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Old 10-11-2012, 11:52 AM   #151
redprimo
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Originally Posted by Twin-shocker View Post
You dont need to use PVA on moulds after the first couple times you make a part. Once the mould is fully cured, and used a few times, properly applied wax is all thats needed.

In regard to making moulds, filled polyester resin is what most pro GRP shops use for smaller moulds here in the UK, larger ones are generally vinyl ester. If you want to use epoxy no problem, but do bear in mind the cost of the mould will probably double, and you will need powder bound CSM for use with epoxy.

Its really a waste of time trying to make good a mould suffering from fish eyes, as by the time you have sorted these out properly, it would be possible to make 2 moulds using poly resin system, as long as your plug is 100%.

You can easily lay up about 6mm in one go with filled poly systems, which is generally all you would ever be likely to need for making bike parts.

Properly made poly tools last a reasonably long time, and I am still using ones that were made 5 years ago, with only very minor rectification work needed to impact damage caused by rough handling.
I'm not sure what filled poly systems are could you elaborate. It has been almost 20 years since I switched over to epoxy. Before that I worked at a company doing architectural castings in fiberglass reinforced gypsum and fiberglass reinforced cement. Due to the high alkalinity we used a high stryene monomer resin and it was very prone to excessive warpage and distortion issues if we didn't lfollow a lamination schedule that allowed for heat disipation.
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Old 10-11-2012, 12:00 PM   #152
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poly gel is very prone to aligator and blistering if you apply with a brush. even wihen spraying you have to get it pretty even or you can end up with prroblems. This is another reason why I like the epoxy gels for epoxy molds. I used to try and paint it on as thin as I could with a brush. The gel I used was pretty thick in viscosity and this approach would yeild excellent results.
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Old 10-11-2012, 06:40 PM   #153
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Let's do it!!!

Let's get this second mold made!!! You guys have given me some ideas on how to best approach this situation and I greatly appreciate it...

This is me saying thank you!!!


Here is the new 635 thin epoxy system that I am using for this mold from US Composites. Because I'm writing this after having used it today, I'll have to say that I like it so far. It's easy to dispense, easy to mix, lets go of bubbles fairly well, and seems to tack in a reasonable amount of time.

By the way, for those of you who use, or are thinking about using the Polymer Systems epoxy like th MAX CLR HP epoxy, these pumps will fit on their continers as well. The pumps just making dispensing easier. I think they are 6 bucks for the set.


This is after stirring the two parts together. There aren't too many bubbles and the resin is nice and clear.


I didn't have a heat lamp (yet), so I just set the epoxy next to the heater in the shop.


While it was warming, I cut fiberglass.

This is the new 4OZ plain weave fabric that I recently received.




The 2x2 8 ounce twill...


The plain weave feels a lot different then the 2x2 twill fabric that I have been using. My plan was to lay a couple layers of this fabric first followed by three layers of the 2x2.

When the time came to lay the plain weave down, it did not want to conform to the little divits in the clay at all and kept collecting bubbles under it. More about this later...

Two coats of epoxy and no fisheyeing. Yeah!!!! It layed down nice and flat. Looks kindof shiney and weird...

One note about applying the first two layers of epoxy over the plug... After brushing on each layer, I fired up the torch and swept the epoxy with the flame. The bubles came righ out. It worked perfectly and I think that this picture shows it.




The two coats of epoxy had set up nice and tacky and the time had come to lay down some fabric on this thing, so what did I do, well I mixed up some epoxy.

Just as I was about to start brushing it on the plug in prep for the first piece of fabric, the family needed something. I thought, "I'll be right back, so no worries right?" Wrong!!

The epoxy experienced thermal runaway and this is the result; hard as a rock epoxy and a very melted cup. The whole thing was very hot. This all happened in only about 10 minutes.


Moving on...

I mixed another batch of epoxy that I promptly divided into two cups to keep the heat down a little bit. I dont' want anymore surprises.

So I brushed on a layer of epoxy, then applied that 4oz plain weave fabric. I hate the stuff. It was like trying to lay screen door screen on the plug. So what did I do, I decided to pull it off very carefully. This mostly worked, but in a couple of spots the more cured layer of epoxy next to the surface of the plug pulled the PVA a little bit. I culd see that the PVA had wrinkled on the surface. Damn it!! I should have just left it on there...

But you have to move on, so I applied the three layers of 2x2 and a few scraps on the ends for added strength and called it good.




If hadn't pulled the PVA, I know that this mold would have turned out perfect. We'll have to see what we get...

While this was setting up, I headed out to run some errands. Picked up some paint masking materials, quality SS screws for the exhaust shroud, a new spray bottle for acetone, and a heat lamp bulb. The bulb was $9 at Home Depot and it KICKS ASS!! Thanks Earling!!



It got the plug up to 140 degrees F in no time. I dropped it down to about 110 and left it like that for about an hour.

The heat helps the epoxy cure in case anyone was curious. It's not just so the mold feels warm and cozy while it cures.


Let me get a few thoughts down here while I'm thinking about it...

First, sweeping a torch flame over your freshly brushed on epoxy works wonders to remove bubbles from it. I couldn't believe my eyes when I saw how well it worked. You literally see the bubbles popping all over the place. If you are going to try this, make sure that you aren't going to set your resin on fire. Do your homework. But if your resin is safe around a flame then go for it. It's like magic!!

Second, heat lamps are great. They work well for heating your resin, heating your layups, and heating painted parts to help cure paint. They are pretty affordable too so get some...

My last thought. If and when you lay a piece of fabric onto a perfect layer of tacky resin. Don't pull it off if it isn't laying perfectly. Only a stupid person would do this. You don't want to be a stupid person, do you?

OK... I was done with the mold construction and needed something else constructive to do. So I pulled out the fancy masking tape that I had picked up today, and grabbed my trusty mini CF fairing. Like I mentiond before, this thing is like my CF canvas; it's good for all kinds of experimenting...

A little while back I was over at Mike's house showing off my fairing. The thought came to mind to show how strong it is, so I grabbed his hammer and gave it a wack on the nose. Don't wack your carbon fiber stuff with hammers.


I got to sanding on it with 400 grit to get it nice and smooth...


Then I layed down the fine line tape and covered it with masking tape. I traced a cut line over the fine line tape on the masking tape. I cut this line with a razor blade.

I didn't try to center the design at all. I just wanted to get paint on there and see how the tape worked.




I put more masking tape to protect the surrounding area, then applied a coat of paint.

Time for some more heat lamp time. The heat lamp helps cure the paint much more quickly then just letting it sit at room temperature.


After about 5 minutes I pulled the tape. The lines were accetable.


Then it was time for the clear coats. The heat lamp not only helps the clear cure faster, but it seemed to help it lay out a lot smoother as well.

I applied probably 5 or so coats of clear with a heat cure between all coats. It's smooth enough that futher sanding and polishing probably isn't necessary, but I'll probably do it anyway because practice makes perfect, right?


Anyway, that's it for now. It was a good, long day. I'll have to say that I learned a tone of great stuff. I feel much more comfortable using epoxy, and I'm confident that I could lay a perfect mold in the future.

Thanks everyone for tagging along. You guys are great!!

Of course I'll post more when I pop this mold. Everyone, cross your fingers and say a little prayer. Hopefully we'll be making this part in CF soon...
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therivermonster screwed with this post 10-11-2012 at 06:59 PM
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Old 10-11-2012, 07:35 PM   #154
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Very interesting and informative! I look forward to the next installment!

Jim
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Old 10-12-2012, 12:28 AM   #155
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Originally Posted by therivermonster View Post
Let's get this second mold made!!! Y...
Thanks everyone for tagging along. You guys are great!!

Of course I'll post more when I pop this mold. Everyone, cross your fingers and say a little prayer. Hopefully we'll be making this part in CF soon...

I am looking forward to seeing the new piece.
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Old 10-12-2012, 01:15 AM   #156
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Just read this and thanks for sharing, I am in the same position. I recently did a course in composites from amt composites and I am hooked. Went through the same stages as you!
Very usefull info on their web site. Www.amtcomposites.co.za


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Old 10-12-2012, 06:42 AM   #157
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Quote:
Originally Posted by JimVonBaden View Post
Very interesting and informative! I look forward to the next installment!

Jim
Thanks for hangin' out, Jim! Are you thinking about doing something like this?

Quote:
Originally Posted by 100mpg View Post

I am looking forward to seeing the new piece.

Me too!

I popped the mold this morning and the surface looks pretty good I think (PVA still on the surface so it's hard to tell). The mold is a little more flexible then I would have liked. I wanted to blame this flexibility on the new resin, but the mold is missing two layers of 8 oz fabric compared to my last mold. The decision here really can't be made at this time as to which component is the culprit. However, the mini fairing was only 3 layers of CF and it was super stiff, so maybe it is the new epoxy. If it is, I'm not really digging that aspect of its properties...


Quote:
Originally Posted by mtbbker View Post
Just read this and thanks for sharing, I am in the same position. I recently did a course in composites from amt composites and I am hooked. Went through the same stages as you!
Very usefull info on their web site. Www.amtcomposites.co.za


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mtbbker, thanks for posting that link!

I bet the AMT composites course was great. Do you have any tips to offer the thread?

Thanks for hanging out, man!
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Old 10-12-2012, 10:04 AM   #158
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The way you are making moulds means the cost is around 4 times more than it needs to be. You will also find using cloth means that its difficult to make more complicated shapes. Also time taken to make a mould that is around 3 times as thick as the parts you intend to make, will very likely be a 2 stage process, that will take twice as long as using filled polyester and CFM, which can be done in single stage.

http://www.ecfibreglasssupplies.co.u...lingresin.aspx outlines how professionals produce tooling, using filled poly tooling resin

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Old 10-12-2012, 12:44 PM   #159
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The way you are making moulds means the cost is around 4 times more than it needs to be. You will also find using cloth means that its difficult to make more complicated shapes.

I know that poly products are cheaper then epoxy, and I am giving serious thought about trying poly resin with mat FG. It does seem like the mat glass would conform better the the plug.

Also time taken to make a mould that is around 3 times as thick as the parts you intend to make, will very likely be a 2 stage process, that will take twice as long as using filled polyester and CFM, which can be done in single stage.

Do you mean to say that the mold should be three times as thick as the parts that are to be made from it? For example, if the part to be made would be layed up with 2 layers of fabric, then the mold should be made with 6 layers of fabric or mat?

Twin, could you explain why this would be a two stage process if using epoxy and fabric? Heat maybe?


http://www.ecfibreglasssupplies.co.u...lingresin.aspx outlines how professionals produce tooling, using filled poly tooling resin

The videos are great! Thanks for the link!!
Thanks again, Twin!!
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Old 10-13-2012, 07:45 AM   #160
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Mold number 2...

I pulled the second mold off the plug. Looking good...


Now it's time for a little trimming.


Remember, this mold was made from three plys of 8 oz glass fabric. It was supposed to be a total of 5 plys, but the other two didn't work out. The result was that this mold was way too flexable.

It needed to be much more rigid to dependably make any straightish parts, so back onto the plug it went in preperation for 5 more layers of 8 oz fiber glass.


I layed the glass and resin, then headed out for a nice dinner with friends...


This morning I pulled the mold (again) and got to trimming and sanding the edges. after that I washed it with warm water and dish soap.

Here is the mold. This is the one. I'm not making one more mold for the stock exhaust shroud. I'm done with it.

The surface quality of the mold is actually very nice despite me pulling that fabric off the setting epoxy as mentioned earlier in the thread.


You can see the two different applications of fabric in this picture. Now it's nice and strong and ready for some CF.


Mike and I will be laying up the first CF shroud today. I think I'll do the layers like this: layers 1 and 2 CF, layers 3 and 4, 8 oz e glass, layers 5 and 6 CF. This should make the shroud nice and strong.

I'll post the proceedings later today...
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Old 10-13-2012, 08:40 AM   #161
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IMO you should really start using gel-coat or face coat for your molds
a lot can be said for epoxy over PE. At this stage and the parts your building you could save a little $ using polyester for molds. when you need to control movement and shrinkage go epoxy.

When I need to make a high end mold I use a graphite filled face coat and bulk up with tooling resin
For fiberglass body parts I use a lot of Vinyl Ester resin and it also works well with Kevlar.

this is a epoxy mold with filled face coat for a BMW roof



you can get carried away with this stuff if you have $ to spend
this is my bond console for curing pre preg
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Old 10-13-2012, 08:06 PM   #162
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Hey, Skunk!! Thanks for another great post!

I posted a few questions for you regarding your last post...

Quote:
Originally Posted by SkunkWizard View Post
IMO you should really start using gel-coat or face coat for your molds
a lot can be said for epoxy over PE. At this stage and the parts your building you could save a little $ using polyester for molds. when you need to control movement and shrinkage go epoxy.

I am really thinking about going with poly and glass mat for mold making. It really does make sense money wise as well as functionality wise.

When I need to make a high end mold I use a graphite filled face coat and bulk up with tooling resin
For fiberglass body parts I use a lot of Vinyl Ester resin and it also works well with Kevlar.

What is graphite filled face coat, and why would you use it for a high end mold instead of a regular tooling gel coat?

this is a epoxy mold with filled face coat for a BMW roof

Could you explain what a "filled face coat" is, and why it would be used?

you can get carried away with this stuff if you have $ to spend
this is my bond console for curing pre preg

WOW!! Crazy!! How does the bond console help you cure prepreg?
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Old 10-13-2012, 08:28 PM   #163
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Shroud attempt #1...

I made a little stand for the shroud mold. Just a piece of plywood and two little pieces of 2x4.

The first coat of 635 epoxy has been applied to the mold.


I followed up the epoxy coat with 6 pieces of CF and FG with resin between each layer of course.

Now the layup was left to set. The areas on the side of the shroud where the 90 degree bend took place from the side wall over to the flange didn't want to stick very well, but I though that I might have convinced the fabric to stick. We'll see...


I popped the part out of the mold and it was immediately aparent that the fabric had pulled on the top edges. Darn!! Also, the part was super flexable, however it had only been 8 hours since I layed it up. We'll see if it hardens over the next day or so.


I trimmed the extra meterial and did a bit of sanding to smooth things out.


Then I washed the part in the sink to get rid of the PVA and was the dust off.



Here you can see where the fabric pulled away from the mold. Crappy...


I probably should have kept the part in the mold for longer, but I had a pretty good feeling that the part had badly pulled areas.

There are a few ways that I know of that might help this issue:
-letting the first couple coats of resin sit in the mold for a bit before laying the first piece of fabric.
-vacuumm bagging. I'm really interested in this.
-making prepreg fabric before laying up in the mold. I might give this a shot.

If anyone has any tips on how to approach this issue, I'm all ears.

I'll probably try another layup tomorrow, so I'll report back...
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Old 10-14-2012, 03:02 AM   #164
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For a small part like that, compression moulding will work very well indeed. Use male and female moulds, with a gap between a little under how thick you want the finished part to be, and clear poly casting resin.

The moulds you have made up to now though need quite a lot of work, and you would find it much easier to make them using poly gel coat, and filled poly tooling resin.

You also need to spend much more time on making the plugs, and unless you are making a rough skin mould for a part thats going to be painted, these have to be 100% A1 surface finish, which can be achieved through spraying with high build 2K primer, and top coat with 2K, and finally buff to very high shine.

Before going any further with this I would suggest you get your moulds as close to perfect as possible, and then decide whether you are interested in making parts commercially, or if you just want to make a few for your own use.

If you want to do them commercially, then look at vacuum or RTM, and move away from using epoxy systems for anything thats cosmetic only, as this increases costs, and slows down production quite a bit.
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Old 10-14-2012, 04:26 PM   #165
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For a small part like that, compression moulding will work very well indeed. Use male and female moulds, with a gap between a little under how thick you want the finished part to be, and clear poly casting resin.

Twin, are you able to describe how to go about making the male mold for a two part mold as described above? I am interested in this technique.

The moulds you have made up to now though need quite a lot of work, and you would find it much easier to make them using poly gel coat, and filled poly tooling resin.

I am seriously considering using poly products for future molds...

You also need to spend much more time on making the plugs, and unless you are making a rough skin mould for a part thats going to be painted, these have to be 100% A1 surface finish, which can be achieved through spraying with high build 2K primer, and top coat with 2K, and finally buff to very high shine.

Regarding the mold that I made for the shroud; what could have been improved (besides the clay)?

Before going any further with this I would suggest you get your moulds as close to perfect as possible, and then decide whether you are interested in making parts commercially, or if you just want to make a few for your own use.

I only plan on making parts for myself at this time. With the quality that I am producing right now, I couldn't even think of selling any parts... Maybe some day...

If you want to do them commercially, then look at vacuum or RTM, and move away from using epoxy systems for anything thats cosmetic only, as this increases costs, and slows down production quite a bit.

I am very interested in vacuumm bagging especially given the recent problems that I have had with the exhaust shroud mold.

I'll probably seriously look into this option in the very near future.
Thanks again, Twin!!
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