Cluster Center Ring Construction Question

I have to rebuild my rocket I destroyed, which had a 3x24 cluster mount. I used 1/8" lite ply for the rings. This time around I'll be using the thicker LOC engine tubes and I was considering making my center rings out of the thick card stock that they sell at Apogee. I have a few pieces left and thought maybe I should use them up and this way I won't need to place another order and it will keep the weight down.

https://www.apogeerockets.com/centering_rings.asp#Cardstock

I know I can have Bill BMS custom make the rings to fit the thicker tubes, but if I went that route I would like to place a big order not only for clusters, but a variety of different sizes and right now I'm not sure what my next few builds are going be.

My main concern using the card stock rings is how long they will last. I know the engines will be producing a lot of heat, but then again I'll be using the thicker tubes so this might be reduced. I just don't want the rings to fry like my old thinner engine tubes I used on my last rocket. I will more than likely add small tabs to add extra strength and reinforce the rings.

Any feed back is appreciated. Thanks

RocketManDan said:

I have to rebuild my rocket I destroyed, which had a 3x24 cluster mount. I used 1/8" lite ply for the rings. This time around I'll be using the thicker LOC engine tubes and I was considering making my center rings out of the thick card stock that they sell at Apogee. I have a few pieces left and thought maybe I should use them up and this way I won't need to place another order and it will keep the weight down.

https://www.apogeerockets.com/centering_rings.asp#Cardstock

I know I can have Bill BMS custom make the rings to fit the thicker tubes, but if I went that route I would like to place a big order not only for clusters, but a variety of different sizes and right now I'm not sure what my next few builds are going be.

My main concern using the card stock rings is how long they will last. I know the engines will be producing a lot of heat, but then again I'll be using the thicker tubes so this might be reduced. I just don't want the rings to fry like my old thinner engine tubes I used on my last rocket. I will more than likely add small tabs to add extra strength and reinforce the rings.

Any feed back is appreciated. Thanks

Click to expand...

I'm not sure the card stock will be a problem. For example, the stock Big Daddy rings are thick card stock.

That said, I've made all mine from balsa plywood. I draw up the bits using a CAD program - in my case, Adobe Illustrator or an old version of Autocad. Either way, I print out several on a sheet. (BTW, there are some patterns here and here which will work. Make sure they're printed without scaling.)

Then I make up some balsa ply by laminating a sheet of 1/16" balsa with 1/32" balsa on either side. This 1/8" balsa ply is much less susceptible to breaking than ordinary 1/8" thick balsa.

Versus aircraft or birch ply, it's much easier to work with. You can readily cut it with an exacto knife, then sand it to size with some 100 or 150 grit.

I glue the printed patterns to the plywood and let it dry. Then I rough cut the bits, then sand them to shape. A piece of 150 grit wrapped around a BT-50 makes a great sanding tool for shaping the inside arcs.

I don't sand the outsides of the three pie pieces until after they've been glued to the 3-tube cluster. Once the glue is set, I then begin sanding the outsides while making frequent test fits.

That's how this adapter was made. It fits perfect and uses little in the way of "store-bought" parts. BTW, you can see the remnants of the paper templates still glued to the wood. Doug .



.

My second choice is 3/32" basswood, which I have in stock. The card stock from Apogee is thicker than the Big Daddy kit. I'm pretty sure it is. I am working on the Big Daddy so I can compare the two tonight when I get home from work.

are the fins TTW? or could you use a 3 x 24 cluster mount kit?
If the fins are not TTW you could make the mount easily removable/replaceable.

for .040 paper stock you could use matt board from the craft stores. not sure if it's the same material apogee sells but I have used it before for custom rings.


all the rings and discs on the cutting mat below were made from matt board with a compass cutter.

The fins are not through the wall and its 3x24mm. I posted a link on thread of the material I will be using. I think the card stock will work. I might give the tubes a light coat of epoxy.

Andy here are specifications for the card stock. I think it's thick enough.

Cardstock Sheet Dimensions:

8-1/2" X 11" X .048" thick
Centering Ring Cardstock

P/N: 44002
Price: $1.81 each sheet

RocketManDan said:

The fins are not through the wall and its 3x24mm. I posted a link on thread of the material I will be using. I think the card stock will work. I might give the tubes a light coat of epoxy.

Andy here are specifications for the card stock. I think it's thick enough.

Cardstock Sheet Dimensions:

8-1/2" X 11" X .048" thick
Centering Ring Cardstock

P/N: 44002
Price: $1.81 each sheet

Click to expand...

I'm sure the card stock will work. But, if there's any concern you can beef it up by coating it with a thin layer of epoxy after it is in place.

-- Roger

jadebox said:

I'm sure the card stock will work. But, if there's any concern you can beef it up by coating it with a thin layer of epoxy after it is in place.

-- Roger

Click to expand...

agreed!

also agreed .

btw the matt board in the photo is .055 thick but they don't always have that size . usually closer to .040 thck. sorry I should have mentioned that., several ways to beef it up if you think it needs it anyway

0.048 should be plenty strong.and as you said coating them will be even better !

When I built my Tube Daddy, I built it with a 3x24mm motor mount. I made the centering rings out of cardboard (actually more like a heavy mat board) with a layer of 110# cardstock glued to it as a pattern. It ends up being about .058" thick. I've flown it about a dozen times so far (motors are friction fit), at least two or three of those on E9s and I've had NO trouble with the centering rings. They are just as solid as the day I built it. (Can't say the same for the tube fins... gonna have to do a little strengthening and reinforcing on them.) Cardboard fins should work just fine unless you are planning to light three F motors in there! (Hey, three E9s are expensive enough to burn on one flight - I don't wanna think about even pricier motors! )