Finishing A Foam Nose Cone

[Gary Byrum]

I'm building a 6" squat rocket, and I just finished turning the nose cone on the lathe. It's my first foam cone. The shoulder length is only 1" because it gets mounted permanent. (rear ejection) My question is, what is your suggestion on finishing it? I WON'T BE GLASSING IT. I've read using Elmer's filler putty in multiple coats and possibly some finishing epoxy is a way to go. Am I on the right track? I suppose I'll need a good lead on a finishing product if that is your suggestion and in a small quantity. No more than a quart. FWIW, this doesn't have to be a "hard as nails" finish, as it's just a draggy mid power rocket.

 

[rharshberger]

Epoxy thickened with cabosil and phenolic micro balloons to make a lightweight sandable fairing putty. Sand,then coat with finishing epoxy and finish normally.

 

[rstaff3]

Don't know why the original post stayed after I edited it?????

 

[rstaff3]

Your cone looks nice! I have generally glassed my foam cones, although I did go the Elmer's FillnFinish on one. It's about 2" in diameter and after a dozen or so flights it is pretty dinged up. I went cheap because it was a rocket that had a high probability of ending up in the trees. Go figure, if you count on losing them they just keep coming back to make a liar out of you. I shot it with H2O paint which saved the foam but did a bad job in general. In my experience, even a thin veil of glass on a foam cone will give a better finish but still tends to crack like an eggshell. I know you said 'no glass' but I recommend glassing nonetheless.

 

[Gary Byrum]

Guys, the reason I'm not glassing, is because it's not my forte. And please don't tell me I should learn it, because I rarely-to-never have a need for glassing. I'll be quite satisfied with a nice firm finish that I can use what ever kind of paint I want. Be it 2X or auto colors as my usual choices. I'm guessing the finishing liquid/epoxy,whatever, will harden the filler putty....maybe? I suppose I could always harden that with a big swab and some CA. Then give it a nice hardening finish. Brands of finishers would be helpful too.

 

[rstaff3]

Guys, the reason I'm not glassing, is because it's not my forte. And please don't tell me I should learn it, because I rarely-to-never have a need for glassing. I'll be quite satisfied with a nice firm finish that I can use what ever kind of paint I want. Be it 2X or auto colors as my usual choices. I'm guessing the finishing liquid/epoxy,whatever, will harden the filler putty....maybe? I suppose I could always harden that with a big swab and some CA. Then give it a nice hardening finish. Brands of finishers would be helpful too.

I fully respect your desire not to glass. However, any other coating will be subject to dings. Painting it with epoxy will superficially harden it but it will still dent. Instead of a soft ding you will get cracked holes. On my thinly glassed foam cones, I fill the holes with FillnFinish or Epoxy filler (have done both) and then sand even. Repainting has been optional

 

[Gary Byrum]

I fully respect your desire not to glass. However, any other coating will be subject to dings. Painting it with epoxy will superficially harden it but it will still dent. Instead of a soft ding you will get cracked holes. On my thinly glassed foam cones, I fill the holes with FillnFinish or Epoxy filler (have done both) and then sand even. Repainting has been optional

Yeah, I use a lot of balsa for nose cones and I get my share of dings and gashes too. Generally, those are the least of my concerns. Easy fixes usually. I'm sure the foam is less forgiving than balsa, but surely the fix couldn't be much harder. Our sod farm has great grass to land in and even still, I'm more likely to crack a fin than dinging up a nose cone. I'm now in a position to up my game on this fin issue too. Another thing to know and understand, I can turn a nose cone like this one for just a few bucks. Much cheaper than a honking big ole heavy duty expensive plastic job. There is also the need for this particular shape. It's not my usual preferred nose cone shape, but it all but identical to the....uh.....er.....person/alien it's designed after?

 

[Gary Byrum]

I just remembered I have a can of this stuff. Dries much harder than Elmer's putty. Anybody ever try using it?

 

[rharshberger]

It will dry harder but after sanding it will be jusr as brittle.

 

[Gary Byrum]

It will dry harder but after sanding it will be jusr as brittle.

I suppose a finishing test is in order. I already have some drying on a block of wood so I can sand it to see the durability. Next I'll try it on some scrap foam and test the strength that way also.

 

[Lowpuller]

Gary,

Nice lathe work.

You can always paint it directly with Liquitex spray paint. That's what I did with the MIRV I showed you. Which by the way, I rebuilt and tried again when I got home but regretfully one motor didn't light and I trashed that section. The good news erockets has them for $15 everywhere else was $30+

You could also try protecting its with liguitex and then top coating the liquitex, that's on my list of things to try. Look for my next build thread and you'll see why.

Good luck and again nice lathe work.





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[rocketguy101]

Would paper mache be a little more forgiving to dings?

 

[rstaff3]

You could make a reverse mold from it and then cast a water putty cone (sorry for being a smartass, but I couldn't resist )

 

[BABAR]

Thinking ahead, seems like major concern with anything other than plastic or glass nosecone (still a problem with balsa) is dings, either from snap back Estes Smileys or from ground impact.

If you end up with a delicate nose cone, wonder if using mid-body separation (to prevent snap back Smileys) as well as an external tether (may only be used in flight, removable for display) that allows the nose cone/forward section to descend nose tip up would be helpful.

 

[Gary Byrum]

Gary,

Nice lathe work.

You can always paint it directly with Liquitex spray paint. That's what I did with the MIRV I showed you. Which by the way, I rebuilt and tried again when I got home but regretfully one motor didn't light and I trashed that section. The good news erockets has them for $15 everywhere else was $30+

You could also try protecting its with liguitex and then top coating the liquitex, that's on my list of things to try. Look for my next build thread and you'll see why.

Good luck and again nice lathe work.

Thanks. You'd be totally surprised how I carved this thing. I'll post a couple pics of the...ahem...alternate tools I used.
I'm not familiar with this Liquitex you speak of. Maybe if you're at the October launch, you can show me your finished results on that MIRV 1.

Would paper mache be a little more forgiving to dings?

I read where it works pretty good, but I'm not sure I really want to go that distance. That's always a really messy application for me.

You could make a reverse mold from it and then cast a water putty cone (sorry for being a smartass, but I couldn't resist )

That's really not such a bad idea. Not sure how well "Rock Hard" would serve as a mold though.

 

[Gary Byrum]

Thinking ahead, seems like major concern with anything other than plastic or glass nosecone (still a problem with balsa) is dings, either from snap back Estes Smileys or from ground impact.

If you end up with a delicate nose cone, wonder if using mid-body separation (to prevent snap back Smileys) as well as an external tether (may only be used in flight, removable for display) that allows the nose cone/forward section to descend nose tip up would be helpful.

This is why I am testing the strength of the putty as we speak. Surely, whatever I use on the exterior, should be helpful in preventing some dings. This nose is so light weight anyway. I expect using an extra long shock cord will assist in preventing any snapping/Smiley issues. At least I hope.

 

[Gary Byrum]

When I started this assembly, I knew I wanted to try gluing the 2” layers together with Great Stuff canned foam. That worked better than I thought it would. My bad, was using the hot knife way too hot, and I wound up with a crystallized cut surface that got really hard. Here’s what that difference looks like. This particular leftover could be used for a BT 101 or other tube up to 5”.



That being said, I knew I’d need hand held tools since I couldn’t get my usual tool rest to go under the massive bulky block of foam. So, “Mr. Improviser” sought out some reasonable substitutes in place of my high end turning tools. It was a bit touchy at first, but once I got through most of the crystallized foam, the tools of choice worked like a charm. Can you guess these tools?



Mind you, I did not attempt this kind of turning without some recent upgrades to my vacuum system. I customized my box to fit an exhaust/suck hole with accompanying elbow and adapters to fit the large hose on the new vac system I bought. This works quite well with a minimum of 6-7% of debris landing on the floor. Dust was almost nonexistent and I didn’t even have to wear my nose guard. My glasses didn’t even dust up.

 

[rharshberger]

When I started this assembly, I knew I wanted to try gluing the 2” layers together with Great Stuff canned foam. That worked better than I thought it would. My bad, was using the hot knife way too hot, and I wound up with a crystallized cut surface that got really hard. Here’s what that difference looks like. This particular leftover could be used for a BT 101 or other tube up to 5”.

View attachment 328912

That being said, I knew I’d need hand held tools since I couldn’t get my usual tool rest to go under the massive bulky block of foam. So, “Mr. Improviser” sought out some reasonable substitutes in place of my high end turning tools. It was a bit touchy at first, but once I got through most of the crystallized foam, the tools of choice worked like a charm. Can you guess these tools?

View attachment 328913

Mind you, I did not attempt this kind of turning without some recent upgrades to my vacuum system. I customized my box to fit an exhaust/suck hole with accompanying elbow and adapters to fit the large hose on the new vac system I bought. This works quite well with a minimum of 6-7% of debris landing on the floor. Dust was almost nonexistent and I didn’t even have to wear my nose guard. My glasses didn’t even dust up.

View attachment 328914 View attachment 328915

Dude, Alton Brown would be pleased, no single task tools in your kitchen 😁

 

[blackjack2564]

Durhams is a bitch to sand, like sanding concrete.
If it will stick, I would try good ole Elmer's fill'n finish or plain Bondo. Both easy to use/spread & sand.

 

[Gary Byrum]

Dude, Alton Brown would be pleased, no single task tools in your kitchen ��

YO, I got one on Alton this time....hahaha

Durhams is a bitch to sand, like sanding concrete.
If it will stick, I would try good ole Elmer's fill'n finish or plain Bondo. Both easy to use/spread & sand.

I know Elmer's will stick. I made some stuff years ago that worked well with it. I just painted that project though. It just seemed a little flexible with such a thin coat. Hadn't thought of regular Bondo though. Plus, I will be using some sort of finishing epoxy for a surface. I just need to know if that will be enough to make a fairly strong shell.

 

[Lowpuller]

https://www.liquitex.com/US/


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