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  1. #31
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    Quote Originally Posted by ian View Post
    Hi Graeme
    although it hurts your feelings, your retired metal fabricator mate is right.
    A good weld will hold lots of weight a poor weld almost nothing at all, and telling the difference between the two is more science than art.

    Unless you are an experienced welder -- and, let's face it, if you were you wouldn't be asking -- stick with bolting.
    and there's nothing wrong with using pinus radiata
    Hi Ian

    You are much kinder than Baz, but saying essentially the same thing.... But if I look useless enough he might take pity on me and come and do the welding!


    Cheers

    Graeme
    H

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  3. #32
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    I absolutely didn't mean it as an insult, just that wood is fantastically strong and I think we all default to steel as its readily available and has unbelievable strength per millimetre.

    Though, I dont know that much about functional wood structures and the engineering therein. BUT there are many buildings going up now that are all-wood, plus multi story houses are built using it as a base structure. In the "past" they were built entirely of it.

    At the back of my mind when I was writing my original comment, was this video of a guys sawhorses and the stupendous loads they put on them to test them: https://www.youtube.com/watch?v=cEUgNjT1nGU

    Of course, I'm no engineer. I'd think MGP10 with the same bolts (plus good thick/wide washers) you'd use for the steel ones could be similarly made at a vastly reduced price.

    I agree on the wall. I would be reluctant to use it at all for anything other than bolting to it for support. I've asked a few times what people know of brick structures and weights they can support, but I've found nothing anywhere on it. There is an ancient thread here where I was considering how to make an outside storage rack of MGP10 and was asking around about load tolerances of walls....

    OTOH, I've seen some shabby looking outside racks that were loaded up to absolute buggery!

  4. #33
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    Quote Originally Posted by GraemeCook View Post
    You are much kinder than Baz, but saying essentially the same thing.... But if I look useless enough he might take pity on me and come and do the welding!
    works for me
    regards from Alberta, Canada

    ian

  5. #34
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    Hi Graeme
    your post gives rise to quite a few comments
    Quote Originally Posted by GraemeCook View Post
    The whole tenor of this thread has been to discover the appropriate level of engineering required for this project, at the most affordable price. But there are also a couple of constraints that must also be taken into account.

    First, the ceiling height is 3 m, say 2.9 m after I redo the floor, and I want to fill the entire wall with fairly close spaced racks and shelves. It is an absolute imperative that we maximise the amount of usable storage space on the racks/shelves.
    for most people 2m is well above head height and 2.9 m (call it 2.6 to the bottom of the top shelf) well beyond reach.
    How do you intend accessing the upper shelves, say those higher than 1.8 m?

    If it will be by way of a pair of library ladders, your shelves will need a beam 2.9 m above the floor to hook the ladder onto. Depending on how your roof is constructed, this beam could be attached to the roof timbers.
    If you intend using the sort of mobile platform as used by Bunnings staff, you will need to factor in space to store said platform. BTW, I do not recommend you use a vertical ladder attached to the face of the shelves, a step ladder, or worse plan on shimming up the shelves.

    Second, the wall in question is an 80 year old double brick parapet wall. Thus it is shared with a neighbour and I do not want to upset him or damage his property, and there are legal issues.
    me thinks you worry too much.
    In Sydney I lived in an 1890s terrace with similar walls. The only likely difference being my walls were built with lime motar, which is soft. Legally, the property boundary was in the middle of the wall and I could do what I liked with my side of the wall provided I didn't remove support required for my neighbour's side. In practice that meant that I could dynabolt (or use rawl plugs) in my bricks, but not his. The only time either of us had a problem was when, during a renovation, his builder got a bit energetic removing bricks on his side which led to a bulge in my wall, which went away when the bricks were replaced.

    Those light weight shelves look fine for three fairly low level shelves, widely spaced. But the stresses involved are quite different for eight or nine shelves on a post that is 3 metres high - much more torque, and we really don't know the ability of the 80+ year old bricks and mortor to resist that strain. I am yet to be convinced that it is a good idea to hang the shelves from the wall.
    whilst I might be dubious about suspending the entire shelf system from the wall, I'd have little hesitation tieing a floor supported post to your walls to prevent the post tipping over.

    I have looked at those racks from Bunnings and elsewhere, but the posts in the front of the shelves make it too difficult to store and access long pieces of timber. I have a lot of timber at 4 metres and some up to 5.4 m. Therefore, the racks and shelves must be cantilevered.
    only some of the shelves need to be accessible for sticks 4.0 or 5.4 m long, and the long shelves could be located above 2.0 m giving you many metres of shelving between 0.1 and 2.0 m from the floor which have posts front and rear.

    And the Bunnings racks that I looked at were only about 2 m high.
    this is more about needing a platform to access shelves higher than 2.0 m than the structural limit of the uprights.

    Our objective is to get a very functional racking and shelving system at an affordable price. If it fails - buckles, bends or breaks - then it is not functional. But I certainly do not want to pay for excessive strength.
    I'm still thinking 45 x 38 Pinus radiata
    regards from Alberta, Canada

    ian

  6. #35
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    Oh, and without intending to be impertinent, why do you need to store 5.4, or even 4.0 m, sticks in the first place?

    Very few furniture components are longer than 2.0 m
    regards from Alberta, Canada

    ian

  7. #36
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    Quote Originally Posted by ian View Post
    Oh, and without intending to be impertinent, why do you need to store 5.4, or even 4.0 m, sticks in the first place?

    Very few furniture components are longer than 2.0 m

    'coz I have them, and if I cut them I will need the extra length next week.

    They were actually bought for a kitchen rebuild, then we changed our plans and they were not used.


    Cheers

    Graeme

  8. #37
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    Quote Originally Posted by woodPixel View Post
    I absolutely didn't mean it as an insult, just that wood is fantastically strong and I think we all default to steel as its readily available and has unbelievable strength per millimetre......
    Hi WoodPixel

    I was not insulted, just rather disappointed in my own efforts.

    I had invested a lot of effort trying to solicit very specific information and advice, trying to optimise the appropriate and effective engineering solution at an affordable price. And you post highlighted that what I was broadcasting was not the same message that was being received.

    And while I am comfortable designing and making furniture, metal is a foreign world, as is large scale structural timber.

    for the resi of your post we are pretty much on the same wavelength.


    Cheers

    Graeme

  9. #38
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    Thanks so much, Ian

    I will try to briefly address the issues that you raised.


    Quote Originally Posted by ian View Post
    Hi Graeme
    your post gives rise to quite a few commentsfor most people 2m is well above head height and 2.9 m (call it 2.6 to the bottom of the top shelf) well beyond reach.......
    I would love to keep all shelving low, but my shed size is limited and I must optimise what I have. The high shelves will be used for rarely accessed items. For high access I will use a step ladder for small items and a plank between two step laders for larger items. There is simply not enough room for a movable platform as used by Bunnings, etc.

    The shed has a skillion roof and the original lathe and plaster ceiling in poor condition. Immediately below the plaster are barrens screwed through to the ceiling joists and then a pine VJ ceiling. Accessing the ceiling joists from below is rather difficult.


    me thinks you worry too much.
    I have been accused of being a perfectionist.


    In Sydney I lived in an 1890s terrace with similar walls. The only likely difference being my walls were built with lime motar, which is soft. Legally, the property boundary was in the middle of the wall and I could do what I liked with my side of the wall provided I didn't remove support required for my neighbour's side. .......
    I sought legal advice on this issue twenty years ago concerning another property. I was basically told that it was a "party wall" and simultaneously belonged to both parties - my neighbour and I. Our "sole ownership" effectively ended at the interface between the bricks and the plaster. I could not drill more than 50 mm into the brickwork, and if I should inadvertently cause damage to the neighbour, such as cracking his plaster, then I was legally obliged to fix it to his satisfaction. I do not know whether the law has changed. I very much doubt that it is policed unless significant damage is done.


    whilst I might be dubious about suspending the entire shelf system from the wall, I'd have little hesitation tieing a floor supported post to your walls to prevent the post tipping over.
    Mmmn! Are you suggesting that the posts should simply rest on the floor, or should we also add some sort of foot to spread the load and to counteract torque forces.


    only some of the shelves need to be accessible for sticks 4.0 or 5.4 m long, and the long shelves could be located above 2.0 m giving you many metres of shelving between 0.1 and 2.0 m from the floor which have posts front and rear.

    this is more about needing a platform to access shelves higher than 2.0 m than the structural limit of the uprights.
    This makes a lot of sense; the logical hemisphere says yes, the aesthetic hemisphere says no. If there were front posts which rested on the floor then they would take a lot of loading off the wall. Logic is ahead.

    There isn't room for a dedicated mobile platform, but I do have a pair of steel framed assembly benches. They are plenty strong enough and would be safer than step ladders for larger items on high shelves.

    I'm still thinking 45 x 38 Pinus radiata
    My belts and braces approach says 90 x 35 radiata for the rear posts and the cantilevered arms and, perhaps, lighter for the other arms and front posts.


    Thanks again, Ian. I feel that I am making real progress towards being able to make a well informed series of decisions.



    Fair Winds

    Graeme

  10. #39
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    Quote Originally Posted by GraemeCook View Post
    Thanks Justonething

    I don't agree with this assertion. The studs will certainly carry a lot of the load, but as the arms will radiate from the studs there must also be substantial torque forces in operation. The question then becomes - How significant is this torque in relation to the 80 year old brick wall??? Probably OK, but I need to be sure, or as close to that as I can be.
    I think we agree more than we disagree. Also, I agree with the views of others who proposed timber studs. Woodgear.ca has a good design, and I hope through some simple calculations, I can demonstrate his idea is more than strong enough for what you want.
    I would first suggest that the studs/posts should be floor to ceiling, and tie to a rafter if at all possible. The full-length stud design is an essential part of the idea. 95 x 45 timber studs are more than adequate to do a good job.
    WhatsApp Image 2018-12-29 at 10.47.59.jpeg
    For a simple calculation, let assume you have a ceiling height of 3m and the overhanging arm is 400 long and is carrying a load that is uniformly distributed along its length. It is loaded with 300 Kg which is equivalent to a downward force of 3000 N. ( if you are spacing your studs one every m, then 300Kg is quite a heavy load for carrying timber because a 3m long shelf is carrying 900KG). Since it is an overhang, torque is being applied to the shelf. Since the load is uniformly distributed, and the centroid is about 3/4 way down the length of the arm, at 300. So torque applied is 3000 x 0.3 = 900N-m. As we know action = reaction, the downward force is carried via the stud to the floor, and the floor provides a reaction of 3000 N. Moreover, to resist the torque that is trying to rotate the shelf clockwise (tipping it over), the tie to the ceiling is providing the reaction. Because the stud is 3m long and the fulcrum is at the base of the stud, the force exerted on the tie is 900 N-m /3m = 300 N or 30 Kg. It is a lot less than you think because of leverage. There is also no (significant) force being applied to the wall.
    However, if one doesn't use full height studs, then the wall will be subject to a lot of stress/force. One can improve the full height design by dynabolting the stud to the wall at the regular intervals, which stiffens the studs and with having only very moderate stress on the wall.

    This is the reason the dude in the video was happy to swing from his shelf.
    My view is that his design is perfectly adequate for what you want. Even if you load up five shelves, that is an only 150Kg force on the rafter (and probably a lot less). If you are carrying timber, then this is good enough and cheap enough.

  11. #40
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    Quote Originally Posted by GraemeCook View Post
    .... And you post highlighted that what I was broadcasting was not the same message that was being received
    I've often been told that I hear what I want to hear, or have some sort of impenetrable reality distortion field 😀😀

  12. #41
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    Quote Originally Posted by justonething View Post
    I think we agree more than we disagree. Also, I agree with the views of others who proposed timber studs. Woodgear.ca has a good design, and I hope through some simple calculations, I can demonstrate his idea is more than strong enough for what you want.
    I would first suggest that the studs/posts should be floor to ceiling, and tie to a rafter if at all possible. The full-length stud design is an essential part of the idea. 95 x 45 timber studs are more than adequate to do a good job.
    WhatsApp Image 2018-12-29 at 10.47.59.jpeg
    For a simple calculation, let assume you have a ceiling height of 3m and the overhanging arm is 400 long and is carrying a load that is uniformly distributed along its length. .......................................
    Thanks JOT

    All good stuff; really making me exercise the old grey cells.

    I had basically dismissed the idea of tying the shelf posts to the ceiling joists as being too difficult. The shed dates from pre-WW2 and has a skillion roof:
    • access to the roof cavity is very restricted, so it would be very difficult to screw/bolt anything to a roof joist within that cavity,
    • Below the joists is the original lathe and plaster ceiling in, I guess, poor condition,
    • Battens have since been screwed or nailed under the joists,
    • VJ pine tongue and groove timber has been nailed to the battens.

    Thus going through the ceiling or removing a section of the ceiling is a very major undertaking.
    I have tried to CAD draw the ceiling:

    Ceiling 1.jpg


    But there may be an easier alternative. I could attach a "cross batten" - not sure what to call it - under the ceiling and screwed through the ceiling layers into the joists. We could then attach the shelf posts to that cross batten. I have also tried to draw this idea:

    Ceiling 2.jpg


    I think this might spread the loads acceptably and be doable.

    Thanks for reminding me how to do parallelograms of force calculations - must be 50+ years since I last did one!


    Cheers

    Graeme

  13. #42
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    The stop (cross batten) can be in just about any thickness equal to or above 25mm.

  14. #43
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    Hi Graeme
    I still think you are overthinking it.
    Build yourself a waist high bench the length of your required storage shelves. Space the uprights for the bench at what ever spacing seems reasonable -- my suggestion would be 800 mm. Importantly use 2.9 m long 90 x 45s for the rear uprights. What you should end up with is a series of frames in the shape of a lower case "h" connected by battens and shelving.
    Divide the under bench space into shelves or drawers to store smaller and/or heavier "stuff"
    plan on storing the small amount of really long timber you have above head using brackets attached to the rear uprights.


    why do I suggest this?
    you only will ever have a small quantity of really long sticks that need a completely unobstructed front to allow access.
    The rest of the stuff you wish to store will more easily be stored on shelves that have both front and rear supports.
    regards from Alberta, Canada

    ian

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