Banishing Tube Spirals
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mh9162013
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Just an observation from today:
I tried to deal with spirals with CWF, only this time I did it with a BT-50 body tube and used my thumb to smear it into the grooves. Seemed like this smearing technique worked well and I will see if it works with BT-20 body tubes on my next build that uses that sized tubing.
Perhaps it's already been mentioned before (I think it has, but not sure when or which thread), that when getting the best finish on a body tube, sometimes there are spiral ridges to deal with, in addition to the grooves. I never noticed this with BT-20 tubing (which is my primary rocket size), but when working with Estes BT-50 tubing, I noticed this issue. So I think using a hybrid approach of sandable/filler primer + CWF might be a great combination with certain body tubes to deal with both as efficiently as possible.
I tried to deal with spirals with CWF, only this time I did it with a BT-50 body tube and used my thumb to smear it into the grooves. Seemed like this smearing technique worked well and I will see if it works with BT-20 body tubes on my next build that uses that sized tubing.
Perhaps it's already been mentioned before (I think it has, but not sure when or which thread), that when getting the best finish on a body tube, sometimes there are spiral ridges to deal with, in addition to the grooves. I never noticed this with BT-20 tubing (which is my primary rocket size), but when working with Estes BT-50 tubing, I noticed this issue. So I think using a hybrid approach of sandable/filler primer + CWF might be a great combination with certain body tubes to deal with both as efficiently as possible.
That is extremely common practice.
If you haven’t already done so I highly recommend reading @hcmbanjo ’s blog (http://modelrocketbuilding.blogspot.com/) where he show this process very clearly.
I hate sanding filler/primer but it is so darned effective that I usually just suck it up and deal with it.
mh9162013
Well-Known Member
Yeah, I thought I saw him talking about using both before, but me being lazy, I hoped I could get satisfactory results with just one of the techniques.
I don't care to build all my rockets where appearance is that important, but I want have the skills to get perfect results when I want (or need) them.
Sometimes you can get by with only one. For my current build the tubes have very minimal grooves, so I'm just doing filler/primer without the CWF step. Some folks always just do it with the filler/primer, sometimes using several coats.
For me, CWF + filler/primer is my "standard" approach for body tubes, as learned on Chris's block. It almost *always* produces excellent results. Occasionally I will diverge as the circumstances allow.
mh9162013
Well-Known Member
That's what I had been doing. But if I have to choose between 1 filler/primer coat and 1 application of CWF, or 3 primer/filler coats, I choose the former.
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I have started blocking the glassine with 400 grit on a long sander just to knock down the highest spots before doing anything else. Seems to make a little difference and doesn't take long. The few, small fibers that are raised go away in the next steps.
Oh, wait! There are already pictures of the "Gnome-Hawk" Frankenrocket in this thread on TRF:
https://www.rocketryforum.com/threads/tube-coupler-hack.172910/
Here are couple more I found on my phone:
For @CoolRockets
I should calarify. The Quest Big Rage "payload bay" is not the payload bay from the Big Rage. It is just an intact piece of pre-colored body tube from a crashed Quest Big Rage.
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CoolRockets
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@hcmbanjo, I tried posting directly on your blog, but it wouldn't let me, for some reason.
https://modelrocketbuilding.blogspot.com/2011/11/cwf-filler-mix-ratio-for-body-tube.html
What is the mix ratio you're using for spirals these days? In that post, you only say it's "thicker" than the 2 1/2 : 1 you use for fins. Do you have a number?
The godson is looking to do filler on his Crossfire ISX.
I know you didn't ask me but I'll answer anyway: it's not that critical. Chris's formula is a good starting point but really it doesn't require measuring.
Basically you're looking to get it so you can mix it without too much problem, and if you dip your finger in it a little dollop should stick to it.
The best results I've gotten are when I *vigorously* squeegeed off the excess with a credit card before it hardened up. Very little sanding required and it also helped push the CWF into the grooves.
Basically you're looking to get it so you can mix it without too much problem, and if you dip your finger in it a little dollop should stick to it.
The best results I've gotten are when I *vigorously* squeegeed off the excess with a credit card before it hardened up. Very little sanding required and it also helped push the CWF into the grooves.
hcmbanjo
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Over the years, I've ended up using the same mix ratio for both the fins and body tube spirals.
This "starter" mix ratio is just that, a starting place.
https://modelrocketbuilding.blogspot.com/2010/09/carpenters-wood-filler-mix-ratios.html
Have your Godson brush with the grain, then against it to push the filler into the grain pores.
At one time, the Elmer's Carpenter's Wood Filler (CWF) was found at many home improvement stores.
The only place I see it now is at ACE Hardware.
Try to find the basic orange lid CWF, meant for indoor use - not the MAX variant.
The MAX filler is like sanding fine rocks.
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MidOH
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Half my low power rockets are pretty smooth by the time I'm done with a couple coats of primer.
I've done the filler once or twice. Meh, haven't found a technique I like. Clay epoxy is a big nope.
The ones that still show some sanding or spirals, get painted a bright color to hide that.
That's why you see so many dark paint schemes on fiberglass rockets, and bright on paper.
I've done the filler once or twice. Meh, haven't found a technique I like. Clay epoxy is a big nope.
The ones that still show some sanding or spirals, get painted a bright color to hide that.
That's why you see so many dark paint schemes on fiberglass rockets, and bright on paper.
MidOH
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The above.
Then polish with an orbital buffer locked in a vise. Maguires cutting polish and a medium foam pad, then a fine foam pad with finishing coumpoind.
It's super easy to burn through clear coat. And it's such a pita to apply. Does it go on rough sanded paint? Or smooth paint? After a cure of 3 days, or while the paint is tacky.
I've had plenty of clear coats need sanded off, and redone. Or they peeled off later. Or they wrinkle the paint.
I save clearcoat only for fiberglass and plastic now. I can polish a pretty good shine in most enamels.
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Something that might make this easier would be using vinyl/electrical tape. Also use @neil_w ‘s idea of sticking the tape to something else a view times to prevent it from being TOO sticking. Vinyl tape is one of the few cheap and easily available tapes that easily deform to make a true helical ribbon. Standard tapes will require either multiple cuts or overlaps.Once smeared with a razor, it looks like this
View attachment 575271
Here are the results
View attachment 575272
After sanding with 400 grit (I prefer 400 grit on CWF as it is less abrasive on the tube, I use 220 on primers / fillers) it looks like this
View attachment 575273
