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T-bolt Boxes

I find it very difficult to assemble boxes with T-bolts. I have to use tweezers to hold the nut while I start threading the bolt.

And, there’s not much room to grip the nut with the tweezers without blocking the nut hole. Consequently, the nut often drops inside the box. Then I have to start all over again, removing all successfully fastened nuts just to get the nut out of the box.

Are the nut holes supposed to be small enough to hold the nuts? Maybe my nuts have a smaller outside dimension than what the templates I’m using were designed for.

If the nuts are supposed to hold the nuts firmly when starting the bolts and tightening, how much bigger should the holes be than the nut outside dimension?


Dave Thomas

For future projects, I would recommend designing the slots so that the material does not allow the nut to rotate with the bolt. This width should be greater than the width of the hex bolt, but not wider than the diagonal. This should allow you to assemble the box without holding each nut with tweezers,and also help reduce the likeliness of the nuts falling into the box. If this alone doesn’t keep the nuts from falling in, you might also try applying a piece of tape across the outside of the box (making sure it sticks to the nut too!) and removing the tape after the box is fully assembled.

When designing the slots, you’ll want to keep in mind that all laser-cut hole dimensions are going to be slightly larger than drawn, since a small amount of material is melted away by the laser’s beam. The amount of material is approximately 0.007", but it can vary depending on many factors such as the design, material type, material thickness, and the exact setup of the laser when cutting. I usually recommend a line offset of ~0.004" to account for the laser’s beam width. You can read more about setting up your file for laser cutting here.

If you’d like to further discuss your design, feel free to contact us!

- Arthur

Sorry, I missed this reply until now. Thanks!

(I thought I’d set up for email on replies).

I’ll try your suggestions on a new design. For now, I changed to 4-40 threaded inserts adjacent to the box sides. This works really nice for my 1" thick box, but obviously wouldn’t work well for boxes that don’t have a dimension less than about 1.25" (difficult to get bolts that long).


Dave Thomas