This design is based on a toggle clamp and the difference is that the last part of the stroke is linear. As an example, this feature is useful for applications in which a probe must come in contact with a PCBA to test or program it. This is where I got the idea from. This design can be used like a normal toggle clamp because a fair amount of force can be applied at he end of the stroke and the clamp will hold just fine. I tried it with the kitchen scale and 3kg was not a problem but this was the maximum value of the scale.
This design consist of 16 parts (2× part 12) as can be seen in the PDF drawing. The linear stroke is as long as the slot in part 6 and 11 which is 10mm.
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EDIT: I have created a T-slot plate which can be used to fixate things to grind them and I have modified the two brackets to match the 20mm pitch https://www.thingiverse.com/thing:3641151. The updated files are: LTF-M-50105 and LTF-M-50115.
The thread of part 4, 5, 9 and 15 is a modified M8 trapezoidal thread with a pitch of 2.5mm. Regular M8 thread is to small to print. I recommend printing part 5 individually at a slightly lower temperature like 190°C and a layer height of 0.2mm and with a 8mm brim. You want to put as little heat as possible in this part. The infill of the axes, (part 1, 7 and 10) and the threaded parts (4, 5 and 15) is 100%. In other words, completely solid. This is not important for the other pieces.
The two 6mm holes of part 6 and 11 must be drilled afterwards to 6mm and the same goes for the 5mm hole of part 13 and 14. The parts 1, 7 and 10 are then pressed into these holes. I just did this with a hammer and a 6mm socket wrench. Don’t forget to place part 2 before mounting the axes. The rest speaks for itself.
End result of the linear toggle clamp
The video I have made in which I use these clamps