Portable Wood Rack Stability

[derek labian]

You're going to move a 6 1/2 foot tall rack around that weighs as much as my car on small swivel casters, with brackets and bracing that even you have doubts about. What could go wrong?

My dad used to work with an older guy, more experienced and set in his ways. When Dad tried some novel approach Milton would say, "Go ahead and do as you've a mind to, you're going to anyway- you goddamn nut!" Good luck.

What is your point, that you don't like my design? You are seeming to imply that I dismissed your concerns or comments. I can't see how this could be further from the truth.

I did the math and it looks very safe.

I built a scale model, very stable, more weight, more stability, just like the math.

If you read my OP, my concern was mainly around cantilevered shelf stability. That is still my honest concern, but no sagging as of yet.

Here's the feedback you provided, although I felt it was already addressed.

That is a lot of weight for a moveable rack at about 4#/bd ft. I have a commercial shopcart 22" x 60" with 6" swivel casters and it is all I can do to move it alone when fully loaded with sheet goods (1/2 ton or so), especially when reversing direction.

As stated in my previous post, the additional weight makes the rack more stable, and not less stable. Yes, its very difficult to move, and reversing the direction isn't ideal, but not bad enough to change them out.

Loading sheet goods on the back side, leaning against the uprights, will increase the load on the front braces.

I believe it's negligible, to the point of being irrelevant. I just don't think that much force, in comparison to the cantilevered shelves with white oak, is applied. It might be worth while to reinforce the uprights with steel L bracket though on the sheet good side. The uprights are glued, lagged, and tenoned into place though.

A sudden stop against a piece of scrap on the floor could be a real problem, especially with much weight up high.

Yes, I agree, and I addressed this in my previous post which was a static calculation. Moving something with that much weight has to have very low velocity. It also safest to move from the base. I'm adding a pully system to make it easy to push and pull from the base.

I will say again that I'm not wheeling this all over, its being moved like 2' at most once in a while (once every month or two).

[Kevin Jenness]

If it works, it works. Time will tell. The idea of moving that much weight around on the rack you have built leaves me skeptical, but it's your call. It doesn't hurt my feelings in the least if your judgment is different from mine. Milton wasn't always right, he just had an amusing (to me) way of expressing his disagreement. I meant no disrespect and I hope your solution works out long term.

[derek labian]

If it works, it works. Time will tell. The idea of moving that much weight around on the rack you have built leaves me skeptical, but it's your call. It doesn't hurt my feelings in the least if your judgment is different from mine. Milton wasn't always right, he just had an amusing (to me) way of expressing his disagreement. I meant no disrespect and I hope your solution works out long term.

Fair enough. I'll post an update in a year. If I don't post, you know it didn't work out so well

[Tom Bender]

Hi Derek
Nice job on the model. Actually I was suggesting making a model of the arm to upright joint and test that to destruction. My concern is mostly with the potential for a failure which could cascade like the World Trade Center.

And my concern about height is getting lumber on your head.

[derek labian]

Hi Derek
Nice job on the model. Actually I was suggesting making a model of the arm to upright joint and test that to destruction. My concern is mostly with the potential for a failure which could cascade like the World Trade Center.

And my concern about height is getting lumber on your head.

That is also my concern. Very time consuming to build a scale there. I think it would almost certainly cascade if it failed. I mentioned I may reinforce the 2x6 brace against the upright with an additional 4x4 wedge. Right nownimnjust going to check for sagging.

I think it would be easier to take a full size shelf and check the failure load. You can scale that out. Maybe I'll that.

[Steve Tripp]

I also agree with bigger casters. I have almost all of my tables and storage on wheels and they are the first things I'm going to upgrade. In my case, 4 inch wheels "may" be large enough.