Just curious, why did you choose those weights on the fabrics?
I use the 1.5 oz matting because its easy to wet out and builds up quickly. I use the 2 oz biaxle fabric so that way I can get a more rigid piece. I realize only two layers will not keep it from flexing, but that is why I’m also reinforcing it with metal tubing.The two layers of biaxle fabric is to help stiffness diagonally across the mold.
What do you think I should have used? I wanted to try woven roving, but didnt think of buying it while I was at my suppliers.
In general, start with a low weight mat all over the tool. (0.5 oz or similar, preferably low-tex, so with fine strands).
Usually done with high-Tg vinylester. Leave this to cure, then add another layer, and leave this to cure as well. Combined with your tooling gelcoat this gives you a surface which will not suffer from higher peak exotherm resins. Usually good up to at least 100C, the boiling point of water.
Then beef up with a tooling resin, with low shrinkage, or preferably no shrinkage at all. This is done mostly with CSM 1.5oz (450 gr/m2). Strength is usually no issue with moulds, but stiffness is. CSM is a product that gives thickness fast.
For the shown product I would recommend a thickness of at least 1/4" or more. Support the mould around the perimeter with a steel frame, which can be laminated to the tool. Another option is to make the steel frame, then apply packing tape, so resin will not stick. Mix a putty, apply to the perimeter of the tool, and press the steel frame in. Tidy up with a mixing stick, add more putty where needed. After cure, remove the steel frame, pry off the tape, degrease, and re-mount the frame bedded in a thick layer of MS polymer bedding compound. (some 1/8" thick). This will prevent distortion. Paint the backside of the tool with topcoat, and the steel frame with rustoleum or similar. (or just paint over it with topcoat).
This will give a high quality tool. The steel frame can optionally support all kind of gadgets (probably not needed for this product) such as top moulds (hinges and locking mechanism), locator jigs, or fit into carts which make working and moving the mould easy.
So you are saying tape up where u want to put the frame, putty the frame in. Then remove the frame, and add it in again permanently? I got a little confused haha. So far what I’ve been doing is ill tape up an area, slather in resin mixed with corona flox, push the frame in, smoothen out the putty seam, AMD fiberglass over that. will that work?
I also will be building a Formica frame around the mold and attaching handles to carry it easy and attach equipment to. 
Attaching anything directly on to a mould surface is asking for printtrough. Only attach permantly on flanges, with glue, laminating, etc. If you need a bit of support on the mould area itself aswell, use MS polymer bedding compound, but I would prefer not to at all, just build a stiff mould.
I would also recommend to build up your mould with a symmetrical layup, to prevent stresses in your mould, wich can loose it’s shape otherwise. So basically mirroring the whole layup, cloths, directions, wheigts, etc.
If you’re not using tooling resin, build up slowly to prevent deformation as much as possible. start with a light layer, double the next in wheigt, end the next, until the thickness is achieved. Let it cure in between layers. Don’t release, attach a stiffening frame, or stringers, or whatever first. The same goes for attaching frames to tooling resin moulds too.
Thanks for all the good info susho
So far what I did today was demoled, trimmed, sanded the edges, and then add reinforcement bars one the flange. The reason I demoled then added the reinforcement is because I was unable to see the edges of the mold and know I had to trim some of the flanged area off.
So farthe mold is coming out very well. It demoled easy from the board. The only problem I had was that the plug came out wit the mold, but what did I expect since I adhered the plug to the flange with joint compound haha. The plug popped out just as easy :).
Overall I am very please with the outcome. I was scared at first since there was no pva over the plug. Just lots of sealer and was. But to those of you who are wondering… The answer is, “yes”. The mold looks ten times nicer with out any pva on the plug.
Looks like I won’t be using pva any more :).
We make our moulds as follows:
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Brush out an epoxy surface coat (no gel-coat) as all of our tools are in epoxy laminating resin.
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First layer is 10oz plain weave glass, we lay it edge to edge around sharp corners etc… so no air gets in behind the surface.
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We follow up again with 2 more layers of 10oz plain weave glass, all wetted via brush
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We put 1/2 inch thick of epoxy dough (sandwich core) on the tool, we pre-mix the dough with the resin to make a slurry and brush that on as a binder first, then pack it with the dough. We roll the dough out on a steel table with a fairly industrial looking rolling pin till we get our thickness and then cut it into squares ranging in size, usually 8 to 12 inch sided sqaures.
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After that, we let the tool “tighten up” a bit and lay our final 3 layers of 10oz tooling cloth.
The mould based on the resins we use can go either up to 150 degree’s F or if we use high-temp laminating resin we can take it to 275 degree’s F. Absolutely no flex what-so-ever with this method…you can beat it with a hammer on the back-side and nothing…very strong tool.
I was thinking based on the fabric weights it may flex under vac, especially if you envelope it…Like Susho mentioned, we try not to add sub-structures to the back side unless required and when we do it is a steel frame on casters. With the tool being as I mentioned above, no worry for print-through.
I tried getting you off PVA a year ago when I was going to mail you that free can of Partall #2… :rolleyes:
Just a tip for the future.
If you put some aluminium angle around the outsite parimeter of your plug/pattern flange before you wax or anything then when you do your lay up of the mould also layup the side of the aluminium angle. This will add a huge amount of stiffness to your mould before you even add any stiffening ribs or frames. This will also define the outside parimeter of your mould so that you can add any stiffeners or frames before demoulding.
Looks like your building a nice mould tho.
With moulds thickness is always a good thing. The thicker the mould the better as it is less likely to twist. Less likely to crack over time and will last a lot longer.
Thank you everybody for all the help and tips :). The next mold we make I’ll do it differently. I’d like all of our molds to be ale to go to at least 250f before distortion but the bad news I that when I ordered tooling gel coat from Florida fiberlglass it came with a very poor HDT. It’s 122f at room temp cure and 205f at 150f cure or something like that. For this part we can cure at less than 100f because we will be using a vinyl ester resin. But in the future, I’d like us to get not using epoxy for the molds. Or at leat use a VE tooling gel coat so we can have a high HDT.
Right now I’m rubbing n and rubbing off the sealer. I’ll be doing three coats of this fifteen min in between. I’ll wait one hour and then apply 10 coats of wax five min in between. I’ll let it sit for the night, and then do three more coats of wax tomorrow. Then ill either layup the mold with the carbon and no gel coat, or wait till my motor for the air compressor mes back. It seized :(.
My only worry about not using a clear gel coat is heat distortion. In the pat I’ve made many parts with out a clear gel coat and they distort when the temp of the part is 100f or more. I have Hydrex 100 and would like to use that, but Hydrex 100 is a VE resin. I’m scared that, that resin will bond to the PE tooling gel coat on the mold? And if not that, how can. Make sure that the resin I infuse with can actually reach its HDT wit out giving off the print through? Yes I will be cler coating, but it never seems to be enough.
I can also use this isophthalic PE tooling resin I have to infuse into the part, but I just don’t want to deal with print through.
I know I know :o. I should have listened before haha. This is way better than using pva. I might have to still use it on a few other molds I have because of the roughness of the cavity. Usually the roughness is there because it was molded off of a plug that had pva on it :notrust:.
Your plug had a real nice gloss finish so I’m anxious to see your mould it should look just as good.
It came out great. It wasn’t as glossy as I wanted it to be, so I sanded the lip with 800 - 1200 and then buffed it with Presta’s cutting cream. I then buffed it it’s swirl mark remover. The cavity of the mod ahead a few tiny imperfections I had to sand, but then I hand buffed and polished the cavity. Right now the mod looks amazing. After I put on a few coats of wax in a hour or two ill snap some pictures.
So we started the day out by demolding our new mold from the plug :). The plug was destroyed, but the mold came out nice and easy :D.
After that I trimmed the edges using a 4" cut off wheel.
1/4th inch thick :D.
Then I added the reinforcement bars.
Then I cleaned off the debris and left over putty that stuck to the mold’s surface. It was easy. I would rest a paint stick on the edge of the putty, then tap it with a hammer. It all popped off.
Then I sanded the entire lip with a palm sander using 600, 800, and 1200 grit paper. After that I sanded off the imperfections inside the mold’s cavity. Once that was complete, I buffed and polished the mold :).
So far I have several coats of chemlease 15 on the mold and a few layers of wax. I did not get a chance to finish waxing it, but I will tomorrow.
Sorry for the mess in the background :P. The past two days we have just been shuffling things around and throwing everything on the floor. We have lots of cleaning to do tomorrow before we begin the next mold. sigh
Nice Moooold!!!
Good luck placing the layers without briging 
Thanks! I dont think ill have any problems ;).
Nicely done John, that’s a nice tool, I always envy seeing a high polish tool, we don’t deviate from epoxy in anything and there is not a surface coat which buffs to that shine in epoxy. The parts and mould always have a dull-ness or matte finish.
I don’t think you should have problems with bridging, although there is a lot of dips and upswings in the part, I think keeping the weave straight will be a bit challenging but you’ll figure it out.
You should be proud, it is a nice mould :cool2:
I have always been told that epoxy is the best gel to use for making molds. I use SmoothOn Epoxycoat Red and it shines pretty well when polished. What other gels are used for making molds? I would be willing to try something besides epoxy if people on here don’t think it will be an issue. I make small carbon fiber parts. Any advise is always appreciated.
Thanks for the compliment guys :). It feels good to hear them :D.
Today we went to Joes Fiberglass Auto Marine in Dania Beach, Florida with our mold to show one of the reps to see if he has any opinions or advise. He turned us to some real good rubbing compounds and polishes to repolish the mold with. I’ll post the brand’s name when I see the bottles. Forgot the name…
Anyways, right now I’m fishing dinner and then I’ll go back to the mold to buff and polish it again. I’ll then have to seal it again and wax it ten more times ha. What ever… It’s all worth it in the end :).
I’ll post more pics later on. Tomorrow I’ll be making the first part out o that mold.