Airdale CPO

My Feedback: (3)

I have just purchased a new Engine Cowling for my CG Extra 300. Its still in the joined position and I have yet to cut it out. Its three piece plastic. Once cut out and fitted to the aircraft, what is that best way to make a clean and strong joint. Also when adhering the front cowl piece to the 2 halves, do I just epoxy it on?

Thanks for your information.

Campy

My Feedback: (1)

I typically use thin CA AND a 2" wide strip of 2 oz fiberglass on the joints (CA to the inside of the cowl ). I also CA a strip of fiberglass around the back side of the cowl to re-inforce the screw holes so the cowl will not crack in those areas.

After the cowl is assembled, I normally use spot putty to fill the seams on the outside of the cowl.

For ABS/plastic cowls use thin CA for assembley - epoxy will not provide a strong joint, and depending on the cowl material, may damage the cowl. For a fiberglass cowl you can use either CA or epoxy - I still suggest using thin CA though.

Hope this is of some help.

RCKen

My Feedback: (9)

When it comes to ABS plastic I go back to the days when I built plastic models and the cement I used there. Best stuff in the world. It's call IPS Weld-on #4. [link]http://www.ipscorp.com/[/link] You can find it locally by finding a glass/window shop in your area. They use this stuff for building with plexiglass.

You use capillary action to apply it. Put you parts together dry, then use a small paint brush (sizes used for building models) to apply the Weld-on to the joint. It will seep into the joint. What it does is "dissolve" the plastic, the two sides blend together, and then it hardens. It only takes about 30-60 seconds to join parts. After doing this I put a strip of fiberglass tape on the back side of the joint.

Now with that said, throw away the ABS and get a fiberglass cowl. The ABS really is weak on the plane and will start getting damaged after just a few flights. Best source I have found has been Stan's Fiber Tech. [link]http://www.stansonline.com[/link] . Yes, it's a little bit of extra expense, but well worth it. They hold up better, are easier to paint, and easier to repair if you do damage it.

When you go to mount your cowl (ABS or fiberglass) use fuel tubing to securely mount it. Position the cowl on the plane and drill a small hole through the cowl and the fuselage underneath. Use a blind inside the fuse. I use 6-32 hex head bolts to mount the cowl. Widen the hole in your cowl (usually 3/16"). Cut about 1/8' of fuel tubing and place on your bolt. When you mount the cowl and put the bolt in it will compress the fuel tubing which will expand and hold the cowl secure. This is an incredibly easy shock mount for you cowl. It will hold your cowl secure, but also isolate it from engine vibration and hard knocks and bumps.

Hope this helps.

Airdale CPO

My Feedback: (3)

Thanks to both for your responses. I sure did not know about using epoxy on ABS. If I cannot find the weld-on then I will use the thin CA. Using the fiberglass on the inside of joint I will still need to use CA or the Weld-on correct?

To late of just throwing away a brand-new ABS cowl. (Unless someone needs one they could have it for what I paid for and shipping) I will use it until I get rid of the plane.

MinnFlyer

My Feedback: (4)

Either use medium CA, or be VERY careful! Thin will run all over the place (I would suggest taping the outside of the joint with masking tape to prevent it running out and onto the outside of the cowl)


Here it is best to use CA. Weld-on is for plastic-to-plastic joints

Phlip

Check out this thread:

[link=http://www.rcuniverse.com/forum/m_1686789/anchors_1686789/mpage_1/key_ABS%252Bparts/anchor/tm.htm#1686789]http://www.rcuniverse.com/forum/m_1686789/anchors_1686789/mpage_1/key_ABS%252Bparts/anchor/tm.htm#1686789[/link]

Airdale CPO

My Feedback: (3)

Great reference Phlip. I was talking to a buddy about the same thing but with full scale aircraft but was not sure of what was used to melt the ABS. So many procedures out there and I appreciate all the help. Now I just have to find time to do it.

Oh by the way, what type of liquid is to be used to melt the ABS? Thinner or Acetone? Whats the best and is it available from Home Depot or Lowes?

Thanks

Phlip

I used dope thinner. I think MEK would work, also. I don't know about other thinners or acetone. If you have them on hand, give it a try.

Phil