How does one get the ultra-thin sprue stretch. Once in a blue moon I can get it to stretch out thin enough to use for an antenna half the time it breaks or the best I can get is somethinng that I could sustitute for a 20mm barrel in 35th. IS it the type of sprue or the heat source. I've been using the burners on an electric stove. Do I want soft bendy sprue or brittle.

I use a bic lighter to heat the sprue. I heat the plastic in the center of a piece and when it begins to bend under it's own weight I stretch it as long as I can till it is of the thickness that I need. Be careful and not pull it till it breaks. I find that it will curl if you do. I keep it straight until it cools off. Then I cut it to the lengths I need.

Waht Animal Dave just said. That's how I learned to do this. I think the concentrated heat of a flame, Bic style lighter or candle concentrates teh melt in a smaller spot giving you more control. Some plastics do work better than others. Even pressure on your pull. Ive been able to pull it as far as my arms can reach. That, of course is way yoo thin for most applications, however.

so flame heat is best. might do the candle bit because I usually do a bunch at a time...I use the "mouth" method to cool. when I've achieved the stretch I desire...still keeping the even pull on both ends, I run the sprue through my mouth back and forth until it cools...it always seems to keep it from curling on me

Hey Steve, you really can't beat buying a pack of round styrene from Plastruct or Evergreen. I know you can make it for free with your left over tree sprues, but this way you get 10 pieces at 10"in long and super-fine for around $2.00. I have a pack at 0.4mm / .015", it's thin. They won't break as easy and their straight.

It's probably not what your'e really looking for Blaster76 but apart from Mother's good idea of just using styrene you could also use fuse wires for your antenna. Fuse wires come in various thickness (depending on the amp ratings) and they'll give your antenna the "slightly curved" look.

As for your 20 mm. barrel, styrene rods to brass rods are best to get an even diammeter. You might even want to give pencil lead a go. Can't remember the exact dimensions for a 1/35 20 mm. cannon but pencil leads come in all kinds of diameter. Cheap too and they come with a "weathered metal" color. I've used acrylic on them and they're okay. Only problem is they don't cut as well. A fine hacksaw and some sandpaper will help.

Blaster, We did a demonstration of just how far you could stretch sprue at one of my club meetings a while back. How does, 23' 6" grab you? That was with a piece that was about 6" long when we started. It was ultra, ultra thin when complete. Now this might be a bit extreme for what you need, but I think you get the idea. I have found the trick is once the plastic starts to sag, is to give it a slight twist, and then begin pulling. I use my extra sprue for interior detailing my a/c models, turret interiors, etc. And best of all, its all free. If you want nice straight pieces, just keep the tension on it until fully cooled, which should be no more than just a few seconds. Just my .02 cents worth. "Q"

If you stretch it vertically, instead of horizontally, you will not end up with a sag, or curling. If you leave it hang for a day or two with the heavier sprue end, at the bottom, you will have extrememly straight stretched sprue, that will remain straight. With practice you can stretch it as fine or finer than a human hair.
If you shape the sprue before stretching, it will retain that shape. Airfoil will remain airfoil, hex, will remain hex, and if your sprue is not round and suffers from mold shift, before stretching, so will your stretched sprue.
Don't forget, you can also stretch plastic tube, for all those gun barrels. Works the same way, just need a little more practice, melts faster, so less heat, or not as close to the flame and you definitely have to stretch in a vertical movement, and leave hang for a day or two. I use to clamp the top to a shelf, and put a cross action tweezer on the bottom to insure it would remain under a slight pulling action.

Thanks guys and some excellent tips. Buying plasticstruc is definitely a consideration. I do buy it in sheets, large round tubing and wider strip pieces, might check out their ultra light gauge. I'll try the twist before I pull method. Donts need 28 feet, but it would be nice to get a 2-3 foot spread

I dropped this technique after having burnt my fingers several times and spoilt each try with it.
I shifted to soft metal wire for grab handles and other things to be bent and piano strings for the antennas as they're straight and rigid.
Plastic rods are good for nuts and rivets too.

olivier

for antenas I use 0.010" guitar strings.
I prefer them to sprue antenas though maybe a thicker gauge will give a better scale appearance.

Just to throw out one little safety hint. I know that Tamiya at least warns that some of it's sprues aren't recommended for doing this with. I think it was my Churchill, not the crocodile but the other one, that mentions this. I THINK it was the sprue with the extra figures that said it gave off toxic fumes if it was heated.

I have used guitar string and been pleased with the results, last time I went into music store they were all out of ultra-light gauge E and B strings. I also have to figure a way to get the heavy curve out of the m after you unroll them. It was suggested to put them on guitar, but you lose a couple of feet there by making the stuff less cost efficient

You can also try the R/C section of your LHS. I believe the size I have used in the past is .015. Works well as it has a nice spring to it and it is straight as can be. "Q"