What type cardstock is used for centering rings?

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Jan 18, 2004
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I am trying to build some some rockets from the Kosroc site but I don't have an idea of the weight of the centering rings. I thought of using poster board but it feels a little too weak. Where can I get some that will work. I also thought about using ply but I thought that by the time I finished the rocket it would weigh too much. So I'm back at the idea of cardstock. Any help:(
For centering rings in low power models I usually purchase some mat board (0.050" thick) used in picture framing from a craft shop like Michaels. Some times they will even give me scrap pieces of this material for free! This materail cuts easily with a hobby knife, I put a hobby knife blade in a compass to cut out custom centering rings. You can now buy a similar device for scrap-book made projects.

Bruce S. Levison, NAR #69055
Is this material comparablre to the original stuff. Would you have to coat the material to make it stronger. I would hat e to build a rocket just to loose it to a motor mount failure!!:)
My wife had one of those circle cutting things for her scrapbooking and was getting a new one (bigger and better - you know... just like us rocketeers!), so I inherited the old one that she had bought for about $8. It's not quite sharp enough for her scrapbooking, but it works wonders for my centering rings!

I use the mat board material in place of the original 0.05" thick card stock and have yet to see any failures! I used it for the fins on my Centuri Jayhawk clone.

Bruce S. Levison, NAR #69055
I found some really heavy cardstock at Micheal's craft that is about the right weight...maybe a little heavy.

It's about 3/32" thick and it's poster stock. It's white on one side and gray on the other.

As strong as lite ply but even lighter.

Are ya gonna make a Saturn 1B????:rolleyes: or a Mars Lander?


Well, Sandman, I'll be trying the Mars Lander after I complete the RIM-2 Terrier project. I guess that I haven't thanked you for the fine workmanship of the couplers. I'm in process of getting the parts together to start the booster. I'll post pics as soon as I figure out how. Once again thanks.
I also use picture matte board for centering rings, and it works very well. You can also strengthen it by soaking CA into the edges of your cut CR (you may have to come back and do a bit of touch-up sanding).

If you need heavier/stronger material, try either home-made balsa plywood (sheet stock laminated with grain crossed 90 degrees), or even better, get some foam-core board.

Foam-core is the stuff sold at craft stores (2 ft x 4 ft sheets and smaller) and office supply stores (4 ft x 8 ft sheets) as a mounting or backing surface for large artwork. It has paper face sheets and a core made of foam that is usually about 1/4 inch thick. Cuts with X-acto blades, sands to shape with sandpaper, and for fine-tuning you can roll it on a hard surface to compress the perimeter. Foam-core can be installed with white and yellow glues and is more durable than the rest of the rocket materials.
I agree on the foam core. It's a good lightweight, strong product. The only hard part is that it is so thick that getting your hobby knife to cut straight through it requires a lot of control on my part. It's very easy to accidentally get a slight angle in the blade while I'm cutting and end up with an uneven cut.

wwattles is absolutely correct, foam-core is a fairly difficult material to cut. You have to use a SHARP blade, be very careful about what/where you are cutting, and have a little patience. I don't use foam-core very often because it is more trouble to build from, but it is also pretty strong stuff if you have to have it.
I make centering rings out of just about any solid cardboard material I can find. I've found the backs of paper pads works great for LPR models. I've used it as the forward ring on 3 and 4 motor cluster models as well. 14ply sho-card stock is wonderful for centering rings but must be cut with a drill-press type cutter as it's just to tough for the compass type cutters. The stiffener boards in most clothing is also a good source for centering rings.
my centering rings are the closest thing to me... cardboard or balsa whichever... havent ever had a failure (yet) so i guess my lazyness is rewarding...
I got a sheet of 5 ply Bristol board from Jerry's Artarama. It is finished on just one side. They have thinner sheets (2, 3, and 4 ply) that are finished on both sides.
If you think your CRs are looking a little wimpy, try soaking them in CA after you cut them out. That stuff will wick into the paper fibers and harden the CR quite a bit. You will likely have to touch up your CR again with a little sandpaper, but it will be much stronger.

Another trick is to use the same cardboard material to make three or four shear webs to fit between the fwd and aft CRs, and that span from the outside of the MMT to the inside of the BT. Space them evenly around the perimeter of your MMT just like fins. When I use these webs, I assemble the MMT tube and fwd CR, then add the webs. I install this into the rear of the main BT without the aft CR so I have access to get glue all over all the inside corners. After a day of letting the glue dry (I use white glue) it is OK to go ahead and put in the aft CR and close it up. These internal reinforcements will make the whole motor mount assembly much more stiff.
I've used the thin corrugated paper from the gigantic cereal boxes they sell at Sam's Club with some success. It cuts very easily and for added strength you can cut multiple rings and glue them together with the grain crossed.

After lots of looking in my local area I have found a product called Master Illustration Board. WalMart just started carrying this at our store. I dont know what weight is is but it is quite thick and very sturdy. Not as hard as Estes material but I think that it will work very well, especially if you soak in CA. Item # 712-169 comes in white and it measures 20"x30". Enough to build many centering rings. Cost is about $3+.
I plan to start a Mars Lander, so this will give me alot of material to work with.
I like foam core board, shirt boxes, balsa, or lite ply for cluster mounts. Foam core is tough stuff if you learn how to use it. I have used it successfully on 4 and 6 inch 29 mm G projects.
Question,would It be better to coat rings in cya AFTER installation(especially the edges)?

seems like if they were soaked with cya beforehand, any glue used for fillets would not penetrate very well

so far 3 posters have mentioned cya'ing the ring prior to installation... so I had to ask
If I soak the CR material with CA, I usually just go ahead and use more CA (or epoxy) for the installation.
One thing that will probably happen when you pre-soak the rings with CA is that some of the surface fibers may rise, and solidify in place, and you may have a *slightly* larger diameter. You will probably have to do some LIGHT touch-up sanding on the outer edge to get the diameter back down to a snug fit.
I think white and yellow glues will work with a CA-treated component, especially if you leave the front and rear faces rough so the glue can get a little extra grip. I just prefer to go ahead and use a 'like' adhesive once I have covered the rings with CA.
Originally posted by powderburner
Foam-core is the stuff sold at craft stores (2 ft x 4 ft sheets and smaller) and office supply stores (4 ft x 8 ft sheets) as a mounting or backing surface for large artwork. It has paper face sheets and a core made of foam that is usually about 1/4 inch thick. Cuts with X-acto blades, sands to shape with sandpaper, and for fine-tuning you can roll it on a hard surface to compress the perimeter. Foam-core can be installed with white and yellow glues and is more durable than the rest of the rocket materials. [/B]

Sorry I'm so late picking up on this part of the thread, ometimes we all skim;)

Cutting thick materials 14 and 28 ply Sho-card and Railroad board Is a bit more difficult if your only using an X-acto knife. I strongly suggest using any one of a number different type Circle and circular matte cutters available in most art supply, crasft stores and a lot of hobby shops. Pick one that will handle the sizes you cut most. No one circle cutter will handle everything. Be sure the model you purchase has replacable blades and is stiff. Compass types with beam attachments work, as do adjustable beam cutters. I'll post a pic of some that have proved up to the challange of cutting rings even in light plywood. I still cut most CR's in stacks of 10 or more on my band and scroll saw but individual or a couple can be handled with these tools easily.
Foamcore is a band name but is also used generically for a number of products with a light foam core sandwiched between 2 outer face materials of paper, cardstock, or styrene. Most craft stores only carry 3/16" and 1/4" thick "Foamcore" while 1/8" 3/8 1/2" and up to 3" thick materials like Gator foam, Jet-mount, FoamX and Ultra board can be purchased from all sign supply and most plastic supply houses. all in 4' x 8' sheets only, some of the thicker .010 styrene ultra board material can be expensive.at about $3.00 per Square foot..

Now the trick. If working with 1/4" or thicker foam core. punch a needle or pin hole as straight as possible through the material. I use a piece of scrap wood about 1/2" thick I drill press drilled a hole slightly larger then the pin in. With a pin tip dot the locations for easy finding on both sides. Set the circle cutter to the desired dia. and cut through the paper only from both sides. Finish the cut carefully about half way though the foam remaining with the cutter. presto accurate centering rings. This works with thicker material also but you have to use a knife to finish holding the blade as perpendicular to the foamcore face as you can. 3/8 and thicker rings don't need to be as exact as long as the cuts through the facing materials are accurate. I try to make them on the tight side.
PS Plain old styrofoam can be shaped the same way... from both sides.
Hope this helps.