I'm not sure if this is the right forum, but here goes...
To quote Rod Serling, "For your consideration..." I have a workshop with a large loft for wood storage. I want to install an I-Beam for an electric hoist to lift wood up and down. I would want to support at least four sheets of furniture grade plywood @ 75lbs each (300lbs) and, to be conservative, would like the WLL to be greater than or equal to 500 with DF=5:1.
I have included several Sketchup snapshots of my current thinking and would like your professional opinion about the implementation and any pitfalls I might have missed.
The details are:
1. The total height from ground to beam is: approximately 18' 8". This allows me to use a double line on the hoist, which will help slow down the lift speed to help maintain safe control and, I believe, help keep the hoist hub more or less centered under the beam.
2. The hoist is a 750/1500lb rated unit from Northern Tool.
3. I'd like to use an aluminum I-Beam so that it is reasonably easy to ship and install (and doesn't rust - I'll use Hot Dipped Galvanized hardware). The I-Beam is 6061 T6 AL, 10 feet long, S6x12.5. 5 full feet are cantilevered outside the loft door, with the remaining 5 feet attached at three points to cross beams.
4. The first cross beam is a triple 2x10 SYP header with 1/2" plywood spacers (the outside walls are 2x6) supported by 2x6 studs. The span is 6 feet. The Beam will attach to the header with 2 10" 1/2" galvanized bolts, through the header, with tapered washers at the beam flange and large, heavy washers at the top of the header.
5. The next two cross beams are attached to the existing trusses by way of 2x10 SYP cross beam and 2x4 compression braces. The span is 12' 10". The I-Beam is attached to each cross beam with 2 5/16"x6 lag bolts, again with tapered washers, with pull out rating (in SYP) of 2250 lbs each.
6. There are 3 wire rope braces. One running lengthwise with the beam, operating as a tension brace, and supported in the center by a 3" sheave. The sheave is really there to provide a gradual radius for the rope, I do not expect it to turn (at least I HOPE it doesn't!) The rope is 3/16 galvanized steel, not sure what 'wrap' to use... Again, galvanized fittings with a turnbuckle at the inside end. The angle between the beam and rope is approximately 33.7 degrees +/- 1 degree.
7. The other two ropes, also 3/16" diameter, will provide side to side stabilty, and are tied to the vertical studs framing the loft door opening. The angle between the beam and each rope is 30 degrees +/- 1 degree.
8. The truss/loft floor is rated for 40PSF, 360 deflection. I don't know (but can find out if necessary) the snow load rating but it was designed for central NC. By the way, the SKetchup model shows the bottom chord of the truss as being 2x10 in the middle and 2x6 on the ends. In reality it is fabricated from 2 2x10s. Span across the workshop is 30 feet. Span between the attic posts is 14 feet.
Let me know anything else you need to know... The Sketchup model is fairly accurate so I can easily take any measurements you need.
TomBeamOverview.jpgBeamFrameOverview.jpgBeamSupport.jpgTrussLayout.jpgVerticalBraceDetail.jpg
Hi Tom and welcome to the forum. Not wishing to dump on you, but there is a lot wrong with that design. I'm at a friend's place and using my netbook so elaborating on the issue is not going to happen this evening. Probably would be a good thing as the beers and red wine are uncorking as I type. I will assist more in the morning. We are not ignoring you.
Well, I certainly do not expect to compete with Beers and Red Wine! I wholeheartedly accept second place to those options! Looking forward to your observations!
Thanks,
Tom
PS: I'd accept third place to Laphroaigh or equally valued Islay Single Malt...
I realized last night that the shaft for the sheave was only being supported by the end grain of the SYP vertical posts.This morning I added 1/8" steel bearing plates to both sides of the posts (4 plates in all). Below are the updated images.
Tom
BraceSheaveDetail.jpgBraceSheaveDetailSideView.jpg
Hi Tom,
Well I survived yet another Friday night and hope I am in a collected enough form to offer some advice. Please regard the following plus any and all future comments as in, In My Humble Opinion (IMHO)
Your system, while inventive, is way over complicated and elaborate for what you are trying to achieve. These beam hoists have been around for a zillion years, so here's how I would attack this. I would start at the other end, kinda.
Conventional wisdom suggests we use at least a 2-1/2:1 safety factor so for 300-lbs, that's a design start point of 750-lbs Safe Working Load (SWL). In Engineering terms, not a lot of weight, less than half a ton. I would next look at the trolly you intend to run on the beam. You could make your own or buy a 1-ton version often available for 40-bucks.
http://www.harborfreight.com/1-ton-p...ley-97392.html
That will define your minimum flange width for the beam.
Having said that, industrial sliding doors can provide components well in excess of your SWL, two of these...
http://www.grainger.com/Grainger/BAT...ox-Track-4PE55
Two of these...
http://www.grainger.com/Grainger/BAT...&cm_vc=IDPRRZ1
A chunk on 1/2" steel plate and four holes, a 1/2-ton U-bolt (for car leaf-spring) as hook for the hoist and you are pretty much done with the trolly. Add in a wooden beam and scrap the guy ropes.
I would have the beam with twice the length inside as outside. I would design the beam stiffness (size) as a cantilever of at least equal to outside for a minimal deflection at initial lift. The opening (door) needs to have more than the two vertical 2x4s shown as that will be taking most of the initial load.
So, I will stop there for now and let you mull that.
I like the idea of the Door Tracks. Hadn't considered putting two side by side but makes sense and certainly is easier to manage (and acquire) than an I-Beam! Thanks!Originally Posted by PinkertonD
<...snip>
Having said that, industrial sliding doors can provide components well in excess of your SWL, two of these...
http://www.grainger.com/Grainger/BAT...ox-Track-4PE55
Two of these...
http://www.grainger.com/Grainger/BAT...&cm_vc=IDPRRZ1
A chunk on 1/2" steel plate and four holes, a 1/2-ton U-bolt (for car leaf-spring) as hook for the hoist and you are pretty much done with the trolly. Add in a wooden beam and scrap the guy ropes.
I would have the beam with twice the length inside as outside. I would design the beam stiffness (size) as a cantilever of at least equal to outside for a minimal deflection at initial lift. The opening (door) needs to have more than the two vertical 2x4s shown as that will be taking most of the initial load.
So, I will stop there for now and let you mull that.
I was going to use a similar trolley to the one you suggested, but with this new suggestion that's moot.
FYI, the header support studs are 2x6, not 2x4. Does this change your assessment?
The suggestion to have the beam twice the length on the inside is to distribute the upward force over more of the trusses?
Are the cross beams & compression chords I've suggested sufficient (or way overkill)?
Thanks again. I'll update my drawings and posting Rev. A.
Tom
Probably not.I assume they are sized to support the roof, snow and wind loads. You will be adding 1/2 ton extra at times so you need to make sure there is enough leeway on the vertical supports to accept that.
Yes, trusses are designed for downward loading. Although I note the angular sticks (hey, I am not a carpenter) leading up. Personally I would use a standard truss design then add supports as shown in the attached rough sketch. Ooops, make those hangers 4x4 or similar since we are bolting through both faces. More coffee, quick, bring me more coffee!
Ooops again, you should also bolt those hangers though the bottom beam of the truss. Woman! Where is that coffee????
Finally, if you do embed the tracks as suggested, don't forget to calculate the beam from the top of the tracks and not the bottom. The small amount of material hiding the tracks will not add any appreciable strength.
Last edited by PinkertonD; 01-28-2012 at 12:41 PM. Reason: Dyslexics of the World Untie.
My personal favorites would be Theakston's Old Peculiar and a Bowmore's single.
Let me clarify that.
When calculating beam size, the cantilever length would be the outside length x 2. With Five feet outside, the length of the cantilever calculation would be for a ten foot beam with probably around 1/2" deflection at the max. at the outside end when at the full rated SWL.
You can safely ignore the remaining five feet of the beam inside as once inside the door, the load is going to be dsitributed over ten feet and six trusses and door Lintle. It's a kinda cross over thing using the ten foot cantilever, then the ten foot inside for the standard distributed beam where there is a common middle five feet of the fifteen foot beam.
Does that makes sense? I mean the explanation.
The Bowmore's Single makes the most sense of all you've mentioned, but yes, I've got it. You've got to try Ardbeg's Uigeadail. You might need to go to UK to get it, however... You can also get it in Durham, NC.
I did realize that I'd have to factor a smaller 'inside' beam. Given this 'non-standard' configuration, however, I'm not sure how to calculate the proper sizing for inside/outside elements of the beam. For example, do I use 3 2x6 for inside, 2 2x8 for the outside (following your suggestion of 'hiding' the track within a beam channel)? My plan would be to construct this channeled beam from PT dimensional lumber, glued and screwed (to build an effective laminate), and capped with a 1x PT element to prevent water in the seam.
I had planned to bolt the box tracks through the beam at a reasonable pitch (eg 16" OC).
Tom
By the way, the Box Tracks are a bit less expensive at DrillSpot and free shipping... http://www.drillspot.com/products/51...PE55_Box_Track
Where you buy stuff is up to you, I just link to the first site that has the items I want to show and that happened to be Graingers this morning.
Attaching the track: It will have holes every so often as deemed best by the manufacturer. They will also recommend the fasteners to use. Listen to them.
Make the beam a single even uniform piece for the full fifteen feet. Changing profile will introduce failure (weaker) points. It will be over designed inside but it will present fewer problems. You would only be saving maybe 5% in cost and to me, IMHO, not worth messing with.
You can use a manufactured beam as they use for floor joists, Could even Siamese two of those but then you may not be able to embed the tracks. There are formula pages here on the Edge that will help you arrive at the size.
Start with a 6x6 chink of building grade Pine or something. Keep changing sizes upwards until the deflection at the outer end is less than an inch. I am NOT a wood person so take that ALL with a grain of sawdust.
There is no scientific approach to that "inch," it is just what I think is reasonable. Others here may jump in an advise more or less. Up to you. Given there will be ten feet of beam inside, the uploading of the trusses will be well distributed and should not cause a great concern if the deflection was even a little more. As I mentioned earlier, that 750-lb-SWL is a small load, in fact you may want to go to a bigger beam than needed just to make it look in proportion.
Because this is an overhead thing, and it could hurt people if something broke or bent, I would always err on the side of excess rather than pennies extra.
Thanks for all your help! I think I'm good to go. I'll update when I finally have this put together.
Tom
Happy to help Tom, and I look forward to seeing a pic of the finished project.
Tom, I hope you are still checking in here as I had a "wake up" moment at 2:44am. I suddenlt recalled the comment about the hoist.
Do not run a double rope and idler for the hoist. If you feel it is important then engineer the beam for 1500-lbs. It would be nuts to have a 750-lb beam and a 1500-lb possibility to destroy it. If something got hooked up on the pickup truck, the hoist can apply double the load the beam was designed for.
There are many ways to prevent swinging of the load, so investigate those and use the single rope.
Doncha just love those "wake up moments"? I think my best designs (and best pitfall discoveries) have either been made at 3AM when I'm totally asleep or in the shower...
Thanks for the tip! I would have never thought of that problem! Then again, I have no intention of getting the hook caught up in the truck...
Given that the hoist will now be supported by the 1/2" steel platform, I can shift the position half the hub diameter and the take up will be centered... There will still be torque on the beam, but the load will be centered.
Here is what I've come up with.
BeamFinal.jpg
I've stuck with using the laminated lumber because:
1. They're easier to make than get a perfect single piece of wood. I am a woodworker, after all...
2. Internal checks are less likely to propagate.
3. Less chance of warping.
Tom
PS: Thanks for thinking about this at 2AM
Tom, I wish I could take credit for the 1500-lb thing but that was between you and my subconscious.
Laminating is good if you glue and bolt.
You may need to notch the top corners of those doors.
Happy to help.
Uh yeah, big time!You may need to notch the top corners of those doors.
Thanks again, this has been very rewarding!
Tom
Happy to help, the brain needed some exercise, but you knwo the rules?
No pics, never happened.
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