Hi

I have a 70 foot net we use for an outdoor cage, and i have been given permission to use it in a city building here during the winter.

The building width is 59 feet the cage is longer but that's no problem, we have been advised to use 1/4 galvanized cable it's either 7 19 or 7 9 i am not sure on the number and or 1/8th cables.

We need 3 strands, sides and middle.


The anchors are to be screw eyes closed with 350# weight, 3 on each end, and 3 turnbuckles with i think 350# weight, then the thimbles and clamps and hooks for the net.

We have to use it on a set up take down basis, so the net has to slide out from the wall on the cables, then when done we slide it back hook the net up and take the cables down on the turnbuckle end, to keep it out of the basketball volleyball space,

Has anyone done anything like this as to safety measures and strength?

The net i think is #21 and actually is 70 feet, may be total weight 100#'s or so?

Any questions feel free to ask.

I first posted this in the general forum, and was directed here.
thanks
Original Post
Hey bop,

First welcome to HSbaseballweb and hope you visit often. It's a great site with a lot of knowledge and perspectives about baseball.

Second you are going to find the retractable tunnel to be an awesome thing to have.

If it's not too late there is a kit you can buy almost anywhere online that has everything you will need to hang your tunnel.

Most kits will include

3 100' wire cables
6 hook and eye turnbuckles
6 eyebolts
70 snap links

Cost is around $200 or less

I had a 70 foot tunnel put into a barn that was close to 90 feet long. I bought a kit and it was more than enough to hang the one tunnel.

The cables are 1/8" thick.

It also wouldn't hurt about once a year to tighten the turnbuckles a little bit as the nets tend to cause the wire to stretch a little.

These are fairly easy to put together. I actually did all of mine by myself except for hanging the wire the net will hang from. I need two others to help pull the wire tight and then clamp it down.

I hope this helps but if you got any more questions please feel free to ask.
Thanks

No, it's not to late, i have priced out some things from a couple different places on the web and have yet an accurate final cost. I went to the local hardware store and looked at all the items in question, and it appears i can buy it locally. I was just concerned about the actual size of the turn buckles and screw eyes for tightening the cables.
1/4 cable looked a little big, but was plenty strong, 1/8th they did not have in stock or could get,

Just so you know, we use this, set it up each time and have to take it down after use. No room to permanently leave it up.

So, my concern i guess is the weight load or size of the screw eyes if i bought them locally as well as the cable and turnbuckles.

Presently it appears we will be putting these into a stud of some sort, the walls are paneled, but have an area where we could put a board across on both ends to attach to.

thanks
Yeah the 1/4 is probably too big and you would might have to get bigger eye bolts but not real sure.

When you say you have to take it down do you mean after each time you use it or the season?

Do you have to take the cables down too or will they get to stay up permanently?

I apologize but I'm not picturing how you are going to use this. From your post it sounds like each time you use the net you will have to put the cables up and hang the net on the cables. If this is correct then I would suggest in finding another solution because that would be a lot of work just to hit.

If I'm wrong (and I hope I am) then if you are going to just slide it back and forth then you will be in great shape.

Also double check the walls and how strong the studs are because you are going to have a lot of tension on them. You might have to add onto the studs to give them enough strength to hold the cables.
thanks

yes it comes down each time, no other way no other location, unless i build a building, the net would be put up one time with cables in place, hooks attached etc, when done the net will slide back to the wall, then be hooked up there to stay, then the cables loosened and just drug back to the net area, net stays hooked to cables, then the next time all we have to do is re hook the cables, tighten the turnbuckles, slide the net out, ready to go,

there is no other choice unless 5000 or so for a ceiling system, and they are not in favor of that.
thanks
Thanks

I just called one of those stores 40 miles from us and i can get 3/16 cable for .26 a foot so i'd only have like at 210 feet $55.00 + in that plus the turnbuckles and screw eyes,. they have those also in heavier specs. Would a screw eye saying 350 #, there will be strong enough, (6) of those , could put 2 in if necessary side by side. The net is like i said around 100#s, so what ever the tension is, the turn buckles are in varying sizes also.

Looks like that's where i'll get the material, no shipping costs.

if you know?

thanks again

this is also posted in the general forum where i first posted after i registered on the site!
To get an idea of how much force will be placed on the turnbuckles and the wall, see this thread.

I think you will find it quite challenging to remove and put up the cables after the cables have been strung and cut to length, even if there is no net strung from it, because the sideways force is so large. Picture yourself standing on a step ladder, with more than a hundred pounds pulling sideways. Probably the ladder will tip over.

Really long turnbuckles might work, but also consider putting in two eyebolts on one of the walls. One would be attached at the intended cable height, and the other below the first by several feet. Run the cable through a pulley attached to the top anchor, and attach the cable and turnbuckle to the lower anchor. Putting tension on the cable in order to remove or reattach the cable from/to the lower anchor is done with a straight down pull, and that's much easier to generate than a sideways pull. Probably body weight would be enough. Then you'll be able to remove/attach the pulley with very little tension in the cable, because you've temporarily added a yard or so to the horizontal length of the cable when it is disconnected from the lower anchor.
Thanks

I did not explain this or if i did it was overlooked with all the questions - so -

Once the cage is up once, and used, when we take it down, all we do is slide the net back to the walls, cables still up no tension released. When the net is back to the side wall, a cable will be hooked on the wall in 3 screw eyes above where the cables are and the net will be snugged up to hang on these screw eyes. All weight is released from the cables. Then we loosen the cables, take them down, roll them back by the wall, and when ready to use all we do is string the cables and tighten the tension, slide the net out, i think i should get a patent on this????

what do you think now,.?

i have been there don that, putting that up outside ,understand your position, i am eliminating that issue i hope?
thanks

i read your your link i overlooked sorry, on tension and load, what happens if you add 2 more cables on 59'? the way we have this setup in the summer is it goes over the top of 5 sections of 1"galvanized pipe i'ts 10 x 10 x 70, then we pull 2 ropes over the top and under the net to lift it up and tie it off, just small cloth type ropes., if necessary i could have some interior supports in 1 or 2 places also be easy to do. 1/2" electrical conduit would rasily give the sag and tension release?
what do you think?
quote:
Once the cage is up once, and used, when we take it down, all we do is slide the net back to the walls, cables still up no tension released. When the net is back to the side wall, a cable will be hooked on the wall in 3 screw eyes above where the cables are and the net will be snugged up to hang on these screw eyes. All weight is released from the cables. Then we loosen the cables, take them down, roll them back by the wall, and when ready to use all we do is string the cables and tighten the tension, slide the net out, i think i should get a patent on this????

what do you think now,.?


I think that might work. Still going to be a lot of work but better than what I was imagining. I thought you might have to take the net off the cables each day. That would be a pain in the butt.

I think if you get big / long enough turnbuckles to release the tension that will help tremendously.

It's great you will be getting the stuff cheaply at a hardware store because I think you will be saving a lot of money that way.

Once you get it up take some pics and post them here so we can get a look at what you have done. May help some others one day.
OK, now I understand better. Assuming that you can get all the weight off the 3/16" cables while taking them down or putting them up, and assuming that the turnbuckles are long enough to take up 0.5" plus however much you need to clear the end of the hooks, which I guess would be another 0.5" to 1", then you'll only need to provide a 20-30 pound sidewise pull to release the hooks. Should be pretty doable.

Also, if the nets weigh 90 lbs, or 30 lbs per cable, I calculate that you need to provide 9" of sag to keep the sideways force on the screw eyes to about 300 lbs when the nets are suspended. So be careful not to try to get less sag.

The other thing to worry about is if the building is all concrete, and therfore very rigid. As the temperature changes, the cable and building are likely to change length at different rates. That may stretch the cable or fittings, and then if the temperature returns, you'll get a larger sag. In a wood framed building or one with steel studs, this won't be a problem because the wall will just bend. For example, to reduce the tension from 1000 lbs to 300 lbs, the walls only need to deflect by 0.004 inches!

Adding stable supports in the middle of the span will significantly reduce the tension for a given sag, but it doesn't look like you need that. If the top of the supports can move in a direction perpendicular to the cable, I don't think the tension will be reduce much at all. So it's probably more trouble than its worth.
Thanks

This bulding was built as a commercial use some 40 years ago i think, it is unknown to me if it is steel framing or wood, but it is wood sided, paneled inside
, cement floor, well heated.
I can't do it today, the REC director is home ill, but i could get you a picture of the inside if there is a way to email it to you or post it here on the site? I have an outside photo from last year as the building was sand bagged to protect from flooding.


I don't have the ability to understand movement of the building, without an engineer doing a report and i don't know who i'd get to do that.

I did call a site that was mentioned on one of the pages here (sterling maybe)a netting company and all they did was sell the kit and had no idea on weight loads.

In regards to changes in cable, we will not be having it up that long of times-2-3 hours minimum to 8 hours max, 1-3 x a week, guessing, if i need more cable to adjust for that i can add extra length.

I just called ]http://www.wwewirerope.com/aircraftcable/, they were listed on another discussion here on this web site,, and they indicated 1/8th cables were sufficient with 1/4 x 4 turnbuckles? 3 strands.

thanks

quote:
Once you get it up take some pics and post them here so we can get a look at what you have done. May help some others one day.


When life hands you gators - make Gatorade

I will gladly do that!
Hi

Now another issue has come up.

On the cables that have here 3/16 7-19 i believe, they call it 840lb "working load".

They do not show a "breaking strength" of 2000 or 3200 etc.

What is the deal on this?

This is both Ace Hardware and Farm and Fleet and this site,

http://kochmm.com/UserFiles/Image/KochIndustries/catalogs2/Chain.pdf#page=8

the site below has different ratings


http://www.wwewirerope.com/aircraftcable/
bop,

Don't worry about a concrete building unless the eyebolts will be set directly into concrete. If there is any kind of intermediate wall or facing that the eyebolts attach to, there won't be any problem. And if the temperature stays with a few degrees, there won't be a problem even with a concrete building.

Cables can be rated by their breaking strength, which means that for a cable rated at 2100 lbs, it typically will break if the tension exceeds 2100 lbs. Good engineering practice (and just common sense) says that we don't want to try to use the cable at the breaking strength; if the cable is imperfect, or the load is bigger than designed, the cable will break. Please note that if a tensioned cable breaks, the result is not simply that the net falls down. There is a pretty good chance that the broken cable will whip around at high speed, and potentially seriously injure anyone in the vicinity.

So people design with a safety margin. And to make it simpler, many suppliers of cable specify a working load, which has the safety margin built in. The margin chosen for cables seems to be a factor of 2.5. That is, 840 lbs times 2.5 equals 2100 lbs. This is a reasonable margin which should cover both manufacturing imperfections, and loss of strength due to aging and corrosion.

1/8th inch cable generally is listed as 400 lbs (sometimes as low as 350) working load, and according to the calculations I posted above, that should be adequate for a 90lb net, provided you keep the sag to 9 inches or more.
Thanks

I made a couple calls this am and it appears a 4200 lb breaking strength is 840 lb working load, 1/5th or 5x which ever way.

Always little things like these pop up,. but your statement about safety was my concern.

There was mention here some where about a pulley to lift the net up on the wall when we pull it back to hang it, can you advise on that again.

When we are finished will advise.
thanks
bop,
When I mentioned the pulley system, I was mistakenly believing that the weight of your net would be on one end of the cable. Since you plan to lift it up, there is only the weight of the cable itself to pull against. In a post above, I said that pull would only be 20-30 lbs for a 3/16" cable, and I think you'll be able to pull that hard, even on a ladder. So don't bother with the pulleys.
ok
Thanks we are meeting tomorrow, to go over what i have drawn up, looks like a go, i was there today also.

Do you think the 1/8th 7-19 is ok or should i go the 3/16th?

I left 2 samples with them today but one was 1/4 and that is rather bulky, i don't have a piece of 3/16th yet

Can you specify screw eye size, 1/4 or 3/8 by 6 or better, and the turn buckles size you thin 1/4 or 3/8 by 6 or so?


thanks

no pulleys then
I shudder to even ask this, but when i was at the cc today waiting for the rec director, i was eyeing another thought.

The building has open trusses, boxed in 12 feet apart , if we put a screw eye in vertical in 2 of those 60 feet or 65 feet apart and then hooked the cables to them saying the cables would clear the other trusses, these 3 cables would be at different heights being it is a vaulted ceiling, but they would be running 12 feet apart, one in the middle, 65 feet or so long, then we put cables vertical at 6 feet or closer attached to the net and overhead cables, the upper end would have a quick link or ring of some sort to slide on the cables. The tension we would have would be on the trusses then not on the side walls. This would be a overhead system i guess. Can you visualize this to work?

Much harder to install, would get more use of the full cage , would push back out of the way better without a hookup
For the original scheme, I do think that 1/8th inch will work. I don't really have a good idea about the eyebolts or turnbuckles.

For the new scheme, I'm not at all sure I understand your idea. But I suppose that you are thinking of putting up 3 cables that are parallel to each other but at different heights. The cables would be high enough to not interfere with basketball or volley ball, and so they could remain in place all the time. You'd put in vertical sections of cable, attached by a ring at the top, and to the net at the bottom. Because the 3 horizontal cables are at different heights, the vertical cables would have 3 different lengths.

There might be 3 sets of 10 vertical cables, so the spacing between cables would be around 6 feet.

I haven't given this much thought, but there are two related likely problems.
1) The horizontal cables will sag, and there will be a tendency for the tops of the vertical cables to slide downhill toward the center of the cable span. Maybe there will be enough friction to keep this from happening, but I don't know.
2) The bottoms of the vertical cables will move toward the center of the net, and there will be significant sag in each section of the net between the vertical cables. The roof of the net will also sag. The amount of sag depends on the length of the cables and the weight of the net. I don't know how much. So you would need to space the 3 upper cables further apart than the width of the net, and make the horizontal cables longer than the length of the net in order to keep a reasonable tension on the net itself.

It is possible (but not easy) to estimate the needed configuration of the cables. Frankly I don't want to calculate that unless you're pretty sure that you'll be allowed to go forward with the idea.
Thanks

You have it pretty well, the assembly would slide back to the wall on the upper cables once finished, the cables would stay up on the trusses at 18 feet or what ever, but i thought about the slide also, they probably would not stay in place with out a tie back arrangement. Probably would be the same on the sides.

In regards to the first one, the sides are free hanging at this point, no supports as a frame cage i suppose we can pull one side out easily and weight that down , on the other side we have the wall to put some rope on to hook it also

We are meeting tomorrow instead of today, and i made another drawing on the 2nd one and gave them last night so we will see.

thanks

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