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RE: Dirty Birdy Build Thread
Thanks for the kind words.
I'm still not sure what to coat the plug with. I'm thinking Bondo will work nice. It should sand to a nice finish and withstand some hot plastic. I'll pick some up tomorrow along with some PETG. I'll get my buddy Chris (Cspaced) to get started on the vacuum box. David, if you've got a plug made, I can form a pair of wingtips. Send me a PM. |
RE: Dirty Birdy Build Thread
Looking good Jeff, I thought I saw your workshop light burning ;) We'll have a replacement back on your DB before the weekend is out!
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RE: Dirty Birdy Build Thread
Jeff, Sending a PM |
RE: Dirty Birdy Build Thread
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This is bascially the same method we'll use for the replacement canopy. This is a mold we used to make Texan cowls for the old House of Balsa pylon racer.
The mold is mounted to a base, which has holes strategically drilled through it to suck the plastic down over the plug. The bottom of the base is lined with foam tape to ensure a good air seal. The base is then placed on a platform which has the vacuum attached to it (such as a shop vac), which also has guides to hold the mold in place as well as the frame that will have the PETG stapled to it. After the PETG is stapled to the frame, it is placed in an oven until the plastic starts to sag. The vacuum is turned on, and the PETG frame is immediately placed over the mold where it is held in place by the guides until the plastic cools. Then its just a case of trimming the new part. [8D] Jeff, I already have a couple of PETG sheets cut to size for the cowl mold, we may as well make those up too. |
RE: Dirty Birdy Build Thread
I just got an Email from Bluejay informing me that they do not have spare canopies at this time. Well at least they answered...
I was out sanding on the plug - blending the foam/balsa seam and decided that epoxy and micro balloons will make a great coating. I attached the balsa to the foam with epoxy and there was no adverse reaction. Before I commit, I mixed up a test batch and smeared it on some scrap. I'll check it in the morning. I also smeared some Bondo spot puddy on some scrap and the spot puddy dissolved the foam. |
RE: Dirty Birdy Build Thread
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ORIGINAL: CSpaced This is bascially the same method we'll use for the replacement canopy. This is a mold we used to make Texan cowls for the old House of Balsa pylon racer. The mold is mounted to a base, which has holes strategically drilled through it to suck the plastic down over the plug. The bottom of the base is lined with foam tape to ensure a good air seal. The base is then placed on a platform which has the vacuum attached to it (such as a shop vac), which also has guides to hold the mold in place as well as the frame that will have the PETG stapled to it. After the PETG is stapled to the frame, it is placed in an oven until the plastic starts to sag. The vacuum is turned on, and the PETG frame is immediately placed over the mold where it is held in place by the guides until the plastic cools. Then its just a case of trimming the new part. [8D] Jeff, I already have a couple of PETG sheets cut to size for the cowl mold, we may as well make those up too. Chris, don't suppose I could purchase a couple of those from you? It must have taken us a good couple of evenings to make the wood cowls! (So long coke bottoms...) David. P.S. Model trim is incomplete. |
RE: Dirty Birdy Build Thread
By the way Jeff - nice going! She'll be mask free in no time now.
David. |
RE: Dirty Birdy Build Thread
ORIGINAL: doxilia Ooohhhh...! [sm=tongue_smile.gif] Chris, don't suppose I could purchase a couple of those from you? It must have taken us a good couple of evenings to make the wood cowls! (So long coke bottoms...) David. P.S. Model trim is incomplete. |
RE: Dirty Birdy Build Thread
ORIGINAL: AllTheGoodNamesAreTaken I just got an Email from Bluejay informing me that they do not have spare canopies at this time. Well at least they answered... I was out sanding on the plug - blending the foam/balsa seam and decided that epoxy and micro balloons will make a great coating. I attached the balsa to the foam with epoxy and there was no adverse reaction. Before I commit, I mixed up a test batch and smeared it on some scrap. I'll check it in the morning. I also smeared some Bondo spot puddy on some scrap and the spot puddy dissolved the foam. Epoxy and micro balloons should work great. |
RE: Dirty Birdy Build Thread
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ORIGINAL: doxilia ORIGINAL: CSpaced This is bascially the same method we'll use for the replacement canopy. This is a mold we used to make Texan cowls for the old House of Balsa pylon racer. The mold is mounted to a base, which has holes strategically drilled through it to suck the plastic down over the plug. The bottom of the base is lined with foam tape to ensure a good air seal. The base is then placed on a platform which has the vacuum attached to it (such as a shop vac), which also has guides to hold the mold in place as well as the frame that will have the PETG stapled to it. After the PETG is stapled to the frame, it is placed in an oven until the plastic starts to sag. The vacuum is turned on, and the PETG frame is immediately placed over the mold where it is held in place by the guides until the plastic cools. Then its just a case of trimming the new part. [8D] Jeff, I already have a couple of PETG sheets cut to size for the cowl mold, we may as well make those up too. Chris, don't suppose I could purchase a couple of those from you? It must have taken us a good couple of evenings to make the wood cowls! (So long coke bottoms...) David. P.S. Model trim is incomplete. Chris has the coolest looking Texan, but I can't find a picture of it on this computer. |
RE: Dirty Birdy Build Thread
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ORIGINAL: AllTheGoodNamesAreTaken David, Nice Texan. Our old club used to host AT-6 pylon racing events twice a year. Chris has the coolest looking Texan, but I can't find a picture of it on this computer. I should also mention that the yellow and red one Jeff's holding in the picture was the lightest Texan ever built I think :D |
RE: Dirty Birdy Build Thread
ORIGINAL: CSpaced I should also mention that the yellow and red one Jeff's holding in the picture was the lightest Texan ever built I think :D |
RE: Dirty Birdy Build Thread
A few years ago, a mold-making friend turned me on to Piranha Putty instead of Bondo. Bondo is well-known for voids and how it doesn't work well when you need to fill them. Piranha doesn't make the voids, and it sands much better than Bondo. I haven't tried comparing it weight-wise for use as a part of an airframe, but when it comes to making a quick mold it's the cat's meow.
Andy |
RE: Dirty Birdy Build Thread
ORIGINAL: CSpaced I'll have to grab some extra PETG, but I don't see a problem making a few extra. very nice Texan's indeed! A quick glance at the yellow and red one gives you the feeling that it is very light. Nice Red Bull and Aeroshell versions! Does this last have a stretched wing? Mine came in at 34 oz built stock covered in MK - fuel extra. I have another in box which I was planning to lighten up some day. Chris, I appreciate the offer to pull some extra cowls. PM me with payment details when you can. Many thanks, David. |
RE: Dirty Birdy Build Thread
ORIGINAL: AndyKunz A few years ago, a mold-making friend turned me on to Piranha Putty instead of Bondo. Bondo is well-known for voids and how it doesn't work well when you need to fill them. Piranha doesn't make the voids, and it sands much better than Bondo. I haven't tried comparing it weight-wise for use as a part of an airframe, but when it comes to making a quick mold it's the cat's meow. Andy |
RE: Dirty Birdy Build Thread
ORIGINAL: doxilia ORIGINAL: CSpaced I'll have to grab some extra PETG, but I don't see a problem making a few extra. very nice Texan's indeed! A quick glance at the yellow and red one gives you the feeling that it is very light. Nice Red Bull and Aeroshell versions! Does this last have a stretched wing? Mine came in at 34 oz built stock covered in MK - fuel extra. I have another in box which I was planning to lighten up some day. Chris, I appreciate the offer to pull some extra cowls. PM me with payment details when you can. Many thanks, David. The covering is Coverite MicroLite. The engine mount was trimmed, the fuel tank is a Hayes 4oz (lighter than Dubro or Sullivan), Futaba S3110 Micro servos (6) one per aileron / elevator half, 160mAh battery, 1/2a pushrods, MPI wheels and one wheel collar per axle. Chris' cowels are very thin and light. With a plane that size, every little bit helps. |
RE: Dirty Birdy Build Thread
There are lots of ways to skin the cat, even from where you are. I would lay up a few thin glass/epoxy layers on your foam plug, then dissolve the foam and replace it with plaster. That will give you something good enough to pull a few clear ones off. Make sure you spend lots of time getting that mold surface perfect. The clear will show any imperfections VERY plainly.
Andy |
RE: Dirty Birdy Build Thread
ORIGINAL: AndyKunz A few years ago, a mold-making friend turned me on to Piranha Putty instead of Bondo. Bondo is well-known for voids and how it doesn't work well when you need to fill them. Piranha doesn't make the voids, and it sands much better than Bondo. I haven't tried comparing it weight-wise for use as a part of an airframe, but when it comes to making a quick mold it's the cat's meow. Andy [link=http://www.autobodytoolmart.com/3m-piranha-advanced-finishing-putty-05821-p-10961.aspx]Piranha Puddy[/link] |
RE: Dirty Birdy Build Thread
Here is a product you guys may be interested in...I like it allot and use it quite a bit:
http://www.aircraftspruce.com/catalo.../quickPoxy.php Boy I'm a bit behind on my thread reading!! I love the work you guys are doing and love the Summit III (another one of my favorites)... Chuck |
RE: Dirty Birdy Build Thread
Last time I vacuum formed a canopy I covered the plug with light weight glass and finishing resin. Then used Bondo glazing putty for final filling. Worked out great.
By the way, if you don't have a vacuum box made yet, there's a good article here http://web.archive.org/web/200701051...y/vacuform.htm Dave |
RE: Dirty Birdy Build Thread
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WOW great thread
I have had my Dirty Biridi now for 3 years started stopped started stopped now I have started agin and have been making some good progress I haver the 60 size with the fiberglass fuse and form core wing with glass over it going to put a Rossi 60 that has been upgraded to a morrishobbies and a tuned pipe should fly really nice and fast anywho here is some pics I have the first coat of primer on and finishing the inside rigging etc... |
RE: Dirty Birdy Build Thread
Flynaples, who told you this plane is a Dirty Birdy?
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RE: Dirty Birdy Build Thread
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First coat of resin.
I poured straight finishing resin on the plug and rubbed it in the foam, then let that soak in for 5 min or so. Then I poured micro balloons over the mold and rubbed that in. Then I scraped the excess material off with a thin piece of cardboard. The last pic shows a slight sheen to the plug. Once this sets up, the next coat will be 50/50 finishing resin/micro balloons. then sanded with 600 grit. |
RE: Dirty Birdy Build Thread
ORIGINAL: flynaples WOW great thread I have had my Dirty Biridi now for 3 years started stopped started stopped now I have started agin and have been making some good progress I haver the 60 size with the fiberglass fuse and form core wing with glass over it going to put a Rossi 60 that has been upgraded to a morrishobbies and a tuned pipe should fly really nice and fast anywho here is some pics I have the first coat of primer on and finishing the inside rigging etc... http://www.trentonrcflyers.com/patte...t%20Escape.jpg |
RE: Dirty Birdy Build Thread
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Coat #2.
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