I got the itch to scratch...

[SPONGE]

...build a new big rocket. When I was visiting the family for the holidays, my brother gave me a very nice 5.25in x 36in tube. When I saw it, I knew I would by trying to turn my first cone from a foamular block. I glued up a block from 3/4in foamular board that was 18x6x6 and a 3/8in wood rod in the center with Liquid Nails Foam Board and Project glue.

Next time I'm going to use Super 77 spray adhesive. It seems like all of the glues that I tested with the foamular were having a hard time drying in the middle, but Super 77 was the fastest and by far the strongest.

I chucked the rod in my drill that I had fastened to the bench and realized that I had neglected to trim the corners, so after some work with the belt sander and the wood file it was ready to be turned. It was going really well until the center rod ripped loose. Again the glue in the center was not fully dry. So I spent nearly a week pouring layers of yellow glue down the center rod, thinking that would be better then just filling the whole cavity up, and then let it sit for a week to dry. When I thought it had sat long enough to by dry for sure, I turned it again with the drill. I got most of the shaping done before the center rod spun free again. Nope, the glue was not dry. So I removed the center rod and finished the shaping free hand on my upside down belt sander.

I'd like to know if anyone else has found a better method for fixing center points to turn these foamular blocks with.

The attached pic is how the cone looks today sitting in the BT. The next step is going to be to cover the foamular with something so it can be sanded smooth and painted. I was thinking of trying Bondo home repair paste. My neighbor was using some to fix her house, and it seems like it would be easy to spread and it's sandable. Has anyone used this? Any other suggestions on what I could do to get a nice paintable finish on the foamular?

I haven't settled on a fin design or motor configuration yet. I'll cut the fins next and rough cut a couple of solid plywood centering ring blanks to get an idea of what kind of weight I'm looking at. I was thing of a two or three engine cluster with 29mm mounts so I could fly it on Fs and Gs. If it's heavy enough, maybe it could be my L1.

 

[KenParker]

My experience in making nose cones is from years ago and all I ever made was balsa nose cones for LPR. (IOW - little nose cones) Soooooo... I'm just taking a shot in the dark here.

Couldn't you glue the center rod in with epoxy? Epoxy does not depend on air contact to set up.

At any rate, I'm sure sandman or carl or somebody will jump in here and give you a much better answer.

- Ken

P.S. - I think your nose cone turned out pretty darn good.

 

[SPONGE]

Thanks, Ken.
I'm not 100%sure, but I think the foamular will melt if glues like epoxy or CA are used on it. Can someone confirm or deny that for me?

 

[Austin]

Sandman used Gorilla Glue I believe, available at most hardware stores, to glue the foam together for my foam nosecone. He said it worked well, jump in here any time Sandman! I will tell you shortly (within the week) whether or not Epoxy melts the foam.

Carl

 

[PGerringer]

Good work on the nosecone. Because epoxy is a resin I dont think it will melt the foam. CYA on the other hand is like an acid. Designed to melt and bond. Although I could be wrong. Ive been sniffing CYA...

 

[sandman]

Well,....I was gonna use Gorilla glue but, man is it expensive.

I tried contact cement...quickly ATE the foam up.

Then wood glue...same results as sponge...D**n glue wouldn't dry!

Scratched my head for a few days and nights and while I was going to put on my coveralls to work under the car I notices some yellow foam like stuff stuck to them...it wouldn't come off...felt foamy...IT WAS FOAM!! It had been stuck on those coveralls for at least 2 or 3 years!

It was the sealant foam that comes in a spray can!! UREKA!!!

The stuff is really really a strong glue!! I use a brand called "Great Stuff".

Yes, the best glue for foam IS FOAM!!!

Balsa is easy...wood to wood glue.

Here are the tricks.

I made a plywood disk and glued the biggest wood dowel that would fit into my drill chuck (I use a drill chuck adaptor on my lathe) into the center...long enough to hold all the foam sections together.

Chuck it into the lathe and turn it down 'til it fits really tight into the tube.

Leave the whole assembly in the chuck and glue sections of foam glued with "Great Stuff" foam used as glue...lightly clamp it together...it foams up a lot, so leave room for expansion!

Let it cure a day or two 'til it's hard. Make sure you made the hole that the wood dowel goes into big enough (i.e. sloppy) for some foam to get around it.

Cut the corners off with a regular old hand saw.

Turn on the lathe and go to town.

sandman

 

[powderburner]

great discovery, and thanks for sharing the idea!
I can see how that stuff would indeed work excellently

however

I never have been able to use just part of a can of that #$(*^ stuff and save the rest for another day (and it costs like $4 a can, too much to use one little squirt and throw the rest away)
the stuff always seems to set up in the spout and self-plug the remaining foam, no matter how I try to 'seal' it
I always end up having to save up a bunch of sealing projects until I get enough stuff to use up an entire can at once

so, do you have any great ideas on how to plug a can of Great Stuff so the rest is still useable next week?

 

[rbeckey]

Pour acetone down the straw and into the spout on top of the can right after use. This will disolve the liquid foam and leave it ready for the next project. It will not last forever, though. The pressure will bleed off eventually.

 

[sandman]

Or...make up a WHOLE bunch of nose cone "blanks" ahead of time.

"HEY!! anybody in the house need anything epoxied...I mixed up too much again!"

sandman

 

[KermieD]

How 'bout 2 part foam? The issues brought up here make me nervous about keeping my US Composites 2 part foam fresh after I use it. Or is this okay?

Phil? You're the USC guy here?


P.S. For roughly the same price as you pay for the 2 part foam from PML, you can get these huge, whoppin' cans of the US Composites stuff, about the same as that rectangular tin of acetone or isopropyl alcohol you got at Home Depot that you've been using.

 

[SPONGE]

Man, I wish I had thought of that. I have a whole can of Great Stuff sitting on my work bench. I'll have to rember that for next time. I went to Home Depot last night and got a can of that Bondo all purpose putty. I'm going to try a test section this afternoon. I'm let ya'll know how it goes.

 

The best and least expensive glue to use on Foamular is DAP panel and foamboard adhesive which can usually found at True Value for $2-$3 for a normal size caulking tube.

PS. Don't forget to get the caulking gun if you don't have one. They are well worth the $$$.


A while ago I posted a thread called ' The Foamular Files" and recently I have re-wrote the article for John Coker of Rocketry Online and he has now posted the re-written article in his Info- Centeral. The article is called Foam Turning. I hope it will help you in your experiments with foam. I also would be interested in perfecting a protective epoxy coating if you find one.

Info-Central: Foam Turning
https://www.info-central.org/index.cgi?construction


James Pierson Manager
Rocketry Preservation Society
https://groups.msn.com/ROCKETRYPRESERVATIONSOCIETY/_whatsnew.msnw?pgmarket=en-us

 

[Micromeister]

I'm not sure what kind of foam you guys are useing. I'm in the Sign industry, Mainly Outdoor Illuminated stuff but we do a good deal of "Food Store" interior Foam letter. We use 1" and 2" thick Styrofoam SM, it's blue, very firm, closed cell and very nice for turning nose cones. I've seen the same material on construction sites as insulation board. the difference is the insulation boards are scored at 16" centers for easy snaping. Styrofoam, Inc. recommends three materials as "adhesives" the SM, #1 is a material called liquid nails, it comes in a 16oz. caulking gun tube, and has a two year shelf life, smells to high heaven and will give you a "Buzz" real quick. We use this material to glue up panels and end joints up to 12" thick, or 8 feet long. for Turning and shaping, the second material recommended is a material called "Tacky Glue" This stuff is like "Elmor's" White glue only thicker, this stuff however sets up in about two minutes and is completely dry in about an hour. The company buys this material in 5gal pails, but I've seen it in Craft and Art supply stores in as small as 1 oz. squeeze bottles or as large as gallon jugs. I understand the craft and flower arrangment ladies, could not function without Tacky glue
we have had excellent results with the third recommended material 2 part urethane epoxy's. We've had very good results with any of the Devcon 2-part epoxies, 5minute, two-ton (30 min.) and their "coating epoxy". I have personally used the coating epoxy on a 5" x 30" foam Nose cone to seal and than sand smooth. I well tell ya, this material does not sand easily but Man is it hard when your done. This stuff takes two coats minimum and you have to have your piece in a holder that will allow you to turn the piece every 5 minutes or so until it sets up in about an hour, there will be runs!. After set up, let it sit overnight and repeat with the second coat. Sand with 80 and 120 grit sand paper on a block or use an electric palm sander. Yeap its that tough!, Finish sanding with 220, prime and paint.
I've used the Tacky glue to glue up, lathe, and then fill and sand smaller cones. it sands Way easier then the epoxy. again set up and complete drying usually takes overnight depending on the humidity.
Hope this helps

 

I have had Tacky glue all along but have never tried it. Also Devcon epoxy is what I use to coat my Foamular (Foamular Pink==Dupont Grey) foam rocket I named "IT" however I just knocked it off of the workbench and "IT" snapped in half. One advantage of foam is it is easy to re-glue back togather . The Devcon seems to be hard but also very brittle and can be expensive on larger projects. I have heard of an gel-epoxy with lightwieght fillers which maked it more sandable form Wests Systems at: https://www.westsystem.com/ but have not decide to make the initial small investment in the Wests Systems just yet.
I also intend to use 1/2 ounce fiberglass for durability. The extra strength will be worth the added wieght.

My plans for the next project when my uninsulated garage warms up is the "Super Sleek" with built in tube fins.


James Pierson Manager
Rocketry Preservation Society
https://groups.msn.com/ROCKETRYPRESERVATIONSOCIETY/_whatsnew.msnw?pgmarket=en-us

 

[SwingWing]

For more information on epoxie go to www.raka.com. Larry runs a small business selling supplies to the boat building industry. The min size is kinda large, but its worth going to his site just for the info and IIRC he has a sampler kit for sale. He has some good info about epoxie in his user man. His epoxie is similar to West syetems (also boat building epoxie) but 1/2 the price and a little bit thinner. Epoxie is 100% solids, so it should never be thinned, but can always be thickened (with cab-o-sil or glass ballons) I have built a cedar strip canoe with Larry's epoxie. Very staisfied.

 

[SPONGE]

Well, the nose cone is almost finished. Since my last report I covered the whole thing in a layer of yellow glue to harden and stabilize the surface of the foam, and then I spread on a layer of Bondo All-Purpose Putty.

The Bondo is kind of tricky to work with on such a large project. The instructions on the can say you get a three to five minute working time and they are not kidding! I wasted half of the first scoop that i mixed up. The putty if the consistancy of sticky frosting and is easy to spread. It sticks pretty well to the glue covered foam. It sands like a dream, but the dust is very fine and hard to clean up. After the putty was dried and sanded I filled in some of the irregularities with spackle paste and sanded again. This has produced a surface that is pretty hard and smooth, but it will crack if it gets hit with very much force.

I also put in the hard point for the recovery attachment. I did this by tying a loop of speaker wire and inserting it into the hole in the base of the cone and then I pushed a wood dowel through the base of the cone from one side to the other, making sure it went through the wire loop. Then I fixed everthing in place with hot glue. The hot glue sticks to the foamular very well and did not seem to melt it on application.

I have decided on the fin shape. It's going to be a clipped delta with a 8in root and 6in span. This is turning out to be pretty heavy. The tube and cone weigh 38oz at this point. I'm thinking that it's going to need a 3x29mm cluster. It also has a name now. Since my brother gave me the tube I let him name it. He dubbed it "Tubus Giganticus"

 

[SPONGE]

Yesterday the weather was too cold and crappy to do anything outside, so I ran the heater in the garage for a while to get it over 50 and started working on the fins and slots. The fins are made from 1/8th in aircraft plywood. I cut them by hand with my coping saw and cleaned them up with the belt sander. With just a little beveling they were perfect. This is the first time I have ever tried to slot a body tube, so I was a little nervous. A slip here might mean the end of the project. I got everthing measured and marked, and put down a layer of thin CA to help get a clean cut. I did the cutting with the smallest round woodworking bit I have for my Dremel, and cleaned it up with a file and and an Exacto knife. I am quite happy with the way the slots came out. The fit with the fins is straight and tight. I dry fitted the fins, and with the nosecone in place, was able to see the final shape for the first time. I don't know why my dog looks so nervous in the picture. It's obvious she won't fit in the rocket (this time!).

 

[Stones]

Originally posted by SPONGE
...I don't know why my dog looks so nervous in the picture. It's obvious she won't fit in the rocket (this time!).

Looks like she's comin along nicely Sponge.

 

[SPONGE]

Here's a more detailed look at the fins and the rear of the rocket. The fins are TTW to two of the centering rings. I could not cut the tabs long enough out of a 6x12 piece of wood to go all the way to the MMT.

 

[SPONGE]

I got the motor mount tube from Magnum today, so I spent a little while in the garage cutting the tubes and cutting the holes in the centering rings. I don't happen to have bit that will cut clean holes that big, so this was dremel work. It came out pretty well. one of the holes is a hair too big, but nothing I can't fix with more glue As soon as I get the rail buttons I will be able to do the full assembly, so I am on schedule for a March 1st launch.
Here is a shot of the dry fit.