As I started to work on cutting the door panels out of the Hobbycraft J-3, something didn’t look right. I finally managed to find some scale drawings, and indeed the lower door panel inscribed on the right side is incorrect. The rear line for that door should go from the existing location on the lower edge (hinge line) up to the corner of the rear window, not slightly aft of this corner as in the kit. Even if you are not going to cut out the door, you need to fill the existing panel line and scribe a new one to the window corner. The window should not protrude into the door opening!
I am still working on cutting out the two door panels, and it is a bear of a job. I believe the fuselage sides are acrylic, rather than transparent styrene. It is some sort of plastic harder than styrene. Not sure how many #11 blades I will dull before I finish the cuts. I have one of those photo etched razor saws, but there is only clearance along one of the 5 cuts to be made- the other four need cutting with a knife tip.
Hey, I finished the cutout in one day! Rather than thread, I used dental floss (I had read about that once). Now, the floss did not do the cutting. For that I still used the X-acto blades. However, I found two techniques aided the process. First, I used water as a lubricant. I did not want to use oil for fear of contaminating the plastic and hurting the finishing process. Water works. I guess it acts as a cooling agent- the blades did not stick as frequently. Especially the PE razor saw- I could saw for a minute or two at a time without the blade sticking.
Secondly, the dental floss cleared out the residue of the cutting. So I would cut a little, then use the floss to open up the cut. In spite of the water, I believe the plastic gets soft and sticky enough from the heat that the dust and particles stick in the groove. Once it was cleared out, the floss would stop cutting, though, so I don’t think floss or thread would work well as the only cutting method. Anyway, the door opening is complete, merely smoothing up the cuts now.
Yes, fuselage only (and windshield and top window). Latest problem- the wings are bowed- serious reverse gull wing bend- the tips curve way up
First thing I will try is to stick them (jigged straight) into my paint drying box for a couple of days. The box runs at a stead 105F. If that doesn’t work, I’ll try a trick I read about awhile ago, heating them in microwave. Downside of that is that you cannot jig it with any metal while heating. I can always try the hot water trick too.
Interesting, using a microwave to soften plastic, does that work? I once successfully ruined an old slightly warped 45 record by putting it in hot water. It had a nice ruffled edge when “complete”.
I am admiring your work on this kit, having done one myself in the recent past. Seems the only thing I didn’t have trouble with was the wings. I was able to use the engine but it took extensive grinding on the inside of the cowl to get it to fit. I swapped the tires for some larger ones to represent Tundra Tires on a bush plane. Also had to create an exhaust system since the one in the kit escaped through a hole in the box.
I didn’t have to resort to microwave. I stuck inner ends of wings in a small metal vise, clamped the tips together, and heated the assembly with my stamping iron for a couple of minutes. A stamping iron is like a small, lower powered hair dryer, used by scrapbookers to do something with rubber stamps. I got mine at Michaels- normally use it to tighten monofilament rigging on ships and WW1 airplanes. I hope the wings stay straight now, it has been only about 12 hours since I straightened them.
Drying box didn’t get hot enough. That didn’t work. Stamping iron seems to have worked. Had to give one wing an extra shot, but they are lying flat now.
While microwaves are tuned mainly for water molecules, they will heat other molecules. Organic materials like plastic have a lot of complex molecules- I know some sorts of plastic get hotter than others. We had put some harder plastic bowls in microwave, not knowing they were not microwave safe, and they were destroyed quite rapidly.
Slowly but progress. I have been having problems gluing in the instrument panel. There are no positive locating aids. Having trouble getting it level, and centered left to right (there needs to be a slight gap between panel and sides to allow for some wing support tubing pieces.
Also, I am cutting slots in the gear legs. the kit shows the gear legs solidly attached to the fuselage, while in reality the gear legs are hinged with hinges at front and back of legs.
Cowl will be another challenge. Cowl must be put on AFTER engine, but the kit cowl is split left and right, whereas the real cowl is split top and bottom. Decided now I will glue together cowl before hand, fill can clean up seams, paint, and then saw apart at actual seam. Then I can attach it at last minute after engine is glued to fuselage.
This must be a 1/48th kit. I suppose the halves of the cowl will fit over the engine cylinder heads once the correction is complete. Have you found a suitable engine? I’m a Cub fan, and I’m watching this with a keen interest. I have a little electric Parkzone RC Cub that I just love to fly, it’s a 3 channel; about a 30" wing span and a foamy. (now I’m off topic).
I thought of using the engine out of a Piper 140 and flipping it over, but the quality was even worse, so I am back to the kit engine. I’ll see if I can score the cooling fins better with the tip of an X-acto blade.
Latest problem- my own goof- I lost the upper door/window. Not a big thing. If I cannot find it after a second look, I can cut one out of sheet celluloid. Since it will be open, stowed against wing the fit doesn’t have to be perfect.
Got most of the cockpit details glued in- may be able to close up fuselage today.
Yes, that’s what they are. On the back of the cowl they are welded to the engine mount. On the front they were attached to the lower cowl and passed through the upper cowl. About 1/4 inch round tubing with a clip pin passed through a hole drilled in the posts.
Hey Don, good luck with this build. I have the same Hobbycraft 1/48 kit and plan on building the US Army O-59 version. A few years ago I built an R/C Goldberg Anniversary edition of this plane with a 76 inch wingspan. It flew well until a tree eventually collected it. I have the Paul Matt 3 view drawings and I took a ton of photos with my old Olympus OM-1. I know that the raised lines on this kit’s wings are not correct. I plan on doing mine without a lot of detail inside because I want to hang it from the ceiling but I do want to sand down and correct the rib lines, including adding them to the bottom of the wings and ailerons. After studying the real thing I can tell you for sure that the kits lines are too high and they should be sanded down to be thin. If you have a small airport close by maybe you can go to check one out closely. Please keep us updated. Bob
