Blind bolt holder for 1" square extrusion

prusaprinters

Simple bolt holder that allows just one hole drilled in one side of 1" square extrusion so bolt head doesn't protrude.  Eliminates need to drill a much larger hole on other side to fit a socket or pair of pliers in (which weakens the extrusion and allows moisture in to corrode the inside of the extrusion)I needed this to make a buggy to carry my windsurf gear but could be used for other applications.   I needed the crossbars to be removable to enable buggy to fit in vehicle and couldn't have the bolt heads protruding as all weight of board would just be on bolt heads.Its easier to use galvanised bolts (or something magnetic).   The key to success is drilling the hole right in the middle of the extrusion.   Then with the drill bit in the hole and spinning, tilt the drill bit slowly along the axis of the extrusion.  The longer the bolt you want to insert the steeper the angle.  The alternative is to Dremel an oval shape, or drill two holes and file them into an oval.    To insert the bolt use two rare earth magnets to move the bolt inside the extrusion into position and then tilt the bolt so it drops into the slot.  Hopefully the photos show the process.  One magnet on same side of the extrusion as hole at the thread end and other agent on other side of extrusion at the bolt head.   You may need to tap the bolt from the inside.    Then feed the print in, you will be able to see enough of the bolt through the slot to align, then gently tap the print into place.  If you make a mistake with multiple bolts in one piece of extrusion you can destructively smash the print and remove the debris and try again. I've attached some wing nuts that I used in this buggy, one is for 6mm nuts for use with this blind bolt holder.   If you need other bits to further construct stuff with 1" square extrusion you can see the others parts at: https://www.printables.com/model/138308-van-windsurf-rack1-inch-couplings