DAESSY Mounting System
Fitting a DAESSY Mount


The purpose of a wheelchair mount is to securely hold an augmentative communication or laptop computer in the correct position for the person using the wheelchair to access the device as comfortably as possible.

Fitting a wheelchair mount determines the location and size for the Frame Clamp attached to the wheelchair frame and the correct lengths and bends for the stainless steel tubes that support the mount. These lengths are determined by the relationship between the position of the mounted device and the location on the wheelchair where the Frame Clamp will be attached. It is essential that the optimum position for the mounted device be located before the fitting procedure is done.

By following the fitting procedure the purchaser will ensure that the correct components are specified in an order. When the mounted device will be used by direct access and the wheelchair is a medium size in many cases the standard mounting assemblies, with correct Frame Clamp Inner Piece size, will be suitable.

When the device will be used in a scanning or head-pointer mode, or when the wheelchair is unusually large or small it is essential that the fitting procedures be followed to determine the correct lengths and shapes of tubes as well as any other necessary component adjustments.

The fitting procedure will require an accurate ruler or tape measure.

[GO TO: Fitting the Frame Clamp] | [GO TO: Fitting the Mount Tubes]

Selecting the Attachment Location for the Frame Clamp Inner Piece

All DAESSY mounting assemblies can be mounted on either the left or right side of a wheelchair as defined from the position of the person seated in the wheelchair. With the exception of the DAESSY Lockable Rear Folding Mount DLRFM8 the parts comprising each mount may be mounted on either side of the wheelchair. The Lock Mechanism of the DLRFM8 is specific to either the right or left side of the wheelchair from the User’s point-of-view, and this side must be specified at the time of order.

On a Non-Tilting Seat System

The Frame Clamp Inner Piece (UFCxxxxIP) requires slightly more than two inches of length and three-quarter inches of space above and below the wheelchair frame tube to which it will be clamped. There should be sufficient room for a hand to reach behind the tube to tighten bolts. It does not matter how the wheelchair frame tube is oriented because the Swivel Clamps allow the Offset Links and Rear Folding Adapter to be rotated to any angle relative to the Frame Clamp Inner Piece.


The selected location must be part of the wheelchair frame, not a removable armrest or footrest.

Often the best location for the Frame Clamp assembly will be near the front caster wheel but preferably not above it. The Vertical Tube for the mount protrudes down through the hole in the Frame Clamp Outer Piece and the range of height adjustment for the mount may be limited if the tube interferes with the caster wheel.

In most situations the Frame Clamp Inner Piece will be located forward or backward from the position for the mounted device and the Vertical Tube supported by the Frame Clamp Outer Piece will have an S-bend.

[GO TO: Gallery of photos of Frame Clamp Locations]

On a Tilting Seat System

On a wheelchair with a tilting seat system, the mounting assembly should be attached to the tilting seat to maintain positioning of the device relative to the user, independent of the configuration of the wheelchair. On tilting seat systems it is strongly recommended that a Removable Frame Clamp be used.

[GO TO: Information on Mounting with Tilting Seat Systems] | [GO TO: Gallery of photos of Frame Clamp Locations]


Obstructions directly above the selected location, such as the brake lever or other controls that are closer than 10 inches, may interfere with insertion and removal of the Vertical Tube. To avoid this interference it may be necessary to use an Offset Link (O3L) or a Frame Clamp Spacer (UFCSPCR) between the Inner and Outer Piece of the Frame Clamp to move the Outer Piece further out or position it sideways from the location of the Inner Piece.

Quick Check

A quick check for a suitable location for the Frame Clamp Inner Piece is to find a part of the frame tube which has enough space to be gripped by three fingers when reaching from inside the wheelchair frame.

Unusual Situations

Some wheelchairs do not have any tubing freely accessible on the frame or may not have a tube frame. When a seat pan restricts access to the upper edge of the wheelchair frame tubing, it may be possible to use a Side Mount Frame Clamp Inner Piece, which requires no clearance on the topside of the tube and only 1 1/4" clearance on the bottomside.

When the wheelchair does not have a tube frame it may have boltholes or other possible attachment methods for a Bolt-on Adapter.

Measuring and Specifying the size of Frame Clamp Inner Piece

More information on the range of available Frame Clamp Inner Piece sizes is available in the Frame Clamp Section. For wheelchair frames with round or rectangular tubing it will be necessary to measure the dimensions of the tubing to obtain the correct frame clamp size.


The DAESSY Gauge is a specially designed tool provided with DAESSY Assessment Kits. The calibrated semi-circular cutouts along three edges of the DAESSY Gauge can be used to quickly determine the diameter of wheelchair tubing. A five-inch ruler with 1/8” gradations can be used to measure the dimensions of rectangular or square tubing.

Other Measurement Methods

Measuring the Tube Size - Round

The preferred method for measuring the exact size of round wheelchair frame tubing is to use a micrometer or dial caliper to directly measure the diameter.

If these instruments are not available an alternative method is to measure the circumference of the tube. A thin strip of paper, a pencil, and a straight ruler marked in inches are the required tools. Wrap the strip of paper around the tube so that it overlaps slightly. Draw a line across the edge of the paper to put a mark on both the inner and outer wrap.

Unwrap the strip of paper from the tube and using the ruler measure the distance between the two pencil marks – this is the circumference of the round tube. The measured circumference can be converted to the corresponding diameter measurement using the following table.

CircumferenceDiameterCorrect Frame Clamp Size
2.36" – slightly less than 2 3/8"3/4"UFC750IP (or UFC1000IP+SLV)
2.75" – exactly 2 3/4" 7/8"UFC875IP
3.14" – slightly less than 3 3/16"1"UFC1000IP
3.53" – slightly more than 3 1/2"1 1/8"UFC1125IP (or UFC1500IP+SLV)
3.93" – slightly less than 3 15/16"1 1/4"UFC1250IP (or UFC1500IP+SLV)
4.71" – slightly less than 4 3/4"1 1/2"UFC1500IP
6.28" – slightly more than 6 1/4"2"UFC2000IP
Measuring the Tube Size - Square or Rectangular

The dimensions of square or rectangular tube can be measured with a good ruler; normally the square tube will have square corners and the ruler can be held accurately against the tube. It is unusual to find any sizes other than 3/4 inch, 7/8 inch, 1 inch, or 1-1/2 inch.

Some wheelchairs have what appears to be rectangular tube, but is actually an aluminum extrusion. These nearly rectangular shapes are more difficult to measure particularly when the corners or sides are rounded and it is almost essential to use a proper measuring instrument such as dial calipers. The circumference measurement is not useful for square or rectangular tube.

Bolt-on Adapter and Wheelchair Specific Sizes

See Frame Clamp Inner Piece - Wheelchair Specific Sizes for more information on Frame Clamp Inner Piece styles for some specific wheelchair styles.

Additional Frame Clamp Components

It may be necessary to include extra frame clamp components such as Offset Links or Frame Clamp Spacers to ensure that the mount will not interfere with or contact any other parts of the wheelchair, for example the wheels, brake levers, or power-drive controls. More information on connecting Frame Clamp components can be found HERE.

Fitting Mount Tubes

In most mounting situations the standard STR16 horizontal tube will be sufficient to place the Quick Release Base and mounted device in a central location in front of the user. There will usually not be any need for excess tube to protrude beyond the device.

If the mount requires an Opposite Side Support it may be necessary to order a longer horizontal tube.

DAESSY Rigid Mount and DAESSY Folding Mount

The standard Vertical Tube supplied with the DAESSY Rigid Mount and DAESSY Folding mount is 22 inches long with a 3 inch S-bend to offset the tube ends (S22x3). This tube is suitable for many mounting situations.

DAESSY Locking Swing-away Mount

The standard tube supplied with the DAESSY Locking Swing-away Mount is the RT22x16. For smaller wheelchairs or for situations where the frame clamps is attached high on the wheelchair (for example onto the seat frame) it may be necessary to order a modified Right-Angle tube with a decreased vertical dimension. Tubes are available in RT20x16, RT18x16 and RT16x16 sizes.

DAESSY Rear Folding Mount and DAESSY Lockable Rear Folding Mount

The standard Side Tube for the DRFM6 and DLRFM8 mounts is the STR22. It is possible to substitute this straight tube with an S-Bent tube for clearance around obstacles along the side of the wheelchair. The Side Tube may also be ordered in a different length (available in 2" increments). The length of the Side Tube affects both the In-Use location and the Stored location behind the chair, so both locations must be considered when choosing a non-standard Side Tube length.

DAESSY Mounting System

Selecting a DAESSY Mount Assembly

Rigid Mount

Folding Mount

Locking Swing-Away Mount

Rear Folding Mount

Lockable Rear Folding Mount

Positioner Mount

Desk Mount & Clamp Desk Mount

Rolling Mount
RM-24 & RM-32

More information on the DAESSY Mounting System

Catalog, Ordering and Prices


Copyright 2006