I replaced the belt tensioning mechanism in my cheap vietnamese drill press. Originaly it came with a steel rod, a knob and a spring that you can see dissambed in the first picture and the position of them in the drill press side in the second picture, that primitive solution represented a pain in the..lower back. every time i wanted to change pulleys. Today i replaced this rod and spring with a toggle clamp, as you can see in the third picture, that seems to work very well.
Step 1: Select a Toggle Clamp
I choose a linear motion toggle clamp, i bought it in an industrial hardware store here in Vietnam, i think if you are in USA you can get it from Mc Master Carr or a similar place, there are many different models. The second picture is another Clamp that did not work in the limited space i have, to install it on the side of the drill press.
Step 2: Measure the Angle for the Support of Toggle Clamp
I dont have pictures of this, i fiddled with some cardboard mock up to see the optimal angle for the toggle clamp head to push perpendicular to the base of the motor, i used the red false square in the picture to transfer the angles to cut the piece of steel, for this bracket i used some scrap pieces of steel, aprox 3 mm thick
Step 3: Welded Steel Support, for the Toggle Clamp
Here is the welded and painted support, the angle between the two "walls" is not at 90 degrees, it is wider than that, to position the toggle clamp head perpendicular to the motor base plate. It was welded from three pieces, one for the toggle clamp screw, that is the big hole, about 16 mm, another plate with four holes to accept four M6 x1 mm screws to fix it to the side of the drill press body, and a small triangular piece as a reinforcement, that is above the holes, probably from the angle of the picture, you cannot distinguish the triangular shape very well. I apologize if don't have more steps during cutting and welding, i work alone, but i think you can get the idea.
Step 4: Drill and Tap Holes for the Bracket
I positioned the bracket in the side of the drill press head, center punched the four holes, and drilled with a 5,5 mm drill bit. For the M6x1mm screws, the tap size tables recommends to use a a 5.4 mm drill bit for such screws, but i did not have that drill size at hand. I used a M6 x1 mm tap to thread the four holes.
For those that are used to imperial measurements, i think 1/4 x 20 screws and suitable tap will work for the same purpose.
Step 5: Screw the Bracket to the Side, Adjust the Length of the Toggle Clamp
Assemble the toggle clamp in the bracket, using the 16 mm hole, attach the bracket to the side of the drill press, the toggle clamp head screw can be adjusted in length screwing or unscrewing it and fixing it in the desired position with a locking nut. Make sure the toggle clamp does not interfere with the levers in the drill press, adjusting the position of the red handle accordingly.
Step 6: Remove the Old Mechanism
Here is the toggle clamp in action, in the "closed position" after adjusting the length of the toggle screw, if you are satisfied with the tension, remove the obsolete spring and rod system.