Smooth fillets

I am having a hard time getting smooth fillets (I.e. No tape lines) using Rocketpoxy on my MPR rockets. I was thinking of adding the Titebond trim glue over the epoxy fillets to help smooth the lines. Any thoughts or suggestions?

It's hard to diagnose without knowing your whole methodology, but I can say this it's unlikely you would ever be able to get perfectly smooth edges/lines without a step that most folks seem to ignore - yep, sanding! In fact the only way to get REALLY smooth/perfect fillets is to do a bit of filling and sanding (using something like Bondo).

Everyone has different criteria for what is "smooth" or "perfect" to them, but if your standards are very high, then you can expect to have some filling and sanding in your future.

s6

I have been sanding quite a bit but just didn't know what I could use to help "fill" the tape line.

Some rocket builders spend 90% of their time sanding, and it shows in their finished work. Rockets are gorgeous and they fly really high.

Me? I lay down my fillets, make sure look like they will hold the fins on, and go to the pad.

My suggestions would be:

Pull the tape before the epoxy is completely cured. Feather the tape dams with a nitril gloved, alcohol dipped finger.

After full cure, I use water thinned Elmers wood filler to smooth any remaining transitions or voids in the fillet. I'd guess other fillers would work just a well.


Hope this helps.

I use a Estes 18mm spent casing as a sanding block with some 3m 150 sandpaper .

You can sand the fillet itself if not uniform , and also smooth down the tape line .

If you are painting the rocket (or fin can) ,apply some Glazing Body putty over the fillets including the tape line - and use the sanding technique above to take down most of it uniformally.

After the shape right you can sand the last bit with just the flat paper to blend it . At this point I would shoot some high fill primer and touch up any blemishes left with some putty just where needed .

It sounds time consuming but you can literally make 4 putty/primer passes in a day if you try .

Kenny

level rocket in both directions. tape to desired edge. pour just short of tape... epoxy should just kiss tape in a few minutes- if still short add a tiny bit more. Remember to pull off tape while fluid- we dont need it now that epoxies poured.

I use Rocket Poxy all the time. I first mix batch big enough to do a fillets on 2 fins at a time let epoxy set for 10 min. Than go back a apply the fillets dip what ever I am making the radius with in alcohol pull excess epoxy in one pull. And take tape from the two fins right away. I never sand. There not perfect but good enough fro me.

samb said:

My suggestions would be:

Pull the tape before the epoxy is completely cured. Feather the tape dams with a nitril gloved, alcohol dipped finger.

After full cure, I use water thinned Elmers wood filler to smooth any remaining transitions or voids in the fillet. I'd guess other fillers would work just a well.


Hope this helps.

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I hadn't considered hand-feathering the edges. That's a really good idea.

Well here is the final outcome. I ended up using glazing putty from 3M to finish the fillets! Thanks for all the suggestions!

bertaadele said:

View attachment 269845

Well here is the final outcome. I ended up using glazing putty from 3M to finish the fillets! Thanks for all the suggestions!

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Nice Job !

Gonna work on AFischer for fillet tutoring next .

Kenny

bertaadele said:

View attachment 269845

Well here is the final outcome. I ended up using glazing putty from 3M to finish the fillets! Thanks for all the suggestions!

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Great outcome; and all good suggestions from Sam, warnerr, et. al.

My rule of thumb whether RocketPoxy, Proline, filled West, etc., pull the tape sooner than later. If good epoxy it will self-level and you should only have a bit of clean up on the fore and aft of each fin.

Smooth fillets? Oh you mean like these?

Nathan said:

Smooth fillets? Oh you mean like these?

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What's your secret?!

A couple "raw" high-temp Proline-type done tonight. Should be no evidence of tape removal if done at the right time interval.

Nathan said:

Smooth fillets? Oh you mean like these?

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Beautiful work. Care to share your materials and methods?

Banzai88 said:

Beautiful work. Care to share your materials and methods?

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Hard work & willing to sand........sand.......polish.........sand....finer & finer grit till you get the "mirror".

Banzai88 said:

Beautiful work. Care to share your materials and methods?

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He has been doing just that for several years. While awaiting his response to this thread you may want to search this forum for threads he's started.

For example:

https://www.rocketryforum.com/showthread.php?61757-38mm-LOC-Onyx-Build&p=652971#post652971

https://www.rocketryforum.com/showt...olishing-I-finally-finished-my-Estes-Partizon

https://www.rocketryforum.com/showt...-The-Magg-(or-How-I-Spent-My-Summer-Vacation)

Banzai88 said:

Beautiful work. Care to share your materials and methods?

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Thanks, those rockets were built over the past three years and my techniques have evolved and improved over time. For fillets I use Bob Smith 30 minute epoxy which I smooth out with a gloved finger. I never use any tape. On rockets that need stronger fillets I use Aeropoxy and then after it dries cover it with a layer of the 30 minute epoxy, because I like the way the 30 min epoxy sands (sanding Aeropoxy is like sanding a rock). I then sand the fillets with 220 grit sandpaper. After that I fill imperfections with slightly diluted carpenter's wood filler, then sand again.

That's how I did the fillets on the fiberglass Frenzy XL that I am working on now, and they look really good. Right now I'm in the process of wet sanding the base color coat so I still have several weeks before it's finished. I'll post some pics when it's done.

I've seen Nathan's rockets in person and they are gorgeous. I am just too D@^^N lazy to put that much time in. Well, and I want to stay married, too.

This is a great thread and Nathan's rockets are incredible! Thanks for sharing!

Try using Metalset epoxy. Easy to work. Sandable. After I tape off and apply the Metalset A4, I wet my fingers with rubbing alcohol and smooth the fillet. Once hardened simply sand with 120 grit or finer.

How much does the Metalset weigh compared to RocketPoxy or Bob Smith 30?

It's like working with JB Weld but, comes in a bigger tube.
Highly metalized, it costs about $20 per set.

JD

Bat-mite said:

How much does the Metalset weigh compared to RocketPoxy or Bob Smith 30?

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