How to Use Round Shank Tools in a 1/4-28 Threaded Drill

To use a round shank tool in a 1/4-28 threaded drill, fit a threaded drill collet between the two. A straight shank bit has no thread, and the drill spindle has no chuck. The WES1605 threaded drill collet threads into the 1/4-28 spindle, and the round shank tool goes into the collet. Drill bits, reamers, countersink cutters and deburring cutters all fit, as long as the shank matches the collet size.

Threaded drill or round shank bit

Angle drill motors used in aircraft assembly have a 1/4-28 threaded spindle. So does the output spindle of a pancake drill attachment. The drill bits made for them have a matching 1/4-28 thread on the shank and screw straight in. Most other drills, reamers and cutters have a plain round shank made for a chuck.

The WES1605 collet has a 1/4-28 male thread on one end and a collet sized to one shank diameter on the other. With it in the spindle, the drill or attachment takes a standard shank tool of that size.

The 1/4" (0.250") round shank collet

A common example: a shop buys drill bits or cutters with a 1/4" shank and needs to run them on a 1/4-28 threaded angle drill or a pancake drill attachment. The WES1605-2500 1/4" threaded drill collet takes a 1/4 inch (0.250") round shank and threads into the 1/4-28 spindle, so those tools run on the drill without a chuck.

If your bit or cutter has a 1/4" or 0.25" straight shank and your drill has a 1/4-28 threaded spindle, the WES1605-2500 is the part to order.

How to use a round shank tool in a threaded drill

1. Pick the collet that matches the shank diameter of the tool.
2. Thread the collet into the 1/4-28 spindle of the drill or attachment.
3. Insert the tool shank into the collet.
4. Tighten the collet nut with a wrench.

The collet has a 120 degree seat that matches the spindle of most aircraft angle drills, so it seats square on the drill and the tool runs true.

Each WES1605 comes with its collet nut. The collet body has a 7/16" hex and the nut a 1/2" hex. Overall length is 0.88".

Sizes

WES1605 collets come in wire gauge, letter, fractional and decimal sizes from #50 (0.0700") to F (0.2570").

Custom bore sizes are made to order for shanks outside the stock range. Order one from the WES1605 product page by choosing the custom size option. WES1605 collets ship in about two weeks. All WES1605 collets are made in USA.

To order, open the WES1605 threaded drill collet series and pick a size.

Frequently asked questions

How do I use a 1/4" round shank tool in a threaded drill?

Thread a WES1605-2500 collet into the 1/4-28 spindle of the angle drill, insert the 1/4" shank and tighten the collet nut with a wrench.

What collet fits a 0.25" round shank bit?

The WES1605-2500. It holds a 1/4" (0.250") round shank and threads into a 1/4-28 threaded drill spindle.

Can I use the collet on a pancake drill attachment?

Yes. A pancake drill attachment has a 1/4-28 output spindle, so the WES1605 threads into it the same way it threads into an angle drill.

Where can I buy a 1/4-28 threaded drill collet?

Wescon sells WES1605 threaded drill collets online at wesconusa.com in sizes from #50 (0.0700") to F (0.2570"), with custom sizes made to order.

What seat angle does the WES1605 collet have?

120 degrees, which matches the spindle of most aircraft angle drills.

Can I get a collet for a size that is not listed?

Yes. Custom bore sizes are made to order. Choose the custom size option on the WES1605 product page.

Running quick change tools instead

If your tools have a quick change shank rather than a round shank, put a quick change chuck on the drill instead of a collet. The WES1760 short quick change drill chuck fits a 1/4-28 threaded angle drill or pancake drill attachment. The WES1750 quick change drill chuck threads onto most pistol grip drills, usually a 3/8-24 spindle. For round shank bits in a quick change chuck, Wescon makes WES1615 short and WES1625 standard quick change collets.

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