restore49
Aluminum
- Joined
- Apr 18, 2008
- Location
- Central Maine
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I read description, and looked at the pics, still not understanding what you are doing, please elaborate.
Needed to be able to clear objects at 34" and extend to 45" to reach furthest lathe spindle with chuck - so Barn door track would not work - this will slide like a greased pig with 150lbs hanging. In theory the anchors are good for 2000lbs each - the concrete is my only concern???. Not clever enough to figure the load on the VW bearing hanging 250lbs at the full 44" extension ( hope it is less than 2000lbs spread over 4 anchors)? Bob
If such a scheme was essential ,then I would drill right thru the concrete floor,through bolt, and place a plate on the top surface to spread the force of the bolts ......The OPs design relies on the tensile strength of concrete ,a risky thing to do,even if within theoretical limits.
You have a 44" lever there to pop those anchors out.
I think the math would show you are way beyond capacity of those anchors.
250 pounds working on a 44" lever arm (need to divide the 44" by twelve to get into feet) yields 917 foot pounds. Typical code crane load LRFD (load and resistance factor design) criteria I believe is 1.6 for crane loads. 917 foot pounds multiplied by 1.6 equals just under 1500 pound, divided by four fasteners equals 375 pounds per fastener. If, (and that's a big if), as the OP stated, the fasteners are rated at 2000 pounds each, that's a factor of safety of 5.33, so he's probably ok. Having said that, I would not stand under it...
Kevin
I think you have missed the boat here. You attempted to convert a moment load to tension but they're not compatible in this case because the fasteners are not evenly loaded. The one(s) in the back are in compression, ie not helping at all, and the ones in the front (toward the jib) are not much more heavily loaded.250 pounds working on a 44" lever arm (need to divide the 44" by twelve to get into feet) yields 917 foot pounds. Typical code crane load LRFD (load and resistance factor design) criteria I believe is 1.6 for crane loads. 917 foot pounds multiplied by 1.6 equals just under 1500 pound, divided by four fasteners equals 375 pounds per fastener. If, (and that's a big if), as the OP stated, the fasteners are rated at 2000 pounds each, that's a factor of safety of 5.33, so he's probably ok. Having said that, I would not stand under it...
Kevin
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