tube split

[A_pyro_rush]

Has anyone ever had a problem with sdr11, hdpe mortars? The type various vendors sell premade ready to shoot from.
To be more specific, has a tube split open in any way? I'm not meaning the ones suppplied with Excals either.
My reason for asking is I'm planning on building some new racks and if the
sdr11 doesn't have a track record for problems, then wood like pine would be OK for building. Pine wood has a very high split ratio compared to ash, oak, birch and others. Cost for the other woods would be a factor. But safety is the first concern.

[graybeard]

It is very unlikely that you could split an HDPE mortar using consumer shells. What can happen with HDPE, is that it gets soft and bulges out when it gets very hot. This could happen if your were to speed load several shots in the same mortar, one right after another. The problem with using soft pine in building mortar racks is the wood tends to crack where it is nailed or screwed. If you are firing a finale volley from a rack made of poor quality wood the recoil of the shells leaving the mortar could cause a structural failure in the rack. If your rack is on uneven ground during firing this can add to the stress in the wood. Think of what would happen if your rack started coming apart halfway through a finale shot.

[A_pyro_rush]

Greybeard,
Do you think that using a 2x4 for the bottom and 2x4 for the ends would control all the shock? 3 inch deck screws (predrilled&chamfered) should probably be suffiecent? 1x4 for the sides seem to be more for stabilty,to me.

[Deweycoon]

I make my racks with 2x6's and 1x4 or plywood sides.

Check these out;http://www.pyroreview.com/gallery/showphoto.php/photo/3163/sort/2/cat/520/page/1

[graybeard]

Good to see you are putting safety first in your rack construction. Your plan looks good in the way of good solid construction. I like the idea of a heavy base board, as that is where all the recoil will be absorbed. In addition to holding up against recoil, your racks will stand up to rough handling, such as sliding around in the back of a pick up, etc. Give some thought as to how you will stabilize your racks from falling over. I like the idea of using relatively large triangles made of plywood that you screw on the ends of your racks. I call them 'batwings'. You leave these loose during storage and transport, and screw them on with a cordless drill, when you set up your racks. You can angle your racks using this method, simply by setting the angle before you drive your screws. Use square drive screws, and you can back them out quickly when you break down your show. I have seen a lot of racks stabilized with a single pivoted cross piece under the rack. I am not at all sure of that method. It looks like the cross piece could move around and fold up on you if your rack gets to bouncing around. A lot of guys use eye bolts with short rebar rods to stabilize their racks. The rods can be a problem with pavement or real rocky soil like we have here in the Ozarks. I also fear someone could stumble in the dark and fall on a rebar rod sticking up. I also don't like the idea of having to sledge hammer in the rods to the point of being solidly planted, and then have work to get them back out after the show.

[MNPyro]

I agree, safety should be put at the top of the list when it comes to pyro, and especially when something is shooting.

Though, I somewhat think that a 2x4 on the bottom AND the sides will make that rack quite heavy...well maybe this is just a 5-10 shot rack, then it won't be really heavy. But with my 25 and 50 shot racks, I used 1/4" board on the bottoms. For the 25 shot racks, I used solid 2x4s for the sides, 1x4s for the bottom, everything in between(Picture (http://www.pyrouniverse.com/gallery/albums/userpics/10056/IMG_0001.JPG)). And on my 50 shot racks, I used 1/4" plywood all around, a somewhat different design, but still the same idea. I glued and stapled these guys together.

What about a string of shells going off? I had, for the finale, both my 25 shot racks and my 50 shot racks filled, and stickymatched. So, per rack, I had either 25 or 50 shells going off within seconds. Not a single one of my racks cracked, splintered or in any otherway "changed" from the way I made them. These were shot on somewhat uneven ground.

So my thoughts, yes 2x4 will withstand a lot of force, probably will last a bit longer than my 1/4" thick racks, depends how much use it gets put through. But if you're building "bigger" racks, i.e. 20+ shots, 2x4 all over is going to get quite heavy.

Just my thoughts....

MNPyro

[A_pyro_rush]

Thanks guys,
I have looked at alot of already made racks all over this forum and pyroreview. My main concern was the type of wood. That is settled.
The size would be no more than 10, for this type of setup. I have a milk crate to try for a 24 tube rack with fiberglass tubes. I'll post them when completed.

[St1dinoh]

i made a rack out of deck lumber and plywood.

i ripped some 2x6 in 1/2 then made the "U" shaped side brace. then sandwiched the tubes between some pieces of plywood with some cardboard shims to allow it to pinch the tubes when i screwed the plywood to the 2x's. this way the tubes won't "jump" out of the box when you fire them.

after the boxes were built i just added 4 eyehooks (2 on each side) and i use 1/4 inch electrical conduit as rebar to anchor them into the ground. this way i can angle the box anyway i want. i made 5 of these and they each hold 5 tubes. so all together i can line them up and make a long 25 shot rack, or spread them out for front fire, or anchor them all together in a block for a mini 25 shot finale/barrage box.

i'm thinking of doing my next 100 like this. set up and clean up is so much eaiser. you just pound the rebar into the ground through the eye hooks (one pole on either side) and you're good to go.

[graybeard]

Pyro Rush, you mentioned using a 24 shot milk crate rack. There is a safety consideration using a milk crate for a rack. You don't want to get into a situation where you are reaching across the top of the closely grouped mortars in order to ignite individual fuses in the center area of the crate. When using milk crates, you should use chain fusing only, having the ignition start point of each fuse line, reaching beyond the outside edge of the rack.

[leeca]

Pyro Rush, you mentioned using a 24 shot milk crate rack. There is a safety consideration using a milk crate for a rack. You don't want to get into a situation where you are reaching across the top of the closely grouped mortars in order to ignite individual fuses in the center area of the crate. When using milk crates, you should use chain fusing only, having the ignition start point of each fuse line, reaching beyond the outside edge of the rack.You can still use grouped mortars to ignite individual fuses in the center area of the crate. Just add a leader fuse or a long piece of sticky match to hang off the side of the milk crate rack, or e-fire them.

[A_pyro_rush]

The idea on the crate is to fan 3 rows of eight

\ | /

1 row chained together. 3 separate fuses, aluminum foil to prevent preignition of each row.
I plan on doing a much scaled down version of July4th... on Memorial Day weekend to see how my planning goes.
If I were to have to light one in the middle, I probably wouldn't (1/2 hour rule)

[pennst26]

Hey guys, after reading your posts, I thought I'd just add a couple things. First off, I am a carpenter, and I have been building for a very long time. One of the things I have learned, is that the old ways of heavy lumber are not necessarily the strongest methods.
The old 2x12 floor joists have been replaced by TJI which is basically 1/2" sheathing on end. I am no engineer, but I know that these can span further distances, and do not split.
I use this with every rack I build. 5/8" roof sheathing (not plywood as plywood seperates easily, and is not as strong) gives you plenty of strength, and is not too heavy. I rip the wood into approx. 5" strips. I use 3/4" on the bottom. I use plenty of PL400(liquid nail) before I screw it together. The glue does a much better job than screws or nails, but I wouldn't rely on either by itself.

This provides a very sturdy rack, that is both inexpensive, and light. If you are worried about moisture...stain it.

[lamrith]

PENN - You should post some pictures! We are all always looking for better options to our set-ups.

Hey guys, after reading your posts, I thought I'd just add a couple things. First off, I am a carpenter, and I have been building for a very long time. One of the things I have learned, is that the old ways of heavy lumber are not necessarily the strongest methods.
The old 2x12 floor joists have been replaced by TJI which is basically 1/2" sheathing on end. I am no engineer, but I know that these can span further distances, and do not split.
I use this with every rack I build. 5/8" roof sheathing (not plywood as plywood seperates easily, and is not as strong) gives you plenty of strength, and is not too heavy. I rip the wood into approx. 5" strips. I use 3/4" on the bottom. I use plenty of PL400(liquid nail) before I screw it together. The glue does a much better job than screws or nails, but I wouldn't rely on either by itself.

This provides a very sturdy rack, that is both inexpensive, and light. If you are worried about moisture...stain it.

[pennst26]

I will :D

It may take some time, as my magazine and storage is quite far from where I live :(

But I have some questions about how best to wire with my particular setup..... So I will get some pics together soon.

[A_pyro_rush]

http://www.pyroreview.com/gallery/showphoto.php/photo/4847/sort/2/cat/520/page/1
I made some changes to better fit what I have planned. Took awhile but hey, still early.