Paint rash on older diecast models

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karlis
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Re: Paint rash on older diecast models

Post by karlis » Fri Dec 01, 2017 1:54 pm

Recently I ordered a set of polishing bits, I want to try them out with my slow-speed (700 - 2000 rpm) hand drill and Tamiya or similar compounds, I want to decrease the time necessary to deal with paint rash and, hopefully, make the process easier and safer (no need to go for rough grit sandpaper which leaves deep scratches when you can use smoother polishing compound just many more times over).

I already tried out this with cotton swabs, it works but the process is too slow due to minimal contact area and low rpms and the result is the same as with hand. In fact, mathematically I get only 2x the speed of hand sanding. With larger diameter bits, the process should be way faster.

One thing that needs to be watched is temperature. I test this setup on my finger first, if it does not get too hot only then on the model.

I'm waiting for the bits to arrive impatiently. I ordered from 3 different manufacturers.

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[KRAFTIG]
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Re: Paint rash on older diecast models

Post by [KRAFTIG] » Fri Dec 01, 2017 2:31 pm

Be very very careful using these brushes. I assume Dremel tool? Start with the cheapest model first :D

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karlis
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Re: Paint rash on older diecast models

Post by karlis » Fri Dec 01, 2017 5:34 pm

Dremel tool is way too fast. I will begin with my Bosch hand drill (can regulate speed from 0 to 2000 rpm) and only the softest drillbit. Car polishers recommend no faster than 2000 rpm, Dremel is like 10x faster, way too fast.

I just need to get the proof of concept. If indeed machine polishing works well, then we can buy a dedicated and more handy machinery (which can come from nail care industry).

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karlis
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Re: Paint rash on older diecast models

Post by karlis » Mon Dec 04, 2017 9:23 pm

The bits arrived, tried them out today at 1300 rpm and with Tamiya compounds and my hand drill. They somewhat work, but the process is still too slow and much too scary with the huge hand drill. So I ordered this baby.

Image

I believe I will also need:
1) a drill clamp converter to use Dremel buffing bits with beauty industry nail drill
2) if it does not work, I will have to try some liquid micromesh equivalent (aka polishing pastes of specific grit)

If I find a quick way to safely remove paint rash and then get the new-look shine back, this will be worth it.

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Re: Paint rash on older diecast models

Post by [KRAFTIG] » Mon Dec 04, 2017 9:32 pm

Seems like an expensive tool!

Did you consider the Dremel Micro? Cordless and variable speed. I have it, very nice piece.

Image

https://www.dremel.com/en_US/products/-/show-product/tools/8050-micro

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karlis
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Re: Paint rash on older diecast models

Post by karlis » Tue Dec 05, 2017 8:43 am

Yes, I researched Dremels for 2 hours. Slowest Dremel speed setting is 5000 RPM which makes it scary - too easy to burn the paint while nail drill seems to allow really slow speeds. I figure I need around 2000 - 3000 RPM (just guessing, because bosch hand drill provided max 1300 RPM and not 2000 RPM as I previously thought are a bit too slow)

The made in china "expensive tool" cost 39 EUR shipped and due to EU warranty I can send it back within 14 days. Hope it works, it is almost too cheap not to blow up instantly, but girls on Youtube videos demonstrate that it should work and that speed regulation works.

We shall see...

And I really need a broken or beat up model to test this with, yet it has to be of correct brand. Experimenting on full-time collection members is scary...

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Re: Paint rash on older diecast models

Post by [KRAFTIG] » Tue Dec 05, 2017 4:34 pm

Slowest Dremel speed setting is 5000 RPM
That has to be an error, noticed on the website too. My unit goes to zero, though it is not actually off it is pretty darn close. I suggest you look into one.

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karlis
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Re: Paint rash on older diecast models

Post by karlis » Tue Dec 05, 2017 7:20 pm

Older models are said to be slower, but could not find used one. The new ones start at 5000 RPM, I did go through all models and all specs. Spend an hour on various DREMEL official sites. Found one model with foot pedal that goes from 0 RPM, but too expensive and too specific model. Checked also Proxxon models, same there. I believe with some drills the sped can be regulated with a dimmer, but I do not have time for building my own drill.

Anyways let's see how the cheapo solution works out.

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Re: Paint rash on older diecast models

Post by [KRAFTIG] » Tue Dec 05, 2017 7:31 pm

I work with Dremel and other like tool vendors. I'll mention this next time I see the account manager.

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karlis
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Re: Paint rash on older diecast models

Post by karlis » Wed Dec 06, 2017 2:47 pm

Would be cool to find out.

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Re: Paint rash on older diecast models

Post by slightlyevil » Sat Dec 30, 2017 10:20 pm

I've actually found some of my models' windows have started to fog/fade rather than the paint. Some of my favourites too - like the Autoart 1/18NSX and LFA both have this 'haze' on the windows that seems to be in the window not on the surface. I'm not sure what causes it as they haven't been exposed in sunlight at all.

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Re: Paint rash on older diecast models

Post by Atalante » Sun Dec 31, 2017 12:57 am

I’d be interested to see what kind of equipment you come up with for buffing. In my experience this may work very well for light paint rash or finishing. But to remove important paint rash you need to level out the paint and the micro wash wet sanding is the most appropriate solution as you erase the bubbles without wearing (too much) the “healthy” paint. The scratches can always be removed (takes time though) and the rotating polishing tool may be the right answer for the finishing operation.

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karlis
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Re: Paint rash on older diecast models

Post by karlis » Sat Jan 20, 2018 1:53 pm

So at last everything arrived. Here is what I got:

1) Micromesh cloth 4000, 6000, 8000, 12000 and Tamiya polishing compound set (coarse, fine, finish).

2) Variable speed nail polisher. In contrast to Dremel, it sits very comfortably in hand, allows speed adjustment from 0 to 20000 rpm and mine came with a pedal which is useful if you need both hands. The device is really cheap (~50$ shipped) and is most certainly a low quality product from Chine, but it works and is quite handy. Note, while it has rpms, it is no good fro grinding as it is very weak on power (a good thing for avoiding damage - too much pressure and it slows, very good for polishing) Image

3) Soft buffing bits compatible with the above chuck diameter (2.3mm). Now there is a problem with these, they generate a lot of dust at least when new, so I wash them before first use. Image

The process:

Unfortunately the Tamiya compounds are too fine for removing paint rash bubbles, so I either need to find rougher compound or stick to 6000, 8000 micromesh paper for initial removal of larger paint rash bubbles. So, for now, the procedure is not fully automated as the initial steps are done by hand.

A) Wrap the model using cloth, paper and tape as machine polishing produces dust and dirt. Leave only the current work area exposed.

B) Go through following manual Micromesh wet sanding
- Micromesh 6000
- Micromesh 8000
After each step wash the area carefully so the previous polishing cloth / compound crystals are not left.

From my experience you really do not have to grind off the paint rash bubbles completely level with the paint. It is usually enough to smoothen them out to some degree. The final polishing usually smoothens them out further so the bubbles are almost invisible in the end. If they do not, you can always restart the procedure, however if you go too deep than you can run through the bubbles which is irreversible.

C) Machine polish for final shine. I mix a drop of Tamiya compound with a droplet of water and smear that onto model. Then use nail polishing machine with the buffing bit to do polishing using low to medium rpm range.
- Tamya Coarse x 3 iterations
- Tamiya Fine x 3 iterations
- Tamiya Finish x 3 iterations

I will try to perfect the procedure with the time. For now, the machine saves a lot of time in the department of gaining the final shine / gloss.

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Re: Paint rash on older diecast models

Post by [KRAFTIG] » Sat Jan 20, 2018 2:06 pm

Thanks for the info. That machine doesn't look cheap?!?

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Re: Paint rash on older diecast models

Post by Atalante » Sat Jan 20, 2018 8:37 pm

Thanks for all this info. I may get one but I don’t like the fact the polishing generates dust and you need to wrap the models. Is the dust that bad even in slow speed?

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