Hungry Jack
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Post by Hungry Jack on Jun 13, 2021 11:55:46 GMT -8
I purchased a pullup rack to hang in the garage. It mounts on studs at 48". I also intend to hang a heavy bag (80 lbs) on it for additional workout options. Or I may do like Rocky Balboa and hang a side of beef on it in the winter time.
The arms extend 33" from the wall. Thus a fair amount of additional force based on the length of those arms.
I think the recipe calls for lag bolts, but I think I prefer construction screws. The issue, I think, are the strength of the screw heads. Lag screws have much thicker heads.
Thoughts?
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Travis
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Post by Travis on Jun 13, 2021 12:17:12 GMT -8
I would stay with the lag bolts, but it all depends on how many mounting holes and the diameter of the screws, as well as thickness of the heads of the screws. You clearly want the rack to withstand some weight. Presumably those who engineered the product calculated the size of the bolts/screws needed to reliably hold the weight.
But you are planning to add additional weight and perhaps use weaker screws. I'd drill the holes tightly for lag bolts and keep the mounting as least as strong as recommended.
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zeke
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Post by zeke on Jun 13, 2021 12:41:10 GMT -8
Structural screws are much tougher because they are heat treated, despite the lags looking beefier. There are lag screws with ratings for sheer, but they are not the ones you can buy at the local hardware store. also, consider that the heavy bag is the lesser of those strains you will be putting on the bar. Pull ups put dynamic stress, as well as your weight, which I am assuming is more than the heavy bag. If you are really concerned about the stress from the 33" arms, you could run a support (cable or solid wood) back up to the ceiling joists, wherever they cross the arms of the pull up bar. Look at the shear values for the 2 screws. I think you will be surprised. the GRK screws available at Home Depot 5/16 x 2.5 to 4 have a shear rating of nearly 3000 lbs. link I can shear off the head of a lag screw with a 1/2" rachet. |
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zeke
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Post by zeke on Jun 13, 2021 12:57:41 GMT -8
Looking further into this, even Hanger Bolts are not as strong as a Structural Screw. |
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Post by bradmacmt on Jun 13, 2021 13:04:48 GMT -8
GRK's...
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Hungry Jack
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Post by Hungry Jack on Jun 13, 2021 13:18:48 GMT -8
No offense to anyone, but the kit comes from China and I am suspect of the mounting hardware. This is in part due to the soft-as-butter screws that came with the bike rack I purchased a few months back.
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Deleted
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Post by Deleted on Jun 13, 2021 17:15:32 GMT -8
if you use lag screws, predrill before driving so you don't split the studs. Or Wood studs - FastenMaster LedgerLok external Hex drive screws Masonry - Red Head concrete sleeve anchors.
If you want to be nutty about it, open the wall, put solid blocking (2x6 at least) between the studs, replace the drywall. Bolt the pull up bar to another 2x6 and use multiple 4" screws to fasten it to the newly installed framing.
PLEASE do NOT use black drywall screws!!! they have no shear strength at all. |
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Hungry Jack
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Post by Hungry Jack on Jun 13, 2021 18:43:53 GMT -8
I thought about putting up a ledger board but Mrs Jack objects (she likes very clean lines), so the FastenMaster sound like a good choice.
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Travis
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Post by Travis on Jun 13, 2021 20:13:43 GMT -8
Zeke is right to point out the strength of steel in structural screws being an improvement over lag bolts. And I especially like his suggestion about running extra support up to the ceiling joists. My concern is not so much with the strength of steel but with the grip into the wood. I’ve twisted off my share of bolt heads — but never into wood with a lag bolt. I suppose that is possible with hardwoods, but I’m having trouble conceiving it going into a pine wood stud. Of course, I don’t know what type wood you are fastening to. Studs in my area are generally pine, occasionally fir, and, more rarely laminate. So you may wish to consider type of wood. But when I spoke of “weaker screws,” I mean the grip of a smaller-diameter screw compared to the grip of a much larger-diameter lag bolt. One of the claims I've read elsewhere is that the strength of structural screws allows use of smaller-diameter threads. In this context, I have doubts. If you were going into pine studs, I don’t see the steel (whatever rating) being the weaker element in the attachment. The weakness, it seems to me, is in the wood, in the diameter of the screw, and in the resultant bite that the thread can take into the wood for a secure grip. My impression is larger thread means stronger grip. That said, I think either lag bolts or structural screws could be made to work. And in fact, in similar circumstances I’ve used both. But with my limited knowledge of your project, I still prefer the lag bolts. I really don’t see the grade of steel to be the question. But you might add Zeke’s extra support to ceiling joists just in case there is something I’m not seeing here.  |
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Hungry Jack
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Post by Hungry Jack on Jun 14, 2021 6:09:39 GMT -8
Lots of good info in this thread. Thank you all.
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Hungry Jack
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Post by Hungry Jack on Jun 14, 2021 6:12:08 GMT -8
Zeke is right to point out the strength of steel in structural screws being an improvement over lag bolts. And I especially like his suggestion about running extra support up to the ceiling joists. My concern is not so much with the strength of steel but with the grip into the wood. I’ve twisted off my share of bolt heads — but never into wood with a lag bolt. I suppose that is possible with hardwoods, but I’m having trouble conceiving it going into a pine wood stud. Of course, I don’t know what type wood you are fastening to. Studs in my area are generally pine, occasionally fir, and, more rarely laminate. So you may wish to consider type of wood. But when I spoke of “weaker screws,” I mean the grip of a smaller-diameter screw compared to the grip of a much larger-diameter lag bolt. One of the claims I've read elsewhere is that the strength of structural screws allows use of smaller-diameter threads. In this context, I have doubts. If you were going into pine studs, I don’t see the steel (whatever rating) being the weaker element in the attachment. The weakness, it seems to me, is in the wood, in the diameter of the screw, and in the resultant bite that the thread can take into the wood for a secure grip. My impression is larger thread means stronger grip. That said, I think either lag bolts or structural screws could be made to work. And in fact, in similar circumstances I’ve used both. But with my limited knowledge of your project, I still prefer the lag bolts. I really don’t see the grade of steel to be the question. But you might add Zeke’s extra support to ceiling joists just in case there is something I’m not seeing here. The house is 120 years old, but I think the garage is possibly newer (though it does have Chicago common brick). The studs are almost certainly pine. |
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Post by High Sierra Fan on Jun 15, 2021 12:16:44 GMT -8
For an outward tension, probably the upper connections, i’d use lag bolts, if you’ve concerns use domestic replacements; they’re good for outward pull resistance.
The lower connections that are resisting sheer structural screws would suffice I expect.
If you’ve access to both sides: through drill and use full bolts. The wood fails before they’ll pull out.
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