Pancake Drill Attachments: The Most Compact Way to Drill Where the Motor Will Not Fit
By the Wescon Engineering Team · Last updated September 12, 2026A pancake drill attachment, also called an offset drill attachment, is a thin gear head that mounts in the drill motor chuck and moves the bit away from the motor. The motor stays outside the airframe structure while the flat steel body and the bit reach the hole. Wescon's WES900 series uses a 1/4-28 spindle for standard threaded drill bits.
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. The bit fits, but the chuck and motor body do not. An offset drill attachment moves the bit away from the motor so the hole can still be drilled.
Photo: Wescon Industries Inc., CC BY 4.0
A pancake drill attachment 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 tool goes by several names depending on the catalog: flat offset angle drill attachment, angle drill attachment, offset drill attachment, L-type drill attachment, drill offset adapter, and right-angle drill attachment. Most mechanics simply call it a pancake.
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, the WES900 fits.
How a drill attachment works
A drill attachment has three segments:
| Segment | Purpose |
|---|---|
| Drive shaft | Attaches to the drill motor and takes the rotational input from it. |
| Body | Runs parallel to the work surface. Its length sets how far the bit can reach from the motor. |
| Drill bit holder | Holds any drill bit or reamer with a 1/4"-28 thread. |
When an obstruction above a hole keeps the drill motor from lining up with it, the attachment provides the offset. The mechanic holds the motor at a comfortable angle where there is clearance, while the bit works in the tight space.
Using a drill attachment
- Attach the drill attachment to the drill motor.
- Thread the drill bit into the holder end of the attachment, sized for the hole the job calls for.
- Slide the attachment until the drill bit sits exactly over the hole location, then drill.
Understanding drill attachment specs
These are the key dimensions that define how a drill attachment is used. Knowing them also explains how drill attachments are selected and operated.
| Spec | What it means |
|---|---|
| Spindle thread | Thread of the attachment that drill bits screw into |
| Spindle offset (O) | Spindle centerline to the closest edge. Defines how close you can drill to a wall. |
| Drill offset (X) | Distance between the drive shaft centerline and the spindle centerline. Defines reach. |
| Overall length (L) | Horizontal end-to-end length, usually the part that runs parallel to the work surface |
| Overall height (H) | Vertical end-to-end length. Defines how deep it can reach, and whether the job needs the extra grip of a long handle. |
| Body thickness (T) | Vertical thickness of the gear body. Defines whether the attachment fits in the gap. |
| Body width (W) | Side-to-side width of the gear body. Also defines whether the attachment fits in the gap. |
| Offset angle | Straight, right-hand bend, or left-hand bend |
Drill offset and body thickness matter most:
- Drill offset: reach. How far past the last point the motor can sit the bit has to land.
- Body thickness: access. Whether the head can slide into the gap to get the job done.
Most standard offset heads run 0.33" or thicker and 0.88" wide. Wescon's WES900 series is 0.25" thick and 0.563" wide, so it gets into gaps other attachments cannot fit.
Choose your drill attachment configuration
Check these before choosing a drill attachment:
- Locate the drill site, the exact mark where the hole goes. Measure the distance from it to the closest spot with enough clearance to hold the drill motor.
- Measure around the drill site: the vertical clearance between the drill site and the closest obstruction above it, and the horizontal clearance.
- Check for obstructions along the path the attachment body will sit in while drilling.
With those measurements, use the table below to choose:
Standard handle
Long handle (hex grip shown)
| Body style | Offset | Standard | Long handle |
|---|---|---|---|
| Straight Pancake Drill Attachment | 2.29" | WES930 | WES935 |
| Straight Long Reach Pancake Drill Attachment | 3.05" | WES960 | WES965 |
| Right Hand Drill Attachment | 2.63" | WES970 | WES975 |
| Left Hand Drill Attachment | 2.63" | WES980 | WES985 |
Angled attachments
Step 3 tells you whether an angled attachment is needed to clear an obstruction on the way to the drill site:
- Choose a Right Hand Drill Attachment (WES970) or the long handle WES975 if the clearance lets the offset arm turn clockwise around the obstruction.
- Choose a Left Hand Drill Attachment (WES980) or the long handle WES985 if the clearance lets the offset arm turn counterclockwise around the obstruction.
Handle options
A standard drill attachment is 1.85" tall. When the hole is buried deep in a bay and the drill motor needs more height to work clear of obstructions, choose the 5.45" long handle.
A hex grip handle is also available for better ergonomics. It does not change performance. It is a quality-of-life option, so choose it on preference.
Rotation
Sometimes the drill site can only be reached with the drill bit on the same face as the input shank of the attachment. In that case the spindle rotation has to be reversed, which is what the Reversed Rotation Drill Attachment (WES930R) is for.