Does anyone have the secret as to how to butt join two styrene strips together such that the joint is virtually invisible. Parts will be painted after assy.
Plastic cement with a thin coating of putty or ca cement. Sand.
Like David, I butt the joint together and use Tenax or MEK to “weld” it together. I let the joint dry thoroughly and give it a light sanding. I follow this with an application of filler (I use Squadron Putty) and after it dries sand again. If needed I repeat the putty and sanding until the joint is finished. The most important thing is to make sure and allow the joint and the putty to harden completely before sanding or you won’t get good results.
Joe
Estimated drying time?
Unless I’m joining two very irregular shapes, I usually try to get the joint as tight as possible and avoid using putty. I try to soften the edge of the plastic with glue and sort of “mash” them together. If a little bit of soft plastic oozes out, then I sand, cut or file it off. I’ve never had a lot of success using putty and getting it totally smooth. But that’s just me.
Jim
A problem I’ve always had with squadron putty is that it shrinks as it cures. That’s why I use J*B Weld steel epoxy for areas that need filled-in. It sticks to almost anything [except maybe delrin?], dries super-hard, and is very easy to sand or sculpt.
Mee too! In fact, Ken was the one who got me started on it. Literallt, squadron putty is still not cured until you can no longer detect the laquer smell. Sometimes a week or more! JB Weld 16-24 hrs. [;)] But still, you want your joint as tight as possible, and if a little plastic ooozes out like Jim described, then thats great!
I only use putty now to fill tiny tiny voids
Right Clamps makes a special clamp for butt joining. I use a strip of styrene behind the joint to cement the sections together. The key is to ensure that the ends of the sections to be cemented together are square. I bought a mini square from Micro-Mark.
http://www.micromark.com/steel-square-4-inch-blade,6478.html
Here is another one.
I use lacquer thinner to bond styrene, and I strongly dislike having to use fillers of any kind (not that I won’t use them if needed, though [swg] ).
As mentioned, the surfaces to be joined should mate perfectly, with the edges perpendicular to one another. I like to coat both surfaces with the solvent, let them stand for 10 or 15 seconds, then re-coat both. I then press them firmly together with their back surfaces lying flat atop a sheet of glass, and leave them for about 24 hours until the joint is completey hardened.
When the two edges are pressed together, the softened plastic will ooze onto the surface - do not touch it until it has hardened. Once hard, use an X-Acto #17 or #18 chisel blade to remove the excess - done carefully, no sanding will be required.
If filling is needed, I dissolve some scrap plastic (small bits or the dust from sanding styrene work best) in a disposable metal container using lacquer thinner or your preferred solvent-type cement. I use the metal caps from paint bottles, with the plastic or cardboard seals removed. Use an old X-Acto blade to apply the putty thus-formed to the areas requiring filling, then let it fully harden. Use the chisel blade to remove the excess, then sand as required.
When joining large pieces, such as wall sections, it’s also a good idea to back the joint with a wide strip of sheet styrene applied using solvent cement - this can be added after the visible butt joint has been completed.
Wayne
I recently had reason to join .020" x .020" styrene pieces together, also .030" x .030" --making in both cases a sort of box shape outline that in turn was joined to other identical shapes. I initially joined the pieces using the tiniest bit imaginable of old fashioned Testors “tube” type cement, applied with a toothpick, because I needed something that would actually grab and hold the pieces together. The joins were fragile but once they had hardened I gave them a good dose of Plastruct liquid cement, allowed that to harden, and then another dose of the Plastruct (which had the effect by the way of melting any tiny “threads” that resulted from using the tube type goopy cement). After the two applications of the plastic softening/welding liquid product the joints themselves were strong and virtually invisible and I felt no need for putty of any kind.
Dave Nelson
Yup, scrap material dissolved in solvent - best filler you can use.
I’ve done ok with Squadron Green, but it take time and patience. Long drying time, plus the need to apply many coats, sanding in between. Unless you are trying to fill a very minor imperfection, this is what it takes to use the putty.
I made the mistake once of trying to fill a small hole left by removing a horn from a loco with putty. after 5 coats and still not having a flush surface, I ended up drilling it out bigger than the original hole and using a sprue scrap to plug it, cut off flush with a sprue nipper, and sanded smooth. MUCH better results.
–Randy
Lots of interesting advice here and I so appreciate everyone’s time and attention. I am sure I will find the best answer for me in these responses with a little practice. Thanks again…
Unless you add backing to a hole, putty is not the way to fill it. While sprue will do the job just fine, I keep a good supply of Evergreen rod and strips on hand for such purpose. Select a piece of rod or strip material (the latter for square or rectangular holes) about .005" larger than the hole to be filled. If the hole cannot be matched in this manner, drill it out appropriately to fit a larger size.
Apply some solvent cement to the hole and to the filler piece, then jam the filler into the hole until it’s tight. Roughly trim off any excess (leave some material sticking out - you don’t want to disturb the just-made joint). When the joint is fully hardened, slice off the excess material and, sand if required. This method will also seal holes in metal, such as a cast loccomotive boiler or a sheet metal boxcar. Obviously, there’s no need to apply solvent to the metal part, but for sheet metal, I prefer to use contact cement to affix .060" sheet styrene behind the holes to be filled, drilling out both the metal and the plastic backing to suit the rod size needed.
Here’s an old Varney car modified in that manner:
[IMG]http://i23.photobucket.com/albums/b399/doctorwayne/freight%20cars/Freightcarphotosandlayo