Personally, I love 3D printed parts--but the arthritis in my knuckles makes me HATE sanding them. Therefore, I'm going to do a test on filling them smooth instead of sanding them smooth.

The product I'm trying is Rustoleum gray filler primer #249279. I've never used it before so I know nothing about the results. The object I'm testing it on will be one of the spare 3D printed fins that came with the Boyce Pershing 1A builder's kit.

Stay tuned!

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__________________
Never trust an atom. They make up everything.

4 out of 3 people struggle with math.

Chemically, alcohol IS a solution.

NAR# 94042
SAM# 0078

That's what I used on my boyce pershing. BTW, if this is the BT-101 kit, the recommended CG of 3" back from the end of the tube is incorrect, they did not model it in rocksim/openrocket, my first flight took a hard right about 100' up, I built a sim and using rocksim stability which I trust after many many pershings of all sizes have been flown, I'm recommending 1" back from the forward end of the body tube as a starting CG. They did not use the same size fins as the maxi kit, they are smaller, the only sim I found on rocketreviews mistakenly uses 4 fins instead of 3 which is also quite wrong.

My CP shows to be about 25.64" from the tip of the cone, I use about 1.3x stability for these, leading to CG at about 20.3" from the tip. His spec would be about 22.5 from the tip which is only .75

If you use openrocket or rocksim with barrowman it shows the cp at 22.5, right where the spec says to balance it which I did, the fact that it did not corkscrew wildly confirms what I've found in practice that the pershing 1A is better modeled using rocksim stability and that barrowman is conservative by quite a bit.

Frank

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RC Rocket glider kits
www.dynasoarrocketry.com

Thanks. It IS the BT101-based kit.

So, how did the primer work out for you? I’m just waking up and I haven’t shot it yet.

__________________
Never trust an atom. They make up everything.

4 out of 3 people struggle with math.

Chemically, alcohol IS a solution.

NAR# 94042
SAM# 0078

I hope the Rustoleum Filler/Primer works well on the 3D printed parts. I have yet to venture down the 3D path. However, I have used the Rustoleum Filler/Primer for several years to fill body tube seams. I think it’s a great product. I stocked up a few years ago getting cans for $3.03 each from Walmart.com, with free shipping to a Walmart store! Those bargains are gone these days.

I’m looking forward to hearing your results. I have a Maxi Honest John that needs new fins, and I am about ready to order from Boyce.

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Lee Reep
NAR 55948

Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor
In the Paint Shop: Nothing! Too cold!
Launch-Ready: Farside-X, Maxi Honest John, Super Scamp

Worked great, I had about 1/3 of a can left and just used that for several coats and then did one sanding before using tamiya white on the top and krylon camo colors OD on the bottom, the cone filled pretty well, it was pretty nice as printed, the fins had some more ridges, but I didn't feel like doing more and the flat OD looked nice enough on them.

I've also used this which is a hi build forumla which filles just a bit better I think.

https://www.rustoleum.com/product-c...er-primer-spray


Frank

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RC Rocket glider kits
www.dynasoarrocketry.com

I’ve used the Rusto sandable filler/primer and the high build filler/primer and both work ok. The only 3D printed parts I’ve used high build on so far are the nose cones on my little Rocketshipgames MMX R3s which turned out great but due to the tiny size may not be representative of typical 3D parts. I’m interested in seeing how things go since I have a set of M-R fins courtesy of the late John Pursley that I definitely want to do well with.

As far as differences between the two kinds of Rusto filler/primers not surprisingly the sandable sands easier (yeah, no kidding, right?) but the high build fills better (again, no kidding!) - I generally use two coats of the sandable vs. one of the high build to get about the same level of smoothness though the sandable MAY come out just a bit smoother.

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My local Ace hardware use to carry the Rustolium filler primer and I absolutely love love love that stuff.
They don’t anymore but if I try harder I can probably find it.

The A e brand is pretty good and comes in a really big can!

I don’t do 3D printing but the rustolium primer covers tube spirals in 2 or 3 light coats.

On balsa I seal it with Elmer’s glue and 3 coats makes the wood grain disappear.

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"I'm a sandman. I've never killed anyone. I terminate runners when their time is up." Logan from "Logan's Run"

http://sandmandecals.com/

I bought it at Home Depot. My local HD has a buttload of it.

__________________
Never trust an atom. They make up everything.

4 out of 3 people struggle with math.

Chemically, alcohol IS a solution.

NAR# 94042
SAM# 0078

My local Home Depot is 25 miles away…I’m sure I could get it there.

I just don’t want drive that far for primer.

I’m lazy like that.

__________________
"I'm a sandman. I've never killed anyone. I terminate runners when their time is up." Logan from "Logan's Run"

http://sandmandecals.com/

I didn’t realize that Fort Gratiot was that far from you, but it looks like it is.

__________________
Never trust an atom. They make up everything.

4 out of 3 people struggle with math.

Chemically, alcohol IS a solution.

NAR# 94042
SAM# 0078