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Old Nov 23, 2010, 03:53 PM
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alexhaben's Avatar
Eureka, CA
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Quote:
Originally Posted by wyowindworks View Post
Alex, it's possible to glue ply-wood peices to the perimeter of the mold and use a 1/4" blind nut into the plywood.

I glue washer and nuts to molds all the time using resin and WS 404 Filler. It's important to soak them in acetone and abrade them to facilitate the bond. I use a wheel in a dremel tool to abrade them. I also use nuts with those attached "goofy teethy washer things". The resin seems to really hold onto them.
Good advice, I didn't think of using wood and the blind nuts. I did try the 404 and the resin but it seemed to be more brittle than the JB weld. I did abrade/clean the nuts, but maybe I am having a problem bonding since I choose all stainless hardware rather than the zinc coated which seem to stick better to epoxy. I did try to find some of those toothed nut/washer but they didn't have any in the right size at my LHS, but that would be the ticket. Next time.

Thanks Adam, sorry Jim for talking over your build.
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Old Nov 23, 2010, 06:59 PM
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Bellingen NSW Australia
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Nuts and bolts

Quote:
Originally Posted by alexhaben View Post
. I did try to find some of those toothed nut/washer but they didn't have any in the right size at my LHS, ...........
Alex,

You will have more success if you go to your closest fastener supplier for the nuts. Some kind of general engineering supplies shop.

And,

"sorry Jim for talking over your build" -- no problem at all, it is all most relevant! Thanks for the contribution, as always.

Jim.
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Old Nov 25, 2010, 12:14 AM
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Bellingen NSW Australia
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Parting board

Yesterday I cut out the parting board and routed some full length alignment keys as per Adam's example. Interestingly enough, this is turning out to be the easiest way to provide keys, and surely the most effective. The parting board is laminated MDF (medium density fibreboard), so I sealled the keys with polyester resin (2 coats) and will give a final application of polyester gel coat.

The plug is nearing priming stage, it is nicely surfaced up with the polyester/"Q" cells/wax in styrene mix. It will require very little priming and sanding now. I am seriously thinking of spraying it myself with 2 pack after receiving a quote from the local auto shop for $50 to do it for me. My spray gun has a 1.6 mm nozzle, I understand that is a suitable size. Is that correct?
I am very concerned about the toxicity of this substance, as I have a compromised liver already! I plan to use the best mask I have, do it outdoors and to have either a breeze or a fan blowing air across my face. To be sure, to be sure. I have already made myself ill due to lack of prudence while using resins and paints. I want to stay healthy to continue building for a long time yet!

Jim.
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Old Nov 25, 2010, 12:21 AM
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Jim

I'd suggest going to a different car place and asking if they'd do it the next time they do a job (surely it doesn't matter what color it is to you?) and swap them a couple of cases of beer. I work with a guy who trained as a spray painter and he told me that they always mix up too much as it is muuuch harder to mix up a new batch and match it plus the drying time so there is always excess at the end of a job.

Worth a shot anyway

Is there any reason you are going with polyester - cost, time, availability etc. when it is more toxic?

Steve
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Old Nov 25, 2010, 02:17 AM
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Toxicity

Quote:
Originally Posted by flyonline View Post

Is there any reason you are going with polyester - cost, time, availability etc. when it is more toxic?

Steve
Hi Steve,

I will try another auto painter in Coffs Harbour. As you say, the colour doesn't matter etc.

I am using polyester for all the reasons you mention as well as following the advice of a very helpful local fibreglass proffessional. I am using the best mask I can buy, and besides, there is some controversy about which resin is more toxic. I don't know the actual scientific evidence here, but only that there is some dispute about the comparison. Toxicity is most certainly a concern for me, as I have explained formerly.
I am planning to use Vinylester for the mould. And of course, epoxy for the fuselage and the remainder of the plane.

Anyone reading this know anything about air supplied breathing masks/hoods for painting etc.? It seems that they provide the most thorough protection while spraying etc.

Jim.
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Old Nov 25, 2010, 02:54 AM
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Cody, WY
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I've heard that a cartridge respirators us unable to block the "iso"s in modern catalyzed urethane paints. I've also heard that they can block them, but that "iso"s are so ugly that your don't want a leak letting them in. That is why a supplied fresh air masked is recommended. If they leak, the positive pressure is blowing them out rather than letting them be sucked in. There are serveral systems like this one for under $400.
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Old Nov 25, 2010, 03:21 AM
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Bellingen NSW Australia
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Thanks Adam,

That looks good! I will consider buying one very seriously.

Jim.
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Old Nov 25, 2010, 06:55 AM
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Lima, Peru
Joined Jul 2008
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Hey Jim,

You mention having used surfacing wax (styrene wax) to finish your plug. Be sure to sand the styrene wax residue off and clean with acetone, otherwise you'll find that paint will not stick well to your plug!

When using polyester, I really like Silmar 49. It's the standard for surfboard manufacture, cures water clear and very strong. Contains no surfacing wax, but rarely has curing problems.

-Alex
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Old Nov 25, 2010, 07:22 AM
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Mill Hill - London
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A friend in the motor trade here in the UK once told me that the isocyanate based 2 pack paints produce cyanide whilst curing. The nasties produced are absorbed through any exposed part of your body. Hands, eyes arms etc and the effects are cumulative. In my opinion a cartridge type respirator isnt good enough protection. The sealed full body suit and air fed hood is the way to go. The equipment may seem expensive, but what cost your health ?

As an aside i used the Klasskote system for the first time a few weeks back. It contains no Isocyanates! The distributor here in the UK advised that a cartridge type respirator would be fine for ocasional work done outside. Advice heeded, job done outside, respirator used and no ill effects noted. The paint system is simple to use but I need to work on the spraying technique, more practice required.

Regards,

LB
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Last edited by Lawrence B; Nov 25, 2010 at 04:55 PM. Reason: More Info
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Old Nov 25, 2010, 11:00 AM
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Germany, Berlin
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my respirator setup... adequate??

Thanks for this wide ranging thread!

I spray duratec surfacing primer occasionally which is polyester based, catalyzed with MEKP. Here is the MSDS. 'Reportable' substances include MEK, benzene, and styrene. No isocyanates??

I use a 3m multi purpose respirator which seems to block all the fumes no prob.

I also use a tyvek suit and goggles and two layer nitrile gloves.

Of course I spray outside.

I wonder if I need to worry about these 'isocyanates' with this setup?

Trying to be safe....thanks for any advice.

Ben
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Old Nov 25, 2010, 12:07 PM
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Bellingen NSW Australia
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Precautions.

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Originally Posted by skinnydoc View Post
I also use a tyvek suit and goggles and two layer nitrile gloves.

Of course I spray outside.

Ben
Ben,

I am interested in details of the "Tyvek suit and goggles". Do you have any please?

And Lawrence,

If I decide to use the 2 pack myself, I will most certainly do it outdoors like you, and maybe even with a fan blowing air across my face (as well as the 3M mask) if there is no breeze at all. I expect that I will need to spray a plug about twice a year only, so getting some proffessional to spray them for me, or taking these simple precautions myself will be sufficient.

Thanks for these contributions fellows!

Jim.
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Old Nov 25, 2010, 12:25 PM
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Bellingen NSW Australia
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Symmetry - Mid line

I use this simple method to find the mid line of the plug for fitting into the parting board. I use 2 scraps of the parting board offcutts as spacers and place them on the top or working side of the parting board along side the plug, after the approximate position of the plug has been established.
Using 2 set squares to avoid parallax errors. When the curve of the plug appears to intersect the horizontal line of the spacer and the parting board when viewed in line with the set squares, the plug is mid way into the parting board.

I hope these pictures describes it better.

Jim.
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Old Nov 25, 2010, 01:37 PM
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Bellingen NSW Australia
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Wax In Styrene

Quote:
Originally Posted by Alex.Schweig View Post
Hey Jim,

You mention having used surfacing wax (styrene wax) to finish your plug. Be sure to sand the styrene wax residue off and clean with acetone, otherwise you'll find that paint will not stick well to your plug!
-Alex
Thanks for that warning Alex! I would not have thought of it otherwise.

I still haven't decided which way to go for the final finish yet, polyester gel coat or the 2 pack.
I will ask another spray painter for a quote and decide accordingly.
Both will be equally satisfactory. The gel coat has to sanded after spraying, while the 2 pack, before (of course).

Jim.
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Old Nov 25, 2010, 01:50 PM
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Bellingen NSW Australia
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Wing servo mounts

Meanwhile, I have been doing some more preparation on the wing cores. I have inserted some 1.5 mm plywood strips into the foam to take the servo cover retaining screws.
I am planning to install my servos in the under/over configuration. ie. with the pushrod going diagonally through the wing, servo horn down, control surface horn up. This will only then need a flush/flat servo cover. Probably make these from a couple of layers of light carbon. The control surface horn and short amount of pushrod exposed will only need a small fairing hood like these on my new plank (see picture).

Jim.
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Last edited by Jim.Thompson; Nov 25, 2010 at 01:59 PM. Reason: Additional information
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Old Nov 26, 2010, 07:10 AM
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Angleton, Texas
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What white filler did you use on the foam core? Is there a full top to bottom spar, or is it laid on the foam core?
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