Quoted for additional emphasis.I small hobby file makes quick work of scraping off primer, CWF, and even glassine at the fin joint before gluing on the fins. Any imperfections get covered by fillets and primer/paint.
I small hobby file makes quick work of scraping off primer, CWF, and even glassine at the fin joint before gluing on the fins. Any imperfections get covered by fillets and primer/paint.
Quoted for additional emphasis.
You can either mask off the areas where the glue joints will be, or else sand off the primer there, which is very easy. Certainly, you wouldn't want to glue directly to the primer.
Filler/primer can be done after assembly as well, but it's harder to sand around the nooks and crannies, especially at LPR sizes.
Regarding PRIMING before sanding, as opposed to CWF, I think it was @hcmbanjo that said that PRIMER before gluing was a no-no, as it is like trying to glue fins on after painting, the glue sticks to the point, no the rocket body tube. On the other hand CWF was supposedly porous, so, asssuming it wasn’t super thick, glues would adhere “through” the glue, so that was okay.
A primer exception (true for painting as well) is if you mask the adhesion sites before priming and/or painting. But if you guys have good luck with fin adhesion AFTER priming, I am probably misquoting Chris.
Now that is an interesting way to fill & sand. I'm going to have to give that a try.Kind of new to all of this and I hope these pictures work. Taking others ideas this is how I do my spirals:
A. Mark all spirals to be filled.
Using 120 grit, spin tube and lightly rough up surface.
B. Using ??-putty from Hobby Lobby. Dip finger in alcohol if needed, cover spirals “thinly“. If it makes little clumps don’t worry, don’t overwork putty. Set aside to dry in sun about 5 minutes, while shaking primer and get cordless drill.
C. I use dowels with tape to adapt the tube to drill & spin tube during process.
I start very lightly with 120 grit. 1 soft pass up and back with slow spin to remove chunks. Then green scratchy pad, a quick spin on 200 grit, 400 grit, then fine steel wool at a higher speed.
if needed touch up areas with putty, spinning smooth after. You will notice the spinning sanding creates heat, heat creates quicker drying of the putty. Give it five minutes and then spray primer.
While spinning rocket tube with drill spray primer. Wait 5 minutes or so. Use 400 grit, smooth, then steel wool.
Repeat as needed.
The process isn’t perfect but tube is done quickly. From start to finish, about 40 min. depending on outside temps.
spin when painting too!
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I wouldn't recommend spraying filler/primer then using CWF.
In the first picture below you can see some CWF left in the tube seams after sanding.
Before spraying the body tube with filler/primer I mask off the fin gluing line with a strip of masking tape.
The tape strip is a hair wider than the fin for better adhesion of the glue fillet later.
The fins in the left side picture hasn't had the filler/primer sanded down yet.
The second picture shows the root edge fillet area sanded down (a little more filler/primer removed)
for better glue fillet adhesion.
In the photos I try to show the various stages. The spiral is of course the putty being smoothed and then I primed it and smooth again as needed etc., If it‘s to blotchy spin and sand with 400 grit. Just takes a moment to take it back to cardboard. If it looks mostly good on one end that’s the nose and the roughest end be the fins.Well I have to say I never thought of using a method like that. Interesting idea.
I have to wonder if the greyness of the tube is due to the grey putty, or tiny particles of the steel wool embedding themselves in the tube? If the steel wool, would that affect the finish in time, due to the steel particles oxidizing?
@Mx2 You could try fine ScotchBrite pads instead of steel wool. They don't shed like steel wool does. The maroon pads are about 320 grit and they do make them finer.In the photos I try to show the various stages. The spiral is of course the putty being smoothed and then I primed it and smooth again as needed etc., If it‘s to blotchy spin and sand with 400 grit. Just takes a moment to take it back to cardboard. If it looks mostly good on one end that’s the nose and the roughest end be the fins.
yes, I believe the steel wool may be creating some darker areas In the primer coat, possibly by Heat that is created and or stain impregnated into primer which thus far hasn’t seemed to effect painting.
My Desire is not to obtain a perfect paint job for a showpiece. What I seek is to launch eye appealing rockets from 10 ft away or whatever. It took me a couple to get it right but I can actually prime a Single rocket body tube in < half hour. (But as earlier discussed When attaching fins or launch lugs, you have to scratch away the primer to allow adhesion back to the cardboard.). It works and not that complicated.
Just some more questions that I don't see discussed as often. What are the tools and techniques that you use for application of whatever filler, be it bondo or spot putty or CWF? I think the primer method is pretty self explanatory, but in that case I wonder how you avoid raising fibers from the substrate while sanding.
Lol, I looked at the picture and my first thought was, “What is he doing to that poor squirrel?!”Primed tube.View attachment 423094
Great tip! Thanks, I'll have to give it a try.https://modelrocketbuilding.blogspot.com/2016/04/estes-hi-flier-xl-3226-build-part-8.htmlThe advantage to this method is the filler is directed into the seam with the CWF on the knife blade.
Best to use an older blade.
The CWF coverage area ends up narrow, a little wider than the seam being filled.
Like any new technique, it takes a little practice.
CWF filler first and sand. Then follow with filler primer and sand.
Two steps and the seams are filled.
That's a sound solution. I just finished spraying my new LPR and I got to a point where I said "that's all the primer I'm willing to use on a low power rocket." On to paint. It's mostly smooth but there are still a couple of unsightly bits of spiral here or there.While it can bring it's own set of issues, I am getting to the point where if I really want my spirals filled perfectly, I'll build a fiberglass kit.
Mach 1 has made it nice for LPR in that regard...That's a sound solution. I just finished spraying my new LPR and I got to a point where I said "that's all the primer I'm willing to use on a low power rocket." On to paint. It's mostly smooth but there are still a couple of unsightly bits of spiral here or there.
Please expand how you use dowels to fit body tube to drill...did you buy a dowel that is exactly the size as tube or do you "beef it " up until tube frictions fits on dowel ?Kind of new to all of this and I hope these pictures work. Taking others ideas this is how I do my spirals:
A. Mark all spirals to be filled with marker.
Using 120 grit, spin tube and lightly rough up surface, Usually a soft pass up and back To remove waxy covering. (see step C.)
B. Using ??-putty from Hobby Lobby. Dip finger in alcohol if needed, cover spirals “thinly“. If it makes little clumps don’t worry, don’t overwork putty. Set aside to dry in sun about 5 minutes, while shaking primer and get cordless drill.
C. I use dowels with tape to adapt the tube to drill & spin tube during process.
I start very lightly with 120 grit. 1 soft pass up and back with slow spin to remove chunks. Then green scratchy pad, a quick spin on 200 grit, 400 grit, then fine steel wool at a higher speed.
if needed touch up areas with putty, spinning smooth after. You will notice the spinning sanding creates heat, heat creates quicker drying of the putty. Give it five minutes and then spray primer.
While spinning rocket tube with drill spray primer. Wait 5 minutes or so. Use 400 grit, smooth, then steel wool.
Repeat as needed.
The process isn’t perfect but tube is done quickly. From start to finish, about 40 min. depending on outside temps.
spin when painting too! (as always light coats of paint)
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i cannot see unfilled spirals from the range head while the rocket sits on the pad.That's a sound solution. I just finished spraying my new LPR and I got to a point where I said "that's all the primer I'm willing to use on a low power rocket." On to paint. It's mostly smooth but there are still a couple of unsightly bits of spiral here or there.
I beefed up the dowel to make it snug against inside of rocket body. Doesn’t have to be tight. Snug works. Go from there.Please expand how you use dowels to fit body tube to drill...did you buy a dowel that is exactly the size as tube or do you "beef it " up until tube frictions fits on dowel ?
Training myself to take some more time rather than slapping something together in the morning and launching it that afternoon. My dad used to do body work, and cited the 20/20 rule often. If a car is moving 20mph 20ft away and the defect isn't noticed, then it isn't a defect.i cannot see unfilled spirals from the range head while the rocket sits on the pad.
No one else can either.
To be honest I will touch up paint chips with Sharpie markers but that’s pretty much all I’m willing to to do.
Agreed.Training myself to take some more time rather than slapping something together in the morning and launching it that afternoon. My dad used to do body work, and cited the 20/20 rule often. If a car is moving 20mph 20ft away and the defect isn't noticed, then it isn't a defect.
Kind of new to all of this and I hope these pictures work. Taking others ideas this is how I do my spirals:
A. Mark all spirals to be filled with marker.
Input appreciated, clarification adjustments added:View attachment 423010
You mentioned you are new to this -
I'd shy away from using a marker (or pen) to mark your spirals.
Inks can bleed through your finish paint. You'll have better end results with a pencil.
120 grit is pretty aggressive for a paper or Kraft tube.
Start with 220 and move to 400 grit.
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