I have three chains that I rotate when needed then pay the 7 bucks each at the local shop. I bought the kit raybonz posted a while back and watched the videos and understand the process, but no one mentions how you know which size to use for what chain. Help me out here. I've got a Dremel and certainly not opposed to an attachment to do the job. Looked at the timberline doohickey online but seems pricey for what it is.