Seems like there is a lack of information regarding the use of ball locking pins for anchoring to concrete floors… Has anybody actually done this? I’ve seen the suggestions of using drop in anchors, which definitely seems relatively simple, but I would love to see what is involved when it comes to using ball pins instead.
If you’ve used ball pins for floor anchoring, could you maybe share some photos and thoughts on how you made it work, and how you feel about it overall?
I backed the original Maslow a while back, never got a chance to build it… Sold it so I could back the M4, and now I’m ready to get cutting! Any advice would be greatly appreciated!
Update: I also see that bar was experimenting with these pretty early on, and has since suggested using the drop in anchors as well.
If you want to go with ball pins, I would try to use a double shear connection. IE, have material above and below the belt end fitting. If you can’t do that, you need to minimize the exposed length of the ball lock pin, and probably need to plan for some kind of structure below the belt end that keeps down the bending moment applied to the pin.
Ball lock pins want a pretty close fitting hole, and also like to have a groove or something for the ball to lock into. The don’t lock in a smooth hole.
They tend to be pretty high yield stainless steel, and the center hole isn’t a big hit on bending strength.
Thanks, and after a little more searching through the forum, it looks like the 3D printed anchor points are meant to be glued/epoxied to the floor… (Not gonna go that route)
I have an idea for mounting to a cement floor using the ball pins which is similar to what you are saying. I should be able to build it out over the weekend, and share my results.
My plan is to use 3/8" wide drop-in anchors (anchor hole will be ~1.55" deep and 1/2" wide). I’ll use a short length of 3/8" threaded rod down to the anchor with about 3/4" of the rod sticking above the floor. Above the floor, I’ll attach a modified 3/8" hex coupler to the rod (1.75" in length) as the pin receiver. My idea with the couplers is to drill some 1/8" holes a bit off from the middle and through the sides of the coupler (ball is ~3mm and 1/8" hole is ~3.175mm) to catch the balls (will give 6 holes to potentially catch the balls in). I’ll then take a 10mm drill bit and bore down the coupler about halfway, effectively making an unthreaded 10mm to threaded 3/8" reducer (this should only really remove the threads and less than 0.5mm of the coupler’s walls). I’m grabbing the 31mm length ball pins (rather than the 20mm length in the Not Shop) in order to have more pin shank in the coupler/reducer (I measured the belt ends at ~16.23mm so the 20mm pins would leave less than 4mm of shank before the ball). I’ll need to be pretty precise with the placement of my ball holes, but otherwise, I think it should work really well. I plan on making a small jig and doing some test drilling into wood to get the ball placement just right.
Assuming all goes well, the belts should sit a little more than 2" off the floor and be sandwiched in snugly on the pin. The distance from the floor could even be raised up a bit by threading the coupler up the rod or even threading the rod out of the anchor a little (would probably add a nut and a washer underneath the coupler as a spacer). When not in use, I should be able to unscrew the rods and drop in short hex bolts and washers or just get some plastic plugs to keep the holes clean with minimal profile (could even grind down the bolt heads a little to make them sit flusher).