29 June 2017
29 June 2017,

Drill bits and end mills are the most common cutting tools in CNC machining. Each has its place in the shop. Chucks hold drill bits in place.  Collets or end mill holders hold end mills in place. End mill holders are more expensive than collets and they don’t grip as well. That’s why we aren’t going to cover them in this blog.  There are two types of collets: Morse taper and R8. A common question is does the R8 tool holder work better, worse or equal to the Morse taper. Let’s take a look.

The Morse Taper Tool Holder

The Morse Twist Drill Company developed the Morse taper. Stephen Morse founded the company in Massachusetts.  Morse invented the twist drill and needed a way to hold the tool. Behold the Morse taper is born.

The Morse taper has a continuous taper.  A set screw holds this type of collet in place. Machines that utilize a drawbar are rare and are generally the result of a modification.

The Morse taper is designed for infrequent changes. It really isn’t made for automated tool changing. If your shop has upgraded to auto tool changing, you must switch to the R8 tool holder.

You find the Morse Taper used in mini mills and hobbyist’s machines. It is not commonly used in an industrial setting.

R8 tool holderThe R8 Tool Holder

The Bridgeport Machine Company in Bridgeport, Connecticut developed the R8 tool holder to respond to the need for quicker tool changes.  R8 tapers are straight and then flare to a taper.

The R8 tool holder does not use a set screw; it utilizes a drawbar. Because it allows for much more efficient tool changing, it is more common in industrial settings. Maintain the same z height every time you remove and reinstall the tool with an R8 tool holder. Another plus for professional machining.

Many R8 endmill holders are readily available. Because they are common, they are much less expensive.

r8 tool holder protects collets

R8 Tool Trays

If you use R8 collets, you need a place to put them. Sierra America Multi-Systems makes trays to handle R8 collets securely. The strong, high-impact plastic protects tooling.  If you want the best, only use R8 tool holders and demand a tool tray made in the USA by Sierra American. Ask for it by name.



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