If I had to describe my ShopBot CNC in one word, it would be, ‘versatile’. I can’t think of any other tool that I have purchased during my lifetime that can do as many tasks that my ShopBot can. I think that ShopBotters are also equally versatile, especially when it comes to doing big things on a small budget or inventing new economical solutions to seemingly expensive problems.
One really great aspect of a ShopBot tool, is that you can add accessories and customize your machine as your budget allows. This means that if you can’t initially afford a spindle, you can still get started right away with a standard woodworking router as your cutting tool. (Spindles typically run smoother and quieter than your average garden variety wood router. They have precise speed control, higher duty cycles and offer collet sizes that can accommodate bits from 1/16” to 5/8” diameter, typically in 1/16” increments.)
But I know that many ShopBot owners who have a standard wood router on their ShopBot, want to try their hand at engraving, or take advantage of 1/8” shank tools for finer work. The problem is that most router manufacturers don’t make accessory collets for their tools outside the normal ¼” & ½” sizes. The first thing that I tried was one of those collet-sleeve adapters; you know, the kind with the ¼” shank and set screw? It was hardly worth the effort because the run-out caused by the poor fit of the 1/8” bit made precise cutting impossible. That’s where the story ends for most of us stuck with ¼” & ½” collets.
Stubby Collet Chuc
Well I’ve got some good news for all of us with a standard router! While browsing for metalworking tools, I stumbled across a ½” shank ER-11 “Stubby Collet Chuck”. The ER-11 chuck slips into any ½” collet like any other tool, but has a miniature collet & nut on the tip of it. It has an overall length of 3.5” and it only costs $65. For about $15 apiece, you can get collets that accept 1/32, 1/16, 3/32, 1/8, 3/16, 7/32 & ¼” shank tools. This means that you can use cheap end mills and specialty bits in your standard wood router! To add to this new-found flexibility, you can buy the ETM-brand collets, which give you a collet range of .04” +/- advertised diameter to fit those odd-sized or even metric shank bits in your router. The collets & holder are designed for high-precision and have an advertised run-out of only .0002”; which is a lot better than the set screw insert I initially tried. ER-11 stubby collet chucks are available from many of the larger industrial supply houses. Be sure to get a set of ER-11 wrenches so you can use your small bits as soon as the collet chuck arrives!
Here’s a link to Enco, who sells the collet holder & ER11 collets: www.use-enco.com
[Enco Part Numbers: Stubby Collet Chuck: Model #308-0018, 1/8″ ER11 ETM Brand Spring Collet: Model #891-6984]