Hi
wish you good luck !
IMHO, 3D printing may be a good option to build secondary parts like Hull internal supports were no high surface finish and high precision required.
Warping and geometrical deformations due to machine vibrations may jeopardize dimensional precision when Z axis is getting longer.
Professional printers are very expensive a lot of $$$.
Discussed with Sculpteo manager, min. resin/alumide thickness 1mm generally 2mm and specific weight of 1.2 to 1.35 g/cm3 . PLA/ABS not used. Waiting detailed technical proposal for a Class M 3D printing !
Cheers
Claudio
From the end result on MY current machine I agree about the finish.
That’s why I’m doing this mold appoach. The printer is well calibrated in a sealed enclosure and my dimensional issues are minimal 
Once the part is taken out of the mold I’ll revert back to good old sanding and buffing to get the high gloss finish.
The first haf of the first mold is 1/2 way done. I’m running quite slow on the print speeds to try get a nice uniform wall.
well, it looks like we might be onto something here.
As with most things I do there are some disclaimers here.
My printer and 3d printing skills are a work in progress so the moulds have finishing issues.
However my whole approach was to get decent airfoil profiles on the finished pieces as opposed to perfect finishes. I actually quite enjoy sanding etc. as I sit in a recording studio all day and do nothing tangible - it’s quite relaxing for me.
The history…
I attempted to print a rudder which just melted at the top and then recalled someone hinting at doing a female mould instead (I’m afraid I cant remember who it was - I apologise for that)
So I tried the previous white half mould as a test. It looked promising and Phil 42 on RCgroups said I should try doing a core with cloth on either side.
So I drew up a pretty simple planform rudder in CAD using airfoils and printed the two moulds.
there are small ridges along the sides of the actual planform to act almost like a stamp when I compress the mould together.
As stated, you can see issues with the print but the actual foil shapes came out very well.
I then took some of the packing tray used for meat and cut the very basic planform out, Put it between the mould halves and clamped them together.
Woot woot!!
Phase two was to try put glass on either side.
I am using bog standard resin and chopped strand matt on these tests as its cheap and readily available… those of you who are experienced with resin might see an impending failure coming …
I wetted out the glass, put the core in and it melted immediately on contact with the resin lol.
I thundered on and this was the product in its weird glory - but it points towards a decent outcome.
Attempt two…
3mm balsa rough sanded to fit the mould.
Chop strand matt on either side and clamped.
Here it is in the autoclave…
It went very well IMHO.
After cutting the excess glass off and a quick 100 grit sand (2 minutes max)
I did a spray with red rattle can (I have no painting equipment) to show the the finish. Obvious lines from the mould and some bad pits/holes from my lack-lustre layup. I’ve tried to get the light to show the issues as much as possible.
From here on in I didn’t bother doing any body filling - only fast sanding with 200, 400 and a quick 1200. Total time on the finish was probably 20 minutes of sanding so I can definately get it way better than this but look at the foil!!!
This is after 200 grit to show the bad lines I got from some z-axis issues.
More red
And here it is on the scale, and the foil with calipers.
It seems very strong to me. I put the 675g bulb on the end and it took it so that was good lol.
I’m keen to get CF cloth and epoxy and see how the foam core works now.
I need some help with the layup though.
I currently cut the cloth and put it on a plastic packet.
Put on the resin and scrap as much excess as I can off.
Place in bottom half of the mould.
Put in core.
Wet out the second piece of fabric and place it on top of the core.
Put the top of the mould on and compress.
Should I put the second piece of glass on the top mould and then put it on the core instead?
Thanks 
I forgot to add that I dropped my bulb after I balanced it on the rudder to check strength.
Looks like I’ll be re-casting it :mad:
Round and round and away we go…
3b_printed version… looked good until assembly. Ended up being too finicky to fit my fingers into 
Who knew that hatch design was so bloody important/finicky.
The bonus was that each piece was printed as a complete section with all internals attached to the hull.
The pic with the weight includes the winch and batteries (4x AAA, GWS winch@ 60g and I think the rudder servo is on there - 20g)
nArrow3b_Again is on the cards now. I’m building up the guts to try a print.
I’ve got a very different method in my head that’s been done in CAD and will either be very cool or yet another set-back.
I have also done some hair-brained ideas because I didn’t have the booms I wanted and tried something different. Looks awesome but will probably suck in practice knowing my luck.
Very nice looking printing, Andrew. Keep up the good work, and don’t let any of the naysayers deter you Despite all the people who say it won’t work, Selwyn has been winning with both his RG65 and his IOM…and my Footy fleet is winning, too.
Once you finish this boat, I’ll give you the files for our RG65, and you can get a friend to do some match racing.
Good job…Bill
Sounds like a plan
Revised hull is quite a bit stronger and I’m using somewhat erroneous settings in SLic3r… but 3 of 4 sections are printed (so one less than the previous pictures) and I’ve gone down to a much higher res on the Z-axis.
Hopefully in the next two weeks I’ll be able to do a proper run-down on how it works out and what was a win and a fail. The mainsail boom looks epic but it may cause endless grief with wind… we shall see 