Landracing Forum
Misc Forums => How To Section => Topic started by: tauruck on June 09, 2017, 05:09:38 AM
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I asked Jon if i could start this thread/"helpline".
He agreed. Thanks Boss. I'll give it my all.
Hopefully I can save some of the members some heartache and money.
I'm not #1 in my industry but I learned by trial and error so maybe we can avoid
costly mistakes.
I'm open to questions. Fire away guys. Thank you. :cheers:
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Mike, I am itching to learn.
BR
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Mike, I have a good friend who's about to get into a project where he's going to be drilling right through carbon fibre tubes. Have you any hints on how to get a clean result. The tubes will be roughly 1 1/4" dia. and the holes roughly 3/8". It's important to make the holes as clean as possible. Do you have any hints?
Pete
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Bill, I'll do something tomorrow with pics. :cheers:
Pete, the best is you use a drill bit but it should be dressed.
The standard angle bites into the material and if it's thin it's even worse
so I normally sharpen the bit to a more pointy pencil shape but drill a small pilot hole first.
Slow speed is better with light pressure. The tubes are normally well made and I've never
had a problem using the above.
That should do.
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I have built a few M/C bodies out of fiberglass. All have been made by building a plug by gluing insulation foam sheets together, then rasping, sanding etc. But towards the final shape it needs to be covered with something to make it smooth and to fill gaps, etc. I have used Bondo (hard to sand), plaster of Paris (more difficult to sand), sheetrock mud (never dried and cracks a lot).
What do others use to coat the plug for a final sanding to the right shape?
Don
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Mike:
I am fascinated by the vacuum bag process. Also how do you get the carbine fiber surface to a gloss like I see on some parts.
BR
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http://www.fibreglast.com/ Is a good place to order materials and they have a "Learning Center" that has some very good information.
John
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Those little bits on a Dremel tool can be used to bore a small hole and enlarge it so the sides are nice and smooth.
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Laminate Cutting & Finishing
Traditional cutting tools are generally not effective in finishing composite laminates. They not only can chip or melt the laminate but they often result in rough, unclean edges. Also, because composites do not typically transfer heat, the life of traditional tools is very short when used with composites. Perma-Grit tools are tungsten carbide grit abrasive tools that are renowned for their longevity and their ability to work with composite materials. Whether you are finishing a fiberglass, carbon or Kevlar® laminate, Perma-Grit tools will offer a clean edge and a smooth surface.
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I found this site that has some decent how to's in the How to section.
http://www.fiberglasssupply.com/ (http://www.fiberglasssupply.com/)
BR
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Sorry guys. Been busy working.
Don, the best material to use for finishing is fairing paste.
Available at fiberglass suppliers. You'll love it. Sands so easily.
Any of the fast tools like grinders etc are a no no on composites IMO. You'll
itch so bad and that's probably why people hate composites.
I use a reciprocating saw with an 18T hacksaw blade of good quality to cut
glass and Carbon. Kevlar on the other hand does not cut well once the resin has cured.
Ever tried polishing a sheep?????. :-D I usually leave the Kevlar about 1/2" shy of the
mold edge but if required to be on the edge I cut it with a box cutter just as the resin
goes "green" (not quite cured). Takes a little practice to know when to cut. When it's hard
and not sticky.
Bill, the fancy finish on Carbon is clear coat. Carbon always seems to have pin holes in
the finished product so you need to sand the surface and apply a coat of resin with a brush to fill
them. Resand and apply clear. Never wet sand Carbon!!!!. The pin holes fill with a white paste
and you can throw the part away after that.
I never use gel coat on the parts I make. Gel coat is for molds. I spray MS primer into the mold
after it's had release agent applied so that when you have the final product painted all you do is
wet sand with 1000grit and apply color.
Gel coat is heavy and cracks after time. If you use gel coat on a final product you need to sand it
to get a "key" so you can add primer and then paint.
On release agents I only use the PVA variety. The fancy systems with 5 products that make up
a release agent don't work for me. Tried them all. :evil:
My two favourite weapons. CP saw and palm sander.
If you guys want to do projects but lack experience I suggest Epoxy and woven fabrics over
Polyester. More on that later. :cheers: :cheers:
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I appreciate the guidance, Mike.
Regards, Neil Tucson, AZ
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Seen his work personaly
He is a master at the trade.
Sent from my SM-G925F using Tapatalk
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Mike..I`m building ANOTHER `32 3 window...This one is full fendered w/ a roll pan and bobbed rails,So the fenders need to be sectioned so as not to have long, beagle ear looking tails hanging down, So far I have shortened them up and re-attached the "tails" with metal strap and self tapping screws...Should I join them together from the inside with cloth and then remove the straps, grind the surface down 3-4 inches beyond the seam and join the outside together with more cloth? maybe fill the trough at the seam with random strand?
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Jerry, your process would work but if you had Clecos it would make life easier.
Sand the cut edges back a few inches so you get a mechanical bond.
Put one layer on and when it's just about cured remove the Clecos. After that you can
build up the joint with more material. I'm assuming you're using Polyester resin?.
You have 24 hours working time before you need to sand it again. Yes fill the trough
as described. I don't think you'll need more glass cloth on the outer surface.
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I would respectfully disagree. After doing the inside, taper the outside (grind) and do scarf layups to fill. It will reduce the tendency to crack across the joint. :wink: :cheers:
Wayno
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You are right Wayno. I never read Jerry's question properly.
This is difficult to describe without pics or video.
I was going to say he should sand the two edges to a razor sharp finish (into the Gel Coat).
That's the stuff that will crack. :cheers:
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Indeed..Pics would be a great help...The screws are close to the seam to assist in getting the surfaces flush w/ one another....So the cleco`s would end up bonded to the fender..I used screws so I could grind the points off and even w/ the surface. But I think I am on the right path. Thanks Bro` :cheers:
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I have used aluminum pop rivets and drilled them out after glassing the inside.
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Another ??? for you Mike...Should I re-apply gel coat over the spliced area??
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I said remove the Clecos when the resin goes green (just before initial cure).
That way you save the Clecos and keep them in a jar of thinner or Acetone.
Gel Coat and I are enemies. I was told that gel coat lacked certain chemicals
but those missing compounds were in the resin. Gel Coat only fully cures when
resin is applied to the surface. Could be BS but I'm not a chemist so I don't know.
In saying that I've seen Gel Coat stay tacky when applied to an already cured surface.
There is a coating for what you need but the name escapes me now. I'll check with
my supplier later this morning. I don't work with Polyester resins anymore but if the splice
is a good fit, grind the surface and use a filler you can mix yourself. Buy some Microballoons
from a composite supply store. That works.
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You can spray PVA over the Gel Coat. I beleave that air keeps it from curing.