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Mit123
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Group: Forum Members
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Hi,
I have skinned some car parts for my car using the XCR kit.
I have skinned quite alot of parts and have got to the final stage of finishing with 400-1200 grit sandpaper.
I am looking to speed up the process by using a sanding machine with the 400-1200 grit papers.
Which is a good sander to use?
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Hanaldo
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Group: Forum Members
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Any sander, it doesn't really matter. Air is better than electric for this sort of work, but you need a fairly capable compressor. Electric can work too if need be.
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Mit123
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Group: Forum Members
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+xAny sander, it doesn't really matter. Air is better than electric for this sort of work, but you need a fairly capable compressor. Electric can work too if need be. Thank you so much for your response, I have ordered an electric sander/ polisher from Amazon with next day delivery. I will try it out tomorrow, hopefully it will cut down the time needed sanding and help me get the correct finish 😁
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Mit123
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Group: Forum Members
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Visits: 69
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Hi guys,
So I have tried sanding one of my parts.
I used the following grits- 320, 600, 800, 1200, 1500, 2000.
It gave me a decent result, but not up to the standard I was hoping for. The final product is smooth but is slightly dull (not a nice reflective part which looks new) and almost looks like a 2 year old part. When the light hits it from the correct angles, I can see tiny little scuffs on the surface.
I am making the assumption that this effect has been caused by not sanding well enough that all of the scratches caused by the previous grit have been removed. My question is this; how can you really tell if you've sanded the piece well enough using a particular grit; before moving onto the next?
I guess I am going to start from 320 again to try and hopefully I get a better finish this time; but I need to work out the above first.
Also, I've sanded this particular part quite a bit now- trying to improve the imperfections from the surface and I am weary that I may at some point sand too deep and effect the cloth. If I was to drop down to 320 grit and then applying another few layers of resin over the top- would the scratches lower down still be visible or would it be just like starting afresh with the finishing process?
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Warren (Staff)
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Group: Administrators
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Yes it could well be fine scratches from jumping the steps in paper too soon or not keeping the paper and part clean enough thus picking up a coarse bit of grit. I would do the 1500 and 2000 grit by hand and wet so you can clean it easily and help avoid paper clogging. You should then get that fine finish you want. You can then use a polishing compound to take it up to a high gloss finish.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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Hanaldo
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Group: Forum Members
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Yeh there really is a bit of an art to refinishing, it took me 6 years of doing composites professionally to get to a stage where I can polish parts and truly get rid of all scratches and swirls. It takes a lot of practice and patience to get the feel for it, so be prepared for the fact that you may get a few results like this one or it will take you many many hours to get to the standard you are after. It may well be a lot easier to get the part clear coated if this isn't something you are wanting to invest a lot of time in.
It is especially difficult to polish out to a true full gloss starting from 320 grit. As a rule, if I have to go rougher than 800 grit to flat the part down, then I don't even bother trying to polish it out, I'll flat it down with 320 and then hit it with clear to bring the gloss back. From there it certainly shouldn't take rougher than 1200 grit to the the desired surface finish, then I move through 1500>2000>2500>3000>4000. You can compound from 1200 upwards so you can skip the finer stages if you prefer, but be aware it does actually take quite a lot of compounding to get rid of 1200 grit scratches. Significantly quicker and uses less polish to go all the way up to 4000, unless the part is very small.
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Mit123
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Group: Forum Members
Posts: 7,
Visits: 69
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+xYeh there really is a bit of an art to refinishing, it took me 6 years of doing composites professionally to get to a stage where I can polish parts and truly get rid of all scratches and swirls. It takes a lot of practice and patience to get the feel for it, so be prepared for the fact that you may get a few results like this one or it will take you many many hours to get to the standard you are after. It may well be a lot easier to get the part clear coated if this isn't something you are wanting to invest a lot of time in. It is especially difficult to polish out to a true full gloss starting from 320 grit. As a rule, if I have to go rougher than 800 grit to flat the part down, then I don't even bother trying to polish it out, I'll flat it down with 320 and then hit it with clear to bring the gloss back. From there it certainly shouldn't take rougher than 1200 grit to the the desired surface finish, then I move through 1500>2000>2500>3000>4000. You can compound from 1200 upwards so you can skip the finer stages if you prefer, but be aware it does actually take quite a lot of compounding to get rid of 1200 grit scratches. Significantly quicker and uses less polish to go all the way up to 4000, unless the part is very small. Hi, when you refer to using a clear coat are you referring to using a spray can or to re-do the final coat of clear resin? Ive unfortunatley hit all of the parts in the 1st batch with 320 now so may have to go down the route suggested .
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Mit123
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Group: Forum Members
Posts: 7,
Visits: 69
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+x+xYeh there really is a bit of an art to refinishing, it took me 6 years of doing composites professionally to get to a stage where I can polish parts and truly get rid of all scratches and swirls. It takes a lot of practice and patience to get the feel for it, so be prepared for the fact that you may get a few results like this one or it will take you many many hours to get to the standard you are after. It may well be a lot easier to get the part clear coated if this isn't something you are wanting to invest a lot of time in. It is especially difficult to polish out to a true full gloss starting from 320 grit. As a rule, if I have to go rougher than 800 grit to flat the part down, then I don't even bother trying to polish it out, I'll flat it down with 320 and then hit it with clear to bring the gloss back. From there it certainly shouldn't take rougher than 1200 grit to the the desired surface finish, then I move through 1500>2000>2500>3000>4000. You can compound from 1200 upwards so you can skip the finer stages if you prefer, but be aware it does actually take quite a lot of compounding to get rid of 1200 grit scratches. Significantly quicker and uses less polish to go all the way up to 4000, unless the part is very small. Hi, when you refer to using a clear coat are you referring to using a spray can or to re-do the final coat of clear resin? Ive unfortunatley hit all of the parts in the 1st batch with 320 now so may have to go down the route suggested . Also should I sand up to 800-1000 before applying the spray clear, to reduce any scratches from showing through?
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Hanaldo
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Group: Forum Members
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Definitely spray, although I don't use a can. Cans are ok for small parts, but I would still highly recommend getting a 2k clear rather than just a single pack rattle can.
The idea is that spraying allows you to get the coating very flat, you don't need to do any harsh sanding to flat the surface. So while you could apply more coats of resin, this will mean you still have a lot of flatting to do. You can develop the technique to get the coating flat enough that you only need to flat it down with 800 or so, but I just always found it significantly quicker and easier to spray.
As for prep, follow the instructions for your specific clear coat, many of them are different. The ones I use most I spray at 320/400 grit. I have used some that wanted a 600-800 grit surface, and others that wanted 1500, so it depends a lot on the specific coating. If the paint you are using doesn't give you this information, just play it safe and go with 600 grit. Should still give plenty of adhesion and not much risk of scratches showing through.
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