scutter
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| posted on 19/1/05 at 04:52 PM |
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Powder coating prep
Greeting Gents,
Having painting all my suspension parts when i started my build a few years ago , they've chipped quite nicely in the mean time, so
I've decided to get them powder coated.
The question is, What's the best method of masking off all the holes and threads for the process? Will masking tape and screws in the threads
be ok or will it pull up the powder coating when i remove them.
Many thanks in advance.
ATB Dan.
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JAG
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| posted on 19/1/05 at 04:59 PM |
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The place I use do that bit for you before they blast/powder coat.
Check with the company you are using first.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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Hellfire
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| posted on 19/1/05 at 06:40 PM |
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quote:
Originally posted by scutter
Greeting Gents,
Having painting all my suspension parts when i started my build a few years ago, they've chipped quite nicely in the mean time, so
I've decided to get them powder coated.
The question is, What's the best method of masking off all the holes and threads for the process? Will masking tape and screws in the threads
be ok or will it pull up the powder coating when i remove them.
Many thanks in advance.
ATB Dan.
Powder coating requires heat (450 degrees fahrenheit) to melt the plastic granules used. Therefore, using anything with the same or lower temperature
than the granules will result in it/them burning off and the plastic not sticking due to carbon deposits.
Also the item to be coated needs to be as clean and keyed as possible. ie no paint, grease or otherwise.
The square chassis plugs often used to block the rear section of tube melts away when plastic coating unless you remove them.
Good luck!!!
[Edited on 19-1-05 by Hellfire]
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kb58
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| posted on 19/1/05 at 08:50 PM |
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I recently had all parts powdercoated, including the aluminum panels.
The place doing the work takes care of everything. All you do is walk around the car with them, pointing out all the holes and threads you want
masked. They usually prepare the surface by media blasting (which is not sand.)
As far as masking 1000s of rivet holes I just didn't worry about it; drilling them out later. It wasn't difficult.
One more thing to be aware of is all the different types of powder they can use. Make sure they give you a brochure explaining the differences. For
example epoxy powdercoating is amazing stuff, but it has terrible (no) UV resistance. I specified a hybrid-polyester for anything that got hit
directly by the sun, and epoxy for everything else.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Terrapin_racing
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| posted on 21/1/05 at 09:16 AM |
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Totally agree - get advice from your PC firm - let them mask etc.
Make sure you let them know the service of the part - UV effects epoxy etc as mentioned by Kurt.
I did a bit of research first (there are cowboys in every industry!)
http://www.pfonline.com/dp/forums/forum_display.cfm?f_id=17&pub=PF
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JB
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| posted on 23/1/05 at 12:51 PM |
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I put bolts into the threads when I had my chassis powder coated and it was a mistake. They were very difficult to remove (head over size due to the
powder coating and stuck in). Once I had got them out I was left with a ridge of powder coating which had built up around the bolt. I had to remove
this with a die grinder.
In future I would just run a tap down the hole afterwards.
However I had my chassis sand blasted before coating and I was worried about the chassis filling with sand.
JB
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kb58
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| posted on 23/1/05 at 04:15 PM |
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Dang... good point that I forgot to mention. When you get your stuff back, make very sure you run a tap through every thread. The reason is that the
blasting media gets in there, then they plug it, it gets "powdered" then baked. I think something happens to that blasting media in the
holes. I ran a threaded rod end into a non-clean hole, *by hand*, then tried to back it out. It had jammed solid. The force required to remove it
very nearly broke the rod end.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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bigandy
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| posted on 24/1/05 at 09:41 AM |
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When I got my chassis powder coated, I made sure that I drilled all the rivet holes about 0.2-0.3mm over size. then when the powder closes the holes
up, rivets fit in with a slight push. This helps to provide a barrier between teh ally rivet and steel chassis to minimise any disimilar metal
corrosion.
I used a place in Chester, and they took the chassis, blasted it with some kind of media, to remove all the crap/rust then degreased it. The finished
coat is brilliant and smooth, but is still a bit vulnerable to chipping if you are as clumsy as me!
Andy
Dammit! Too many decisions....
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kb58
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| posted on 24/1/05 at 03:30 PM |
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Chipping is a very common problem. I've "tested" my powdercoat, often whacking it accidentally with many things, but it's
never chipped. The only thing I can think of is the chosen powdercoat is by the problem. I used either epoxy or hybrid-polyester and have never had
it chip, even after purposely hitting it with a hammer to see what would happen.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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bigandy
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| posted on 24/1/05 at 03:46 PM |
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perhaps scratching would have been a better word to use. I too have tested the powdercoat with a hammer, and it withstands it quite well. however,
catching it with the edge of piece of aluminium tube results in a few bits of powder flaking off.
The tube was a radiator pipe, about 5 foot long by the way,...
Cheers
Andy
Dammit! Too many decisions....
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Jimbo
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| posted on 26/1/05 at 01:34 PM |
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I was the supervisor of a powder paint plant before I retired, all of the above answers are correct, check what paint ref, UV etc. Also you
can't powder paint over "ordinary" paint, it must be removed first, acid wash, sandblast, take your pick. See what pre-treatment
process they apply before painting, (this helps to "etch" the metal for the paint to bond) ally on the otherhand neds to be either lightly
bead blasted, or emery'ed down before going into the paint spray booth, and must be painted within 3 hours of cleaning the surface, or
it's already started to oxidize, and the paint will subsiquently peel off like wallpaper. Threads are best tapped out afterwards, the paint
contractor will have a number of different sized shaped plugs to block off hole, but it will leave a slight ridge around the hole afterwards.
A good job is down to the preparation.
[Edited on 26/1/05 by Jimbo]
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