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Trumpeter 1/32 Junkers Ju 87A "Anton" *Done! 11/19/14*

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Guest Peterpools

John

Persistence sure pays off. Terrific work on the spinner.

Keep 'em coming

Peter

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Thanks, Peter!

 

I still didn't get as much done today as I would have liked. Had to take the girls shopping for basketball shoes and put up my snow fences, as it sounds like we could get nailed in the next couple of days. Fun, fun stuff! :rolleyes:  I did manage to get the wheels/gear painted and the spats together, however. I also did another version of the prop blade and have a mold curing for that, right now. I'll start with the wheels and spats.

 

Using the resin copies that I made of the wheels/tires, I drilled out the holes for the axles and replaced them with aluminum tubing in the final assembly. The gear had to be repositioned just a bit to get the wheels to sit a little more forward, but everything went together very nicely. For some reason, photobucket doesn't like some of the pictures I take with my phone and it will not upload them. I think it has something to do with the position or auto-rotation feature with the camera. In any case, it's starting to piss me off. Half the photos I just took, won't work! :angry2: :fight:   Anyway, the spats are together with the wheels and gear in place and all I have left now is to patch up the bottoms that I had cut off to improve the shape. I'll try to get more pictures of these when I finish smoothing them out. :rolleyes:

 

For the prop blade, I came to the conclusion that the base of the blade should be a little thicker than I had anticipated, where it meets the spinner. So, the first prototype (which I showed photos of a while ago) was turned down far too much in this area. So, I grabbed another blade off the sprue and tried again. I had several photos in front of me, as a guide, so I tried to get the shape as close as I could. The tip was narrowed a bit and the thickness of the blade thinned out some. When looking at only what is visible on the outside of the spinner, both leading and trailing edges of the blade have a little bit different curvature than the kit part. This is especially true if you're not using the unaltered kit spinner. In a conversation with another member, the best number that we would come up with so far, in terms of accurate length, was approximately 51.56mm, measuring from the center off the prop hub, to the blade's tip. There is some question in my mind about exactly which prop this is taken from and what this kit is supposed to have, but I won't go into that here. Using the stock kit parts, the blade would only measure 47.3mm and certainly appears to be short when looking at it. The outline of the stock blade doesn't lend itself well to this appearance, either. However, with the new spinner I made, if I insert the blade "stub" all the way in until the actual blade part touches the spinner, this gives an appearance much more consistent with photos. I did not modify the stub or the point where the actual blade starts, so that is the same as the stock part. But, with the new profiled blade (we'll call it prototype #2), the length comes out as 50.1mm from the center of the spinner, by my measurements. This may still be just over a millimeter short, but it's close enough for my liking and certainly looks much better than the stock parts.

 

Here is the prop blade, showing where I added a piece of stretched sprue to both sides, then CA glue to fill in the area. After that, I sanded the blade to a better shape and then primed it, which is what you see in the last photo. Also, I should give credit to Derek B, as I drew the inspiration for the prop mods from his excellent Spitfire WIP thread. If you guys haven't seen that, it's worth checking out (and I'm not even a Spitfire fan!). :)

 

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Tomorrow I hope to get the spats ready for paint. I'm still not sure how I want to go about this, however. The spats will need some filling where they attach to the wings. Nothing crazy, but the fact that they will be the same colors as the upper surfaces, then mated to the underside, which will be a different color (RLM 65), kind of creates a masking and sequence headache for me. I would prefer to paint them separately, then just glue them on, but I fear I'm going to have to attach them first, then mask everything off very carefully when painting. :hmmm: But, before I even get that far, I also have to fix the windscreen and attach some of the clear parts and there's a similar sequence issue there, due to the rear gun that needs to be sticking through the rear of the "greenhouse". I don't want to let any of this stop me from finishing the model in the next week or so, however. I'm getting very close to the painting stage and then I'll be on the home stretch!

 

Thanks for tuning in and for all the encouragement and assistance!

 

John

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Guest Peterpools

John

Nice work on the prop blade. Always nice to see how it's done, so I can add another technique to my growing bag of tricks.

Keep 'em coming

Peter

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Outstanding work John.  Thought about going that route until I looked at the prop on an Eduard 109.  As long as you are in a casting mood...

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John,

great job you're doing on the spinner and the blades...hadn't checked in lately as i was up to my neck in a 'kit from hell' work in progress that i just finished. I just had a chance to catch up on all the progress now...

fantabulous lol  :thumbsup:  :clap2:

Looking forward to seeing more

 

Karim

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Thanks, all!

 

Quick update. The spats are almost done and I decided that I will install them after painting everything. There will be seams to contend with, but I don't think working around that will be as much of a pain as I had first thought. Also, I worked on the mold for the prop blades. I'm actually on mold number three, now and that should be ready for work today. The first couple had issues with air bubbles and just an improper setup, but molding these things without a pressure pot or injection equipment takes quite a different approach and a lot more forethought. It was a learning experience, for sure. I also modified a Fw 190 tail wheel for use on this one and it should look much better than what's provided in the kit. Here are some pics and I hope to get some more done, later today.

 

John

 

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Thank you, Loic!

 

I just came in from working with the latest prop blade mold (and struggled to get my pics to upload correctly). I wanted to show how I had to go about this, but it's been difficult to document. Hopefully, the pictures that I do have will help to explain it and you'll be able to understand my description.

 

The first mold that I attempted had the master blade mounted to a small block, as usual. However, I tried to mold it laying flat, instead of standing upright. The problem with long, thin parts is that when you pour resin into the mold, it traps air and you can't get the resin to flow to the end of the "tube", or empty space that is supposed to become your part. Without pressurized equipment, the solution is usually to have either have the mold in two halves (very difficult to align properly), or split it on at least one side so that you can pull the mold open to get the resin all the way through the cavity, eliminating the possibility of air pockets. Well, in the first mold, I tried to lay the part into the rubber, but over a sheet of plastic wrap, which clings tightly to the blade face and extends outward towards the edge of the mold, creating a seam. This, in theory, reduces the amount of cutting you will have to do to the mold. When you have to cut this seam, it's extremely difficult to keep the blade cutting on the very edge of the part (in this case the prop blade) in a straight line, or a line that follows the very edge of the part. Well, anyway, in the first version of the mold, because I tried to do it laying flat, there were air bubbles trapped in the mold rubber, underneath the plastic wrap. The bubbles usually float to the top before it cures, or at least far enough away from the part, so as not to interfere or creaty any open bubbles. Not this case with this one so, obviously, it made for a "cratered" looking part when I poured the resin. So, on to the second version of the mold.

 

The second version of the mold I tried in a more traditional way, by standing the blade in the upright position, but this time without the plastic wrap attached. Once the rubber had cured, I attempted to cut the master blade free from the mold, by going down the sides. I did not cut all the way through the rubber from top to bottome, but just  the sides, to the tip of the blade, so that the end would still act as a hinge of sorts and keep thins reasonably aligned. However, my precision in cutting.....wait...there was no precision.....and I cut a channel into the mold cavity that actually came out on the face of the prop blade. I tried a few casts, anyway (what I posted above) and, even though I was able to get some without any bubbles, the way that the mold was cut was leaving a chunky looking mark on the face of the blade, near the tip. The cut channel will also leave a flash line along the part. This is usually pretty easy to clean up, but this one point  in the blade's face was just too deep and choppy, so I had to ditch that mold and start over, once again. That is where I was last night and this morning.

 

Now, the mold that I made last night was done with the master blade standing upright. However, I also used the plastic wrap coming off of one side again. I just licked the blade and the plastic sheet conformed to it perfectly. So, the plastic is sticking out to one side with the master on it's block, glued to a plastic clipboard. Next, I built up a box of Legos around the master. Normally, I would be careful to assemble the blocks in a fashion that would not leave any long, straight lines where the blocks are not staggered (much like you would build a brick wall). This keeps the mold rubber compound from seeping out through a large crack. However, in this case, I had to have one side with a long straight seam, so that I could pinch the plastic sheet between two layers of blocks in one of the mold box walls. I built the entire box with one side of the seam where the plastic would be pinced, then the last corner section that would butt up to it. I got the putty seal around the bases of all the bottom blocks (to keep the rubber from pouring out the bottom) then attached the last corner section, pinching the plastic sheet in between. After that, I mixed up my rubber/catalyst and CAREFULLY poured it into the mold, being sure not to pour it directly onto the thin plastic sheet on the one side, but rather on the other side and letting it fill from the bottom up, to keep the plastic aligned. Here are some photos to demonstrate:

 

Note the tape on the outside of the mold box. This was applied to a couple of straight seams, where I feared that the rubber may pour out before curing.

 

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After the rubber was cured, I began to disassemble the box, starting where the plastic wrap was pinched in.

 

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The plastic wrap did it's job and the only cuts that I had to make were at the very top of the mold (where the casting block was) and a little bit of cleanup around the prop blade's tip. Here you can see the mold upon spreading it open, before removing the master part.

 

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Then I mixed up some resin and did a test shot. I started by spreading open the mold, as seen in the photo directly above, and pouring into the length of the cavity. Then I pinched it back together, being sure it was aligned, and topped it off from above.

 

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And, the result:

 

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The only flaw in this molding was the tiniest little air bubble at the very tip of the blade. This would easily be a useable part, as a tiny bit of CA and a minute or so of smoothing it out would fix it. However, I think that, If I'm careful, I can get a flawless part from this mold.....Finally!

 

Thanks again for following along!

 

John

Edited by mywifehatesmodels

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According to my (limited) experience with moulding parts, what I do to avoid the risk of having this kind of air bubble is that I add to the master an extra bit of styren at the end of the part so that when there is a bubble, it on this extra bit rather than on the part itself.

Then, the bit has to be removed from the part but I find it easier than filling bubble holes.

;)

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Small update (I still can only get about half of my pics to upload to PB. WTH?)

 

I'm still working on smoothing out the bottoms of the spats. That should be just one more sanding session. I've also been casting prop blades and have a great set ready to go. The last thing I did was to add the cross-member to the windscreen. The thing is so tiny and has to be so thin that it took me over an hour to get one worked up and attached, between losing and breaking a couple of examples (try finding a tiny scrap of white styrene on a floor covered with tiny scraps of white styrene! :lol:   ).

 

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Next up is to add the grab handles to the inside of the windscreen (not in the kit, but I'm going to make them from wire), then the glass plate in the reflector sight and I can attach the windscreen and start masking/assembling the rest of the clear parts. Still have to figure out the order that I'm going to do this, as I have to work around that rear gun, too. The rear canopy section fits so well that I may just paint it off of the model and attach it and the gun later. I'll have to test fit all of the panels and see how it's going to work. Hopefully I can be painting by tomorrow night.

 

John

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John ... 

 

Jeepers mate ... I leave you with a slightly off spinner and spats ... and I come back to a whole set of moulds and mods everywhere!! lol :D

 

Reading through - very nice work mate.

 

Not about to try any moulding myself  ... but the cutting technique on the spats is good. I was considering marking off and using a powered sander when the time comes for me - this technique looks a lot 'cleaner', though and obviously gives you a uniform result. I might still try my cordless drill idea with the spinner though! - easier for me if there's enough thickness in the plastic to work with.

 

Rog :)

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