What is the optimal support angle for a steel clothing rack?

In summary, the author is constructing a clothing rack that swings out of the way. The clothing rack will be made of stainless steel tubing with a 1/16 inch thickness and will sit on a lazy susan that supports 200lb. The top of the clothing rack will be firmly attached to a stud in the sloped ceiling. The support bar will start about 18 inches above the clothing bar and will need to be positioned between 30 inches and 60 inches from the upright. The author is not a welder and is going to use stainless steel marine handrail fittings. The clothing rack will support a load of 50lb.
  • #1
DaveC426913
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I'm building a clothing rack that swings out of the way. It's ideally made of 7/8" (or possibly 1") stainless steel tube, with 1/16" thickness and will sit on a 3" bearing (lazy susan) that supports 200lb. The top is firmly attached to a stud in the sloped ceiling. It needs to hold up something more than 50 lb (5 feet of clothing).

There is a support bar that starts about 18" above the clothing bar. I'd like to position the support bar correctly to balance the load on either side.

I have no idea how to determine the optimal point of support to balance the load (minimizing risk of collapse). It will obviously be between 30" (midpoint) and 60" (endpoint) from the upright.
closet-rack.png
 
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  • #2
For all purposes I'd position it at or very close to the very end between 45'-55' . You will have two load bearing points on the vertical rod, the weight at the farthest end of your horizontal rod will impart its maximum pressure on the vertical rod right at the joint 18 inches down so the farther out you put your angular support rod the less pressure you will have at the end of the horizontal joint. You want it to support a load like a crane or counter leaver long gate... if the top and bottom of your vertical rod are securely fastened then you shouldn't have a problem supporting 50lbs at any point on that rig. 1/16 tubing is very strong
 
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  • #3
Thanks. I hadn't really thought about the strain on the upright. I assumed it would be on the bar.
Maybe I should place a very short angled support underneath the horizontal bar to distribute the load on the upright. (Has to be short, or it will waste valuable clothing rack space.)

I want it strong. I've struggled for years & years with movable clothing racks. Ikea racks just fold like a cheap lawn chair under the weight.
 
  • #4
If you are welding it you could add a triangular gusset underneath the horizontal, I'd use 1/8 plate stainless, for best results you'd need to tig it with 316ss 1/6 filler wire at low temp, after you tack it keep most of your heat on the plate steel and "wash" the filler over on your tube steel, weld all the way around and try to prevent it from "sugaring" ( getting porosity) on the inside of the tubing. You could (purge pipe weld) it and you wouldn't have to worry at all about any porosity. You shouldn't have a problem with it supporting quite a bit of weight, I bet at least 100 lbs or more.
 
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  • #5
Not a welder. Going to use stainless steel marine handrail fittings.
mRAzDV0TdI6jvX7NGyZ3khg.jpg

I'll have to drill points to secure them against the load, the little set screws normally used to grip tubing won;t be enough.
I sure hope that doesn't compromise the tube's strength.
 
  • #6
Screws shouldn't if you are using mechanical fixtures and hardware, I wouldn't put a counter leaver on the bottom, even a short one, it would be a waste of steel and could cause the horizontal to bear the load more in the middle in front of the bottom counter leaver. A gusset would just spread the load over a wider area giving the horizontal tube a bigger foot print, thus giving it a better weight distribution on the vertical load bearing tube. I'd put the counter leaver almost to the top of the vertical touching the connecting point at the top if possible to spread the load over a greater area.
 
  • #7
All right, no underbrace then. That'll save me 20 bucks in fittings.

Just bought a couple of 3" lazy susans to act as bearings top & bottom.
41TE0WcXjvL._SX342_.jpg
.
Would've liked them smaller but this is all Lee Valley Tools had.
 
  • #8
As long as you have a way of attaching the tubing on center of your bearings they should work.
 
  • #9
gjonesy said:
As long as you have a way of attaching the tubing on center of your bearings they should work.
Yeah, it's just that it'll be a disc 2√3 inches across.
 
  • #10
If you can, I'd go with a bigger diameter upright, since it's going to be pretty long that will be the 'flimsy' feeling part of it (it'll be about 6-8 ft high right?)
If you have a bigger upright, you could get a 1" hole drilled into it to hold it

If you support the horizontal section by it's end, you could use aircraft cable to hold it up, the angle of the wire would even keep the horizontal section pressed into the vertical.. and using just 1/8th aircraft cable I'm quite certain you could easily hang 100 lbs off the end.

I'd weld it.. for a 50 lb load you'd hardly need a brace.
 
  • #11
If you plan on using screws to fasten the fitting to the pipe, self tapping screws would work good, just don't strip them.
 
  • #12
Rx7man said:
If you can, I'd go with a bigger diameter upright, since it's going to be pretty long that will be the 'flimsy' feeling part of it (it'll be about 6-8 ft high right?)
Nope. Its only 5'6" high (due to sloping roof).
Rx7man said:
If you support the horizontal section by it's end, you could use aircraft cable to hold it up, the angle of the wire would even keep the horizontal section pressed into the vertical.. and using just 1/8th aircraft cable I'm quite certain you could easily hang 100 lbs off the end.
I've considered cable. I don't think it'll look as nice. Also, it doesn't provide any torsional rigidity as I rotate the structure.
 
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  • #13
I would suggest running the top diagonal to the end of the rod and then determining the rod center point deflection by analyzing it as a simply supported beam with a 100 lb distributed load to see if you need to place an intervening vertical member between the rod and the diagonal at that center point to prevent excessive rod center sagging under load.

As for the vertical support, resolve the diagonal end load into its vertical and horizontal components at the the horizontal rod end; and, then determine the vertical pole"s required diameter by analyzing it as a simply supported beam with the horizontal load component as a concentrated lateral load at the horizontal beam connection point height. This will also give you the horizontal reaction forces on the bottom turn table and the top pole socket connections.
 
  • #14
JBA said:
I would suggest running the top diagonal to the end of the rod and then determining the rod center point deflection by analyzing it as a simply supported beam with a 100 lb distributed load to see if you need to place an intervening vertical member between the rod and the diagonal at that center point to prevent excessive rod center sagging under load.

As for the vertical support, resolve the diagonal end load into its vertical and horizontal components at the the horizontal rod end; and, then determine the vertical pole"s required diameter by analyzing it as a simply supported beam with the horizontal load component as a concentrated lateral load at the horizontal beam connection point height. This will also give you the horizontal reaction forces on the bottom turn table and the top pole socket connections.
Yes I Will Um Definitely Do All That. :nb) :nb) :nb)

Do I utilize the Rockwell Retro Encabulator to do that?
 
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  • #15
That's actually not a bad idea, adding a mid angular support to the top counter leaver would distribute the load more evenly on the horizontal tubing. It wouldn't have to be a ridged support. A cable or banding material would work fine. Really anything you find aesthetically pleasing you could actually make an ornamental (S) piece to place in the middle. You could bend it out of some thin flat or square stock, just heat it and bend it to the shape you like, attach it to the leaver and the horizontal with some tap screws. Decorative touch with form and function.
 
  • #16
With the (S) in the middle of it you could name it the super lazy Susan encabulator next gen unconventional clothing storage system or S.L.S.E.N.G.U.C.S.S for short...:woot:
 
  • #17
Also...been thinking about it, when the rack has some weight on it depending on the pivot point and how level you can make it...it may tend to swing out in the middle of your closet or where ever you are placing it. Just a suggestion,...once it's built add a bolt (ferrous metal) to the end of your horizontal tubing. And mount a decent size magnet (cabinet latch magnet) or an old speaker magnet where you want the end of your rack to stay. That way you will have a a way of holding it in place and out of the way. Just a thought.
 
  • #18
DaveC426913 said:
Yes I Will Um Definitely Do All That. :nb) :nb) :nb)

Do I utilize the Rockwell Retro Encabulator to do that?


Does that mean you could use a bit of guidance or assistance in the analysis process?
 
  • #19
gjonesy said:
Also...been thinking about it, when the rack has some weight on it depending on the pivot point and how level you can make it...it may tend to swing out in the middle of your closet or where ever you are placing it. Just a suggestion,...once it's built add a bolt (ferrous metal) to the end of your horizontal tubing.
Its 'stowed' position is not actually against anything. It sits parallel to an inner rack, and is moved away (out into the open) so we can get at the inner rack.

But I think your idea has merit - I should have thought of the risk of the device 'wandering'. I'll incorporate something at the base or head of the upright.
JBA said:
Does that mean you could use a bit of guidance or assistance in the analysis process?
I certainly don't have the chops to do that.

Question though: is it necessary? Hopefully, I've over-engineered it.
 
  • #20
The only issue to consider (for positioning the tie), is the bending of the horizontal member.
Both the thrust of the horizontal member against the vertical pole, and the horizontal component of the tension in the diagonal support (again trying to bend the vertical pole) are independent of the position of the diagonal support. They are determined by the load on the horizontal and the 18".
The tension in the diagonal decreases as its angle to the vertical increases, but once you are half way, you're within 10% of the tension at the end.

My guess is (as yours) to have the tie 2/3 to 3/4along the horizontal, with the cantilever equal to or slightly less than half the beam, but I'm really not familiar with beam calculations. Psychologically I think you will put heavier items near the vertical support and lighter items towards the end, so perhaps the cantilever will tend to have a lower load than the beam and 2/3 is the right spot.
 
  • #21
Put the support at the outer end of the horizontal tube. As Merlin pointed out, the diagonal tension is minimal there. If the clothes weigh F and are evenly distributed, with L for the length of the horizontal tube and H for the vertical support, the downward force at the outer end is F/2, horizontal force is F*L/H, and diagonal tension will be F*sqrt(1+L2/H2). The bending moment in the center of the horizontal tube will be F*L/4, and for the vertical support it will be F*L. Assuming you use the same tubing for the horizontal and vertical members, the horizontal member may be safely ignored.

Given your numbers and neglecting the weight of the tubing, we get
  • diagonal tension: 174 lbf = 774 N
  • vertical bending moment: 250 lb·ft = 339 N·m
You'll want a safety factor of at least 2, better 3, so triple those numbers. The diagonal member shouldn't be a problem. I'm very skeptical about the bending moment, though. You better look for a data sheet, or perform a test.
 
  • #22
DreamSplitter said:
You'll want a safety factor of at least 2, better 3, so triple those numbers. The diagonal member shouldn't be a problem. I'm very skeptical about the bending moment, though. You better look for a data sheet, or perform a test.
Now that you mention the force on the vertical bar, I think I'm going to reinforce it by stuffing a thick dowel up its length.
 
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  • #23
I have done some of the analysis I recommended for your design. The key issue does become the cantilever load on the supporting pole. The beam analyse are based upon the beam equations presented in Machinery's Handbook, 22nd Edition. I have this on an Excel file but don't know how to attach that or a jpeg scan to this post so if you know how I can do either of those please let me know. This analysis is for the diagonal support to connect to the end of the clothes bar and due to excessive .48 inch sagging on the clothes bar I recommend the vertical tie be added between the bar and the support diagonal member at the center point of the bar.
I used an estimated 80 inch total pole height and have specified a 1 1/2 x .125 tubing size for the support pole to reduce the side deflection due to the clothes bar's cantilever loading to 0.15 inches. All other is as specified on your first post. If you would like the Excel file for your own study then tell me how I can get to you; otherwise, if you want to see the effects of any changes to the frame dimensions or tubing then tell me what they are and I will run the analysis and give you the results.
 
  • #24
JBA said:
I have this on an Excel file but don't know how to attach that or a jpeg scan to this post so if you know how I can do either of those please let me know.
You should see an 'UPLOAD' button in the lower right of the test editor when you are sending a response.

JBA said:
due to excessive .48 inch sagging on the clothes bar I recommend the vertical tie be added between the bar and the support diagonal member at the center point of the bar.
Hm. That's going to complicate matters and add a significant cost.

JBA said:
I used an estimated 80 inch total pole height and have specified a 1 1/2 x .125 tubing size for the support pole to reduce the side deflection due to the clothes bar's cantilever loading to 0.15 inches.
Vertical pole is about 66" high, 1" O.D. 1/16th" gauge.

If that's not strong enough in either vertical or horizontal, I run a thick dowel up the centre of the tube.
 
  • #25
Wow, I guess you mean that big UPLOAD button, I always wondered what that was for.

I have updated the calculation sheet to reflect your current dimensions and tubing size. As for the recommended midpoint connection between the diagonal and the clothing bar, assuming you are using the same 1" tubing for the diagonal, then only a 9" length of the 1" tubing plus 2 of the same type of connector you are using for the bar to pole connection should be required for that added brace.

If I have done it correctly the Excel analysis sheet is attached below
 

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  • Clothes Rack Design.xlsx
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  • #27
JBA said:
Wow, I guess you mean that big UPLOAD button, I always wondered what that was for.

I have updated the calculation sheet to reflect your current dimensions and tubing size. As for the recommended midpoint connection between the diagonal and the clothing bar, assuming you are using the same 1" tubing for the diagonal, then only a 9" length of the 1" tubing plus 2 of the same type of connector you are using for the bar to pole connection should be required for that added brace.

If I have done it correctly the Excel analysis sheet is attached below

You have done it correctly. :) (though I'm not sure what to do with the numbers)

Adding a second brace will boost the cost by $35.
The SS goes for $3.50 per foot.
Simple 90 degree joints require only one fitting, whereas non-standard angle joints require two fittings.
Each fitting costs approx $10.
So that second brace is 1 foot of SS, plus one T-joint and one (2-fitting) angled joint.
 
  • #28
I really should have highlighted the primary input cells. Basically, at this point in your project the primary variables that could be adjusted are the tubing sizes and wall thicknesses; but, if you are locked in on these, then it is just some information that show where your design does not exceed the stress limits of your tubing and alert you to potential problem areas such as the need for additional bracing on the clothing bar.
As far as, the need for the that brace, it will clearly add cost, but, even more critical than the deflection shown is that the calculation is based on an absolutely evenly distributed load along the bar; and, a concentration of heavier clothing in center area of the clothing bar can significantly increase the tubing bending stress at that point and potentially result in a buckling failure and a sharp bend in the bar at that point.
While it might not have the appearance you might like, a much less expensive alternative brace that would be as effective as using tubing and fittings would be to use a length of SST flat bar bolted to simple sheet metal wrap around clamps on each bar.
 
  • #29
You don't think my solution of a large diameter dowel through its length will solve the problem? It's cheap and invisible.
 
  • #30
I was able to find a paper determining the Elastic Modulus for commercial wooden dowels, which the critical material property for determining the deflection of beams; and, unfortunately, wood has a modulus that is only 10% of that for SST, which, in simple terms means that the wooden dowel insert is much to flexible to add any stiffness and support to your SST tubes. For example, replacing the SST tube on the bar with a solid 1" dowel results in a center deflection in the bar of 2.75", so if overloaded the SST tube would buckle under the load long before the wooden dowel would add any support.

This is the reason that even after 10 years of retirement from my 40 years of engineering experience, I don't build anything that I don't want to fail without either getting input from someone with solid prior experience on the subject or by doing the best analysis I can before proceeding.

Over those many years of designing all types of equipment, one of the most important things I learned was not to become too mentally invested in any design before all of its elements have been examined and analyzed.
 
  • #31
JBA said:
I was able to find a paper determining the Elastic Modulus for commercial wooden dowels, which the critical material property for determining the deflection of beams; and, unfortunately, wood has a modulus that is only 10% of that for SST, which, in simple terms means that the wooden dowel insert is much to flexible to add any stiffness and support to your SST tubes. For example, replacing the SST tube on the bar with a solid 1" dowel results in a center deflection in the bar of 2.75", so if overloaded the SST tube would buckle under the load long before the wooden dowel would add any support.
Hm. I see your point. I had been assuming that the dowel would preserve the rigidity of the tube, like filling a hollow pipe with sand prior to bending it will prevent a buckle.
 
  • #32
DaveC426913 said:
Vertical pole is about 66" high, 1" O.D. 1/16th" gauge.
If that's not strong enough in either vertical or horizontal, I run a thick dowel up the centre of the tube.
I don't think adding wooden dowel in the centre would add a lot to the stiffness. Most stress is carried by the edge of the cylinder and the stress/strain modulus of wood is lower than steel. The wood would help resist buckling, but we hope you will be well away from that risk.
One suggestion for strengthening the round tube (other than bigger diameter and/or thicker tube) is to locally reinforce the tube at the strain peaks by sliding another tube over . I haven't done any calculations on that yet, but I've seen it used to strengthen tent ridge poles.

An alternative might be to use a square section instead of circular. My estimate of stiffness for 1"sq tube vs 1"diam cylinder is the square is about 5x as stiff, but only 30% heavier (but check that. I haven't done the full sums on square tubes yet.)

I defer to anything JBA might say, but I get a deflection of about 1.25" max on the vertical and about 0.125" on the horizontal with uniform (1.3 lb/") load and support at 42.5". (I now get that as optimum for uniform load. Though if the load is likely to be biased towards the hinge, 40" might still be better.)
 

1. What is the optimal support angle for a steel clothing rack?

The optimal support angle for a steel clothing rack depends on several factors, including the weight and distribution of clothing on the rack, the height of the rack, and the material and thickness of the steel. Generally, a support angle between 45-60 degrees is recommended for maximum stability and weight-bearing capacity.

2. How does the support angle affect the overall strength of the steel clothing rack?

The support angle is a critical factor in determining the overall strength of a steel clothing rack. A steeper angle may provide more stability, but it also puts more stress on the joints and can lead to bending or warping of the steel. On the other hand, a shallower angle may not be as stable but can distribute the weight more evenly and reduce stress on the joints.

3. Can the support angle be adjusted for different types of clothing?

Yes, the support angle can be adjusted for different types of clothing. For heavier items, a steeper angle may be necessary to provide adequate support. For lighter items, a shallower angle may be sufficient. It is important to consider the weight and distribution of the clothing when determining the optimal support angle for a steel clothing rack.

4. Are there any other factors to consider when determining the optimal support angle for a steel clothing rack?

In addition to weight and distribution of clothing, other factors to consider include the height of the rack, the location of the rack (e.g. against a wall or in the middle of a room), and the frequency of use. These factors can affect the stability and weight-bearing capacity of the rack and should be taken into account when determining the optimal support angle.

5. Can the support angle be changed after the steel clothing rack is assembled?

In most cases, the support angle cannot be changed after the rack is assembled. However, some racks may have adjustable support angles that can be altered by loosening and tightening bolts or screws. It is important to carefully follow the manufacturer's instructions when assembling and adjusting a steel clothing rack to ensure proper support and stability.

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