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no checking with very small turnings?

Here's my situation:

1) I'm a complete noob to turning (this is basically my first project ever, and I've never actually seen anyone use a lathe before)

2) I have some 5" or so diameter walnut logs I was going to do some bowyering with (but they ended up with too many knots) that have been sitting in my driveway for 10 months. The ends were checked about an inch into the wood, but the rest seemed reasonable for what I wanted to do.

3) Goal: nice small project that I can finish without getting terribly frustrated that isn't pens (pens just don't do it for me). I decided to try to make some small sake cups (essentially a 2"x2" or so shotglass).

So, what I did was cut off a foot from the end of the log, ran it over the jointer to make 3 sides with 90 degree faces, then quartered it on the table saw. I then cut off the checked ends, and cut the 4 quarters into 4" long blanks to give me plenty of room to work with.

I turned my blanks round between centers, drilled out a 1.5" deep starter hole with a forstner bit on the drill press, then chucked up what I had on the lathe with a self-centering chuck. I scraped out the inside, shaped the outside, sanded both, then used a parting tool to cut the basically finished piece off.

I was fairly pleased with what I got as a first attempt, but figured I could do better, so I just set that aside as-is for a few days. After observing it for a bit, I am a bit puzzled. I can perceive absolutely no checking on my finished cup, and I didn't do anything on it to prevent checking. The end of the log that I cut my starter piece from is already checking badly at this point.

So.. the real questions:

1) Do small things such as tiny bowls or pens not check? (or not check as badly?) 2) In another month am I going to see checking on my cup? 3) If 2) is true, if I polyurethane my cup now, would it then not check since no more moisture could escape? 4) Would my results be a lot different if I was using very green wood?

And one question related to my project, but not the checking:

5) After I part my piece off, is there any convenient way of sanding the bottom (or turning a divot)? Turning it around in the chuck will scratch it all up. Here are the ideas I've come up with: a) rubberized chuck jaws or strips of rubber between the jaw and the piece b) hot glue + face plate (centering would seem to be an awful chore if I wanted to make say... 80 of these) c) jam chuck (I'd have to make all of them exactly the same time if I wanted to make several)
Reply to
quixote
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Reply to
Mizz Patty

You've actually done pretty well for yourself, especially if you've not turned before. I'll try to answer your questions to the best of MY knowledge. Others may do things differently.

Yes, they will. I've had a pen crack 4 months after it was made. The size of the piece is really irrelevant to the cracking or checking process. What is relevant is the dryness of the wood to start with and the overall thickness of the material when you are done. Evenly thin vessels will crack less. They may warp but cracking will be minimized.

You might.

Finish on top of wet wood usually doesn't work. At best it will cloud the finish. It has been my experience that even finished, wood will find a way to crack. I don't think you can truly seal a surface if there is water present underneath. The finish will not "stick" as it should...I think.

Not necessarily but as stated above, turning green is a matter of turnning thin. You can take a wet log, turn it as thin as you can and finish it right on the lathe. But you need to be fast. I have had cases where the wood cracked right before my eyes while on the lathe. Some times the heat from sanding alone will do it.

I think you have exhausted pretty all the avenues open to you. All are valid ways to chuck up the piece, the problem with your question is the "turning 80 pieces" part. As you become more proficient as a turner, you get better at sizing things just right. I've made jaw chucks that have been used to finish pieces in the hundreds and which are still in use today. I just finished turning 500 items and used the same jam chuck to finish the tops in this case so that there was no nub visible.

Practice making a uniform tenon on your pieces, of the same constant diameter which you can mount in a jam chuck. If it gets a little sloppy at times and doesn't fit quite right, you can spray a little water on the chuck which expands the wood to get a better fit. Another alternative is to use a piece of paper towel wedged between the chuck and the piece.

The one thing I would like to point out is that wood will crack much more if the pith is retained. In your process of cutting up your blanks, I would have remove the center completely, then used the rest to make the square blanks. The pith is your worst enemy as far as cracking goes.

I hope this helps.

Mike Courteau snipped-for-privacy@toymakersite.com

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Reply to
Mike R. Courteau

Thin things dry more evenly, which minimizes possibilities for checking. Your long-grain configuration leaves you vulnerable to checks in the bottom, produced by the same mechanism which produced the end checks you removed.

Possible. Depends on how gently and evenly you dry them. I'd put them on stickers to provide air to both sides of the bottom, a method which works for me.

As mentioned, you're going to get gum for a long time. Not to mention that you'll get rough surfaces again as things dry, so you might want to wait a bit until the pieces are dryer.

I part off with a concavity in the bottom using a parting tool and gouge or chisel to trim it smooth where the scrape leaves rough spots or pills fibers. If you leave a half inch stub sticking out, you can whittle it away fairly easily with a curved knife. Some people use a carving gouge, but I find the knife easier, because I can hold the piece in one hand and whittle with the other while bracing with my thumb. Parting off is helped greatly by using a wooden cone center held in place by your revolving tailstock, as is working the outside slim or giving it a stem. Suggest it as a great turning aid. I've a NOVA center which allows me to bolt on any size disk or cone I want, but other methods work.

I use a flexible shaft and small disk to sand, so after carving the stub relatively flush, I can use the curvature of the disk to follow the concavity while leaving the rim unsanded for later levelling.

Reply to
George

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