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When Used with a Screw the 8-32 (M4) Tap Acts as a Rotational Stop

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BA2E Mechanical Drawing
(Click Here for the Metric BA2E/M Drawing)

Features

• Mounting Base with a Ø1/2" (Ø12.7 mm) Double Bore and Flexure Clamping Mechanism
• Mounts Ø1/2" (Ø12.7 mm) Posts
• 0.24" (6.0 mm) of Height Adjustment and 360° Coarse Rotational Adjustment
• 8-32 (M4) Tapped Hole for Rotation Hard Stop with a Post Collar
• Machined Bottom Relief Cuts Ensure Stability

The BA2E(/M) mounting base contains a central Ø1/2" (Ø12.7 mm) double bore and non-marring flexure clamping mechanism that allows for the mounting of  Ø1/2" (Ø12.7 mm) posts. The flexure clamp is actuated by a side-located 3/8"-24 (M10 x 1.5) setscrew and 3/16" (5 mm) hex key.

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Steel Insert Prevents Damage to Flexure Mechanism by Limiting Overall Travel

The double bore that goes through the part allows a post to be mounted within the base and in direct contact to the optical table surface. Standard bases have the post or post holder mounted directly on their surface which will inherently increase the minimum optical axis height and make the system less stable*. The method of mounting also removes the need for intermediary parts, such as a post holder, when mounting a post.

In addition to the advantages stated above, using these bases to directly mount a post will also remove the issue of table flexing, or bridging, that is commonly seen when using standard clamping forks. Please click here for more information on the detrimental effects of table flexing.

A posts height off of the table surface can also be adjusted within the double bore up to 0.24" (6.0 mm) from the table surface. The use of an R2 or R2T post collar will create a hard stop for repeatable height adjustments. Each mount also contains an 8-32 (M4) tapped hole next to the double bore. With a cap screw or setscrew inserted into this hole, the post collars can also be used as a rotational stop, as shown in the image to the above right.

A permanent steel insert at the end of the flexing mechanism, shown to the left, acts as a hard stop and prevents damage to the clamp from over tightening. The base also has two 1.25" (31.8 mm) long counterbored slots for 1/4"-20 (M6) cap screws for mounting to optical tables or breadboards. Please see the mechanical drawing above for details. The use of counterbores along with the double bore flexure mounting design allows components to be mounted close to the surface of the table without interference.

If a Japanese post standard (Ø12.0 mm) needs to be used with the BA2E, an AD12BA barrel adapter will be needed to bridge the 0.7 mm (0.03") gap between the post and flexure arm. The flexure arm will not be able to contact the post without this.

*A stability test was performed with a Ø1/2" (Ø12.7 mm) post mounted in a BA2E so that the post was in contact with the optical table. This was compared with a post mounted via a cap screw to our standard BA2 base. A 20 in-lb force was applied perpendicular to the post axis in both cases and the deflection of the post was recorded. Upon completion, the post within the BA2F had an overall deflection from center of about 0.001", while the post on the BA2 had a deflection from center of 0.002".