Green Jello's Level 1 Build - Wildman Jr. Kit - "Certify With Us" program

[troj]

Ok.....group participation time!

What do you guys use as a fin fillet tool when 1/2" PVC is too large? Since I'm doing carbon reinforced internal fillets, I want to make the external ones fairly small to save weight.

I have a short piece of copper pipe I use, most of the time. I've also used a plastic spoon.

-Kevin

 

[CarVac]

I take woven carbon fiber cloth apart and line up all of the tows, then take 1/8" or 3/32" snips off the end.

 

[jsargevt]

That tool looks perfect for fillets! Ill have to check for one. I have had good success with the rounded end of a west mixing stick, PVC pipe, spoons, Popsicle sticks and so on. It depends on the size of fillet I a aiming for. The key for me is the taping of where the tool touches the airframe. That, in my opinion, is more important than the tool.

 

[Green Jello]

Injected fillets for the Wildman Jr....

Any thoughts on how many ML per fin per side?

 

[ksm2001]

Injected fillets for the Wildman Jr....

Any thoughts on how many ML per fin per side?

Take a look at the Darkstar Jr. instructions on page 5,https://www.wildmanrocketry.com/Instructions/Dark Star jr.pdf . It has split fins but the amount used for 2 fins probably would be close to 1 on yours.

Ken

 

[blackjack2564]

Depending on how close to slot you put you inject holes. I would say 3-5ml [cc] Do the first one [keep track]and see if it starts coming back out hole....you'll know if that's too much then!. Ya can look inside the pipe & see what's going on internally too.

I didn't bother with injecting on mine, it's so small. Just "double dipped" the root & put normal size external fillet.
Double Dip: butter root with epoxy place into slot, tight to MM.....then remove & do it again. I use JB to do this.

 

[jsargevt]

I didn't bother with injecting on mine, it's so small. Just "double dipped" the root & put normal size external fillet.
Double Dip: butter root with epoxy place into slot, tight to MM.....then remove & do it again. I use JB to do this.

I am a big fan of the double dip! Easy to do, rock solid. I did this for my Vindi Jr and a few 38mm-based fiberglass kits based on CJ's recommendation on here.

 

[chadrog]

I didn't bother with injecting on mine, it's so small. Just "double dipped" the root & put normal size external fillet.
Double Dip: butter root with epoxy place into slot, tight to MM.....then remove & do it again. I use JB to do this.

This works well. You can see in the pic that it leaves a nice fillet, and is fast and easy.

 

[Green Jello]

Well, ok.....but the holes are drilled and the carbon is chopped up. This sucker is getting injected!

 

[blackjack2564]

Be careful with that carbon.....everybody wants to add too much first time around & they get a hairball!

Inject slowly so it doesn't splash off the MM tube & back up onto airframe.[inside]
Just barely insert the tip of syringe. The airframe is SO close to MM tube.

 

[cbrarick]

Be careful with that carbon.....everybody wants to add too much first time around & they get a hairball!

Inject slowly so it doesn't splash off the MM tube & back up onto airframe.[inside]
Just barely insert the tip of syringe. The airframe is SO close to MM tube.

Ahh, young padawan, Master CJ has spoken. Heed his words, you must.
May the Wildman force be with you .....

 

[Green Jello]

Drill Fillet Holes and Tack on Fins

Parts Involved:
- 3x Fiberglass Fins (Kit)

Other Supplies:
- 60 Grit Sandpaper
- Xacto Knife
- Masking Tape
- Ruler
- Pencil
- 7/64" Drill Bit
- Drill
- J.B. Weld Epoxy
- Foam Board
- Fin Guide Printout (www.payloadbay.com)


In this step I drilled the holes for the injected fillets and then tacked on the fins.

Step 1 - Mark Hole Locations and Drill: Measure down 1" from each end of the fin roots and mark the body tube with a pencil. Once that is done, drill a small hole at each mark as close to the fin as possible with still leaving some material between the fin and the hole. The drill bit size should be the smallest you can use and still get a syringe tip in. The instructions called for 1/8" but I was able to drop it down to 7/64"


Step 2 - Create Fin Guide: This part should be considered optional, but after doing it this time, I will never make another large rocket again without it. I picked up a piece of foam core poster board at my local Michael's. Next I created a fin guide printout at payloadbay.com. I taped it to the board and carefully cut it out with an Xacto knife.


Step 3 - Rough Up Fin Root Area: Take the 60 grit sandpaper and rough up the entire root area of the fin where it will be held by both internal and external epoxy fillets. I suppose I could also score them with a knife as well, but I didn't do that here.

Step 4 - Tack on Fins: Next I mixed up a small amount of J.B. Weld and buttered the root edge of a fin and fitted it back in it's slot making sure it had good contact with the engine tube. Since J.B. Weld is so dark, you can look in the engine tube and see it through the transparent fiberglass. I should mention that during the sanding and dry fitting process, I labeled each fin and slot they were fitted for. Once the fin was in, I slid the guide over it and let it cure over night. I repeated this process 2 more times every 18 hours or so.
​

 

[Green Jello]

DISASTER! HELP!

Ok....this is what happens to noobs. We get too excited about the build and we forget the little things.

I was doing the injected fillets and forgot to tape the other holes. So now I have a stream of hardened epoxy like this on both sides of one fin. What do I do? Any tips?

 

[jsargevt]

DISASTER! HELP! now I have a stream of hardened epoxy like this on both sides of one fin. What do I do? Any tips?

View attachment 114775

Start Sanding!

I bet you can knock down that drip with a dremel and a sanding wheel pretty easily. Just move slow and careful. Once you get it close you can hand- sand it flat and do a little bondo to smooth it out.

You could also hit it with a heat gun and see if you can peel it off. Since the fin is pretty smooth it will probably come off without much complaint.

I'm sure that someone smarter than me will speak up.

 

[stealth6]

The whole thing is ruined. You will have to bin the entire project and start over from scratch.

Or.

You could simply chisel/scrape off the offending epoxy runs, and then sand down the residue. Shouldn't be a big problem.

btw - I'm liking your documentation in this thread. Good job.

s6

 

[ksm2001]

You can try a heat gun and a scraper

 

[ClayD]

it always happens... now i put tape on that junktion...

I use a single edged razor blade, and just slide it down the drip from tip to root... (sans not cutting myself and requiring stitches...) cleans easy as pie.

 

[cbrarick]

I'll never tell how I know but a flat tip screwdriver (smaller one) works wonders as a chisel....

 

[gdiscenza]

I'm sorry to have to tell you this GJ, but your rocket is completely ruined.

Send the remains to me for disposal and buy a new one.....

G.D.














​(completely joking - for the humor impaired.....)

 

[Green Jello]

I'm sorry to have to tell you this GJ, but your rocket is completely ruined.

Send the remains to me for disposal and buy a new one.....

G.D.

Damn! Please send me your shipping address.

 

[blackjack2564]

DISASTER! HELP!
I was doing the injected fillets and forgot to tape the other holes.

Not just the holes...run tape down the entire fin slot. It can leak out there too.
Looks like the carbon splashed back onto airframe from MM tube.....take it slow.

None of this will affect the end project so don't fret, we've all been there done that.

 

[Green Jello]

Looks like the carbon splashed back onto airframe from MM tube.....take it slow.

No, it's because of the overly large kevlar Y mount in there. That side wouldn't flow at all. I ended up squirting it all in there to have the weight match. The other side I did formed two perfect fillets.

 

[troj]

Less than five minutes with a pad sander, and the problem is solved.

-Kevin

 

[Aksrockets]

I just used a dremel and a sanding wheel when I had the same problem. It took seconds to get off.

Alex

 

[Coop]

Those Dremel wheels can really rip things apart, though... be careful in your fixing, there, Jello --but as others have indicated, it's not the disaster you might originally think. Part of figuring out how to do things well is unscrewing screw-ups.

Let us know how it goes!


Later!

--Coop

 

[qquake2k]

I use my variable speed Dremel and a fine sanding drum to remove epoxy drips from wood fins and cardboard tubes. Just go slow and careful. You shouldn't have any problem removing it from fiberglass.

 

[troj]

Hmmm... Sounds like the general consensus is "Welcome To The Club!"



-Kevin

 

[MasonH]

Honestly, my epoxy scrapes right off if the G10 is smooth and has not been sanded. Take the back edge of a box cutter or paint scraper and push, the whole thing should slide right off. I have done this many times with no problem, most recently on my large Madcow fiberglass Little John

 

[Spooks]

Don't sweat it, it's just a little clean up job, that we all know about now, but no one would tell when you finished...

Keep up the good work!!

 

[Pantherjon]

GJ, that is nothing a bit of acetone or denatured alcohol won't take care of..I had the SAME thing happen to me one of the 1st times I injected(IIRC it was on my WM Jr as well), dabbed some denatured alcohol on a rag and rubbed the offending epoxy 'dribble' it got soft and I peeled it right off..