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ericg

CAC Boomerang A46-217 “Hep Cat” Finished.

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14 hours ago, ericg said:

             The fittings were made by stretching lengths of the piping of cotton buds as per the stretched sprue method.

 

Hey cool !  I'll have to try that.

 

    nGBNjRa.jpg

 

 

Edited by MikeMaben

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I always end up losing one or two parts from every kit I build, probably due to things being pretty hectic in my workshop with 2 of my 3 kids progressively occupying more space in there with the accompanying mess that kids invariably make added to the fact that I have lots going on in there in the first place. Sometimes the part is fairly easy to make and sometimes it is hard. A growing sense of dread within me started to grow however, when a full clean up of the work bench was carried out upon the absence of one of the kits main gear legs. Even an extended clean up of the surrounding area failed to locate it, so rather than blow any more time trying to find it, it set out to scratch build a new one. I had thought about doing both legs for a while anyway, as the kit legs are very SACish in that they are very be dable white metal and would likely be more trouble that they are worth. My hand was forced eventually when the axle of the remaining leg promptly broke off. 

 

I wanted to be able to adjust the legs to be able to get the sit of the model right and not just copy the exact length of the kit part. This was going to require a bit of forward planning. The gear would be built up around a single solid brass core bent to shape, with the oleo being able to be adjusted on demand.

 

IMG_5115-X3.jpg

 

I then made the top part of the gear leg from larger diameter brass tube, with the part that mounts into the wheel well made from solid brass rod drilled and then soldered perpendicular into the first piece. I then drilled a hole vertically through the new part that was the same diameter as the long brass gear leg as in the first pic.

 

IMG_5120-X3.jpg

 

The two new legs. Notice how the top part is able to be adjusted up or down. I have drilled and soldered the axles for the wheels in place and used some plastic tube to hide the area between the curved part of the leg and the straight part.

 

IMG_5121-X3.jpg

 

I used my RP tools ring make to make a small diameter ring of copper wire

 

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I fitted a larger diameter brass tube over the long rod. This part became the oleo and is the part that can be adjusted to give me the required length of each gear leg.

 

IMG_5135-X3.jpg

 

The parts that make up each new leg.

 

IMG_5130-X3.jpg

 

Assembled and test fitted. The leg can be pulled apart at this stage and the oleo lengthened or shortened once I am happy with it.

 

IMG_5132-X3.jpg

 

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Up on its new legs!

 

IMG_5136-X3.jpg

 

IMG_5138-X3.jpg

 

Old and weak vs new and strong. 

 

IMG_5140-X3.jpg

 

 

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Nice work on the gear legs. Now, daft question possibly, but seeing as I'm going to have to do it myself soon and haven't done it before, how did you get such a nice clean bend in the Brass rod? I'm going to have to replicate a 1/24 Bf 109 control stick with its slight bend in the near future.

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1 hour ago, Durangokid said:

That is some serious ingenuity for the gear legs.  I really dig the milling machine.  What kind of machine do you have and is it difficult to learn?

 

Thanks,

Bryan

 

Bryan,

 

I use my drill press as a poor mans milling machine by fitting a Dremel cutting bit in it. The drill press that I have is a Proxxon TBM 220 fitted with the compound table as shown on the link. A very small machine and a little pricey,  it is well worth the investment.

https://www.proxxon.com/en/micromot/28128.php

 

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11 hours ago, ade rowlands said:

Nice work on the gear legs. Now, daft question possibly, but seeing as I'm going to have to do it myself soon and haven't done it before, how did you get such a nice clean bend in the Brass rod? I'm going to have to replicate a 1/24 Bf 109 control stick with its slight bend in the near future.

Ade,

 

I used fine point pliers to gradually bend it as required. Of course I have a mountain of failed pieces to get to the two completed units!

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12 hours ago, ericg said:

Ade,

 

I used fine point pliers to gradually bend it as required. Of course I have a mountain of failed pieces to get to the two completed units!

 

Well luckily I dont need to put such a dramatic kink in the piece I have to do but no doubt will join you in having several failures along the way.

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The cannons stick out quite a bit and I felt that they could do with some extra effort to make them a little less prone to breakage.

 

I drilled out the kit cannons, with a smaller hole drilled from both ends. This was done so that I didn’t have to ‘steer’  the thin drill bit over a long distance. Rather, the holes meet somewhat in the middle then I reamed out the resulting hole with a larger drill bit.

 

IMG_5173-X3.jpg

 

The brass replacement barrel that I had made was slightly smaller than the hole that I had drilled and I didn’t have the next step up. I used one of my micro round files to enlarge the hole.

 

IMG_5174-X3.jpg

 

The replacement barrel compared to the kit one. I have made it longer to the rear of the part. This certainly won’t snap off, that’s for sure. 

 

IMG_5171-X3.jpg

 

I then inserted a larger diameter brass tube into the leading edge of the wing. This is designed to accept the tube sticking out the back of the barrel as per my previous picture. They tightly fit together.

 

IMG_5170-X3.jpg

 

The extra work that I am putting in here isn’t just going towards strength. Rather than glue the barrels on toward the end of the build and hope for the best alignment wise, I am using the larger diameter tubes in the wing to ensure that the barrels are aligned to the longitudinal axis of the model. I am not going quite as far as ensuring the correct harmonisation angles but also making sure that they point the same direction. By setting the angle of one in the wing (which I aligned with the longitudinal axis) I can align the other through the use of longer rods and making sure they visually line up.

 

IMG_5168-X3.jpg

 

IMG_5167-X3.jpg

 

The larger diameter tube has been glued in the wing, cut and filed to smooth to the leading edge. There isnt much resin that it has been inserted into and could do with a bit more strength.

 

IMG_5175-X3.jpg

 

I sometimes use this product when I need extra strength on a part. It is a very fine glass like powder that sets rock hard when it comes into contact with superglue. I poured some of this around the cavity behind the brass tube and then placed some drops of superglue into it.

 

IMG_5176-X3.jpg

 

Now the barrels can be inserted into the wings and are exactly aligned and very strong. I will take them out until I am almost finished with the construction before putting them back in to blend the cannon fairings into the wing.

 

IMG_5177-X3.jpg

Edited by ericg

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