I have been working on a 1/24 P-51 and while building the engine I managed to ruin 2 exhaust ports by drilling them out and having them melt. Any idea how I can fix the small complex shape? I tried filler putty and sanding but the putty just dried and fell out. 
Any ideas?[banghead][%-)]
Something that has worked for me in the larger scales is heat-shrink tubing. You will have to make a master of the exhaust pipe, slip the tubing over it and shrink it to fit. When you pull the master out, the tubing retains its shape, and it is hollow.
You didn’t mention which kit, but I have the old Airfix and new Hobby Craft (Trumpeter) and it looks like a little scratch building with plastic rod or tubing is in order. When drilling out such small plastic items I use a hand drill or pin vise if a varible speed drill isn’t available. Best of luck! Some nice after market “unshrouded” exhausts would be nice if anyone in the resin casting business is reading!
It’s been a while since i looked at the box but I do believe it is a newer Airfix kit, and unfortunatley I didn’t remember to drill out the exhaust until they were installed on the engine.[:(] So I may have to try the scratchbuilding with tubing.[B)]
Bee 17
Bee,
I have opened the Exhuast pipes before by using a NEW sharp pointed hobby knife. Positioning the tip in the center of the pipe, and twisting it back and forth until the proper hole width is achieved.
Doing it this way is dangerous, however, because if you apply too much preasure, the knife will break through the pipes and damage your model (not to mention the damage you could do to your “Blood Pipes”!), as my scared fingers can attest! [:0]
I have used soda straws and ink pen fillers for exhuast pipes in the past, because it provides a nice thin walled pipe which looks realistic.
Frank
actually the pin vise idea is the better idea since it is very dangerous to use a knife to do any hole opening i can attest to that as well since i did manage to slice a fingertip off once cutting a flap off AMT’s 1/72nd scale B-52
Ouch, I’ll remember to avoid that on my Revell BUFF!
LOL no chance in that since the flaps in the Revel B-52 are already seperate and operable 
mikeym…
I also did the same thing working on my AMT B52 (converted the G to an H) with a scalpel. I have a box of disposable scalpels that I use for real tight trimming (they last a long time before I have to chuck them). I didnt takt the fingertip off but there was some bone showing…ouch
Bruce
Ps. gotta love the big bombers in 1/72 wish they were available in 48. (Fantasy dream… having a place big enough to display a Buff in 1/24 & having the Buff to display in it)
Boy, if that was in 1/24th scale, that is either a really big hobby knife or you where spinning that bad boy a LONG time to drill out those exhausts !![:D]
Can’t help you much on the repair part, but the way I drill out pipes is to use the smallest drill bit I have (About 1/32") to create a centering hole. Then use progressively larger bits to increase the hole diameter. Everything is done by just turning the bits in my fingers - no motor driven drill. That way its a little easier to make sure the hole stays centered and you don’t blow through one side of the pipe wall, and there is no problem with generating so much heat.
Had to go to a hobby store to get a pin drill and the really small bits. Most hardware stores I’ve been in don’t have bits smaller than 1/16" diam.