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Best way to 'finish' a LOC nosecone?
#11
Here is an alternate method I've used that seemed to work great.

1. Cut off the base
2. Fit a Bulkhead into the shoulder
3. Add whatever weight is needed in lead shot / epoxy into the nose
4. Use a piece of all-thread attached to the bulkhead and extended forward into the epoxy/lead shot mixture.
5. At the bulkhead a Washer and Bolt are placed inside the bulkhead, and an Eye-Nut on the outside with thread lock.
6. An appropriate number of screws screwed thru the shoulder into the side of the bulkhead. Use as many as you need as you do not want them pushing backwards thru the plastic.

The all-thread holds the shot/epoxy in place preventing it from moving aft
The bulkhead is removable because it's held in with screws.

If you are concerned with the Eye-Nut coming off, replace it with another regular nut and instead add a u-bolt thru the bulkhead.
--
NAR / TRA
Level 1 - Estes Leviathan - CTI 164-H90 Classic
Level 2 - MadCow Sensor - CTI 716-J280-16A Smokey Sam
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#12
I have cut the very bottom off quite a few LOC nose cones, using plain old hobby epoxy attached a ply wood bulk head. you need to sand the heck out of the inside of the cones and clean it with alcohol after. never had one break out yet with lots of flights! Having a long shock cord will go a long way to prevent "forces" of ejection from ripping out the bulkhead.

As for lead pour it in with a bit of epoxy when it dries expanding foam over it.


Bill Clune L3 | NAR#88583
Been a launch Director
Founded a Club
MARS Club|SRC|MDRA - Forever
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#13
What expanding foam do you like and where do you buy it?
Rich Holmes
Camillus, NY
Secretary / newsletter editor
Syracuse Rocket Club

http://richsrockets.wordpress.com
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#14
(07-10-2015, 08:51 PM)Rich Holmes Wrote: What expanding foam do you like and where do you buy it?

It has been awhile since I used any, so I do not recall the brand. I got out of HPR years ago, and typically use epoxy on smaller rockets if I need to seal in nose weight.  

But I got the expanding foam at Home Depot, and I'd think Lowe's would also sell it. Check with the Paint Dept.   It is used to fill gaps in walls and other spaces to help insulate.

Also, since you typically use a pretty large quantity of epoxy in a plastic nose cone to hold in the ballast, be careful due to significant heat from the exothermic reaction.  I've placed a filled nose cone in a container of water to keep the nose cone cool, to prevent swelling of the plastic.
Lee
NAR 55948, L2
In Build: Mars Snooper
Next: upscale Sky Hook (Panavia kitbash)
In Finishing:  Estes Honest John, Red Nova, Super Cobra
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#15
Use a two-part urethane foam from US Composites or Public Missles Limited aka PML, they unlike the the spray can foams will harden completely in the absence of air, the HD and Lowes canned crap won't (yes they will harden on the surface, but they never really get hard inside since they are designed to remain slightly flexible to keep their gap sealing properties during a buildings expansion and contraction due to temperature changes). Giant Leap Rocketry also carries a two-part foam. Another nice thing about the two part foams are they are not one shot cans like Great Stuff (or whatever brand construction foam), you mix and pour from a Dixie cup or plastic cup by equal parts volume and then just throw the mixing cup away.
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#16
+1 on the two part foam from PML. I think the stuff from GLR is the same, but not 100% sure. The other issue with the great stuff, is that it has a tendency to continue to grow and will bulge things it is used in. If you do not need to use weight, another option that I do frequently with Loc cones is to drill holes in the base of the cone as far apart as possible and then I thread a length of kevlar through, passing it back up through the already existing center hole, then knotting it and stuffing it back in the hole. Basically adding a loop of kevlar to the cone. This gives a secure connection point and it is much lighter than adding an eyebolt. I would recommend opening the center hole a bit before trying this. The center hole usually has flashing on the inside of it that generally comes right out with a hobby knife.
P Rudin

Duct tape. the force it is like. both a light side and a dark side it has. Binds the universe together it does.
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#17
(07-10-2015, 08:51 PM)Rich Holmes Wrote: What expanding foam do you like and where do you buy it?

AB foam (or Two-Part foam) is what you need to buy.  You probably will want to go with the two pound variety (expands more), unless you need the additional weight and strength of three pound foam.

Tap Plastics has what I'd use (If I want to buy locally), that or a marine supply store.

Some art supply places have it too.
.
NAR #100544

"The Guide says there is an art to flying", said Ford, "or rather a knack." 
"The knack lies in learning how to throw yourself at the ground and miss."

Launching is Optional... Landing? That Depends on Trees.

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