In response to the post criticizing single point of failure gymnastics chain attachments:
Ian Buttar sends photos of a home made gymnastics bar anchoring rig installed at Phoenix, Edmonton, Canada.
They have 2 concrete anchor bolts on each attachment, not one.
As for the plates. They are made from 3/8″ x 2″ hot roll steel. Two holes for the floor anchor bolts and one for the clevis.
… I think the anchors are for 3/4″ bolts. We used grade 8 bolts as you can see.
A bend close to the end to approximately matches the angle of the cables.
Two anchors means you have to be accurate drilling the holes in the concrete, an impossible task without a jig.
The jig has two different holes. One is the diameter of the bolts (3/4″) the other is the diameter of the anchor drill bit.
The spacing is the same as the floor plate bolt holes.
The hole for the anchor drill bit is raised up as you can see. This helps you to keep your drill perpendicular to the floor. It’s called a drill bushing.
In use, you drill your first hole using the drill bushing. (Someone heavy can stand on it to keep it flat on the floor)
Clean out the hole and install the anchor.
Bolt the jig to the anchor in the floor using the jig bolt hole, and line up with the angle of your cables.
Drill the second hole using the drill bushing.
Remove the jig, clean out the hole, and install the second anchor. Make sure you don’t get concrete dust in the first hole anchor ( or any anchor) this will ruin them.
If you do get dust in an anchor, you must clean them out very thoroughly.
Install the floor plate. Visually inspect regularly.
One of your readers posted a note about the spacing of holes in concrete. He is right. Check the specifications on the anchors that you are using, the minimum spacing will be listed.
THANKS Ian. Thanks George Novak, too.
That’s a much safer alternative to the industry standard single bolt anchor, in my opinion.
Of course there are liability considerations with every piece of home made equipment in your gym.
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