Tru-stone blew up on me.

[Scott.tudhope]

I was trying my first tru-stone today (banded malachite). As I was getting close to the size I needed I stopped the lathe to look at it and noticed some small cracks at the end of it. I fixed those up with some ca and moved on.

I started the lower barrel and had the same thing. Small cracks at the end of the blank once it was close to size. Again with with the ca, only this time as I was getting just about done the whole blank flew apart.

I sharpened my tools at least 5 times while working this blank. Any other ideas on where I may be going wrong on this?

 

[ed4copies]

I suspect it got hot.

 

[THarvey]

heat would be my guess.

 

[Scott.tudhope]

So I need to slow the late down a bit? And maybe a little more patience on my end?

 

[ed4copies]

The heat is built up by friction.

A lathe running fast will cool the blank as it turns, more than a lathe running slow.

I am NOT an expert at sharpening my tools, but when I find that the end of the tool is getting hot, or when I touch the blank and it is too warm to comfortably touch, it is time to attempt to sharpen and let the blank cool off.

Sorry, not trying to be mean but a sharp tool, used to CUT will not generate excessive heat, so either you are not hitting the blank with the sharp edge, or you don't have a sharp enough edge. I have had the same problem---so I feel the blank after each couple of passes. If it is getting too hot to touch---let it cool---it can keep spinning, just have a cool drink and wait a little while.

 

[gallianp]

1. sharp tool
2. turn fast
3. do not try to take off too much material - patience

this is what works for me... I am SURE someone will disagree

 

[Frank Nemke sr]

I have a turncrafter commander and I turn at close to 4,000 rpm.Ttools must be super sharp

 

[ren-lathe]

While I used to use hss, anymore I use carbide on Tru-stone, and I don't get to aggressive when I'm working.

 

[Scott.tudhope]

Thanks for the tips! I'm thinking I'll try another tru-stone in the next few days.

 

[joefyffe]

Scott: Were you turning between centers? Were you turning on a mandrel? Either way, how tight were your bushings and were they sitting against the stone or the tube. If against the stone, it probably wouldn't take as much "skewabuse" as if against the brass. Reason I ask, some folks turn to near size, strictly between centers, before tubing . It could be a comedy of errors!

 

[randyrls]

You can also get cracks starting when you drill the blank. Make sure the drill bit is sharp and sharpen it with a Drill Doctor about every 20 pens or so.

 

[Scott.tudhope]

I was using a mandrel. I'm not good enough to go between the centers yet.

Will a drill doctor work on the brad point bits?

 

[PTsideshow]

Short answer is no it will not you can stone them by hand. Drilling with a brad point isn't a good idea in anything other than wood.
:clown:

 

[leestoresund]

I know that sometimes I leave the blank a skosh longer than the tube. I turn it to close to the final size and then sand it on a mill to final length. Then I turn it to final size. But that will put pressure on the blank and if I turn it too much before sanding it to size it has caused blanks to blow up. Doesn't take much extra length to do that.

Lee