I admire your work as a modeller and educator dearly thank God that you want to share it with us. Since I have just made female mold myself, although I have encountered major trouble at separating, I have following question. What do you use for separating layer? ONLY wax or other chemicals as well? Also what is the trick for such clean applyin of the tissue? I nearly always experience some number of air bubbles that are ruining later on the final gelcoat surface. Gosh, lack of knowledge is killing me Thank you in advance for some anwers. Keep up the good work, can’t wait to see the 123 esterel on the water
rergards,
lukasz k
Hi,
only paste wax with minimum 7 layers every 40 minutes, shining and apply new layer and wait 30/35 minutes followed by soft shining . I use medical cotton renewed when full of residues. No too much pressure to avoid to remove the applied layer.
Application of tissue is a matter of experience and carefulness. The trick : yes I have one , when you see the third picture of post 59, the tissue is initially applied by hands following the shape from center to the side. Easy with both hands making left and right side at once. Let rest for 5/10 minutes as can be seen in the picture where the tissue is starting to begin impregnation with the previous layer resin. From that point onward, I continue with the brush and resin with continuous hammering movement.
Gelcoat, in my case there are two coats to get good thickness, it may help later if extra polishing is needed and further will be not affected by the imprint of the tissue. The tissue are applyed about 3/4 of hour later as function of temperature. The gelcoat surface shall be tacky. This why I use 105g/m² for the first two layers.
All the layers are then applied sequentially “wet on wet” with previous manual ‘caress’ as mentioned above like making pottery by hand on turning table. Important to start from the centerline and skim softly on the sides. Of course the use of latex glovers is mandatory all the times.
Cheers
ClaudioD
I’m sure Jim will advise the same but as far as I’m aware when working with epoxy all latex gloves will do is stop your hands getting sticky. The nasty components of epoxy can permeate through the latex and for this reason nitrile gloves should be used. I remember some advice from Jim a year or so back and that was to wear the nitrile gloves next to your skin and then wear latex over the top, that way the cheaper latex glove can be discarded without worrying about cost once it’s too sticky to handle the cloth.
Other than that, great work on the female mold & I’ll be keeping my fingers crossed that it separates smoothly.
I was a bit surprised to see you overlay three pieces of glass fiber at every layers instead of one continues strip of tissue. Even, if I am not mistaken, for the first layer. Are you doing this because it is easier to manipulate AND because you are doing a female mold over gelcoat… that allows you to do it?
Yes Sylvain,
it is much easier to manipulate especially light tissues when you are alone. For the mold is not a problem, while for hull lamination inside the mold will be a single piece of tissue, generally of twill type.
The last 280g/m² were in one single piece except the bow that was laminated as an added part of tissue.
Cheers
ClaudioD
Hi Gino,
I do not understand your question !
If you read past posts you will find that the wax layers were 7
And more recently the gelcoat layers were 2
Cheers
ClaudioD
I am guessing he is asking if you are using gelcoat with wax mixed in. Some times people use gelcoat with wax so it creates a boundary layer from the air so it sets properly.
When you are putting layers on top of the gelcoat you do not want gelcoat with wax. The wax will prevent the layers of gelcoat and glass from bonding properly. If you use gelcoat with wax, you would need to strip the wax layer off with chemicals and sandpaper before adding any additional layers of glass or gelcoat on top of it.
Hi,
never heard about this chemistry with epoxy and wax, probably is limited to polyester resin only.
The gelcoat I used is specific for female mold.
The gelcoat for external finish as first layer of a laminated hull is another type of gelcoat. This late is very heavy and not used most of the time for racing models.
That’s all I know !
I tried to cut the residues of tissue, to avoid using heavy tools being Sunday, I start cutting with hand saw with metal blade.
I managed to cut only one side since the blade was wear out and me too !!!.
Meanwhile the Esterel is demolded !
The first pull I got the false deck in the hands while the hull was still inside the mold. With the use of thin glass laminated blades I heard the typical ‘crack’ and the master hull came out easily .
While waiting the 24h polymerization, I drawn the short mast version, the CE is lowered by almost 7cm.
Looks like a fantastic result - will you be bonding any additional reinforcement to the mold?
In terms of the ‘wax’ question, like you I’ve never come across wax additives in epoxy, only polyester resins/gelcoats etc. If memory serves, wax additives are never used in gelcoat applications (fairly obvious really!) and for molding purposes are only really used as the final ‘layer’ when producing a male mold. The final layer is usually in the form of a ‘flow coat’ which prevents air reaching the laminate so that when cured it doesn’t leave a tacky surface and also (if applied thickly enough, particularly with chopped strand mat (csm)) covers up any sharp ‘spikes’ to leave a smooth finished surface. As I say, that lot’s from memory - if I’m wildly way off the mark then hopefully Jim can correct me.
Hi Sylvain,
indeed is very smooth but still with a layers/residues of wax, I need anyhow to wash it and probably to pass some wet sanding paper of 1200/1800 grade to get further better finish and before applying another series of wax coatings as done before non the plug.
The false deck was bonded with loaded epoxy, but the contact surface was just the edge of the 3mm strip. This was of course the weak point but the purpose was mainly to have a flat contour (covered with red adhesive)
The blues marks are the guides to limit the dimensions before cutting with scissors.
Cheers
ClaudioD
Hi Row,
how is it with you back ? This is more important then the rest !
Yes, I never heard about this technique and probably is used to repair the skin of polyester boats when damaged.
This morning I managed to cut away the residues with the rotating machine used by the carpenters to cut tiles. A lost of dust the one that generally irritate the skin !!! I was well protected and I should not worry about. Just before I was spraying a lot of water around to saturate the air and avoid floating particles !
The mold is clean now waiting new physical resources to continue… heheh. entered in the 77th now !
Yes, I will add external wooden supports, but I wait the full polymerization before adding the new external lamination to wood supports and to avoid stresses.
Interesting to see that the Displacement is higher then the one coming from the design drawing.
This is due to the added glass /epoxy tissues onto the wooden plug.
The actual real displacement should be around 3800g since with 3900g the water limit was a bit over the blue mark (1150mm). The water was mixed up with a couple of cm3 of liquid soap from the washing machine, this avoid to get the surface tension meniscus.
Here below the last pictures of this morning:
Back is fairly grim at the moment, but in one respect I disagree with you 100%. As far as I’m concerned ‘Esterel’ is far more important!! Once again, your notes & pictures are providing welcome relief from the tedium of pain…
Moving on, I was surprised to see that you’ve gone with a closed in bow on the female mold. I would’ve thought that with such fine sections in the bow laminating the male hull could prove problematic - specifically right up at the ‘sharp end’ where it may prove to be extremely difficult to achieve satisfactory results ensuring a full bond between layers of cloth & no air bubbles. Perhaps it’s down to the experience and skill of the laminater. I’d certainly appreciate your feedback on that point.
I like the idea of the addition of liquid soap to avoid the meniscus. It got me thinking about my ‘Enterprise’ build and specifically checking the weight & ballast distribution to ensure she floats to her designed waterline. One of our baths is of sufficient length to carry out such a test but I was wondering if you thought there may be a minimum or maximum quantity of soap to get rid of the meniscus?
As far as I can tell from the pictures, the quality of the mold surface looks superb - will it require any further polishing before waxing for the male mold? It’s a pity shipping costs are so high - with the amount of interest in this project you could easily cover your financial outlay by selling molds of the hull … . . . . .
Hi Row,
I feel pity for your back, mine is since 82 that produce pain time to time but I always refused to get a surgical intervention. I cannot stand up for more then 1 hour ! That’s life !! and getting old …
Yes I know it may be difficult to laminate in that way, for the time being I will use the mold as is because I would like to try another solution.
Of course here is not considered a soft bumper for the moment, but I could consider a soft polymer/elastomer as replacement of loaded resin.
…
I have two options :
a - fill the bow with loaded resin while keeping the mold upright. Once sufficiently hard, but still sticky, I will start the tissue lamination in the way as depicted.
b - bring the tissue to the strait mold limits and later turn upright the mold a fill the bow volume with loaded resin
Of course I will made a trial first !
If is not working as expected, then I will go back to the classic method by cutting the bow.
For the liquid soap I used 2 or 3 cm3 out of 3 liters of water.
About the mold surface, I will make additional polishing as already mentioned somewhere by using up to 1200 grade or more.
The 7980TH has the same specs as the 7990 but has a potentiometer instead of the magnetic encoder so it is slightly less expensive. Plus if it is still not strong enough with 180 degrees rotation, it might be possible to play with the pot to get more rotation. I don’t know if it would work, I have not modified servos yet, but Claudio seems to have the experience and would know more.
These 2 servos seem fairly fast. If they are too fast, you can limit the speed with a programmer. I am not sure how much current they draw, I know Claudio wants to try to keep the battery light.
That servo is a good choice for a 180 degree arm winch. However it is a high voltage servo, and works best if given the 7.4 volts eg from a 2S lipo pack. But if you do that, you need to make sure that your rX and rudder servo (and trim servo) can also run on the higher voltage, or you add weight and complexity of a voltage reducer of some kind. For what it costs, I would put out the extra $30 pr so and get an RMG (for this boat the 280EL long travel version).
Contrary to Claudio’s concern, the RMG is not a battery hog. I run for 6 hours intense racing on a 2Slipo of 1350ma. The RMG draws very little at rest, compared to an arm servo which is always humming (and drawing current) at close hauled and close reaching. I find that I go through a battery faster with an arm winch. And the 5v output from the RMG is safe and suitable for a normal Rx and other servos.
thank God that you want to share it with us. Since I have just made female mold myself, although I have encountered major trouble at separating, I have following question. What do you use for separating layer? ONLY wax or other chemicals as well? Also what is the trick for such clean applyin of the tissue? I nearly always experience some number of air bubbles that are ruining later on the final gelcoat surface. Gosh, lack of knowledge is killing me 