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Old 04-06-2011, 07:03 AM
Dipterist Dipterist is offline
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Default Balsa filler

I have recently gotten back into model rocketry after a 35 year lag. On my most recent kits, I have had issues with Aero gloss balsa filler in that in shrinks the wood, resulting in warping. I ordered Butyrate dope from an aircraft maintainence company (It is pretty cheap if you can rationalize purchasing a quart) and am pleased with the lack of shrinkage and lack of bubbling between joints. Unfortunately, it does not fill the pores like the nitrate based filler coat. I know that talcum powder is often mixed with the dope to fill the pours. What talc do you recommend? Can I use something else? I am having a hard time finding any that does not smell like a Hallmark stores candle aisle. Will using fragrant talc mess up the finish?
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Old 04-06-2011, 08:39 AM
Scott6060842 Scott6060842 is offline
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I recently bought an 8 oz bag of unscented pure talc on ebay for $8.05 including shipping. They have a store with lots to sell. I have no idea if this is a fair price as I have never priced it before.

I am surprised to here of your warping problems with Midwest balsa filler. I have had good results with it. I just bought 6 16oz cans of the Pactra stuff on ebay for (<$20) so I better like it.
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Old 04-06-2011, 10:15 AM
Dipterist Dipterist is offline
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$8.00 seems a little high but it is alot cheaper than driving all over Dallas in search of the stuff. Thanks
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Old 04-06-2011, 10:28 AM
BPRescue BPRescue is offline
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An alternative that many do on this board is to laminate/wrap the balsa fin in paper as seen here. http://www.youtube.com/watch?v=JnYBSbYr8ZE . There are different ways to do this using regular paper, contact cement, yellow glue, etc.

I have tested a few different ways and had good results with regular paper/yellow glue, however find it is much easier; and can be more precise for clean fin edges to use label paper with the adhesive already on the back. Extends work time, saves prep time, affords even coverage and is not messy; not to mention very simple. I have used 3M full page labels (can get exact type if interested). I have found it creates a perfect surface for the primer, but equally as important creates immense strength and durability on the fins. They do take a beating and really the only true damage I have received as of yet was resulting from my launched rocket landing on the blacktop runway. It was a windy day at the club launch, and I could not recover my rocket until the pad was cleared. So, I just watched as the wind filled the chute and proceeded to drag my rocket about 100’. I was cringing the entire way and it was confirmed when I saw what the 2 grit sandpaper did to the edge of the fin and body of the tube. Easily repairable though…

So, durability has been great thus far. Arguably, I just started doing this a few months ago, so we will see if there is any de-lamination occurring in a year or so… For now I have nothing but positive comments…
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Old 04-06-2011, 10:35 AM
BPRescue BPRescue is offline
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BTW, I do it a little differently than this video and wrap the label around all the edges with exception to the root edge. For the root edge, the fillet’s terminate the paper edge perfectly. Doing this creates a very nice finish on the edges, but also adds strength there as well. I can provide more detail if you desire…
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Old 04-06-2011, 10:36 AM
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Doug Sams Doug Sams is offline
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Quote:
Originally Posted by Dipterist
$8.00 seems a little high but it is alot cheaper than driving all over Dallas in search of the stuff. Thanks
I'm thinking an ordinary container of baby powder ought to do the trick for less than half that.
Doug
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Old 04-06-2011, 10:45 AM
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GregGleason GregGleason is offline
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I looked at the MSDS for Johnson's Baby Powder last week and it was 90% talc.

Greg
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Old 04-06-2011, 10:52 AM
Scott6060842 Scott6060842 is offline
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I guess the question still stands. Will the other 10% be a non-factor when mixed? Also, if your using it to dust chutes to does it bother you to smell like a babys behind?
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Old 04-06-2011, 10:53 AM
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DaveR DaveR is offline
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Quote:
Originally Posted by Doug Sams
I'm thinking an ordinary container of baby powder ought to do the trick for less than half that.
Doug
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I think you can even get it unscented.
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Old 04-06-2011, 10:58 AM
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Bill Bill is offline
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As a kid, I did not know the difference between balsa fillercoat and sanding sealer. I used sanding sealer because that was what the shop carried. But I was given a hint to rub some chute powder into the balsa and wipe off the excess before the first coat of sanding sealer which is essentially what using balsa fillercoat first does.


Bill
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