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Terz1

Repairing plastic hard bodies - what to use

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Hi there. I bought a second hand rc car which has a hard body. The main problem is the area surrounding one of the body mounts. It's basically a big hole which the body post pokes through (much further than it should) and the body just rests further down the post. I'm going to get some styrene sheets to reinforce the body in other cracked areas. I was wondering what filler do people tend to use?

Thanks for any help

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Depends on place and size off the hole, i sometimes cut the area around a hole simultaneously with a piece of sheet.

Glue the sheet into place with cut out bits of the hard body dissolved into glue. and reinforce from the inside with some more sheet if necessary.

For small holes, I like to use superglue with filler (backing powder works nice)

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Thanks Waterbok. I'm completely new to hard body repair so really appreciate the advice. The picture below shows the worst of the body damage. As you can see were the body post mounts on the bonnet of the mud blaster the hole is huge and has cracks coming from it. So you say it's best to cut around this hole with the styrene simultaneously. Which thickness do you tend to use 1.5mm, 2mm?

I'll be using the superglue and baking powder technique too. Thanks!

 

20181015_143243.thumb.jpg.2e319dd046d2ca580e2ad52837fdcd30.jpg

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I use superglue + baking soda method too.  It's good for filling up areas.  

But I would be cautious...on stress points.  Superglue is brittle.  Styrene is flexible.  Even hard bodies give a little.  If you make it too brittle, it would break.  That's why I would prefer "Plastruct Plastic Weld."  It melts the plastic and put it together.  The plastic's characteristic does not change.  Plastic Weld stinks to high heaven, but I have not found anything stronger for plastic.  Super glue is made for skin (quite literally).  Plastic Weld works as well as superglue on your finger.  I once tried to take apart what was already glued with plastic weld.  The original crack stayed glued, but I broke in another place!

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ABS bodies can be repaired using products such as "plastic weld". As it names sais it will weld two styrene parts together and the bond will be much better than any glue.

You can also dillute some styrene bits (part trees with the PS symbol for example) in acetone and use the resulting paste as a filler.

 

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Thanks didcos I'll look up plastic weld. Sounds like it will do the job.

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58 minutes ago, Terz1 said:

I'll look up plastic weld. Sounds like it will do the job.

Liquid polystyrene cement or "liquid poly" in the UK.

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Plastic weld is available in the Uk. It's better than most of the 'liquid poly' glues IMHO (and you get more for your money).

If that was my shell I would patch the inside of the shell with some 1mm or 1.5mm plasticard / styrene sheet. Brushing some plastic weld into the cracks will help to repair them and stop them spreading. Then make a piece to fill the hole in the shell and glue it in. 

If you run a sharp knife along the edge of some plasticard you can shave of fine strands. Worked into position and soaked with plastic weld they make a good gap filler.

Leave it all to set for 24 hours, make sure everything's solid, smooth it out and the re-drill the body post hole.  

Like I said, this is just what I would do, not criticising anyone else's methods or opinions.

Cheers,

Rob

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Wow. So much great advice. I've got a good idea what to do now. I'll get some supplies and try to bring the body up to scratch. I'll post up some pics of it's progress. Thanks Juggular, Fuijo and IBIFTKH too, didn't get to reply to your posts directly.

I'm on holiday this week so I think it's going to be a Tamiya mess around week. :)

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I'd be inclined to actually plastic weld it - using a dremmel and some ABS plastic rod. 

Basically you put the plastic rod in the chuck of your dremmel, fire it up and gently press it onto the crack. As the friction causes it to heat up and melt you add material into the crack and bond it together. It's the only way I'll repair a crack now as I've never had as much success with solvents.

Give me a shout if you want some help - I'd be happy to assist.

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34 minutes ago, jonboy1 said:

I'd be inclined to actually plastic weld it - using a dremmel and some ABS plastic rod. 

there is a basic howto in the tutorial section off the main page, its pretty easy to do

https://www.tamiyaclub.com/showroom_model.asp?cid=118815&id=35302

 

I'd also add that many styrenes can be glued with acrylic glue. I use it a lot of my PLA 3D prints, soak a little bit and apply.

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37 minutes ago, jonboy1 said:

using a dremmel and some ABS plastic rod

I'm going to have to try this...

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Another method I’ve used is to get some old sprue off cuts and soak them in nail polish remover (acetone), after a few hours it can be moulded like putty to fill any gaps, then once it’s dried (say 24hrs) it can be drilled/ sanded etc as required.

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The dremmel and abs plastic rod seems interesting. Just had a look at the tutorial and that body was pretty beat up and it did a nice job. I'll have to have a go at that. B)

That old sprue in acetone will be useful too. On the front bumper there's a corner cracked and missing so I'll have to build the area then sand to shape. Would the bond the putty has to the original piece be strong enough or would you recommend some reinforcing mesh? I've seen some on ebay. May be a section of styrene could be used as a base?

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7 hours ago, Terz1 said:

The dremmel and abs plastic rod seems interesting. Just had a look at the tutorial and that body was pretty beat up and it did a nice job. I'll have to have a go at that. B)

I would add that to get the best weld, the plastic needs to be clean, ie no paint. I noticed on several tests that it can make the join a little brittle.

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19 hours ago, jonboy1 said:

I'd be inclined to actually plastic weld it - using a dremmel and some ABS plastic rod.  

1

This is fascinating!  I've been building model kits since age 7.  I have never heard of friction-heat-weld.  Well, obviously, not delicate enough for scale kits, but for RC, this could be very useful.  Thank you for spreading the knowledge!  

 

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Ordered the styrene sheet and some plastic weld. I want to save this old shell and get it back to what it was. I will be trying the abs rod in a dremmel technique too.

I've tried to save the decals but some of them split while being removed, I'm thinking of patching them back together the best I can as they are original. I've Also ordered some repro versions to replace any which are too far gone. Now on the look out for a suitable glue which can re-apply the decals which won't react to the paint.

Thanks all for the great advice. B)

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