
Even with a catch, which it sounds like you didn't get, this sort of thing is not supposed to happen. I've never seen anything like that either. The tool steel would have to be pretty brittle for it to fragment like that.....
Perhaps some of the really knowledgeable steel people here will give their reaction?

 

[robo hippy]

You should send at least the photos to the manufacturer, and probably the tool as well. I would guess bad steel.

robo hippy

 

[Charlie Knighton]

glad you are ok Steve, thanks for sharing info

 

[tomcatmartin]

Steve,
I've had that happen with a bowl gouge and have heard of it happening to others. I believe that all were pm tools. I think Robo was right that it was bad steel (too brittle). I would contact the manufacturer and supplier. My gouge was only a few months old so it was warrantied. I'm not sure how old your tool was, but they may send you a replacement (and a 25 dollar credit on my next order to cover return postage). In any event I think they need to know that they may have a potential problem with that particular line of tools.
Glad you weren't injured.
Tom

 

[steelguy]

Shattered Tool

Having spent more than a few decades looking at broken tooling, I have an opinion as to what the issues are, but know enough not to speculate because one has to evaluate the microstructure of the broken materials to be certain.

By all means, contact the retailer and the tooling manufacturer. They should be interested in evaluating the tool. They should want to evaluate the failure and determine if it is a "one of" or "one of many". You potentially can be doing a favor for a lot of other turners if it iturns out to be "one of many".

 

[MichaelMouse]

Looks like the straight part at the top of the tool was the culprit. Hopefully it wasn't a used tool that someone had overfed, bent, then straightened, causing the weakness there. Does it show any corrosion or other sign of preexistence compared to the stress fractures? Only tool I ever had - a cylindrical gouge - do that showed obvious sign that there was a preexisting condition.

Wet, or even somewhat wet wood will expand as it steams and grab the sides of the tool as you show there. It's a "catch" by any criterion. Why I part, pull, expand the kerf by half a thickness, then begin again when using my Sorby narrow tool.

 

[waltben]

At least five years back I had a hook shaped heavy duty Sorby bowl scraper from Woodcraft break in two at the tang - without a catch or hard use. The steel was thrown over onto the back of my hand, but landed flat and caused no damage other than getting my heart pounding. Woodcraft refunded my purchase price and I noticed they stopped selling that model some time back. I don't know if Sorby is still making them or not. Tools will once in a great while be flawed internally and fail - I think that comes with the territory. Someone may disagree and want to litigate everything, but I'd rather save that sort of thing for instances of blatant disregard of my safety.

 

[SteveFulgoni]

Thanks for all of your replies and good advice. I sent an email to Craft Supplies and to Henry Taylor in the UK, with the photos.

I purchased the tool new and have used it for about a year. Like I said, the odd thing was that there was very little up-force on the handle when it broke. We've all pushed a scraper a bit too hard and had the handle jump up, it was nothing like that. Also, while it did break at the tang, I believe the initial break was on the top surface about 1" away from the handle. If it broke at the tang, I can't see how it would have split in three pieces.

I was using it long point up, which I almost never do, but should be able to use it this way without the tool exploding. Maybe that is why I used it for a year without it breaking earlier.

Thank you for all of your comments. I have used Kryo gouges and have mixed feelings about them ... but I am now convinced that there is no need to buy a super brittle thin parting tool.

 

[Odie]

Thanks for all of your replies and good advice. I sent an email to Craft Supplies and to Henry Taylor in the UK, with the photos.

I purchased the tool new and have used it for about a year. Like I said, the odd thing was that there was very little up-force on the handle when it broke. We've all pushed a scraper a bit too hard and had the handle jump up, it was nothing like that. Also, while it did break at the tang, I believe the initial break was on the top surface about 1" away from the handle. If it broke at the tang, I can't see how it would have split in three pieces.

I was using it long point up, which I almost never do, but should be able to use it this way without the tool exploding. Maybe that is why I used it for a year without it breaking earlier.

Thank you for all of your comments. I have used Kryo gouges and have mixed feelings about them ... but I am now convinced that there is no need to buy a super brittle thin parting tool.

Thanks for showing us this, Steve.......

I also suspect the hardness of the steel. Too hard = brittle.

It also may be significant that you were using long point up. This may be a contributing factor, since the point is now much higher than the tool rest, over where you normally have it.......this gives much greater leverage, even in the event of a very minor catch.

If I had that broken tool, I could test the hardness where I work......would be interested to know what it was.........

I see a little "black residue" at the very tip. Did this occur at the time of the breakage, or at another time?

hog

 

[Robert Manning]

That was a beautiful tool, Steve. I would not use such a thin tool hand-held with the point up. It's no wonder it shattered.

Here's a parting tool I made from a 1/16" x 1/2" x 4 1/2" HSS metal working cut-off blade glued into a piece of Ipe. I use it with the point down for stability. The top could be ground a little flatter like your tool.

Working your way in by widening the kerf a few thousandths for clearance is also recommended.

 

[Ken Grunke]

Hardened steel is by it's nature fairly brittle and we may not notice it on a thicker tool. But one so thin like this should ideally be tempered back to less brittleness behind the tip. Or just harden the bottom edge, leaving the remainder of the blade at a lower, less brittle temper.
This was a common thing for carbon steel cutting tools way back in the days before HSS became popular.
A good suggestion for the manafucturer. Or it could be bimetal, like the sawblades.

 

[Scott Fruchter]

Thanks for all of your replies and good advice. I sent an email to Craft Supplies and to Henry Taylor in the UK, with the photos.

I purchased the tool new and have used it for about a year. Like I said, the odd thing was that there was very little up-force on the handle when it broke. We've all pushed a scraper a bit too hard and had the handle jump up, it was nothing like that. Also, while it did break at the tang, I believe the initial break was on the top surface about 1" away from the handle. If it broke at the tang, I can't see how it would have split in three pieces.

I was using it long point up, which I almost never do, but should be able to use it this way without the tool exploding. Maybe that is why I used it for a year without it breaking earlier.

Thank you for all of your comments. I have used Kryo gouges and have mixed feelings about them ... but I am now convinced that there is no need to buy a super brittle thin parting tool.

Did you receive any answers from the manufacturer or the seller?

 

[Neil S]

I was using it long point up, which I almost never do, but should be able to use it this way without the tool exploding.

That is the way I use thin parting tools. As I understand it, long point up provides maximum structural strength.

It could have been a flaw in the PM process, not necessarily poor tempering. Microscopic examination by a metallurgist will sort that out.

From what you have said I don't think it was your technique ...

.....

 

[Dave Roller]

Defective tool. Demand your $ back and buy a Sorby replacement. I've never had a problem with them.