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smirk-racing

Kyosho Optima Mid: looks like a gopher ate the lexan body!

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Hi all,

Any tips/tricks on cutting out an optima mid body? It has so many very sharp angles and tight curves... I used all the tools I could get (new, sharp): body reamer, straight lexan scissors, curved lexan scissors, x-acto knife, utility knife, etc...

 

The only parts that came out cleanly were the long straight bits along the bottom/sides of the body. The complex bits in the front, and the rear over the spur gear look like an angry gopher chewed at them.

 

It is quite unpleasant to look at!

 

I am hoping you all have some tips and tricks that can help me. The only saving grace is that I had already planned for a shelfer body and a runner body, so clearly this first attempt is going to be the runner body...

 

Thanks in advance!

 

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I can't help with the technique (so will await others' input and shamelessly follow it myself) but I will offer two things:

1. Don't get a BBX!*

2. I've got a spare mid body new in its sealed pack if you're interested in buying it for your next go? 

*well, do actually, but just bare in mind it's worse in this regard! 

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I use the basic Tamiya 3 piece set file and large nail file to refine the cut at the end.   For the smaller rectangles I use a Testor's brand file that is shaped in a square shape.   Then rest is all hope.. :ph34r:

GL @smirk-racing!!

IMG_2023-4-14-164228.thumb.jpg.39769b0c6a2cb03ff369b3e0cd159cd7.jpg

IMG_2022-11-6-122502.jpg.7afa6cd5e363eb1f77a4bddd6324097e.jpg

IMG_2022-10-23-073905.thumb.jpg.b3c6054539b65ab233d7664c55dfcd30.jpg

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At difficult shapes, I do the fine contour with sandpaper and put it above objects e.g. with the same radius to build a "custom file". The rest is patience.

If you rush it with knife or scissor, usually you get a cut in an area you don´t want it, and often in these edges the body then starts to crack easier from this small cut...

Better luck next time! But you leran with every body you have from the same design. ;)

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1. When scoring the body, do it under bright lights so that you can see the lines clearly.

2. For the front shock recesses, use a straight body cutter (instead of the usual curve one). 

3. For the front and rear body post rectangular cavities, score both sides of the body, put a reamer to it to make a smallish hole, use the body cutter to clip to the 4 edges and lastly, use a small plier to push through. Because both sides of thebody has been scored, it's now easy to shed the excess material by forcing the small plier through. 

Hope this helps.

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One other thing I forgot to note.. I have an extremely bright 4ft LED shop light wired up UNDER my work desk.  This enables me to see the cut line clearly because it is lit from the back.  It is also extremely handy when I drop something on the floor due to old man eyeballs.  :lol:

I file right over my trash bin which is also well lit from the shop light under my desk.

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Thanks guys! Lots of great tips here.

Two more questions:

1. I thought sharp corners (like, 90 degrees) were a no-no, as they create weak spots which can lead to cracking. There are a number of sharp corners in the Optima body... Including for the body mounts (those are rectangles). I could round all the corners and even use a circular hole for the body mounts. The hole would not be a perfect fit over the mounting point like the rectangular slot is, but the issue of corners would be resolved.

2. To sand or not to sand the inside of the body? I've googled this and there's no clear answer - seems like a roughly even number of people in both camps (not that I can measure scientifically...). For the shelfer body it is probably not an issue, as the body won't see any use/abuse, but for the runner, perhaps it matters. Since the rest of the web seems unable to agree on this point, I'll just take what TC says and call it good. Sand the inside of the body or no (for the supposedly better adhesion of paint)?

Thanks for all the rest of the great tips!

 

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@smirk-racing you're right.  Actually if one zoomed into my rectangle cut outs it is rounded as I use a round file on the corners.   There are no sharp corners.

I do not sand the inside body before paint. I just wash with Dawn dish soap (inside and out actually) and rinse thoroughly.  I have zero issue with paint adhesion. 

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I took a couple of long emery boards and thick dowels to do my Mid bodies. It took a lot of time and sanding, but it worked.

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Like Willy iine, I do not sand my bodies. Actually, this is the first I hear of it. However, like Willy, I do rinse the body with soapy detergent to make sure no grease / grim for better adhesion. Having said that, I did notice that some of my racing bodies experienced some flake off after a few races. Maybe a little sanding to make some surface profile is good for adhesion.

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I don't sand the inside, either, but I may lightly scuff the inside (other than clear windows) with Scotchbrite or similar. 

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I recommend switching to using an exacto knife. Pick up one of these 

 Fiskars 163050-1001 Fingertip Craft Knife, 7 Inch, Orange https://a.co/d/9SPR4iC

I trace the cut lines with it. Then I make make multiple straight segment cuts with a scissor so I can bend the lexan. The reason being, If you try to fold a large section, it make buckle and damage the lexan. For wheel arches I do multiple cuts, around 4 to cut line and then fold that piece and it breaks off.  After removing the lexan to be cut, I sand the straight area with a flat sanding tool. For wheel arches, I use the protoform sanding wheel. For smaller areas, I use dremel sanding drums, various diameters.

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I don't know if this video is of any use - I found it somewhere on here, via another thread on here about cutting lexan (which I obviously can't find anymore):

 

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On 11/19/2023 at 8:35 PM, Willy iine said:

One other thing I forgot to note.. I have an extremely bright 4ft LED shop light wired up UNDER my work desk.  This enables me to see the cut line clearly because it is lit from the back.  It is also extremely handy when I drop something on the floor due to old man eyeballs.  :lol:

I file right over my trash bin which is also well lit from the shop light under my desk.

Hey @Willy iine is this lighting up through a translucent desk surface?

Cutting out last bit of my BBX body yesterday I realise I'm same as others - struggle to get the lighting right to see the lines. And my knife's often right between my (increasingly dodgy) eyes and the line as well.

4 hours ago, JimBear said:

I don't know if this video is of any use - I found it somewhere on here, via another thread on here about cutting lexan (which I obviously can't find anymore):

 

The thing I liked about this video is mostly psychological I think. Score one section, cut to its ends with scissors, snap it. Section done. Then you can pick the job off in little bite sized chunks if you want. No pressure. Nice! 

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One trick for the inside corners is to make a tiny round hole with a pin vise or body reamer first, then cut up to the edge of the hole with the knife. That way you're not trying to round out a sharp inside corner; you're never creating one in the first place.

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