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Thread: proper woodscrew pilot hole size

  1. #16
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  2. #17
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    Quote Originally Posted by Jerry Bruette View Post
    What is "superstrut"?
    Unistrut; may be a brand name. I know my local HD carries it.
    Last edited by Jim Becker; 01-10-2023 at 6:53 PM.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  3. #18
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    Like Jim said, it's another brand name of strut channel and appears nearly identical to unistrut in all dimensions. Re another query above, this stuff looks pretty sturdy and according to their engineering tables can support 1000 pounds over a 36" span with minimal deflection. They don't really tout it as trolley channel for a hoist but they sell trolleys and brackets for it that are rated at 1000 pounds and there are several youtube videos of people installing substantial trolley hoists in their ceilings, but none in two axes. Might have to make a video...or maybe it will be an epic fail!

  4. #19
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    Go for it if you feel safe. I'd try to contact the company and float your plan past them, see if they endorse it.

    You might need two trolleys on each rail to keep the traveling rail from racking and binding.

    Here's a link to a store bought system similar to your idea. Check the weight rating and how it's built. https://www.globalindustrial.com/p/h...50-lb-capacity
    It's similar but different.
    Confidence: The feeling you experience before you fully understand the situation

  5. #20
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    Quote Originally Posted by Jerry Bruette View Post
    Go for it if you feel safe. I'd try to contact the company and float your plan past them, see if they endorse it.

    You might need two trolleys on each rail to keep the traveling rail from racking and binding.

    Here's a link to a store bought system similar to your idea. Check the weight rating and how it's built. https://www.globalindustrial.com/p/h...50-lb-capacity
    It's similar but different.
    Jerry, Thanks for the two trolley idea and the link. I can easily retrofit my system to two trolleys per rail if I get racking with the one trolley version.

  6. #21
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    I have to wonder how much drilling screw of any kind into a 2x beam derates the load capacity. Screwing into the thin web seems like it is a more serious problem then into the side.
    Bill D

  7. #22
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    You do you but.... Here is a link for trolleys from McMaster Carr. The maximum weight rating is 300 lbs for a trolley. In my experience they are intended to support lines, cords, or tool balancers but not be used for overhead lifting. Looking at the Unistrut site they mention that strut hangers must be used to keep the track clear. Looking at their imagery it appears there isn't sufficient clearance for a bolt head to be in place. I'd proceed carefully. The problem in this sort of thing is when you exceed the physical strength of the structure the failure is catastrophic. Good luck with this.


    https://www.mcmaster.com/trolleys/st...el-trolleys-5/

    https://unistrutstore.com/blog/post/unistrut-trolley

  8. #23
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    Yes, I fully plan to use hangers, 5 per channel, each of which has a 1200 pound rating. It will be uncommon that I might lift anything more than 200 pounds - The heaviest tool in my shop is my grizzly planer at 600 pounds. I just want to be prepared in case. Except for the ceiling joists, I feel like I have overengineered everything. If load testing of 4-500 pounds shows too much deflection of the joists, I can always add some braces above.

  9. #24
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    Jim, In 2014 I fastened 5- 10' 1 5/8" Struts parrell to garage door in one bay of my two-car garage, this made them perpendicular to the roof trusses. Secured them with the Spax screws I recommended previously to you. Then fastened a 10' stick of 3 1/4" strut perpendicular to the 1 5/8" strut, could not get the outside hangers locally at that time and trolleys could not pass the 3/8" bolt heads when 1 5/8" strut was used. two trolleys support a 30" long piece of 1 5/8" strut to which a Harbor Freight electric hoist is bolted to. Initially installed for unloading my SawStop ICS, gets used every year to hoist up front of zero turn to remove blades and clean under side of the deck. Has been used to unload other tools as they have shown up. Keep thinking I need to add 3 more struts hanging from trolleys in the 1 5/8" struts allowing side to side movement. Definitely would be nicer for unloading the truck just never spent the money to do it yet. Both trolleys used are the 600 lb rated
    Ron

  10. #25
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    Hi Ron,
    Your set up sounds interesting. Could you include a photo? What is the heaviest tool you have lifted?

  11. #26
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    pm sent
    500+- lbs off the top of my head
    Ron

  12. #27
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    FYI, I made a little you tube video testing Spax vs Lag screw shear strength (I'm not an engineer) to satisfy myself. Spoiler alert - which will likely surprise almost no one on this site - Spax won handily. Link below. Thanks again for all your help. I'll post some pics when the trolley is finished.

    https://www.youtube.com/watch?v=Ek4O9If9t10

  13. #28
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    The traveling beam is called the bridge in a bridge crane. As Jerry suggests you will have a racking problem.

    I have never seen a bridge crane with a middle rail, it may just increase the racking problem and will require all three rails to be perfectly level. Best to delete it from your plan. The only result is the need to make the bridge stronger.

    Since the load can travel to all corners the fasteners must be able to carry the max load at all points.

    Safety factor for this should be 5. That means design or testing should be 5,000 pounds plus the weight of the rails, hoist etc. Why so much you ask? Part of it is shock loading. Imagine how much force it would take to drive a nail with just a static load, without the shock of impact. Same for driven screws and sheared bolts.

    End stops need special attention. They sometimes fail, In industry they are attached by chains to catch them if they are sheared off, so they don't fall on your head. And there are double stops so the first failure isn't fatal.

  14. #29
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    Quote Originally Posted by Tom Bender View Post
    The traveling beam is called the bridge in a bridge crane. As Jerry suggests you will have a racking problem.

    I have never seen a bridge crane with a middle rail, it may just increase the racking problem and will require all three rails to be perfectly level. Best to delete it from your plan. The only result is the need to make the bridge stronger.

    Since the load can travel to all corners the fasteners must be able to carry the max load at all points.

    Safety factor for this should be 5. That means design or testing should be 5,000 pounds plus the weight of the rails, hoist etc. Why so much you ask? Part of it is shock loading. Imagine how much force it would take to drive a nail with just a static load, without the shock of impact. Same for driven screws and sheared bolts.

    End stops need special attention. They sometimes fail, In industry they are attached by chains to catch them if they are sheared off, so they don't fall on your head. And there are double stops so the first failure isn't fatal.
    Hi Tom,
    Thanks for your thoughtful comments. I just completed the system and as predicted racking is present, but tolerable with careful movement. If I remove the center rail I'm not sure my "bridge" would adequately support a 8' span but something to look into. I'm not sure exactly how much I'll use the system, but if racking becomes untenable, I have already imagined some 2 trolley attachments to each rail that should improve racking. Not much to do about the safety factor of 5, just have to hope OSHA doesn't make a surprise visit! Thanks for the pointer about the end stops - I'll have to consider some sturdier options.

  15. #30
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    Hi Jim
    You can make good end stops by drilling cross holes and putting in bold. These would not need safety chains.

    The center rail should not cause racking so if it moves well enough as is then it's good.

    Racking will probably be worst with the load at one end of the bridge. A pole with a hook and a helper might ease the travel.

    As to failure, you could load test it at 1000 pounds with the load at each corner of the range (while staying out from under). Then divide 1000 by whatever safety factor you choose and use that as your system capacity.

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