Final layer of mold plug?

If the part is that simple I would just have used a laminate - counter top formica etc ... and be done with it. Will give you the perfect finish in 15 min work.

 

I will most likely be polishing by hand, so it's okay to use a paper towel with the compound to polish?

 

Here it is guys- What I need to do is make both sides smooth, but since this is a one sided mold I am going to build up epoxy on the outside and flatten with a plastic sheet..will keep you posted otherwise let me know what you guys think

And thanks again for EVERYONES help in the thread I really learned a lot!! Will post again soon

 

Yea I dont think I will be able to get it smooth enough, need to figure out how to build a mold that will make both sides smooth as glass and not rough because of the weave

I might be able to get by sanding it though. It's a part that will be in the water so I don't want it to be rough on one side

 

So you can lay some peelply on the layup & that will have a fine fabric crosshatch to it- easy sand & shoot with some clear.
Or you can make a matched mold off the mold you already have & layup against both & squeeze up while wet.... using bolts/ strongbacks/ clamps/ atmosphere... you will need some alighnment pins/guides whatever.

Or make the finished item & then create matched molds to both sides of it.
So what is it- surf hand plane?
Jeff.

 

It's actually for a model boat, it's called a turn fin and is mounted on the sponson so the boat hooks the water and can turn. The inside and outside should be smooth because half of it will be under water when running

It needs to be approx 3/32" thick and is mostly flat except for the bottom third is curved. The curved part will be underwater while the boat is running so it needs to be smooth and cause no drag. The front edge is sharpened line a knife.

I need to think of some idea on how to make a two sided mold. I guess I will start with a solid piece but it needs to be over sized because the part is so thin and cannot use a part line, the mold will need to be sandwiched together...hope that makes sense?

 

So you could just be using the part you already made as the other side of the mold..

 

Yea your right that's a good idea, I am going to try that first- just need to cut the rough edges off

 

Very happy with my work so far, I like how I decided to try a small piece to figure out all the proper steps and materials. I tried a bigger piece last year but the mold got screwed up and doesn't really work right.

So the piece came out perfect except for one side being rough and wavy. Good news is that I cut it over sized and will be able to use it as the second piece to the mold very well. I am going to polish both molds up very nice, #10 each, and sandwich some more carbon fiber in between. I think if I get strong enough spreadable claps that will work to hold the piece pieces together...here are some pictures

 

On second thought- I am going to pull a second mold off the first one so I will have two identically shaped and sized pieces, then it will be a real sandwich with the same type of bread. It will be easier to clamp if the pieces are the same size too

 

AHH Turn fins, I have been down that road for 20 years. Carbon only works for very light (about 5 or 6 lbs) under 50 mph RC boats. Above that, 1/8" 6061 t6 to about 12 lbs and 70. Above that 7075 t6 1/8' or Titanium good to about 80 mph and 20 lbs.

The peel ply tip for the rough side will be less than 5 min. sanding with 400 grit wet.
What boat do want to use it on?

 

good info Jim, do you find the carbon fiber bends in the turns? I will be trying it on a 13 lbs outrigger I made that goes about 75mph, right now I have a titanium turn fin on it

 

Yes, it flexes then breaks.

 

Another tip, when you grind the leading edge bevel in put another coat over the grind area to seal the ends of the carbon, mind delaminated from the water Pressure!

Did you end up with1/8" thick?

 

why not use a core made in the shape of the fin and wrap the carbon fiber around it then vac infuse. No chance for delaminating and you get a much stiffer piece.