First Glass Cowl-please help
04-29-2005, 02:00 PM
#1
First Glass Cowl-please help
I have a 2-piece ABS cowl for the Lanier Ultimate Pitts.
Could I use the INSIDE of this ABS cowl to make a mold and then lay up the glass over the mold to make my fiberglass cowl?
It seams like I could just join the ABS cowl with a strip of glass on the outside. Then it would be smooth inside. I could fill it with mold material and then remove the plug.
Will this work?
If it will work--could anyone suggest a material that I could use for the plug? Something I could just pour inside? Maybe that expanding foam you shoot out of a can?
Thanks very much.
Could I use the INSIDE of this ABS cowl to make a mold and then lay up the glass over the mold to make my fiberglass cowl?
It seams like I could just join the ABS cowl with a strip of glass on the outside. Then it would be smooth inside. I could fill it with mold material and then remove the plug.
Will this work?
If it will work--could anyone suggest a material that I could use for the plug? Something I could just pour inside? Maybe that expanding foam you shoot out of a can?
Thanks very much.
04-30-2005, 10:11 PM
#3
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RE: First Glass Cowl-please help
Rcpilet
You can actually use the ABS cowl as your mold to make your final product. Join it on the outside, get the inner seams smooth. You can then use this as a female mold. Polyester resin will attack ABS, so use epoxy resin.
After you prepare the inside with release agent you can actually spray in the mold before you do the lay-up. I use 2-part paint to do this. That way you can prevent pin-holes and be almost ready to just add some clear coat to finish the cowl once you have done the lay-up and pulled it from the mold.
If you really want to use polyester resin, first spray a few coats of epoxy 2-part paint on the inside. This has the added advantage of getting the inside really smooth. Then prepare the inside with release agent and either paint in the mold before laying up or just lay-up.
Have fun and, Safe Flying!
You can actually use the ABS cowl as your mold to make your final product. Join it on the outside, get the inner seams smooth. You can then use this as a female mold. Polyester resin will attack ABS, so use epoxy resin.
After you prepare the inside with release agent you can actually spray in the mold before you do the lay-up. I use 2-part paint to do this. That way you can prevent pin-holes and be almost ready to just add some clear coat to finish the cowl once you have done the lay-up and pulled it from the mold.
If you really want to use polyester resin, first spray a few coats of epoxy 2-part paint on the inside. This has the added advantage of getting the inside really smooth. Then prepare the inside with release agent and either paint in the mold before laying up or just lay-up.
Have fun and, Safe Flying!
05-06-2005, 11:09 PM
#4
RE: First Glass Cowl-please help
ORIGINAL: blikseme300
Rcpilet
You can actually use the ABS cowl as your mold to make your final product. Join it on the outside, get the inner seams smooth. You can then use this as a female mold. Polyester resin will attack ABS, so use epoxy resin.
After you prepare the inside with release agent you can actually spray in the mold before you do the lay-up. I use 2-part paint to do this. That way you can prevent pin-holes and be almost ready to just add some clear coat to finish the cowl once you have done the lay-up and pulled it from the mold.
If you really want to use polyester resin, first spray a few coats of epoxy 2-part paint on the inside. This has the added advantage of getting the inside really smooth. Then prepare the inside with release agent and either paint in the mold before laying up or just lay-up.
Have fun and, Safe Flying!
Rcpilet
You can actually use the ABS cowl as your mold to make your final product. Join it on the outside, get the inner seams smooth. You can then use this as a female mold. Polyester resin will attack ABS, so use epoxy resin.
After you prepare the inside with release agent you can actually spray in the mold before you do the lay-up. I use 2-part paint to do this. That way you can prevent pin-holes and be almost ready to just add some clear coat to finish the cowl once you have done the lay-up and pulled it from the mold.
If you really want to use polyester resin, first spray a few coats of epoxy 2-part paint on the inside. This has the added advantage of getting the inside really smooth. Then prepare the inside with release agent and either paint in the mold before laying up or just lay-up.
Have fun and, Safe Flying!
Can't I just join the ABS and then fill it with something? Then pull the plug out and glass over that.
I'm not worried about how smooth the plug is. The finished glass cowl will be layed up OVER that plug. I can sand the glass cowl smooth on the outside as I lay it up. Who cares how smooth it is on the inside? Not going to see it when all is done, anyway.
It seams so simple--but I've read hundreds of posts here and it all looks VERY complicated.
Why couldn't you just put a release agent inside the ABS cowl--then fill it with expanding foam. Slice the foam off when it comes out the backside. Wait for it to cure and pull the foam plug out. Then make sure to put something on it so that your epoxy/resin/polyester won't stick. Lay up the glass on the outside and then trash the plug.
Why won't that work. Seams like I could spend a few hours joining the ABS. Then about 5 minutes to fill it with expanding foam. Let the foam cure and then pull it out. Maybe spend a few minutes getting a surface on the foam that my glass cowl wont stick to--and then its a matter of laying up my glass cowl.
I can't see this taking more than a couple hours work from start to finish. Why is it so complicated when I read posts via the search function?
Anybody?
05-07-2005, 11:29 AM
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RE: First Glass Cowl-please help
its not complicated to do the job properly, and there are tips and tricks to speed up the process, BUT there are still basic procedures that have to be followed to insure a good product is achieved.
if you take youre mold from the inside of the abs cowl then the finished cowl will be undersize by the thickness of the abs, unless you are intending to fill it with foan and then lay glass on top of this and then flatten this off dig out the foam and then spray the cowl with paint? this WILL work BUT you will be making it hard for yourself and you still wont have a mold so if you break it thats it game over! where as if you do it properly then you will have a nice shiny mold and you can make as many cowls as you want
goony
if you take youre mold from the inside of the abs cowl then the finished cowl will be undersize by the thickness of the abs, unless you are intending to fill it with foan and then lay glass on top of this and then flatten this off dig out the foam and then spray the cowl with paint? this WILL work BUT you will be making it hard for yourself and you still wont have a mold so if you break it thats it game over! where as if you do it properly then you will have a nice shiny mold and you can make as many cowls as you want
goony
05-07-2005, 10:40 PM
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RE: First Glass Cowl-please help
Rcpilet
If you do a cowl from the inside of the ABS it will be a bit smaller, as you pointed out. Typically the cowls for kits and most arfs fit over the front of the plane. IMHO it looks sloppy. I attach my cowls to a cowl ring which bolts to the front of the plane. The cowl then butt joins the front of the fuse with no "step" in the lines. On my GP330L kit I did the same, I made up a ring which is held in place by 4 dowls and tightened down with 4 bolts which are tightend using a 18" long made-up tool reaching through the front of the cowl. The ring was shaped to be about 1/16" smaller than the fuselage. The cowl was pulled around this and epoxied on. The line from the fuse to the cowl is now clean. It is more work than mounting the cowl around the fuse, but it looks MUCH better.
Safe Flying!
If you do a cowl from the inside of the ABS it will be a bit smaller, as you pointed out. Typically the cowls for kits and most arfs fit over the front of the plane. IMHO it looks sloppy. I attach my cowls to a cowl ring which bolts to the front of the plane. The cowl then butt joins the front of the fuse with no "step" in the lines. On my GP330L kit I did the same, I made up a ring which is held in place by 4 dowls and tightened down with 4 bolts which are tightend using a 18" long made-up tool reaching through the front of the cowl. The ring was shaped to be about 1/16" smaller than the fuselage. The cowl was pulled around this and epoxied on. The line from the fuse to the cowl is now clean. It is more work than mounting the cowl around the fuse, but it looks MUCH better.
Safe Flying!
