Where did that crack come from??

[Jerry Crice]

I looked back at a couple cigar pens I had made 3 or 4 weeks earlier and discovered a crack in each of them. One was made with Cocobolo and the other was Bocote. How could it happen and why did it not show up until later? Since I sand starting at 150 grit and go through 2000 grit I think the wood is getting too hot. Is this likely the cause? Any input will be appreciated. Thanks.

 

[LAKingsFan]

Heat build up when sanding. The cracks would have been so small to the eye. or:

Un-stabilized wood? Maybe

Ron

Happy Holidays

 

[JimGo]

Ron gave you a good lead. When speaking with DCBluesMan about a similar problem, he said that when you sand, if you let the heat build up, it will cause the moisture in the wood to evaporate. In many cases, you can wind up down in the 0-3% range. When the pen comes in the house, it soaks up more moisture from the air, and causes it to expand. Especially where there there is a strong finish, like CA, the expansion can cause the finish to crack.

 

[punkinn]

Jim and Ron,

What would the ideal lathe speed be for sanding? Also, I use a friction polish, Hut PPP, etc for finishing which requires a heat buildup to work... is this different from the potential crack-producing heat Jerry has experienced?

Thanks!
Nancy

 

[wayneis]

Nancy I do all of my sanding at the slowest speed so as to not build up heat, others will say that they do everything at one speed but this is how I do it and I very rarely ever have any heat assosiated problems. Also the other suggestion for you is to give up the friction polish, its a polish not a finish. IMHO Anytime you subject wood to excessive heat you are asking for trouble. Check out Enduro or CA even, they build up a fantastic finish that protects your work and gives a beautiful shine.

Wayne

 

[punkinn]

Originally posted by wayneis
<br />Nancy I do all of my sanding at the slowest speed so as to not build up heat, others will say that they do everything at one speed but this is how I do it and I very rarely ever have any heat assosiated problems. Also the other suggestion for you is to give up the friction polish, its a polish not a finish. IMHO Anytime you subject wood to excessive heat you are asking for trouble. Check out Enduro or CA even, they build up a fantastic finish that protects your work and gives a beautiful shine.

Wayne

Wayne,

Thank you very much! I admit, I'd like to try the CA/BLO finishing method but I don't have the [8][8]. LOL Errr, I mean I haven't worked up the courage. [] I also can't see how you keep the bushings from becoming CA'd to the blanks... but that's another thread. [)]

Nancy

 

[JimGo]

Nancy,
I'm working on my sanding technique, and although I don't change the lathe speed as Wayne does, I can see where this might be useful (kind of a pain to change on my lathe). I do agree with him that you'll want to explore other finishes outside FP's. If you've seen any of Wayne's pens or some of Tom Mullane's (OldGriz) more recent pens, you can see what a beautiful finish Enduro gives. I have cans of lacqor and poly in my "shop", but still haven't worked up the patience to try them; CA is my finish of choice, because I rarely know when I'll be getting out to the shop to do more work, and like to have something to bring inside and show off when the day is over.

Although that is good advice WRT sanding and finish choices, it didn't answer your question about FP's and heat build-up. If I'm not mistaken (which I may well be), many FP's include oils and other materials to help keep the shellac in a liquid form. My guess is that when you use an FP, you're heating it to burn off the other materials, and only leaving the shellac. Thus, although you're heating the wood which should, in theory, allow the wood to soak up more of the oils and other materials, you're also heating it so high that the oils and other materials burn off. So, you're still leaving the wood extra dry. The exception to this may be if you've succeeded in sanding it smooth without overheating the wood. The shellac and other stuff in the FP's may help seal the wood so the moisture can't escape.

Again, this is pure speculation, and I won't have a chance to get out in my shop to experiment for a while. Hopefully Russ Fairfield, DCBluesman, Wayne, or one of the others will jump in and correct anything I've said that was wrong.