September 4, 2026

Pancake Drill Attachments: The Most Compact Way to Drill Where the Motor Will Not Fit

Every airframe has holes the drill motor cannot reach. A rib sits behind a spar cap, a bracket lands inside a channel, a fastener row runs under a flange with a finger's width of clearance. The bit clears it. The chuck and motor body do not.

A pancake drill attachment solves that. It is a flat gear head that mounts in the drill motor chuck and carries the drive out to a spindle at the far end of a thin steel body. The motor stays outside the structure while the thin body and bit go in.

Catalogs call the same tool by several names: flat offset angle drill attachment, angle drill attachment, offset drill attachment, L-type drill attachment, drill offset adapter, right angle drill attachment. Mechanics call it a pancake. Whatever you call it, it's a 1/4-28 bit holder on the end of a flat gear train. The specs below are the same ones every catalog lists.

What the WES900 series is built for

Wescon WES900 series attachments are built around one priority: compactness. The body is 0.250 in thick and 0.563 in wide, and the attachment is light in the hand. No other flat offset head is as thin or as narrow. It is made for holes nothing bigger will reach.

The trade-off is that it is light duty. The WES900 is a light duty attachment for aluminum sheet and light structure with 1/4-28 threaded drill bits, not a heavy production head for thick stacks or large diameters. For high volume drilling in open access, a full size angle drill attachment or a dedicated angle drill motor holds up better. For the hole under the stringer that a full size head can't get near, this is what you reach for.

How it works

The attachment has a drive shaft on one end and a threaded spindle on the other, connected by gears inside the body. The drive shaft goes in the drill motor chuck like any bit. The spindle takes a 1/4-28 threaded drill bit, the standard thread on aircraft drill motors, so the bits already in the toolbox fit.

WES900 attachments have a 1/4 in round drive shaft and a 1/4-28 spindle. A handle on the shaft end gives the second hand something to hold against torque: 1/2 in round as standard, or an 11/16 in hex on the -HX versions so a wrench can hold it.

Reading the specs

Angle drill attachment catalogs, Wescon's included, describe each model with the same set of dimensions. Those numbers tell you if the head fits the gap and if the bit reaches the hole.

Spec	What it means	WES900 series
Spindle thread	Thread the drill bit screws into	1/4-28
Spindle offset	Spindle centerline to the face of the body, how close the bit gets to a surface	0.281 in
Drill offset	Drive shaft centerline to spindle centerline, the reach	2.29, 2.63 or 3.05 in
Overall length	End to end	2.85 to 3.61 in
Overall height	Top of handle to bottom of body	1.85 in standard, 5.45 in long handle
Body thickness	The number that decides whether it fits in the gap	0.250 in
Body width	Side to side	0.563 in
Angle	Straight, right hand or left hand	All three

Two of these matter most. Drill offset is reach: how far past the last point the motor can sit the bit has to land. Body thickness is access: the gap the head has to slide into. Other flat offset heads run 0.33 in or thicker and up to 0.88 in wide. At 0.250 by 0.563 in the WES900 gets into gaps they do not.

Straight, right hand, left hand

The spindle can sit three ways relative to the drive shaft.

Wescon WES930 pancake drill attachment, straight, 2.29 in drill offset — **WES930**Straight, 2.29 in

Wescon WES960 pancake drill attachment, straight, 3.05 in drill offset — **WES960**Straight, 3.05 in

Wescon WES970 pancake drill attachment, right hand — **WES970**Right hand, 2.63 in

Wescon WES980 pancake drill attachment, left hand — **WES980**Left hand, 2.63 in

Wescon WES935-HX pancake drill attachment with long 11/16 in hex handle — **WES935**Long handle, hex shown

Straight Pancake Drill Attachment (WES930). Spindle directly ahead of the drive shaft along the body, 2.29 in drill offset. The default pancake head. Long handle version WES935, long hex handle version WES935-HX.
Straight Long Reach Pancake Drill Attachment (WES960). Same layout with a 3.05 in drill offset, 0.76 in more reach. Long handle version WES965, long hex handle version WES965-HX.
Right Hand Drill Attachment (WES970). The body angles so the spindle sits to the right of the drive shaft, 2.63 in drill offset. For holes beside an obstruction that a straight head would have to pass through. Long handle version WES975, long hex handle version WES975-HX.
Left Hand Drill Attachment (WES980). Mirror image of the right hand, 2.63 in drill offset. Same job from the other side. Long handle version WES985, long hex handle version WES985-HX.
Reversed Rotation Drill Attachment (WES930R). Straight 2.29 in body with the spindle turning the other way, see below.

That is the full WES900 range: 13 part numbers, four body styles, standard or long handle, round or hex grip, plus the reversed rotation WES930R.

Standard and long handle

Each style comes in two overall heights: 1.85 in with the standard handle, or 5.45 in with the long handle on the WES935, WES965, WES975 and WES985 models. The long handle puts your hand farther from the work, for holes buried deep in a bay.

Standard and reversed rotation

The gear train turns the spindle in a set direction relative to the drive shaft. The WES930R is the reversed rotation version of the WES930, also called a reverse spindle type, for setups where the head has to be presented the other way up and the bit still has to cut right hand.

What it pairs with

Check the spindle thread before ordering. Some makers offer 10-32 and 1/4-28 spindles under different suffixes. Wescon WES900 attachments are 1/4-28 only, and take any standard 1/4-28 threaded drill bit. All WES900 series attachments are made in the USA.

Any 1/4-28 threaded bit fits, including Wescon threaded drill extensions when the hole is deep as well as hard to reach.