Catch me if you can

[egnald]

Greetings all - Well, I looked through about 10 dozen blanks this morning looking for the prettiest piece of wood out of the entire lot to turn into a fantastic euro style pen. Maybe I was being too careful? I even trimmed the corners off on my bandsaw so I could start out more round-ish than usual....

At least I was able to find the big chunk after each catch so I could glue it back together. I'm going to wait until tomorrow to make sure the CA has had plenty of time to cure before I put it back on the lathe for one more try. I have a hunch that it is going to blow apart again though. In any case I am certain that the lower half of the blank will to make a beautiful keychain.

Dave

 

[qquake]

What kind of wood and what kind of tool were you using?

 

[leehljp]

Dave, when it blows apart, you can use CA, but for putting it back together, I would use epoxy. IF you do use CA, use thick. You want FULL adhesion on the full piece. Thin and sometimes medium will seek to run or spread out more, leaving small open spots under the piece.

The danger with CA, particularly thin is that it works enough that no one thinks it will happen to them.

The wood is thin, the RPMs exert a great force, a catch or even without a catch, there is little to no strength in the wood itself. Example, one can take a 3/8 in drill bit and force feed drilling into the middle of a 2/4. There is enough wood all around it to support it. But drill a 3/8" hole in a 3/4" blank, there is no strength there. And then turn it round, there is little integrity in a 1/16 to 1mm thick blank. IF there is not adhesion at 100% of the undersurface area, there is a chance it is going to explode.

This is why many do recommend epoxy; it holds better overall, Thin to medium CA will flow away from contact points. And then it works just enough that "it doesn't happen to me" syndrome hits!

Personally, on blanks like you just described - the best one in my stash, or a weak but beautiful blank - I move from epoxy to polyurethane so that it will get 100% adhesion over 100% of the underside. IF I am concerned about a segment coming out, I use gauze on the outside and CA the heck out of it until it is turned to size.

 

[egnald]

Hi all - it was a nice piece of cocobolo and i was using a round carbide. It almost looked like there was some kind of dark inclusion where the chunk came out. (There was a small stripe of sapwood on the outside).

I will most likely wind up with a keychain and start the pen over with another blank tomorrow.

Dave

 

[qquake]

How do you hold the edge of the carbide when you're cutting? Parallel or at an angle? I find when using carbide, when I hold it at an angle for a more "shearing" cut, I get less catches.

 

[tomas]

How do you hold the edge of the carbide when you're cutting? Parallel or at an angle? I find when using carbide, when I hold it at an angle for a more "shearing" cut, I get less catches.

I have found the same thing. I also find my round carbide cutter to be less catchy. I use the corners of the square carbide for roughing and then switch to the round.

 

[qquake]

I have found the same thing. I also find my round carbide cutter to be less catchy. I use the corners of the square carbide for roughing and then switch to the round.

I generally use square cutters with a radius, but I haven't had any problems straight square cutters, either. As long as you're holding it at an angle, it's limiting the contact area.

 

[egnald]

As some have asked, I usually start with a round cutter, depending on the material it is usually the Magical Skew which does more of a shear scrape especially until the material is perfectly round. Then I use a standard EWT round and 2-inch radiused square for final shaping.

Update: I was successful in turning it this morning; however, after sanding I noticed a couple of spots that definitely look like some kind of bark inclusion or something - very porous looking spots not near the repair area. I have some medium CA on them right now so I will go back and re-sand in a hour or so. It might make a pen yet.

Dave

 

[egnald]

It did make it into being a pen, but because of the catch I'm afraid it will need to go to my "less than desirable" collection. I still think the wood was quite pretty. - Dave

 

[leehljp]

Excellent finish!

 

[David350]

Wonderful blank and finish. I'd like to shop in your blank stash....

 

[tomas]

Very nice. I don't mind inclusions in my blanks. I think they give it character. Many years ago I was in the leather goods business with my brother. We had just visited a customer who had a leather covered counter top for their cash register to sit on. In the middle of it was an "ugly" scar. I suggested that we offer them a new leather cover without any blemishes. For the next hour I got a lecture about design, contrasts, character, and relative perfection. That's a beautiful blank, IMHO.

Tomas