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Old Jan 05, 2013, 10:06 PM
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Now where did I put my passport
That might get to be the most expensive beer in your live

Andrés
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Old Jan 08, 2013, 12:05 PM
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Colchester UK
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Well had a bad couple of days. I made a big mistake in using a stain varnish. I was seduced by the marvellous finish that Kent achieved on his Manatee. I did a trial on a scrap piece of ply and thought the choice of the stain varnish was ok. I sensibly tried the bottom first and found that using a brush I produced streaks even with a brush that was lightly loaded. In the end I wiped the varnish on with a cloth in several very thin coats. Also I thought the surface was pretty good and was clean, but I did have some glue marks that I cleaned off that I was sure would not show. How wrong I was... it looks like it has measles in places. I thought I could make a better job on the upper surface but it too was very disappointing. Also I found it very difficult to sand or wire wool the surface as the ply is so weak. I almost reached the point where I wanted to scrap the plane. I left it today and thought about it and I will paint it. However the paint finish will probably not be that good either as it really needs a good rub down.

Anyway recently had the material to make the jet pipe so set to to make it today. Pleased to say that it all went well and I did not even blow any holes in the stainless. I had a spare spun intake ring from the ones I made for the Arado and used it. The material used for the tube is 0.10mm stainless steel.

I made a single wall tube, and will apply some BVM ceramic paint to the upper part of the fuselage to protect it from heat. This should be lighter than making the pipe double walled.

I use a home made spot welder that I made from a Dremel drill press. The coil is a powerful torroid one. The welder uses a digital timer and power surges are filtered/softened so the welder does not trip the switches in the house. Thought you might be interested to see the set up. Finally the completed pipe was persuaded into the fuselage.

John
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Old Jan 08, 2013, 03:33 PM
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I did have some glue marks that I cleaned off that I was sure would not show. How wrong I was... it looks like it has measles in places.
I know exactly what you're talking about. I've never been able to work with wood of any kind without accidentally getting those glue "holidays" in the finished stain. No matter how carefully I work and clean up, the glue spills will seal the wood, thus ruining the finished stain. The only method that works for me is to pre-stain (and seal) the virgin wood the moment it come out of the box, then after the building is all done, you can always wash the project with another layer of stain to make it as uniform as possible. Also, don't "test stain" any areas that are to be glued. My stain also seals the wood. It does so, so well that glue does not penetrate, and thus makes a very weak joint. It will look OK, but you can just peel it right apart with your hands, let alone a hard landing.

Some how Lothar is able to build then stain with good results.....I don't know how he does it. Maybe it's trick photography...

Painting at this point should be do-able for you with the right primer. Very smooth may not be good though. Andres has mentioned a few times that the roughness of the plywood is probably a good thing at our Re numbers. Also, an opaque stain should cover up the measles.

Kent
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Old Jan 09, 2013, 01:15 AM
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Some how Lothar is able to build then stain with good results.....I don't know how he does it. Maybe it's trick photography...
No Kent,

it's not tricky photography, its just good luck

Difficult to explain in english, but I try: First of all, I always have a wet piece of whool cloth beside my workbench to clean evrything from whit glue as soon as possible. So the possibility to get points withe glue on the surface is very small. When the glue is hardened, I don't grind to much, I use a cabinet scraper to remove rests of glue. This works great.

I don't use real stain. I use what we call a "Lasur" in german. May be the translation is "glaze" or " scumble" The product I use is this:

http://www.clou-shop.eu/l17-aqua-com...ack-lasur.html

By the way, as darker the Lasur is (f.E. dark oak) as more difficult is the process to get a uniformly coloured surface. That's why I prefer this beech-tree colour.

After this I put the silk on the plane . And after working with dope, I put some varnish for stairs on the whole wing. This makes a perfect wooden finish.

I hope my explanations could help a bit.

By the way, it took me about 3 wings, until I was happy with my result and I am sure, If I restart building plywood wings, It akes me another wing until I am again happy with my result. It needs a bit training.

Regards

Lothar
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Old Jan 09, 2013, 03:32 AM
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Kent and Lothar

Many thanks for both your suggestions. I have used plenty of varnishes before and done some French polishing so was quite confident that I would be able to do the colouring without any problem. During the build I made sure to remove any glue as soon as I saw it on the surface. These were no visible marks and I was sure I had removed them all. As Kent says the glue affects the ability of the surface underneath to take a stain. Also the ply is so thin it cannot be sanded much or scraped much without revealing the glue line. The problem seems to be using a wood stain. In my case I used a coloured varnish. Actually I did this part right and chose Beech colour.

I had never thought of using Scumble and have never used it before. It is not too late for me to try some. I looked up some videos on Scumbling techniques on YouTube and see how to get an even coverage using a stippling brush. I shall get some and try it before I resort to painting.

John
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Old Jan 09, 2013, 09:16 AM
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Originally Posted by Tijgerhaai View Post
After this I put the silk on the plane . And after working with dope, I put some varnish for stairs on the whole wing. This makes a perfect wooden finish.
Wow.....so all the wood is covered in silk. I had no idea. Nice.

I had tried to keep up with glue spots as they occurred by wiping with a wet rag, but I was never thorough enough. Good to know that it can be done.

Thanks,
Kent
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Old Jan 09, 2013, 09:45 AM
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Wow.....so all the wood is covered in silk. I had no idea. Nice.
No Kent, he meant only the open sections

Andrés (back in the "old" continent)
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Old Jan 09, 2013, 12:12 PM
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Fitted the securing pin to hold the engine hatch. I use some 1.6mm dia stainless welding rod that I bought some years ago. The principle is that the pin runs through the front former and then the hatch before exiting into the rear former. It is impossible to line up a long pin like this without a guide and I use 3mm Festo pipe.

I start by drilling the front former and the front former of the hatch all in one pass. I drill an exit hole at the rear former of the hatch at roughly the same position as it passes through the front one. Both holes are opened out to 3mm and the Festo pipe is passed though them both. This pipe needs supporting and I fit a strip of balsa between the outer part of the hatch and the Festo pipe. I glue the ends of the pipe with some epoxy and use fine plastic particles and Cyano to secure the Festo to the balsa. The ends are trimmed off and with the hatch in place the pin is pushed through and with a pointed end marks the rear position on the rear former. This cane be drilled by hand with a small chuck. this makes a very light and very secure way to fix hatches so they are hidden.

The holes were deliberately made off centre to avoid the top centre where there is a cut out for a spar.

I also had another look at the ply finish and tried painting a thin coat with the brush. This seems to have improved things a bit and I will add some more coats.
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Old Jan 09, 2013, 03:30 PM
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finish looks good

Hej John,

what I can see on the last picture in Your last post looks fine. And of course, silk only on the open fields, not over the whole wing. Sorry for my bad explanation.

Regards

Lothar
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Old Jan 09, 2013, 03:47 PM
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This must be the fixed version John. Your finish is fine. When I get a glue holiday, it is obvious....see the TE in photo.

Kent
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Old Jan 09, 2013, 04:30 PM
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Interesting re the DIY spot welder. There are Lots of Utube videos on building one by rewinding the upper coil of a salvaged Microwave Oven transformer.
Seemingly these Do Not have current draw issues.
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Old Jan 10, 2013, 02:44 AM
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I also have a microwave based spot welder, but it does not have the power that the torriod based one has. It is easy to have more turns through the centre of the doughnut.

John
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Old Jan 10, 2013, 02:55 AM
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Kent

Thanks for the photos, now I can see that my efforts do not look so bad after all. It is great that the Internet provides a means of exchanging ways of doing things and new techniques.

lothar

Thanks for the confirmation. Will do more work on it today.

John
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Old Jan 11, 2013, 08:30 AM
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My first attempts at Koverall. The Oracover heat activated adhesive worked ok. However I found I had to be very careful not to shrink the material too much with the heat gun as it will pull off the surface. I am now giving it a light shrink after ironing the edges on and giving the edges a coat of dope. I then let that dry and then applied the heat gun very carefully. I have just given the first panel 2 coats of dope and they seem ok.

I made a paper template to aid cutting the Koverall accurately with a new scalpel blade and I masked off the area around the template so the glue was applied to the correct place. This worked well.

John
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Old Jan 13, 2013, 01:03 PM
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Hi john,

Perhaps you already mentionned it, but can't find it:
What is your anticipated cubic wing loading and your trust to weight ratio?

Thanks
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