what material do you use to make center rings?

Discussion in 'Beginners & Educational Programs' started by 3boydad, May 11, 2012.

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  1. May 11, 2012 #1

    3boydad

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    there has to be a way to make your own rings without getting raped for 4 rings for 7 bucks. what do you guys use? what kinf of paper/cardboard is it? i have looked at michaels but failed to find what was close enough. my hobby shops local suck they carry crap for making rings r fabricated rings at that for say a bt80, with a large motor mount. i am building a super bertha. i have my fins cuy and sanded perfect but need some help with my motor!
     
  2. May 11, 2012 #2

    El Cheapo

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    What motor mount are you going with, 24 or 29? Are your fins through the wall? All that can make a difference as to what I would use. Personally, regardless of motor mount bp or RMS reload, I'd go with 1/8" balsa laminate on both sides with 110lb card stock. Use cereal box if ya want. It's light, strong, cheap and you can do it with a hobby knife. I use a circle template to mark the OD of centering ring and four quadrants to get a center point. Then I use a straight edge to connect the four points. From that I draw out the center hole for motor mount and get to cuttin and sanding. Hasn't failed me yet. In fact, for my 2" L1 rocket I laminate two 1/8" balsa centering rings (offset the grain) and then 110lb card stock to both sides. All cut by hand. Works like a champ. Most rocketeres over build. I also use a lot of 1/8" foam core for 24mm x bt70 and 80 centering rings.
     
  3. May 11, 2012 #3

    kjohnson

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    Another inexpensive alternative for rockets of that size is dollar store foam core board.

    kj
     
  4. May 11, 2012 #4

    Rocketbuilder

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    I haven't had to make my own centering rings for 24mm mounts yet, but for 18mm mounts I use usually either 1/8" foam core, as was already mentioned here. Or, you can take a paper towel tube, cut it in half, flatten both pieces, put glue on the inside of both pieces (not too much), flatten them again, and glue the two pieces to each other. This might work for 24mm mounts, as I only used a single flattened tube for an 18mm mount and it came out fine. The only problem with this method is that all the glue makes it difficult to cut after it has dried, so cut the rings while the glue is still wet, then place them under something like a heavy book to keep them flat.
     
  5. May 11, 2012 #5

    GDJ

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    I've used cardstock, cardboard from boxes, the stuff from the kits, balsa wood.
    They all work well.
     
  6. May 11, 2012 #6

    AfterBurners

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    I don't know where you are buying, but I never paid that much. If you want to cut your own get a good circle cutter from a craft store or Hobbylinc. You should be able to get one for under $10. You can get some good quality card stock off Apogee's website. The card stock works well and is easy to cut. If you don't have the means to wood you can contact Bill at BMS aka Balsa Machining Service and sells pre-cut rings or you can have some custom made.

    Here's the link to Apogee's website for the card stock material

    http://www.apogeerockets.com/Buildi...ower_Centering_Rings/Centering_Ring_Cardstock

    he also has some videos on the methods he uses to cut them.
     
    Last edited: May 11, 2012
  7. May 11, 2012 #7

    3boydad

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    that card stock material is what i was talking about. Shouldn't michaels sell that stuff?
     
  8. May 11, 2012 #8

    El Cheapo

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    Skip the craft stores and run to Walmart or any office store. With a bt80 to 24mm you are going to need quite a few layers of 110lb card stock. What are you using for fin material? I'd use balsa or foam core like mentioned above over just card stock.
     
  9. May 11, 2012 #9

    AfterBurners

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    I've never seen it at Michael's but maybe office supply stores might carry it? You may have to do some leg work. I would just order it online and be done with it.
     
  10. May 11, 2012 #10

    hcmbanjo

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    If you want something thicker than cardstock -
    Go to a frame store and ask if there's any scrap mat board left from framing.
    You'll usually find it in a scrap box at $.50 each for a 4" x 8" square.
    Sometimes they'll just give it to you for free.
    It's about 1/16" thick and great for centering rings and baffle plates.
     
  11. May 11, 2012 #11

    El Cheapo

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    Copy that.
     
  12. May 11, 2012 #12

    mcderek

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    I make most of my own centering rings out of foam core and 1/64" aircraft plywood. I use a CAD program to draw a template for the centering rins. Print them out on 110 pound card stock. Use a circle cutter to cut them then glue to ply which can be cut with scissors. Glue that to the foam core and sand to the final dimensions. Want it extra strong? Use more layers of ply along with thicker foam core. This techniques makes strong and light centering rings.
     
    Last edited: May 11, 2012
  13. May 11, 2012 #13

    SwingWing

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    Another vote for mat board here.
     
  14. May 11, 2012 #14

    Barracuda

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    Ditto on the mat board:2:
     
  15. May 11, 2012 #15

    Aksrockets

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    Ive used cardboard from pizza boxes to make small engine mounts, Foam board to make things like 24s and 1/8in plywood to make my 29s.

    Alex
     
  16. May 20, 2012 #16

    thobin

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    I use 1/8 birch ply it works for most rockets up to 38mn. If you are looking for LP rings contact balsa machine service and buy their uber bag of thick paper centering rings its cheap and you will never run out.
     
  17. May 20, 2012 #17

    rocketguy101

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    Hobby Lobby sells the mat board and an Olfa circle cutter works great. I bet Michael's sells the mat board too, you just have to look over in the picture framing area, but I don't have a Michael's nearby so I can't be sure of that. I had to wander around HL to find the stuff I needed (about 1/16" thick cardboard, like the material in kits)
     
  18. May 20, 2012 #18

    luke strawwalker

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    yeah, was going to recommend matte board... you can get it cheap at Hobby Lobby...

    later! OL JR :)
     
  19. May 20, 2012 #19

    gdjsky01

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    For LPR I use the cardboard dividers that are in the 36 pack of Fancy Feast cat food from Sams Club. I think Chris Michielssen would call it cereal box cardboard but I think it's a tad thicker. Hey with six felines, I have a lot of them! :y:

    People "over build". Me included. It's not like there is a huge mass (in LPR and even low MPR) to get moving. Good glue joints are all that is needed. The shear strength of the cardboard is pretty good given the mass it has to get moving. Coat the tops of your forward rings to prevent premature wear from the ejection charge.

    That said, it's hard (for me) not to just go to Balsa Machining Service and not just plunk down $15 bucks (or less even) and be set for many builds to come. No fuss, no muss.

     
    Last edited: May 20, 2012
  20. May 20, 2012 #20

    luke strawwalker

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    Excellent points, Jeff...

    Thing to remember is, that strength not only can come from the material and its thickness, but also STRENGTH FROM SHAPE. IOW, thin rings can be reinforced with triangular cardstock gussets from the sides of the motor tube to the top or bottom ring, or rectangular gussets connecting the sides of the motor tube to both the upper and lower centering rings, arranged radially in a 4 point cross pattern or 3 point triangular pattern (viewed from above or below). For thin cardstock, remember it will be MUCH stronger in tension than in compression... meaning that thin gussets from the motor tube down to the lower ring will be in TENSION during the motor thrust phase, pulling on the lower ring, and the rocket body along with it. Of course these gussets will then be in compression during the ejection firing, but that's a very short burst compared to the thrust phase...

    It's remarkable how lightweight a motor mount can actually be when it's build to use strength from shape...

    Later! OL JR :)
     
  21. May 21, 2012 #21

    GDJ

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    I've been playing with a cardstock centering ring with a paper honeycomb inner structure. So far one of my rings for BT-80 29mm motor mount, 13mm thick is 1.5 grams lighter than a same sized Balsa centering ring that's 13mm thick, and it still has excellent rigidity. I'm trying to downsize the thickness to drop the weight at least another 1 to 1.25 grams for low/mid power rockets.
     
  22. May 21, 2012 #22

    gpoehlein

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    Can you give us a picture or diagram, GDJ? I'd be interested in seeing what you've done (always interested in seeing what new things people come up with working with cardstock!).
     
  23. May 21, 2012 #23

    GDJ

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    I'll post up some pics later on tonight. They're a bit crude looking right now, but I think they have promise.
     
  24. May 21, 2012 #24

    gpoehlein

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    Well, I'm really curious how you make the honeycomb - I'm always looking for new techniques.
     
  25. May 21, 2012 #25

    Micromeister

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    For most of my BT-80 and BT-101 size Upscale models one of several choices have given long lasting results for single motor and Cluster centering rings.
    Several have mentioned Foamcore 1/8", 3/16" and even 1/4" can be had cheaply making it easy to cut and wood glue used to install. Matte boards, showcard, and Railroad board (a waterproof 14 or 28 ply shocard) are all good choices also. All these products can be cut with Mat Circle cutters or compass with cutting blades sold at Micheals and other Art & Drafting supply shops.

    Another very inexpensive material is the backs from lined paper tables. typically if I'm using this material I'll laminate two or three with wood glue crossing the flex grain. greatly increasing the strength. or Adding just a couple sheets of computer paper laminate for BT-55 to 70 models.

    Paper honeycomb is a Great idea as well to lower the overall mass of the parts without reducing much in strength.
     
  26. May 22, 2012 #26

    MarkII

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    That's what I use, but I leave out the foam core. Not for any reason other than I hadn't thought of it. I make them out of three or four layers of 1/64" aircraft ply, laminated together. Why don't I just use thicker wood? Because I cut out everything by hand, and the 1/64" plywood is easy to cut. I don't custom-make my own centering rings very often, though, because I can find excellent quality rings for a whole lot less than the price that 3boydad mentioned. Next time I do, though, I'll go with that very cool foam core lamination technique.
     
  27. May 22, 2012 #27

    rocketguy101

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    You can make a really strong mount using "flimsy" CR materials by adding some shear panels to provide support in the axial direction. I built an "F" motor mount from foam core and 110# cardstock folded shear panels. Very light, very stout when all three lines of contact are glued in place (I used yellow glue)

    MMT_ShearMbr.jpg

    MMT_ShearAssy.jpg
     
  28. May 22, 2012 #28

    MarkII

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    Lots of first-class, gold-plated techniques and recommendations in this thread, this one being the latest. Perhaps make the thread a sticky, perhaps after a few more additions? It would be a good addition to the knowledge base.
     
  29. May 22, 2012 #29

    maricopasem

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    I print my CRs on regular copy paper and use a glue stick to attach them to cereal box cardboard or cardstock depending on the diameter of the BT. Works great even for 24mm RMS.
     
  30. May 22, 2012 #30

    gdjsky01

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    Exactly my point. The mass to get moving is small. Think about it. The motor starts to thrust it's transferring energy to the CRs to the body tube. The amout of mass to 'catch up' to the motor mount is pretty small. Good glue joints and the cereal box cardboard (in shear as it transfers energy to the body tube walls) are plenty strong for all BP motors and many smaller AP motors. At least in my testing. :wink:

    (Now a AT F101 or old FSI F100? Or the CTI F240? Not sure. So the advice above is worth what you paid for it. Pls do your own research when in doubt!) ;)
     

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