The Fortis-Tee Mini was a logical creation following the first invention…..the Fortistrut series of clamps. Both the Fortistrut and the Fortis-Tee Mini clamps were designed to be used on an individual strut channel or “T”-slot extrusion respectively. The recent popularity of CNC router machines has created a need to hold down the workpiece. The current methods available are the hold down version of a clamp and vacuum table. The Fortis-Mini Tee is a new addition to the industry. The goal of Fortis Clamp is to provide an alternative to the work holding device choices currently on the market. While trying to find common terminology and CNC work surface preferences, many varieties and choices were found.

The CNC industry that uses “T”-slot tables recommends boards to be mounted to the top of the extrusion table. These are referred to as “Spoiler Boards”, “Bleeder Boards” and “Sacrificial Boards”. It is difficult to determine the popular thickness of these boards. NOTE: unlike many clamps on the market, the Mini-Tee is adjustable and can be disassembled using basic tools.  The user should refer to the Fortis Mini Tee extrusion reference chart. The Mini Tee, although designed for direct placement on the common “T”-slot rails, is also capable of being modified to be used with “Sacrificial Boards” which is the preferred term that Fortisclamp is most familiar with and will be used here.

The information included in this section should be read thoroughly. If the user is not familiar with the company McMaster-Carr (www.mcmaster.com), he/she is encouraged to visit the website after reviewing the information in this section on how to modify the Fortis Mini-Tee when used with sacrificial boards. McMaster-Carr was used in the development of the first version of the Fortis Mini Tee. It is also referenced as a source of one of the extrusions mentioned in the extrusion cross reference chart on the back of the package as well as in the Mini Tee section of this website.

Please refer to the drawings/details in this section as well as the written explanation of each Detail number of the drawing. The reader should become familiar with the Mini Tee clamp before deciding on what direction he/she should take when modifying the Mini Tee clamp to incorporate with sacrificial boards.

Thank you for your consideration in using the Fortis Clamps in your projects.

CLICK IMAGE TO ENLARGE

The information below will be referencing the picture/drawings of this section. All information should be read thoroughly before making a decision on using/modifying the MINI- TEE used on a sacrificial board. The McMaster- Carr (www.mcmaster.com) company has been referenced in this section as well as other sections of the Fortisclamp website. The user should become familiar with this very handy resource. The following details are:

The table in the center of the drawing will assist the user to determine which MINI-TEE modification should be used. The thickness of the sacrificial board “X” (see DET. 1A) and the cutaway (see DET. 1B) should help the user in understanding the needed modifications of the MINI TEE when deciding to use it with a sacrificial board.

(DET. 1): A cutaway detail of the Mini Tee and its use on a sacrificial board

(DET. 2):

(DET. 2A): It is important to know the difference between a standard lock washer and a high collar lock washer regarding the Mini Tee. The Mini Tee ONLY uses a high collar lock washer. The high collar lock washers are typically used with shoulder screws as they have a smaller diameter. This smaller diameter prevents the lock washer from extending beyond the outer diameter of the screw. This is important in “T”-slot extrusions as the width of the “T”-slot is limited. PLEASE NOTE: IT IS A GOOD PRACTICE TO USE A LOCKWASHER OR LOCTITE IF A LOCKWASHER IS NOT POSSIBLE—–READ FURTHER.

(DET. 2B): The low profile of the Mini Tee is based on the limited movement of the Clamp Pin as the Clamp Screw passes through it. (Please see DET.3 for further detail of the Mini Tee parts). The movement of the Clamp Pin during use (tightening the Mini Tee to the extrusion) is +/- 1/16″. This range was based on the variety of “T”-slot extrusions that the Mini Tee will mount to. This function should be understood when understanding the application of the Mini Tee and sacrificial boards.

(DET.2C): The unique feature of the Clamp Pin is its ability to accept a #10-32 threaded or a M5 metric thread. This interchangeability will make it possible to find solutions in metric or English fasteners.

(DET.3): Shows the details of the standard Mini Tee. It should be noted that the HEX Head Bolt thread length is 3/16″. This length is a key design feature for the operation of the Mini Tee. The threaded length of the HEX HEAD BOLT and ANY SCREW/BOLT should not exceed this length as it will interfere with the Clamp PIN movement with respect to the Clamp Screw (see DET.2B).

(DET.4): Sacrificial boards with the thickness range of 3/8″-1″ should follow this detail. The extension of the set screw should not exceed 3/16″(see DET. 4B). This is important to the function of the Mini Tee (see DET. 2B). The #10 high collar lock washer is required in this configuration.

(DET. 5): Sacrificial boards of 1/8″ and 1/4″ should follow this detail. The use of a purchased shoulder screw will be needed. The standard threaded length of the shoulder bolt is 1/4″. This needs to be ground down to 3/16″ not to interfere with the function of the Mini Tee (see DET. 2B). Since the use of the 1/4″ high collar lock washer will not be used, the threads should have 1-2 drops of Loctite #243(Blue) (see NOTE A)

Useful additional information:

The material used for sacrificial boards is based on availability and location of the user. It should be mentioned that some materials (plywood, MDF/LDF, etc.) may be produced in other countries that use the metric system. Many cabinet grade plywood have metric thicknesses. The unique feature of the clamp pin (see DET. 3) is threaded #10-32. This thread (SAE) will interchange with an M5 (ISO). This provides the user with choosing either metric fasteners (shoulder screws/set screws) or English (SAE). The need to provide small adjustments between variances in sacrificial board thickness where shoulder screws are used can be accomplished by adding shoulder screw shim spacers.

When using Loctite products, please refer to Loctite’s website of proper use, safety and preparation. The reference of Loctite #243(Blue) was recommended to be used on Fortis Clamps. Loctite sometimes recommends heat for removal of the treated threads (depending on the Loctite product), but it has been Fortisclamps’ experience that using the same tool that tightened the fastener treated with #243(Blue), can be used to “break” the bond created between the mating threads of both parts.