Shrinking and Swelling issue

[get'n_green]

ok... I have been turning my own calls for about 2 years now... on and off and took about a year to FINALLY perfect one... i only work on them in spare time, which now a days is few and far between because i work about 12-14 hour days... After MUCHO MUCHO trial and error i got the insert where i wanted it to be (alot of spare and broken cocobolo and bois' d arc wasted but thats besides the point). I used the call last year and killed ducks with it but this year, either the barrel swelled up or the insert shrunk down... Long story short, i acetoned the call after it was finished and lightly coated polyurethane on it... any ideas on a way to "harden" the final product to get rid of the shrinking and swelling issue... I have about 25 ft. of cocobolo stock, 20 ft. of bois d arc, and about 10 ft. of true African Blackwood (hasn't been spun yet). Again i am making my own barrel AND my own insert just need some help with the hardening process... Thanks, Wade

[deeksdown]

well thats some of the issues your run into turning wood calls. there are several reason this could be happening.
#1 the wood that your turning has too high of moisture content. typically when buying wood make sure its kiln dried with 10-17% MC some people even like to go lower than that. the more moisture in the wood the more its going to shrink and contract in the summer and winter months.
#2 there are far better finishes than polyurethane for wooden calls. poly is gummy and doesn't really ever cure on oily woods especially coco. i would suggest getting familiar with CA finishes (super glue finish). i have also seen people us 1 min epoxy or UV poxy and work great. CA finishes to me are the most durable and best looking finish there is, but getting it down pat will test your anger skills lol.
#3 another way to releive some of the sticking issues is to O-ring your inserts. being from the south we just have a lot of moisture in the air anyway and unless your really go full lengths to put a total inside and out finish on the call, its still going to expand and contract. therefore by using an o ring it will give you an 1/16th or so tollerance letting you get the insert our when contracted.

If you have any questions or need help with anything feel free to pm me and ill try to help you the best i can!