Microstops for Aircraft Seat Tracks: WES396 and WES596-ER Extended Reach

A microstop countersink cage sets countersink depth by resting its skirt on the work while the cutter feeds through it. On an aircraft seat track the skirt has to fit inside the track channel first, so the skirt diameter and length decide which cage you can use.

The WES396 fits most seat tracks. It is built for tight spaces, with smaller cutters and a smaller footprint. Where the channel is narrower or deeper than the WES396 will take, the WES596-ER extended reach series reaches deeper into tight areas and hard-to-reach sections of an airframe.

How to Choose a Microstop for Seat Track Work

Four checks, in this order.

Step 1: Check the skirt diameter

Measure the clearance around the hole at the narrowest point of the channel. The skirt has to clear the channel walls with the footpiece flat on the work, so that measurement, not the hole size, is what rules models in or out. Start at the WES396, which is 0.688 inch across the skirt and fits most tracks. Where it will not clear, work down Table 1, which runs to 0.375 inch.

Step 2: Check the skirt length

A deeper channel needs a longer skirt. The WES396 skirt is 0.88 inch long. The WES596-ER series runs from 1.25 inch to 5.00 inch, and the three extended reach skirts in Table 1 are all 2.75 inch long.

Step 3: Check the cutter thread

Most Wescon microstops take a 1/4″-28 cutter. The WES596-ER8 takes a 10-32 cutter, which is the thread used for 1/4 inch diameter cutters, and 1/4 inch is its capacity. Check what your cutters are threaded for before you order.

Step 4: Check the shank

The shank is the end the drill motor holds. Both series come with a round, tri-flat or quick change shank. The WES396 also comes with a 1/4″-28 threaded shank for a threaded drill motor. Cutter threads are 1/4″-28 or M6x1 on either series, so a metric shop is covered on both.

Seat Track Microstop Selection Tables

Table 1: Skirts by outside diameter

Find the widest skirt that clears your channel, then read across for the cutter it holds. Most seat tracks take the WES396 at the foot of the table.

WES596-ER8 takes a 10-32 cutter thread, the thread for 1/4 inch cutters. The other three take 1/4″-28.

A narrower skirt holds a smaller cutter. Work down the table only as far as the channel makes you.

Table 2: The full extended reach range

If none of the three skirts above suit the job, the WES596-ER series carries four more.

See the WES596-ER series page for the full list with shank and cutter thread options.

What to Look For

Depth adjusts in 0.0005 inch increments with a solid stop on both series, on a 1/4 inch shaft with dual ball bearings rated to 10,000 rpm.

Shaft travel differs. The WES396 gives 4 mm standard, or 6 mm on the extended stroke version. The WES596-ER gives 0.300 inch, and adds a heavy duty thrust bearing and an integrated dust seal.

Skirt style is a separate choice from diameter. WES396 skirts come in straight, slotted, cutaway, 2-leg, 3-leg, internal thread, external thread and vacuum styles.

Footpieces are nylon or phenolic. Steel is available on request.

Choosing a microstop for seat track work comes down to two things: the skirt that clears the channel, and the cutter thread your shop runs. The WES396 covers most tracks, and the extended reach skirts cover the ones it cannot. Get these right and the depth control does the rest.

Every Wescon microstop countersink cage is made in USA.

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Read next: choosing your microstop countersink cage

The cutter, shank and footpiece choices are the same across every Wescon microstop series. Read the microstop guide.